Border Gateway Protocol (BGP)

The Border Gateway Protocol (BGP) is an exterior, or inter-domain, routing protocol. BGP is used to exchange routing information between multiple transit autonomous systems, between transit and stub autonomous systems, or between two stub autonomous systems.

BGP Details

BGP uses path attributes to provide more information about each route and in particular to maintain an autonomous system (AS) path. An AS path includes the AS number of each autonomous system that the route has transited, which provides information sufficient to prevent routing loops in an arbitrary topology. Path attributes can also be used to distinguish between groups of routes to determine administrative preferences, allowing greater flexibility in determining route preference to achieve a variety of administrative ends. Advanced Routing Suite supports version 4 of the BGP protocol.

BGP supports two basic types of sessions between neighbors: internal (sometimes referred to as IBGP) and external (EBGP). Internal sessions are run between routers in the same autonomous system. External sessions run between routers in different autonomous systems. When a router routes to an external peer, the local AS number is prepended to the AS path. This means that routes received from an external peer are guaranteed to have the AS number of that peer at the start of the path. In general, routes received from an internal neighbor will not have the local AS number prepended to the AS path. Those routes will have the same AS path that the route had when the first internal neighbor received the route from an external peer. Routes with no AS numbers in the path may be legitimately received from internal neighbors. These routes should be considered internal to the receiver's own AS.

External BGP sessions may or may not include a single metric, which BGP calls the Multi-Exit Discriminator (MED) among the path attributes. MED is a 32-bit unsigned integer. Smaller values of the MED are preferred. This metric is used only to break ties between routes with equal preference from the same neighboring AS.

Internal BGP sessions carry at least one metric in the path attributes, which BGP calls the Local_Pref. A route is preferred if its value for this metric is larger. Internal sessions can optionally include a second metric, the MED, carried in from external sessions.

BGP collapses as many routes with similar path attributes as it can into a single update for advertisement. The churn caused by the loss of a neighbor will be minimized, and the initial advertisement sent during peer establishment will be maximally compressed. BGP does not read information from the kernel message by message, but fills the input buffer. BGP processes all complete messages in the buffer before reading again. BGP also does multiple reads to clear all incoming data queued on the socket. This feature may cause other protocols to be blocked for prolonged intervals by a busy peer connection. All unreachable messages are collected into a single message and sent prior to reachable routes during a flash update. Another update is sent once the maximum packet size is reached.

Advanced Routing Suite will determine the immediate next hop to use for a next hop sent in a BGP update by finding the best matching (most specific) route in the routing table that covers the address of the BGP next hop. This allows BGP to support distant BGP peers that might not be directly connected.

BGP allows unconfigured peers to connect if an appropriate group has been configured with a "neighbor allow" command.

Notes:

1. The peer-group command is used to create peer groups that share common attributes.
2. Within the peer-group command, the neighbor commands are used to individually specify peers and to permit overriding specific peering group options.
3. When comparing routes with the same MEDs, BGP first prefers routes learned from external routers (EBGP), followed by confederation external routers, over routes learned from internal routers (IBGP).

BGP Decision Process

BGP uses the following decision process when selecting between multiple routes to the same destination:

1. Prefer the route with the lowest Advanced Routing Suite preference.
2. Prefer the route with the lowest Advanced Routing Suite preference2.
3. Prefer the route with the highest LOCAL_PREF value.
4. Prefer the route with the shortest path, excluding confederation segments.
5. Prefer the route with the "best" ORIGIN: IGP is better than EGP which is better than incomplete.
6. If "bgp always-compare-med" has not been configured, prefer any routes that do not have an inferior MED. Routes are considered to have an inferior MED if two routes to the same destination have been learned with the same neighbor AS, and one of the routes being considered does not have the lowest MED received for routes to that destination from the same neighbor AS. If confed-MED is specified, neighbor AS is considered to be the first AS in the AS_PATH, or the local AS if there are no AS numbers in the AS_PATH. If confed-MED is not specified, neighbor AS is considered to be the first AS in the first non-confed segment of the AS_PATH, or the local confederation-id if there are no AS numbers in a non-confed segment of the AS_PATH.
   
   If "bgp always-compare-med" has been configured, prefer the route with the lowest MED.
7. Prefer the route with the lowest IGP cost to the BGP nexthop. IGP cost is determined by comparing the preference, then the preference 2, then the metric, and finally the metric 2 of the two resolving routes.
8. Prefer routes received from external peers.
9. If "bgp tie-break-on-age" has been specified, prefer the older route.
10. If "bgp bestpath compare-router-id" has been specified, prefer the route learned with the lowest router ID. The router ID is taken from the Open message of the peering session over which the route was received, unless "bgp bestpath compare-originator-id" has been specified, and the route was received with an ORIGIN_ID. In the latter case, the ORIGIN_ID is used instead of the router ID from the Open message.
11. If "bgp bestpath compare-cluster-list-length" has been specified, prefer the route with the lowest CLUSTER_LIST length.
12. Prefer the route with the lowest neighbor address.

Dynamic Capabilities

BGP Dynamic Capabilities allow the communication of a change in a BGP peer’s capabilities without having to restart the peering session.

The BGP implementation is done on a per-peer basis and in such a way that dynamic capabilities are supported as long as the BGP peer supports BGP Dynamic Capabilities. Advanced Routing Suite's BGP advertises Dynamic Capabilities in the OPEN message. If a BGP peer advertises support for BGP Dynamic Capabilities in the OPEN message, then Advanced Routing Suite turns on Dynamic Capabilities. Otherwise, the dynamic capabilities for this peer will be disabled.

The Advanced Routing Suite BGP supports the following BGP Dynamic Capabilities:

• Multi-protocol Capabilities
• Graceful Restart
• Route Refresh

address-family

Name

address-family - configures multi-protocol support for BGP peers

Syntax

address-family [ipv4 (unicast | multicast | vpn)]

no address-family [ipv4 (unicast | multicast | vpn)]

Mode

BGP Router Configuration

Parameters

ipv4 - configures address family mode for either IPv4

unicast | multicast - configures address family mode for unicast

multicast - configures address family mode for either multicast

vpn - configures address family mode for VPN

Description

The address-family command is a mode within a BGP router configuration. It is used to configure multi-protocol support for BGP peers.

Notes

• The vpn keyword is only available if one of these flags is used to build Advanced Routing Suite:
  --enable-vri, --enable-vpn4
--enable-mpbgp_vpn4.

Default

This command is not explicitly configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example will enter address family mode for IPv4 multicast. Notice that the prompt changes to (config-router-af)#.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# address-family ipv4 multicast

(config-router-af)# neighbor 1.2.3.4 activate

Example 2

The following example removes all address-family configuration for IPv4 multicast.

(config)# router bgp 64512

(config-router-bgp)# no address-family ipv4 multicast

(config-router-bgp)# exit

(config)#

bgp always-compare-med

Name

bgp always-compare-med - specifies whether to compare when routes with differing Multi-Exit Discriminators (MEDs) are received from peers in different Autonomous Systems

Syntax

bgp always-compare-med

no bgp always-compare-med

Mode

BGP Router Configuration

Parameters

none

Description

When two routes to the same destination are received from peers in different Autonomous Systems, they can have different MEDs. The bgp always-compare-med command allows you to specify whether to compare those MEDs. When choosing between these routes, assuming that nothing else makes one preferable to the other (such as a configured policy), the values of the differing MEDs are used to choose the route to use. In this comparison, the route with the lowest MED is preferred. Routes without MEDs are treated as having the best possible MED.

Default

If bgp always-compare-med is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no bgp always-compare-med

Command History

NGC 2.2 - This command was introduced.

Examples

The following example enables the comparison of MEDs among confederation paths.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp always-compare-med

(config-router-bgp)# exit

bgp as-path-loops

Name

bgp as-path-loops - specifies the number of times an autonomous system may appear in an AS path

Syntax

bgp as-path-loops loop-count

no bgp as-path-loops loop-count?

Mode

BGP Router Configuration

Parameters

loop-count - an integer in the range 1 to 10, inclusive

Description

The bgp as-path-loops command specifies the number of times this autonomous system can appear in an AS path. loop-count is an integer in the range 1 to 10, inclusive. The negative form of this command, no bgp as-path-loops, removes the configured loop-count value and returns this to its default value of 1.

Notes:

• Specifying a value for loop-count in the no form has no effect on the configuration. Thus, it is displayed above as optional.
• This command should not be used in normal operations.

Default

If bgp as-path-loops is not specified for an autonomous system setting, it is the same as if the user had specified the following:

(config-router-bgp)# bgp as-path-loops 1

Command History

NGC 2.2 - This command was introduced.

Examples

In this example, the router's AS number is set to 7476 and the number of loops is set to 2.

(config)# router bgp 7476

(config-router-bgp)# bgp as-path-loops 2

(config-router-bgp)# exit

bgp bestpath as-path ignore

Name

bgp bestpath as-path ignore - specifies to ignore the AS_PATH length when breaking ties between BGP routes

Syntax

bgp bestpath as-path ignore ignore

no bgp bestpath as-path ignore

Mode

BGP Router Configuration

Parameters

none

Description

Use bgp bestpath as-path ignore when you do not want the AS_PATH length to be considered when breaking ties between BGP routes.

Default

If bgp bestpath as-path ignore is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no bgp bestpath as-path ignore

Command History

NGC 2.2 - This command was introduced.

Examples

In the following example Advanced Routing Suite will ignore the AS_PATH length when breaking ties

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp bestpath as-path ignore

(config-router-bgp)# exit

(config)

bgp bestpath compare-cluster-list-length

Name

bgp bestpath compare-cluster-list-length - enables breaking ties based on shortest cluster list length

Syntax

bgp bestpath compare-cluster-list-length

no bgp bestpath compare-cluster-list-length

Mode

BGP Router Configuration

Parameters

none

Description

Use the bgp bestpath compare-cluster-list-length command to break ties between routes based on shortest cluster list length.

Default

If bgp bestpath compare-cluster-list-length is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no bgp bestpath compare-cluster-list-length

Command History

NGC 2.2 - This command was introduced.

Examples

In the following example Advanced Routing Suite will consider cluster list length when breaking ties and use the route with the lowest length.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp bestpath compare-cluster-list-length

(config-router-bgp)# exit

(config)

bgp bestpath compare-originator-id

Name

bgp bestpath compare-originator-id - specifies to break ties based on lowest Originator ID value

Syntax

bgp bestpath compare-originator-id

no bgp bestpath compare-originator-id

Mode

BGP Router Configuration

Parameters

none

Description

Use the bgp bestpath compare-originator-id command to break ties between routes based the Originator ID value instead of the neighbor’s router ID. When this command is configured, the route with the lowest Originator ID will be preferred over the router ID.

Default

If bgp bestpath compare-originator-id is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no bgp bestpath compare-originator-id

Command History

NGC 2.2 - This command was introduced.

Examples

In the following example Advanced Routing Suite will consider the Originator ID when breaking ties and use the route with the lowest Originator ID.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp bestpath compare-originator-id

(config-router-bgp)# exit

(config)

bgp bestpath compare-router-id

Name

bgp bestpath compare-router-id - specifies whether to ignore router IDs when breaking ties between BGP routes

Syntax

bgp bestpath compare-router-id

no bgp bestpath compare-router-id

Mode

BGP Router Configuration

Parameters

none

Description

By default, router IDs are considered when breaking ties with BGP routes. Use the no bgp bestpath compare-router-id command when you do not want router IDs to be considered when breaking ties between BGP routes.

Default

Router IDs are compared by default. Therefore, if bgp bestpath compare-router-id is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# bgp bestpath compare-router-id

Command History

NGC 2.2 - This command was introduced.

Examples

The following example cause Advanced Routing Suite to ignore router IDs when breaking ties between BGP routes.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# no bgp bestpath compare-router-id

(config-router-bgp)# exit

(config)#

bgp bestpath med confed

Name

bgp bestpath med confed - specifies that confederation segments within a route’s AS_PATH should not be considered when determining the neighboring AS that a route was learned from, during MED comparison

Syntax

bgp bestpath med confed

no bgp bestpath med confed

Mode

BGP Router Configuration

Parameters

none

Description

When comparing MEDs, use bgp bestpath med confed to specify whether confederation segments within a route’s AS_PATH should not be considered when determining the neighboring AS that a route was learned from.

Default

If bgp bestpath med confed is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no bgp bestpath med confed

Command History

NGC 2.2 - This command was introduced.

Examples

The following example enables the comparison of MEDs among confederation paths.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp bestpath med confed

(config-router-bgp)# exit

(config)#

bgp bestpath med missing-as-worst

Name

bgp bestpath med missing-as-worst - specifies whether routes received without a MED are to be considered when comparing BGP routes

Syntax

bgp bestpath med missing-as-worst

no bgp bestpath med missing-as-worst

Mode

BGP Router Configuration

Parameters

none

Description

When breaking ties between BGP routes, use the bgp bestpath med missing-as-worst command to specify whether routes received without a MED are to be considered to have the worst legal MED.

Default

If bgp bestpath med missing-as-worst is not specified, it is the same as if the user had specified the following:
(config-router-bgp)# no bgp bestpath med missing-as-worst

Command History

NGC 2.2 - This command was introduced.

Examples

The following example cause Advanced Routing Suite to consider routes without a MED to have the worst legal MED.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp bestpath med missing-as-worst

(config-router-bgp)# exit

(config)#

bgp cluster-id

Name

bgp cluster-id - specifies the route reflection cluster ID for BGP

Syntax

bgp cluster-id router-id

no bgp cluster-id router-id

Mode

BGP Router Configuration

Parameters

router-id - a router ID in dotted-quad format used by route reflectors to prevent route propagation loops within the cluster

Description

The bgp cluster-id command specifies the route reflection cluster ID for BGP. The cluster ID defaults to be the same as the router ID. If a router is to be a route reflector, then a single cluster ID should be selected and configured on all route reflectors in the cluster. If there is only one route reflector in the cluster, the cluster-id setting can be omitted because the default will suffice.

The only constraints on the choice of cluster ID are the following:

• IDs of clusters within an Autonomous System (AS) must be unique within that AS.
• The cluster ID must not be 0.0.0.0

Default

The cluster ID value defaults to the router ID.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures a cluster ID of 1.2.3.4 for AS 64512.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# bgp cluster-id 1.2.3.4

(config-router-bgp)# exit

(config)#

bgp confederation identifier

Name

bgp confederation identifier - configures the BGP router to be a member of a BGP confederation

Syntax

bgp confederation identifier confed_id

no bgp confederation identifier confed_id

Mode

BGP Router Configuration

Parameters

confed_id - an integer between 1 and 65535, inclusive

Description

A BGP router can be configured to be a member of a BGP confederation where the autonomous system is subdivided into several confederation AS’s. When configured as a confederation member, this router will represent itself as the configured AS number to confederation peers and as the configured confederation identifier to non-confederation peers.

Use the negative form of this command, no bgp confederation identifier, to remove the configured confederation peer identifier.

Default

No BGP confederation identifiers are configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures the BGP router to be a member of BGP confederation 65000.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp confederation identifier 65000

(config-router-bgp)# exit

(config)#

bgp confederation peers

Name

bgp confederation peers - configures a BGP group to be part of a BGP confederation

Syntax

bgp confederation peers as_number {1, n}

no bgp confederation peers as_number {1, n}

Mode

BGP Router Configuration

Parameters

as_number - an autonomous system number of a group of peers that should be designated as confederation peers

{1, n} - When specified, the bgp confederation peers command must include at least one as_number

Description

The bgp confederation peers command configures a BGP group to be part of a BGP confederation. When this command is present, Advanced Routing Suite will treat all members of that group as confederation peers.

Default

Confederation peers are not configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures peers in AS number 65535 and AS number 42 to be confederation peers.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp confederation peers 65535 42

(config-router-bgp)# exit

(config)#

bgp non-leading-confeds

Name

bgp non-leading-confeds - specifies the action to take when malformed AS_PATHs containing non-prefixed confederation segments are received

Syntax

bgp non-leading-confeds [ notify | ignore | drop ]

no bgp non-leading-confeds [ notify | ignore | drop ]?

Mode

BGP Router Configuration

Parameters

notify - specifies that receipt of non-prefixed confederation segments will cause BGP to send a notification message

ignore - specifies that routes containing non-prefixed confederation segments will be logged and ignored

drop - specifies that routes containing non-prefixed confederation segments will be logged and discarded

Description

"Buggy" routers on the Internet will sometimes illegally advertise AS_PATHs containing confederation segments outside of a confederation boundary. If these routes propagate beyond the confederation boundary edge, they will cause the peering session of any router that does not accept confederation segments from non-confederation peers to drop the peering session and thus disrupt service.

drop causes BGP to discard AS_PATHs that are received from BGP peers where there are BGP Confederation AS_PATH segments (AS_CONFED_SEQUENCE, AS_CONFED_SET) occurring anywhere other than at the left-hand side of the AS_PATH.

ignore causes BGP to ignore AS_PATHs that are received from BGP peers where there are BGP Confederation AS_PATH segments (AS_CONFED_SEQUENCE, AS_CONFED_SET) occurring anywhere other than at the left-hand side of the AS_PATH. This option will cause routes containing non-prefixed confederation segments to be logged and stored in the RIB with a preference or distance of -1.

notify causes BGP to send a notification upon receipt of BGP peers where there are BGP Confederation AS_PATH segments (AS_CONFED_SEQUENCE, AS_CONFED_SET) occurring anywhere other than at the left-hand side of the AS_PATH.

The negative form of this command, no bgp non-leading-confeds, removes the user-defined configuration and returns this to its default value of notify. Note: Specifying a parameter for this command in the no form has no effect on the configuration. Thus, it is displayed above as optional.

Default

If bgp non-leading-confeds is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# bgp non-leading-confeds notify

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example causes Advanced Routing Suite to log and ignore non-prefixed confederation segments.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp non-leading-confeds ignore

(config-router-bgp)# exit

(config)#

Example 2

The following example removes the previously configured ignore command and returns this to its default value of notify.

(config)# router bgp 65535

(config-router-bgp)# no bgp non-leading-confeds

(config-router-bgp)# exit

(config)#

bgp open-on-accept

Name

bgp open-on-accept - specifies that Advanced Routing Suite will send the Open message when the TCP connection has completed for configured peers

Syntax

bgp open-on-accept

no bgp open-on-accept

Mode

BGP Router Configuration

Parameters

none

Description

When the bgp open-on-accept command is configured, Advanced Routing Suite will immediately send the Open message when the TCP connection has completed for configured peers.

Default

If bgp open-on-accept is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no bgp open-on-accept

Command History

NGC 2.2 - This command was introduced.

Examples

The following example enables the open-on-accept feature.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp open-on-accept

(config-router-bgp)# exit

(config)#

bgp pass-optional-nontrans

Name

bgp pass-optional-nontrans - specifies whether to propagate unrecognized, optional, non-transitive attributes

Syntax

bgp pass-optional-nontrans

no bgp pass-optional-nontrans

Mode

BGP Router Configuration

Parameters

none

Description

Use the bgp pass-optional-nontrans command to specify whether to propagate unrecognized, optional, non-transitive attributes.

Default

If bgp pass-optional-nontrans is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no bgp pass-optional-nontrans

Command History

NGC 2.2 - This command was introduced.

Examples

The following example enables the pass-optional-nontrans feature.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp pass-optional-nontrans

(config-router-bgp)# exit

(config)#

bgp restart-defer

Name

bgp restart-defer - configures the time to defer route selection after gracefully restarting

Syntax

bgp restart-defer time-seconds

no bgp restart-defer time-seconds?

Mode

BGP Router Configuration

Parameters

time-seconds - time in seconds between 0 and 4,294,967,295, inclusive

Description

Use the bgp restart-defer command to configure the time in seconds to defer route selection after gracefully restarting. This is the maximum time to wait for all peers to come back up and send End-Of-RIB messages. The negative form of this command, no bgp restart-defer, removes the configured time-seconds value and returns this to its default value of 180 seconds. Note: Specifying a value for time-seconds in the no form has no effect on the configuration. Thus, it is displayed above as optional.

Default

If bgp restart-defer is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# bgp restart-defer 180

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures the restart-defer time to be 150 seconds.

(config)# router bgp 2222

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# bgp restart-defer 150

(config-router-bgp)# exit

bgp restart-delete-remnants

Name

bgp restart-delete-remnants - turns on BGP’s deletion of kernel remnant routes

Syntax

bgp restart-delete-remnants

no bgp restart-delete-remnants

Mode

BGP Router Configuration

Parameters

none

Description

The bgp restart-delete-remnants command turns on BGP's deletion of kernel remnant routes when performing a graceful restart after all expected End-of-RIB messages have been received or the restart-defer timer expires. This is used to remove stale routing information that had been retained by the graceful restart procedure.

The negative form of this command, no bgp restart-delete-remnants, turns this feature off. In this case, stale routing information will be retained after a graceful restart until the kernel remnant hold timer expires. (See the command.)

Default

If bgp restart-delete-remnants is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# bgp restart-delete-remnants

Command History

NGC 2.3 - This command was introduced.

Examples

The following example turns off BGP’s deletion of kernel remnant routes.

(config)# router bgp 2222

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# no bgp restart-delete-remnants

(config-router-bgp)# exit

bgp restart-time

Name

bgp restart-time - configures the time advertised within the graceful restart capability when opening a peering session

Syntax

bgp restart-time time-seconds

no bgp restart-time time-seconds?

Mode

BGP Router Configuration

Parameters

time-seconds - the time in seconds between 0 and 4,294,967,295

Description

Use the bgp restart-time command to configure the time advertised within the graceful restart capability when opening a peering session. This is the amount of time it takes to restart within the configured peers. The negative form of this command, no bgp restart-time, removes the configured time-seconds value and returns this to its default value of 180 seconds. Note: Specifying a value for time-seconds in the no form has no effect on the configuration. Thus, it is displayed above as optional.

Default

If bgp restart-time is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# bgp restart-time 180

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures the restart-time to be 150 seconds.

(config)# router bgp 2222

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp restart-time 150

(config-router-bgp)# exit

(config)#

bgp restart-timeout

Name

bgp restart-timeout - configures the time to wait for gracefully restarting peers to come back up

Syntax

bgp restart-timeout time-seconds

no bgp restart-timeout time-seconds?

Mode

BGP Router Configuration

Parameters

time-seconds - the time in seconds between 0 and 4,294,967,295

Description

Use the bgp restart-timeout command to configure the time in seconds to wait for gracefully restarting peers to come back up. This overrides the value that the peer advertised in the graceful start capability. Once this timeout is reached, Advanced Routing Suite will delete all routes learned from the restarting peer. The negative form of this command, no bgp restart-timeout, removes the configured time-seconds value and returns this to its default value of 180 seconds. Note: Specifying a value for time-seconds in the no form has no effect on the configuration. Thus, it is displayed above as optional.

Default

If bgp restart-timeout is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# bgp restart-timeout 180

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures the restart-timeout to be 150 seconds.

(config)# router bgp 2222

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp restart-timeout 150

(config-router-bgp)# exit

bgp router-id

Name

bgp router-id - configures a BGP-specific router ID

Syntax

bgp router-id router_id

no bgp router-id router_id

Mode

BGP Router Configuration

Parameters

router_id - a 32-bit integer in dotted-quad notation to be used as the BGP router ID

Description

Use the bgp router-id command to specify a Router ID value that overrides the globally configured Router ID.

Default

BGP defaults to the globally configured Router ID.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures the BGP Router ID to be 1.2.3.4.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# exit

(config)#

bgp send-group-always

Name

bgp send-group-always - an internal debugging option that causes BGP packets to be sent via the code optimized for sending to multiple peers simultaneously, when it makes sense to do so

Syntax

bgp send-group-always

no bgp send-group-always

Mode

BGP Router Configuration

Parameters

none

Description

bgp send-group-always is an internal debugging option. By specifying this command, BGP packets will be sent via the code optimized for sending to multiple peers simultaneously, when it makes sense to do so. Use the negative form of this command, no bgp send-group-always, to turn this setting off.

Default

If bgp send-group-always is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no bgp send-group-always

Command History

NGC 2.2 - This command was introduced.

Examples

The following example causes BGP packets to be sent via the code optimized for sending to multiple peers simultaneously.

(config)# router bgp 65000

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp send-group-always

(config-router-bgp)# exit

(config)#

bgp tie-break-on-age

Name

bgp tie-break-on-age - specifies that the age of routes should be compared when breaking ties between BGP routes

Syntax

bgp tie-break-on-age

no bgp tie-break-on-age

Mode

BGP Router Configuration

Parameters

none

Description

When breaking ties between BGP routes, bgp tie-break-on-age can be used to specify that the age of the routes should be compared. If this is configured, then older routes are favored over newer routes.

Default

If bgp tie-break-on-age is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no bgp tie-break-on-age

Command History

NGC 2.2 - This command was introduced.

Examples

The following example causes BGP to break ties in favor of older routes.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# bgp tie-break-on-age

(config-router-bgp)# exit

(config)#

clear ip bgp

Name

clear ip bgp - resets BGP peering sessions and sends route refresh requests

Syntax

clear ip bgp [peer | *] [soft]?

Mode

User Execution

Parameters

[peer | *] - specify the IPv4 address of a single BGP peer, or specify "*" to clear all peers

soft - optionally specify to send a Route Refresh message (if supported by the peer)

Description

Use the clear ip bgp command to reset BGP peering sessions or to send a Route Refresh request.

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example specifies to clear the BGP peer 1.2.3.4.

> clear ip bgp 1.2.3.4

Example 2

The following example specifies to clear all BGP peers and send a Route Refresh message.

> clear ip bgp * soft

default-metric

Name

default-metric - causes a BGP MED to be set on routes when they are advertised to peers

Syntax

default-metric metric

no default-metric metric?

Mode

BGP Router Configuration

Parameters

metric - a 32-bit value ranging from 0 to 4,294,967,295, inclusive

Description

The default-metric command causes a BGP MED to be set on routes when they are advertised to peers. This value applies to all BGP peers. It can be overridden on a per-peer or per-group basis. The negative form of this command, no default-metric, removes the configured value. Note: Specifying a value for metric in the no form has no effect on the configuration. Thus, it is displayed above as optional.

Default

The default-metric command is not explicitly configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example causes Advanced Routing Suite to advertise a MED value of 50 to its BGP peers.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# default-metric 50

(config-router-bgp)# exit

(config)#

Example 2

The following example removes the previously configured default-metric value on the router.

(config)# router bgp 65535

(config-router-bgp)# no default-metric 50

(config-router-bgp)# exit

(config)#

distance

Name

distance - specifies the way that active routes learned from BGP will be selected, compared to other protocols

Syntax

distance dist

no distance dist?

Mode

BGP Router Configuration

Parameters

dist - an integer between 0 and 255, inclusive

Description

The distance command specifies how active routes that are learned from BGP will be selected, compared to other protocols. When a route has been learned from more than one protocol, the active route will be selected from the protocol with the lowest distance (or preference).

The negative form of this command, no distance, removes the configured value and returns this to its default value of 170. Note: Specifying a value for dist in the no form has no effect on the configuration. Thus, it is displayed above as optional.

Default

If distance is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# distance 170

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example configures the global BGP distance (preference) to be 140.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# distance 140

(config-router-bgp)# exit

(config)#

Example 2

The following example deletes the globally configured BGP distance (preference) and reverts to the default value of 170.

(config)# router bgp 65535

(config-router-bgp)# no distance 140

(config-router-bgp)# exit

(config)#

distribute-list

Name

distribute-list - provides policy filtering for BGP routes

Syntax

distribute-list access_list_name [ in | out [protocol]? ]

no distribute-list access_list_name [ in |
out [protocol]? ]

Mode

BGP Router Configuration

Parameters

access_list_name - the name of an access list

in | out - specifies whether the route applies to imported (in) or exported (out) routes

protocol - for exported routes (out), optionally specify a redistributed protocol to filter. Valid values include: aggregate, bgp, kernel, ospf, ospf-ase, rip, and static.

Description

The distribute-list command provides a policy filtering mechanism for BGP routes. If the distribute list configured in this command is specified with the in keyword, then the filter will apply to all imported routes (that is to say, routes learned from BGP neighbors). If the distribute list configured in this command is specified with the out keyword, then the filter applies to exported routes (that is to say, routes announced to BGP neighbors).

To delete a configured distribute list, use the negative form of the command. Note: All arguments of the original command must be supplied in order for the entry to be deleted.

distribute-list in

The distribute-list in command configures a BGP import policy (in other words, a policy for BGP to apply to incoming updates). If an inbound distribute-list is configured, then each route received from other BGP neighbors will be evaluated against this inbound list. If the route matches the criteria specified by the inbound list, then the route is imported. If the route does not match the inbound list criteria, then the route is rejected. A route matches the inbound list criteria if it is permitted when evaluated against the referenced access list.

distribute-list out

The distribute-list out command is used to configure export policy for BGP routes. Outbound distribute lists look similar to inbound distribute lists, except that they allow you to optionally specify a protocol, or more correctly, a route source. This allows you to filter exported routes based on whether they were learned from RIP, OSPF, OSPF-ASE or were aggregate, static, or kernel routes. At most one distribute-list out command that does not reference a protocol can be specified. If an outbound distribute list is configured without referencing a protocol, then when a route is being considered for export to BGP neighbors, it must be permitted by the access list referenced in the distribute list. If instead an outbound distribute list is configured that references a protocol, and if the route being considered for export originated from the referenced protocol, then the route must be permitted by the access list referenced in the distribute list. If more of both types of lists are present, then the route need only be permitted by the access list referenced by one of the outbound distribute lists.

It should be noted that an outbound distribute list has no effect in the absence of a "redistribute" command. Outbound distribute lists can be thought of as a way to further refine the export policy expressed with a "redistribute" command.

The negative form of this command, no distribute-list, removes the configured list. You must specify either in or out in the negative form. For outbound distribute lists, specifying a protocol is optional. If the protocol is not specified, then all distribute lists referencing the specified access list will be deleted.

Default

Distribute lists are not configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures two distribute lists. The first distribute list defines import policy using access list "alist1". The second distribute list defines export policy for static routes.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# distribute-list alist1 in

(config-router-bgp)# distribute-list alist2 out static

(config-router-bgp)# exit

(config)#

See Also

"redistribute"

enable

Name

enable - enables BGP

Syntax

enable

no enable

Mode

BGP Router Configuration

Parameters

none

Description

The enable command enables BGP configuration on a router. The negative form of this command, no enable, disables BGP. This command is useful when you want BGP turned "on" on a router, but you want your BGP router configuration details to be turned "off."

Default

If enable is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# enable

Command History

NGC 2.2 - This command was introduced.

Examples

The following example disables BGP on the router. Note that BGP will still be turned "on" on AS 65535, but configuration state will be turned off.

(config)# router bgp 65535

(config-router-bgp)# no enable

(config-router-bgp)# exit

(config)#

maximum-routes

Name

maximum-routes - specifies the maximum number of routes that BGP will accept for installation into the Advanced Routing Suite routing information base (RIB)

Syntax

maximum-routes number

no maximum-routes number?

Mode

BGP Router Configuration

Parameters

number - an integer between 1 and 4,294,967,295, inclusive

Description

The maximum-routes command specifies the maximum number of routes that BGP will accept for installation into the Advanced Routing Suite RIB.

Default

If maximum-routes is not specified, then BGP will accept an unlimited number of routes for installation into the Advanced Routing Suite RIB. The negative form of this command, no maximum-routes, removes the configured value and allows an unlimited number of routes. Note: Specifying a value for number in the no form has no effect on the configuration. Thus, it is displayed above as optional.

Command History

NGC 2.2 - This command was introduced.

Examples

In the following example, Advanced Routing Suite will install a maximum of 50 routes learned from BGP into the routing table.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# maximum-routes 50

(config-router-bgp)# exit

(config)#

neighbor add-communities

Name

neighbor add-communities - adds a community to BGP

Syntax

neighbor ip_address add-communities id

no neighbor ip_address add-communities id

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format.

id - the community set ID to be added

Description

Use the neighbor add-communities command to add a BGP community to this peer. BGP communities are configured with the ip community-set command in Global Configuration mode. The id value corresponds with the ID of the community set.

Default

Community sets are not added or configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example causes the communities described in "comm1" to be sent in BGP updates to peer 1.2.3.4.

(config)# router bgp 60004

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 add-communities comm1

(config-router-bgp)# exit

(config)#

neighbor aggregator-id

Name

neighbor aggregator-id - specifies whether the router-id in the aggregator attribute should be 0

Syntax

neighbor ip_address aggregator-id

no neighbor ip_address aggregator-id

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

Description

When Advanced Routing Suite aggregates a route, the aggregator ID attribute, along with the Router ID are sent. neighbor aggregator-id allows you to specify whether the Router ID in the aggregator attribute should be 0, instead of the ID of the router.

The negative of this command, no neighbor aggregator-id, specifies that the router ID in the aggregator attribute should be the ID of the router.

Default

If neighbor aggregator-id is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address | group-name] aggregator-id

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example causes BGP to set the value of the aggregator ID to 0.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 aggregator-id

(config-router-bgp)# exit

(config)#

Example 2

The following example causes BGP to set the value of the aggregator ID to the router ID.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# no neighbor 1.2.3.4 aggregator-id

(config-router-bgp)# exit

(config)#

neighbor allow

Name

neighbor allow - permits peer connections from addresses in the specified access-list

Syntax

neighbor group-name allow access_list remote-as as-number

no neighbor group-name allow access_list

Mode

BGP Router Configuration

Parameters

group-name - the name of a BGP peer group specified as a string of characters

access_list - the name of the access list from which peer connections will be made

remote-as as_num - the autonomous system (AS) number of a BGP peer. This can be an integer from 1 to 65535, inclusive.

Description

The neighbor allow command permits peer connections from addresses in the specified access list. Access lists are configured with the ip access-list command in Global Configuration mode. The access_list value corresponds with the ID of the access list.

Note: You must specify the remote Autonomous System again in this command, even if it was previously specified in the neighbor command.

Default

The allow command is not explicitly configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example allows incoming peering connections from those peers specified in access-list-1.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor group1 allow access-list-1 remote-as 5

(config-router-bgp)# exit

(config)#

Example 2

The following example will cease allowing incoming peering connections from access_list_1.

(config)# router bgp 65535

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# no neighbor 1.2.3.4 allow
access-list-1 remote-as 5

(config-router-bgp)# exit

(config)#

neighbor as-loop

Name

neighbor as-loop - specifies the number of times an autonomous system may appear in an AS path

Syntax

neighbor [ ip_address | group-name ] as-loop loop-count

no neighbor [ ip_address | group-name ] as-loop
loop-count?

Mode

BGP Router Configuration

Parameters

ip_address - the address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

loop-count - an integer in the range 1 to 10, inclusive

Description

The neighbor as-loop command specifies the number of times this autonomous system can appear in a peer or peer group AS path. loop-count is an integer in the range 1 to 10, inclusive. The negative form of this command, no neighbor as-loop, removes the configured loop-count value and returns this to its default value of 1.

Notes:

• Specifying a value for loop-count in the no form has no effect on the configuration. Thus, it is displayed above as optional.
• This command should not be used in normal operations.

Default

If neighbor as-loop is not specified for an autonomous system setting, it is the same as if the user had specified the following:

(config-router-bgp)# neighbor [ip_address | group-name] as-loop 1

Command History

NGC 2.2 - This command was introduced.

Examples

In this example, the number of loops for peer 1.2.3.4 is set to 2.

(config)# router bgp 7476

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 as-loop 2

(config-router-bgp)# exit

(config)#

neighbor as-override

Name

neighbor as-override - configures all occurrences of a peer’s AS to be replaced with one from an export

Syntax

neighbor [ ip_address | group-name ] as-override

no neighbor [ ip_address | group-name ] as-override

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

The neighbor as-override command specifies that all occurrences of a peer’s AS should be replaced with our address. The negative form of this command, no neighbor as-override, removes this configuration.

Default

If neighbor as-override is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address | group-name] as-override

Command History

NGC 2.2 - This command was introduced.

Examples

The following example turns on the AS Override feature.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 as-override

neighbor aspath-prepend

Name

neighbor aspath-prepend - specifies the number of times that this router will prepend its AS number to a route’s AS Path when it send the route to an external peer

Syntax

neighbor ip_address aspath-prepend num

no neighbor ip_address aspath-prepend num

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

num - an integer between 1 and 25, inclusive

Description

Use the neighbor aspath-prepend command to configure the number of times that this router will prepend its AS number to a route’s AS Path when it sends the route to an external peer. Larger values are typically used to bias upstream peers’ route selection. Most routers will prefer routes with shorter AS Path. Using this command, the AS Path that this router sends can be artificially lengthened.

Default

If neighbor aspath-prepend is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# neighbor [ip_address | group-name] aspath-prepend 1

Note: The BGP protocol specifies you must add your local AS number to the AS_PATH attribute. The aspath-prepend option lets you do it more than once.

Command History

NGC 2.2 - This command was introduced.

Examples

In the following example, the router is configured to prepend its AS number to a route’s AS Path five times.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 10.1.1.1 remote-as 5

(config-router-bgp)# neighbor 10.1.1.1 aspath-prepend 5

(config-router-bgp)# exit

(config)#

neighbor capability orf comm-filter

Name

neighbor capability orf comm-filter - specifies whether the ORF capability for community filtering is to be sent to the BGP peer or group, received from the BGP peer or group, or both

Syntax

neighbor [ip_address | group-name] capability orf
comm-filter [send | receive | both]

no neighbor [ip_address | group-name] capability orf
comm-filter [send | receive | both]

Mode

BGP Router Configuration

Parameters

ip_address - the IPv4 address of a BGP peer specified in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

send | receive | both - specifies the action to take when filtering communities

Description

The neighbor capability orf comm-filter commands specifies whether the ORF capability for community filtering is to be sent from a BGP peer or group, accepted on a BGP peer or group, or both. The negative form of this command, no neighbor capability orf comm-filter, removes the capability.

Default

ORF capabilities are not explicitly configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example specifies that BGP peer 4.3.2.1 will send the ORF capability for community filtering.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 4.3.2.1 remote-as 65001

(config-router-bgp)# neighbor 4.3.2.1 capability orf comm-filter send

neighbor capability orf extcomm-filter

Name

neighbor capability orf extcomm-filter - specifies whether the ORF capability for extended community filtering is to be sent to the BGP peer or group, received from the BGP peer or group, or both

Syntax

neighbor [ip_address | group-name] capability orf
extcomm-filter [send | receive | both]

no neighbor [ip_address | group-name] capability orf
extcomm-filter [send | receive | both]

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

send | receive | both - specifies the action to take when filtering extended communities

Description

The neighbor capability orf extcomm-filter commands specifies whether the ORF capability for extended community filtering is to be sent from a BGP peer or group, accepted on a BGP peer or group, or both. The negative form of this command, no neighbor capability orf extcomm-filter, removes the capability.

Note: When configured in BGP Router Configuration mode, the address family sent will be IPv4 unicast.

Default

ORF capabilities are not explicitly configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example specifies that BGP peer 4.3.2.1 will send the ORF capability for extended community filtering.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 4.3.2.1 remote-as 65001

(config-router-bgp)# neighbor 4.3.2.1 capability orf extcomm-filter send

neighbor capability orf prefix-filter

Name

neighbor capability orf prefix-filter - specifies whether the ORF capability for prefix filtering is to be sent from and/or received on the BGP peer or group

Syntax

neighbor [ip_address | group-name] capability orf
prefix-filter [send | receive | both]

no neighbor [ip_address | group-name] capability orf
prefix-filter [send | receive | both]

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

send | receive | both - specifies the action to take when filtering prefixes

Description

The neighbor capability orf prefix-filter commands specifies whether the ORF capability for prefix filtering is to be sent from a BGP peer or group, accepted on a BGP peer or group, or both. The negative form of this command, no neighbor capability orf prefix-filter, removes the capability.

Default

ORF capabilities are not explicitly configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example specifies that BGP peer 4.3.2.1 will send the ORF capability for prefix filtering.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 4.3.2.1 remote-as 65001

(config-router-bgp)# neighbor 4.3.2.1 capability orf prefix-filter send

neighbor cluster-id

Name

neighbor cluster-id - specifies the route reflection cluster ID for a peer or peer group in BGP

Syntax

neighbor [ip_address | group-name] cluster-id router-id

no neighbor [ip_address | group-name] cluster-id
router-id

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

router-id - a router ID in dotted-quad format used by route reflectors to prevent route propagation loops within the cluster

Description

The neighbor cluster-id command specifies the route reflection cluster ID for a BGP peer or peer group. The cluster ID defaults to be the same as the router ID. If a router is to be a route reflector, then a single cluster ID should be selected and configured on all route reflectors in the cluster. If there is only one route reflector in the cluster, the cluster-id setting can be omitted because the default will suffice.

The only constraints on the choice of cluster ID are the following:

• IDs of clusters within an Autonomous System (AS) must be unique within that AS.
• The cluster ID must not be 0.0.0.0

Choosing the cluster ID to be the router ID of one router in the cluster will always fulfill these criteria. If there is only one route reflector in the cluster, the "cluster ID" setting can be omitted, because the default will suffice.

When a route is received, if it does not have all of the local cluster IDs, then it is accepted. Additionally, when a route is reflected, all of the locally configured cluster IDs that are not already present on the route are prepended to the CLUSTER_LIST.

Notes:

• If configuration results in a change in the set of cluster IDs on the box, then the "clear ip bgp" command is necessary to get the change to effect previous learned routes/announcements.
• You must specify either a remote AS or a peer group before configuring a cluster ID.

Default

The cluster ID value defaults to the router ID.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures a cluster ID of 2.2.2.2 for peer 4.3.2.1.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 4.3.2.1 cluster ID 2.2.2.2

(config-router-bgp)# exit

(config)#

neighbor distance

Name

neighbor distance - specifies the way that active routes learned from BGP will be selected, compared to other protocols, within a BGP peer

Syntax

neighbor [ ip_address | group-name ] distance dist

no neighbor [ ip_address | group-name ] distance dist

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

dist - an integer between 0 and 255, inclusive

Description

The neighbor distance command specifies how active routes within the specified BGP peer that are learned from BGP will be selected, compared to other protocols. When a route has been learned from more than one protocol, the active route will be selected from the protocol with the lowest distance (or preference).

The negative form of this command, no neighbor distance, removes the configured value and returns this to its default value of 170.

Default

If neighbor distance is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# neighbor [ip_address | group-name] distance 170

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures the global BGP distance (or preference) to be 140 and the BGP distance (or preference) for peer 1.2.3.4 to be 80.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# distance 140

(config-router-bgp)# neighbor 1.1.1.1 remote-as 5

(config-router-bgp)# neighbor 1.1.1.1 distance 80

(config-router-bgp)# exit

(config)#

neighbor dynamic

Name

neighbor dynamic - activates the dynamic capability for this peer

Syntax

neighbor [ip_address | group-name] dynamic

no neighbor [ip_address | group-name] dynamic

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

Use the neighbor dynamic to turn on dynamic capabilities for this peer. The negative form of this command, no neighbor dynamic, turns the dynamic capability off for a peer.

Default

If neighbor dynamic is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address | group-name] dynamic

Command History

NGC 2.2 - This command was introduced.

Examples

The following example turns on the dynamic capability feature for 1.2.3.4.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 dynamic

(config-router-bgp)# exit

neighbor enable

Name

neighbor enable - enables a BGP peer or peer group

Syntax

neighbor [ip_address | group-name] enable

no neighbor [ip_address | group-name] enable

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

Use the neighbor enable command to explicitly enable a BGP peer or peer group. Use the negative form of this command, no neighbor enable, to explicitly disable a peering session. Configuration will still be retained.

Default

If neighbor enable is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# neighbor [ip_address | group-name] enable

Command History

NGC 2.2 - This command was introduced.

Examples

The following example disables BGP for peer 1.2.3.4.

(config)# router bgp 65535

(config-router-bgp)# no neighbor 1.2.3.4 enable-peer

(config-router-bgp)# exit

(config)#

neighbor end-of-rib

Name

neighbor end-of-rib - activates the End-of-RIB capability for a peer

Syntax

neighbor [ip_address | group-name] end-of-rib

no neighbor [ip_address | group-name] end-of-rib

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

Use the neighbor end-of-rib command to configure the End of RIB capability for a peer. This is a special form of Graceful Restart that sends End-of-RIB messages, but does not perform graceful restart operations.

Default

If neighbor end-of-rib is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address | group-name] end-of-rib

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures the End-of-RIB option for 1.2.3.4.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 end-of-rib

(config-router-bgp)# exit

neighbor export-localpref

Name

neighbor export-localpref - specifies the Local_Pref value that is sent in the BGP update packet when advertising a route to an internal or confederation peer

Syntax

neighbor [ip_address | group-name] export-localpref
local_pref

no neighbor [ip_address | group-name] export-localpref
local_pref?

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

local_pref - an integer from 0 to 4,294,967,295, inclusive

Description

Use the neighbor export-localpref command to configure the Local_Pref value that is sent in the BGP Update packet when advertising a route to an internal or confederation peer. This value overrides the calculated Local_Pref on the route. BGP will export the route with the calculated Local_Pref value.

The negative form of this command, no neighbor export-localpref, removes the configured local_pref value and returns this to its default value of 100. Note: Specifying a value for local_pref in the no form has no effect on the configuration. Thus, it is displayed above as optional.

Default

If neighbor export-localpref is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# neighbor [ip_address | group-name] export-localpref 100

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures the export Local_Pref value to be 200.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 1.1.1.1 remote-as 5

(config-router-bgp)# neighbor 1.1.1.1 export-localpref 200

(config-router-bgp)# exit

(config)#

neighbor graceful-restart

Name

neighbor graceful-restart - configures the Graceful Restart capability for the family/sub address family pair

Syntax

neighbor [ip_address | group-name] graceful-restart

no neighbor [ip_address | group-name] graceful-restart

Mode

Address Family Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

Use restart to turn on or off the Graceful Restart capability for the family/sub address family pair.

Note: For graceful restart to be useful beyond IPv4 unicast, the corresponding multi-protocol capability must also be in effect.

Default

If neighbor graceful-restart is not specified, it is the same as if the user had specified the following:

(config-router-af)# no neighbor [ip_address | group-name] graceful-restart

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example turns graceful-restart on for IPv4 multicast.

(config)# router bgp 61111

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# address-family ipv4 multicast

(config-router-af)# neighbor 1.2.3.4 graceful-restart

(config-router-af)# exit

(config)#

neighbor ignore-leading-as

Name

neighbor ignore-leading-as - directs Advanced Routing Suite to keep route server routes

Syntax

neighbor [ip_address | group-name] ignore-leading-as

no neighbor [ip_address | group-name] ignore-leading-as

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

Some routers are capable of propagating routes without appending their own autonomous system number to the AS Path. By default, Advanced Routing Suite will drop such routes. The neighbor ignore-leading-as command allows Advanced Routing Suite to keep these routes. This command should be used only if there is no doubt that these peers are route servers and not normal routers.

Default

If neighbor ignore-leading-as is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address | group-name] ignore-leading-as

Command History

NGC 2.2 - This command was introduced.

Examples

The following example enables the ignore-leading-as feature.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 1.1.1.1 remote-as 5

(config-router-bgp)# neighbor 1.1.1.1 ignore-leading-as

(config-router-bgp)# exit

(config)#

neighbor import-localpref

Name

neighbor import-localpref - specifies the Local_Pref value that is received in the BGP Update packet when advertising a route to an external or confederation peer

Syntax

neighbor [ip_address | group-name] import-localpref
local_pref

no neighbor [ip_address | group-name] import-localpref
local_pref?

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

local_pref - an integer from 0 to 4,294,967,295, inclusive

Description

Use the neighbor import-localpref command to configure the Local_Pref value that is sent in the BGP Update packet when advertising a route to an external or confederation peer. This value overrides the calculated Local_Pref on the route. BGP will import the route with the calculated Local_Pref value.

The negative form of this command, no neighbor import-localpref, removes the configured local_pref value and returns this to its default value of 100. Note: Specifying a value for local_pref in the no form has no effect on the configuration. Thus, it is displayed above as optional.

Default

If neighbor import-localpref is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# neighbor [ip_address | group-name] import-localpref 100

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures the import Local_Pref value to be 200.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 1.1.1.1 remote-as 5

(config-router-bgp)# neighbor 1.1.1.1 import-localpref 200

(config-router-bgp)# exit

(config)#

neighbor keep

Name

neighbor keep - specifies the action to take when routes are received containing a router’s own autonomous system (AS) number

Syntax

neighbor [ip_address | group-name] keep [ normal |
all | none ]

no neighbor [ip_address | group-name] keep [ normal |
all | none ]

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

normal - discards routes that contain a router’s own autonomous system number

all - retains routes learned from a peer even if the routes’ AS paths contain the router's own AS number

none - discards routes that have failed import policy

Description

Use neighbor keep to specify whether to keep routes containing a router's own autonomous system number or routes that have failed import policy

normal causes Advanced Routing Suite to discard routes that contain a router's own autonomous system number. Also by default, Advanced Routing Suite will retain routes that have failed import policy so that these routes may be re-examined when import policy is changed during reconfiguration.

all causes Advanced Routing Suite to retain all routes that contain the router's own autonomous system number. In combination with the "loops" command in the autonomous system command, this can allow a healing of a partitioned AS via the Internet.

none causes Advanced Routing Suite to discard all routes that have failed import policy. This can result in a substantial saving in space in the router. In order to re-acquire discarded routes, the "clear ip bgp" command should be issued to either manually flap peering sessions or issue a Route Refresh request (with the "soft" keyword).

Default

If neighbor keep is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# neighbor [ip_address | group-name] keep normal

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example causes Advanced Routing Suite to keep routes learned from this peer even if they container our own AS number.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 keep all

(config-router-bgp)# exit

(config)#

Example 2

The following example causes Advanced Routing Suite to revert to the value of "normal" for keep.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# no neighbor 1.2.3.4. keep all

(config-router-bgp)# exit

(config)#

neighbor keepalives-always

Name

neighbor keepalives-always - causes Advanced Routing Suite to always send keepalives

Syntax

neighbor [ip_address | group-name] keepalives-always

no neighbor [ip_address | group-name] keepalives-always

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

The neighbor keepalives-always command causes Advanced Routing Suite to always send keepalives, even when an update may have correctly substituted for one. This command allows inter-operability with routers that do not completely obey the protocol specifications on this point.

Default

If neighbor keepalives-always is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address |
group-name] keepalives-always

Command History

NGC 2.2 - This command was introduced.

Examples

The following example enables the keepalives-always feature for peer 1.2.3.4.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 keepalives-always

(config-router-bgp)# exit

(config)#

neighbor local-as

Name

neighbor local-as - identifies the autonomous system (AS) that Advanced Routing Suite is representing to a peer

Syntax

neighbor ip_address local-as as_num

no neighbor ip_address local-as as_num

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

as_num - a number between 1 and 65535, specifying a set of routers under a single technical administration and assigned by the Internet Assigned Numbers Authority

Description

The neighbor local-as command identifies the AS that Advanced Routing Suite is representing to a group of peers.

Note: This command is valid only for external peers.

Default

The default AS number for this command is the current AS (configured with the router bgp command in Global Configuration mode).

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example causes BGP to represent itself to the peer 1.2.3.4 as being in AS 100.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 local-as 100

(config-router-bgp)# exit

(config)#

Example 2

The following example causes BGP to cease representing itself to peer 1.2.3.4 as being in AS 100. Instead, it will represent itself as being in AS 64512.

(config)# router bgp 64512

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# no neighbor 1.2.3.4 local-as 100

(config-router-bgp)# exit

(config)#

neighbor log-up-down

Name

neighbor log-up-down - causes a message to be logged via the syslog mechanism whenever a BGP peer or peer group enters or leaves the Established state

Syntax

neighbor [ ip_address | group-name ] log-up-down

no neighbor [ ip_address | group-name ] log-up-down

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

neighbor log-up-down specifies whether a message will be logged via the syslog mechanism whenever a BGP peer or peer group enters or leaves the Established state.

Default

If neighbor log-up-down is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address | group-name] log-up-down

Command History

NGC 2.2 - This command was introduced.

Examples

The following example causes a message to be logged in syslog whenever this peer leaves or enters the Established state.

(config)# bgp router 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 log-up-down

(config-router-bgp)# exit

(config)#

neighbor maximum-routes

Name

neighbor maximum-routes - specifies the maximum number of routes that BGP will accept for installation into the Advanced Routing Suite routing information base (RIB)

Syntax

neighbor [ip_address | group-name] maximum-routes num
[threshold]? [(restart time-minutes) |
(warning-only)]?

no neighbor [ip_address | group-name] maximum-routes num?
[threshold]? [(restart time-minutes) |
(warning-only)]?

Mode

BGP Router Configuration

Parameters

ip_address - the address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

num - an integer between 1 and 4,294,967,295, inclusive

threshold - a percentage

restart time-minutes - an integer from 1 to 65535, inclusive, specifying a number of minutes. This specifies the amount of time that will elapse before a restart occurs.

warning-only - specifies to log a warning message, stop accepting routes, and keep the established peering session

Description

The neighbor maximum-routes command configures the maximum number of routes that a non-group peer or peers in a peer group will accept for installation into Advanced Routing Suite. You can also specify a threshold percentage. When this percentage of maximum routes are accepted, the configured action will occur. In addition, an action can be configured to occur when this maximum number is exceeded. The action can be one of the following:

• If warning-only is specified, log a warning message and stop accepting additional routes, but still keep the established peer session
• if restart is specified, close the peer session and restart after the specified number of minutes
• if neither warning-only nor restart is configured, close the peer session and keep this in idle state until the "clear ip bgp" command is issued

The negative form of this command, no neighbor maximum-routes, removes the configure route limit and returns this setting to its default value of unlimited

Default

If neighbor maximum-routes is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# neighbor [ip_address | group-name]
maximum-routes 4294967295

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example causes Advanced Routing Suite to install a maximum of 1000 routes learned from peer 1.2.3.4 into the routing table. If this amount is exceeded, then the BGP peering session will restart after 10 minutes.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 maximum-routes 1000 restart 10

(config-router-bgp)# exit

(config)#

Example 2

The following example causes Advanced Routing Suite to install a maximum of 1000 routes learned from peer 10.23.12.13 into the routing table. If more than 80% of these routes are installed, then Advanced Routing Suite will close the peering session and keep it down until a clear ip bgp command is specified.

(config)# router bgp 65535

(config-router-bgp)# neighbor 10.23.12.13 remote-as 5

(config-router-bgp)# neighbor 10.23.12.13 maximum-routes 1000 80

(config-router-bgp)# exit

(config)#

Example 3

The following example causes Advanced Routing Suite to install a maximum of 1000 routes learned from peer 4.3.2.1 into the routing table. If this number is exceeded, then Advanced Routing Suite will log a warning message and stop accepting additional routes.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 4.3.2.1 remote-as 5

(config-router-bgp)# neighbor 4.3.2.1 maximum-routes 1000 warning-only

(config-router-bgp)# exit

(config)#

neighbor metric-out

Name

neighbor metric-out - causes BGP to send a metric value when routes are advertised to peers

Syntax

neighbor ip_address metric-out num

no neighbor ip_address metric-out num?

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

num - an integer between 0 and 4,294,967,295, inclusive

Description

The neighbor metric-out command causes a BGP metric (MED) value to be set on routes when they are advertised to peers. The negative form of this command, no neighbor metric-out, removes the configured num value. Note: Specifying a value for num in the no form has no effect on the configuration. Thus, it is displayed above as optional.

Default

If neighbor metric-out is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address | group-name] metric-out

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures a metric value of 50 for routes advertised to peers.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 metric-out 50

(config-router-bgp)# exit

(config)#

neighbor multi-protocol-nexthop

Name

neighbor multi-protocol-nexthop - specifies whether to send a standard BGP nexthop when only sending multi-protocol BGP routes

Syntax

neighbor [ip_address | group-name] multi-protocol-nexthop

no neighbor [ip_address | group-name] multi-protocol-nexthop

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

According to the BGP multi-protocol specification RFC 2858, when a BGP Speaker is only sending multi-protocol routes and is not sending any reachability in the standard BGP NLRI field, it is not necessary to send the standard BGP NEXT_HOP path attribute. Unfortunately, some well-deployed implementations have a bug where this field must be present even if it is ignored.

By default, Advanced Routing Suite will send the standard NEXT_HOP field, even when only multi-protocol routes are being sent. If the reachability is IPv4, the NEXT_HOP field will be the same as the multi-protocol nexthop. In the case of non-IPv4 reachability, the standard NEXT_HOP field will contain "0.0.0.0".

Default

If neighbor multi-protocol-nexthop is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# neighbor [ip_address | group-name]
multi-protocol-nexthop

Command History

NGC 2.2 - This command was introduced.

Examples

In the following example, a standard BGP nexthop will be sent when only sending multi-protocol BGP routes.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 multi-protocol-nexthop

(config-router-bgp)# exit

(config)#

neighbor next-hop-self

Name

neighbor next-hop-self - specifies whether this neighbor’s next hop should be the router's own address on advertisement

Syntax

neighbor [ip_address | group-name] next-hop-self

no neighbor [ip_address | group-name] next-hop-self

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

Use the neighbor next-hop-self command to set this group's next hop to the router's own address even if it would normally be possible to send a third-party next hop. Specifying this command an cause inefficient routes to be followed. It might be needed in some cases to deal with improperly bridged interconnect media (in cases where the routers on the "shared" medium do not really have full connectivity to each other), or when political situations cause broken links.

Default

If neighbor next-hop-self is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address |
group-name] next-hop-self

Command History

NGC 2.2 - This command was introduced.

Examples

The following example specifies that the neighbor will the router’s own address as the next hop.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 10.132.10.15

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 next-hop-self

(config-router-bgp)# exit

(config)#

neighbor orf comm-list

Name

neighbor orf comm-list - sends a communities ORF message with the communities filter to the specified BGP peer

Syntax

neighbor ip_address orf comm-list comm-list-name

no neighbor ip_address orf comm-list comm-list-name

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

comm-list-name - the name of a community list

Description

The neighbor orf comm-list commands sends a communities ORF message with the communities filter specified by the community list name to the specified peer. The negative form of this command, no neighbor orf comm-list, stops the sending of this information.

Note: When configured in BGP Router Configuration mode, the address family sent will be IPv4 unicast.

Default

ORF messages are not sent by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example specifies that BGP peer 4.3.2.1 will send and receive ORF capability for community filtering information. In addition, a communities ORF message with the filter specified by community list comm1 will be sent to peer 4.3.2.1.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 4.3.2.1 remote-as 65001

(config-router-bgp)# neighbor 4.3.2.1 capability orf
comm-filter both

(config-router-bgp)# neighbor 4.3.2.1 orf comm-list comm1

neighbor orf extcomm-list

Name

neighbor orf extcomm-list - sends an extended communities ORF message with the filter specified by the extended community list name to the specified BGP peer

Syntax

neighbor ip_address orf extcomm-list extcomm-list-name

no neighbor ip_address orf extcomm-list extcomm-list-name

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

extcomm-list-name - the name of an extended community list

Description

The neighbor orf extcomm-list commands sends an extended communities ORF message with the filter specified by the extended community list name to the specified peer. The negative form of this command, no neighbor orf extcomm-list, stops the sending of this information.

Note: When configured in BGP Router Configuration mode, the address family sent will be IPv4 unicast.

Default

ORF messages are not sent by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example specifies that BGP peer 4.3.2.1 will send and receive ORF capability for extended community filtering information. In addition, an extended communities ORF message with the filter specified by extended community list extcomm1 will be sent to peer 4.3.2.1.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 4.3.2.1 remote-as 65001

(config-router-bgp)# neighbor 4.3.2.1 capability orf extcomm-filter both

(config-router-bgp)# neighbor 4.3.2.1 orf extcomm-list extcomm1

neighbor orf prefix-list

Name

neighbor orf prefix-list - sends a prefixes ORF message with the filter specified by the prefix list name to the specified BGP peer

Syntax

neighbor ip_address orf prefix-list prefix-list-name

no neighbor ip_address orf prefix-list prefix-list-name

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

prefix-list-name - the name of a prefix list

Description

The neighbor orf prefix-list commands sends a prefixes ORF message with the filter specified by the prefix list name to the specified peer. The negative form of this command, no neighbor orf prefix-list, stops the sending of this information.

Note: When configured in BGP Router Configuration mode, the address family sent will be IPv4 unicast.

Default

ORF messages are not sent by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example specifies that BGP peer 4.3.2.1 will send and receive ORF capability for prefixes filtering information. In addition, a prefixes ORF message with the filter specified by prefix list preflist1 will be sent to peer 4.3.2.1.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 4.3.2.1 remote-as 65001

(config-router-bgp)# neighbor 4.3.2.1 orf capability prefix-filter both

(config-router-bgp)# neighbor 4.3.2.1 orf prefix-list preflist1

neighbor out-delay

Name

neighbor out-delay - specifies the amount of time that a route must be present in the Advanced Routing Suite routing database before it is exported to BGP

Syntax

neighbor ip_address [out-delay time-seconds ]

no neighbor ip_address [out-delay time-seconds ]?

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

out-delay time-seconds - the number of seconds, specified as an integer between 0 and 4,294,967,295, inclusive. This option defaults to 0 and is, thus, displayed above as optional.

Description

Use the neighbor out-delay command to damp route fluctuations. The out-delay time is the amount of time that a route must be present in the Advanced Routing Suite routing database before it is exported to BGP.

Note: Weighted Route Damping may be better suited for improving overall network stability. The use of this option may delay route convergence for well-behaved routers.

Default

This command is not explicitly configured by default; however, if a neighbor address is configured, the out-delay time will default to 0.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example enables an out-delay value of 10 seconds on the neighbor 1.2.3.4

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 out-delay 10

(config-router-bgp)# exit

(config)#

neighbor passive

Name

neighbor passive - prevents Advanced Routing Suite from ever trying to open a BGP connection with peers in this group

Syntax

neighbor [ ip_address | group-name ] passive

no neighbor [ ip_address | group-name ] passive

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

The neighbor passive command prevents Advanced Routing Suite from trying to initiate a BGP connection with peers in this group. Instead, the router will wait for the peer to initiate a connection.

This command was introduced to handle a problem in BGP3 and earlier, in which two peers might both attempt to initiate a connection at the same time. This problem has been correct in the BGP4 protocol, and, thus, this command is not needed with BGP 4 sessions.

Note: If the neighbor passive command is applied to both sides of a peering session, the session will never be established. For this reason, and because it is generally not needed, the use of neighbor passive is discouraged.

Default

If neighbor passive is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address | group-name] passive

Command History

NGC 2.2 - This command was introduced.

Examples

In the following example, BGP will never initiate a connection with the peer.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 passive

(config-router-bgp)# exit

(config)#

neighbor password

Name

neighbor password - configures a TCP-MD5 password for a peer or peer group

Syntax

neighbor [ ip_address ] password key

no neighbor [ ip_address ] password key

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

key - a string of characters

Description

The neighbor password command allows you to set a TCP-MD5 password for a peer or peer group. This feature requires OS support of the TCP MD5 Signature Extension (RFC 2385). Note: You must first configure either a remote AS or a peer group before configuring an authentication password.

Default

A password is not explicitly configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example configures a TCP-MD5 password of "abc" for this peer.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 password abc

(config-router-bgp)# exit

(config)#

Example 2

The following example removes the authentication for peer 1.2.3.4.

(config)# router bgp 65535

(config-router-bgp)# no neighbor 1.2.3.4 password abc

(config-router-bgp)# exit

(config)#

neighbor pedantic

Name

neighbor pedantic - turns on extra, non-critical logging about malformed BGP update messages that are being ignored

Syntax

neighbor [ip_address | group-name] pedantic

no neighbor [ip_address | group-name] pedantic

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

This command turns on extra non-critical logging about malformed BGP updates that are being ignored.

Default

If neighbor pedantic is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address | group-name] pedantic

Command History

NGC 2.2 - This command was introduced.

Examples

The following example turns on pedantic logging for this neighbor.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 pedantic

(config-router-bgp)# exit

neighbor peer-group

Name

neighbor peer-group - creates a BGP peer group

Syntax

neighbor group-name peer-group

no neighbor group-name peer-group

neighbor ip_address peer-group pgname

no neighbor ip_address peer-group pgname

Mode

BGP Router Configuration

Parameters

group-name - a string of characters indicating the name of a BGP peer group

ip_address - an IPv4 address to add to a peer group. IPv4 addresses are specified in dotted-quad format.

pgname - the name of a peer group into which you want the neighbor added. The peer group name is specified using the neighbor name peer-group command, and that command must be specified before neighbors can be added to it.

Description

Use the neighbor peer-group command to create a peer group. BGP peers can then be added to that group. After this command is issued, peers are added to the group using the neighbor ip_address peer-group name command. All peers within a group must have the same AS number.

Note: Once you put a neighbor in a group, it loses all options previously configured on the neighbor, except for its AS number. (See Example 2) Thus, changes to neighbor configuration options should be entered after putting the neighbor in a group.

Default

This command is not explicitly configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example configures peer group "abc". Peers 1.2.3.4 and 4.3.2.1 are then added to this peer group.

(config)# router bgp 7345

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 4.3.2.1 remote-as 5

(config-router-bgp)# neighbor abc peer-group

(config-router-bgp)# neighbor 1.2.3.4 peer group abc

(config-router-bgp)# neighbor 4.3.2.1 peer-group abc

(config-router-bgp)# exit

(config)#

Example 2

The following example configures a peer group called xyz. Peer 10.133.10.23 is configured separately, then a route map named "import" is imported into that peer. The peer is then added to the peer group. The result of adding this neighbor to peer group xyz is that the route-map setting will be lost. This is because once you put a neighbor in a group, it loses all options previously configured on the neighbor except for its AS number.

(config)# router bgp 201

(config-router-bgp)# neighbor xyz peer-group

(config-router-bgp)# neighbor 10.133.10.23 remote-as 201

(config-router-bgp)# neighbor 10.133.10.23 route-map
import in

(config-router-bgp)# neighbor 10.133.10.23 peer-group xyz

(config-router-bgp)# exit

(config)#

neighbor preference2

Name

neighbor preference2 - breaks a preference tie between two groups in a BGP peer

Syntax

neighbor [ip_address | group-name] preference2 pref2

no neighbor [ip_address | group-name] preference2 pref2

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

pref2 - an integer between 0 and 255, inclusive

Description

The neighbor preference2 command breaks a preference tie between groups in a BGP peer. Preferences are the first criteria of comparison for route selection. When a route has been learned from more than one protocol, the active route will be selected from the protocol with the lowest preference.

The negative form of this command, no preference2, removes the configured value and returns this to its default value of 0.

Default

If neighbor preference2 is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# neighbor [ip_address | group-name] preference2 0

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures the global BGP preference2 value to be 20 and the BGP preference2 value for peer 1.2.3.4 to be 10.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# preference2 20

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 preference2 10

(config-router-bgp)# exit

(config)#

neighbor receive-buffer

Name

neighbor receive-buffer - controls the amount of memory requested from the kernel for the receive buffer

Syntax

neighbor [ip_address | group-name] receive-buffer
kbufsize

no neighbor [ip_address | group-name] receive-buffer
kbufsize

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

kbufsize - kernel send-buffer size in bytes, specified as an integer between 4096 and 4,294,967,295, inclusive

Description

The neighbor receive-buffer command controls the amount of memory requested from the kernel for the receive buffer. The maximum supported is 4,294,967,295 bytes; although many kernels have a lower limit. By default, Advanced Routing Suite configures the maximum supported. This command is not necessary on normally functioning systems.

Default

By default, Advanced Routing Suite configures the maximum supported. The maximum supported is 4,294,967,295 bytes; although many kernels have a lower limit.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example limits the receive buffer to 5000 bytes for this peer.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 receive-buffer 5000

(config-router-bgp)# exit

(config)#

neighbor remote-as

Name

neighbor remote-as - configures the remote AS for an IPv4 peer

Syntax

neighbor ip_address remote-as as_num

no neighbor ip_address remote-as as_num

Mode

BGP Router Configuration

Parameters

ip_address - a valid IPv4 address specified in dotted-quad format

remote-as as_num - the autonomous system (AS) number of a BGP peer. This can be an integer from 1 to 65535, inclusive.

Description

The neighbor remote-as command configures the IPv4 address of the host machine. You must specify this command before configuring any other BGP peer commands.

Default

BGP peers are not explicitly configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example configures a BGP peer with an IPv4 address of 1.2.3.4 and an AS number of 5.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# exit

(config)#

neighbor remove-private-as

Name

neighbor remove-private-as - specifies whether to remove private autonomous system (AS) numbers from outbound updates to a peer or peer group

Syntax

neighbor [ip_address | group-name] remove-private-as

no neighbor [ip_address | group-name] remove-private-as

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

Use the neighbor remove-private-as command to remove private AS numbers when sending updates to a peer or peer group.

Default

If neighbor remove-private-as is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address | group-name] remove-private-as

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example causes BGP to strip private AS numbers from updates to this peer.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 remove-private-as

(config-router-bgp)# exit

(config)#

Example 2

The following example causes BGP to no longer remove private AS numbers.

(config)# router bgp 64512

(config-router-bgp)# no neighbor 1.2.3.4 remove-private-as

(config-router-bgp)# exit

(config)#

neighbor route-map

Name

neighbor route-map - specifies a route map for filtering routes to or from a BGP peer

Syntax

neighbor ip_address route-map rm-name [in | out]

no neighbor ip_address route-map rm-name [in | out]

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

rm-name - the name of a configured route map

in | out - specify whether the route map should be applied to routes being learned from (in) or sent to (out) BGP

Description

Route maps are used to control the redistribution of routes between protocols. After configuring a route map, it can then be specified in BGP. Use the neighbor route-map command to specify a configured route map to be exported into or out of BGP.

Default

Route Maps are not explicitly specified by default.

Command History

NGC 2.2 - This command was introduced.

Examples

In the following example, a configured route map named "abc" is specified to be exported into BGP.

(config)# router bgp 4444

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 route-map abc in

(config-router-bgp)# exit

neighbor route-reflector-client

Name

neighbor route-reflector-client - specifies that Advanced Routing Suite will act as a route reflector for this neighbor

Syntax

neighbor [ ip_address | group-name ] route-reflector-
client [meshed]?

no neighbor [ ip_address | group-name ] route-reflector-
client [meshed]?

Mode

BGP Router Configuration

Address Family Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

meshed - optionally specify whether the reflector client is meshed

Description

The neighbor route-reflector-client command specifies that Advanced Routing Suite will act as a route reflector for this group. Configuring the negative of this command specifies that Advanced Routing Suite will not act as an intra-group reflector and thus will not reflect routes back to peers within the same group. This is used when client peers within a route-reflection group are fully meshed.

Default

Route reflector clients are not configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example specifies that the neighbor 1.2.3.4 is to be a route reflector client.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 route-reflector-client

(config-router-bgp)# exit

(config)#

neighbor route-to-peer

Name

neighbor route-to-peer - specifies the actual time to live (TTL) used on a socket in all cases

Syntax

neighbor [ ip_address | group-name ] route-to-peer

no neighbor [ ip_address | group-name ]route-to-peer

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

The neighbor route-to-peer command specifies the actual TTL used on a socket in all cases. In particular, if Advanced Routing Suite realizes that two BGP speakers are peering over a single network, Advanced Routing Suite automatically sets the dontroute option on their peering session. This, in turn, causes the TTL of the packets to be set to 1. The neighbor route-to-peer command prevents the dontroute option from being set. If you specify route-to-peer, but do not specify a TTL, and you are directly connected, then Advanced Routing Suite will set the TTL of your peering session to 1. If you want a TTL greater than 1 for directly connected peers, you must specify both route-to-peer and the ttl_num that you require. Refer to the "neighbor ttl" command.

Default

If neighbor route-to-peer is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor ip_address route-to-peer

Command History

NGC 2.2 - This command was introduced.

Examples

The following example enables the route-to-peer option for this peer.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 route-to-peer

(config-router-bgp)# exit

(config)#

neighbor send-buffer

Name

neighbor send-buffer - controls the amount of send buffering asked of the kernel

Syntax

neighbor [ip_address | group-name] send-buffer kbufsize

no neighbor [ip_address | group-name] send-buffer
kbufsize

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

kbufsize - kernel send-buffer size in bytes, specified as an integer between 4096 and 4,294,967,295, inclusive

Description

The neighbor send-buffer command controls the amount of memory requested from the kernel for the send buffer. The maximum supported is 4,294,967,295 bytes; although many kernels have a lower limit. By default, Advanced Routing Suite configures the maximum supported. This command is not needed on normally functioning systems.

Default

By default, Advanced Routing Suite configures the maximum supported. The maximum supported is 4,294,967,295 bytes; although many kernels have a lower limit.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example limits the send buffer to 5000 bytes for this peer.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 send-buffer 5000

(config-router-bgp)# exit

(config)#

neighbor send-community

Name

neighbor send-community - specifies whether communities are permitted to be sent

Syntax

neighbor ip_address send-community

no neighbor ip_address send-community

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

Description

Use neighbor send-community to specify whether communities are permitted in a peer.

Default

If neighbor send-community is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor ip_address send-community

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example causes Advanced Routing Suite to send any specific community values to peer 1.2.3.4.

(config)# router bgp 60001

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 send-community

(config-router-bgp)# exit

(config)#

Example 2

The following example causes Advanced Routing Suite to not send any communities to this peer.

(config)# router bgp 60001

(config-router-bgp)# no neighbor 1.2.3.4 send-community

(config-router-bgp)# exit

(config)#

neighbor soft-reconfiguration inbound

Name

neighbor soft-reconfiguration inbound - activates the route refresh capability for a peer or peer group

Syntax

neighbor [ip_address | group-name] soft-reconfiguration inbound

no neighbor [ip_address | group-name] soft-reconfiguration inbound

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

Use the neighbor soft-reconfiguration inbound command to activate the route refresh capability for this peer.

Default

If neighbor soft-reconfiguration inbound is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address |
group-name] soft-reconfiguration inbound

Command History

NGC 2.2 - This command was introduced.

Examples

The following example turns on the route refresh capability for peer 1.2.3.4.

(config)# router bgp 60101

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 soft-reconfiguration inbound

(config-router-bgp)# exit

(config)#

neighbor timers

Name

neighbor timers - specifies holdtime and keepalive time values within a BGP peer

Syntax

neighbor [ip_address | group-name] timers
[ keepalive_value holdtime_value ]

no neighbor [ip_address | group-name] timers
[ keepalive_value holdtime_value ]?

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

keepalive_value - the time, in seconds, between keepalive messages with a value range between 0 and 4,294,967,295, inclusive

holdtime_value - the time, in seconds of the BGP Hold Timer with a value of 0 or a value between 3 and 65535, inclusive

Description

The BGP keepalive timer will be set to one-third of the negotiated holdtime by default. Use keepalive to specify the number of seconds that will elapse between keepalive messages.

The holdtime value specifies the number of seconds to use when negotiating a peering session within this group. If Advanced Routing Suite does not receive a keepalive, update, or notification message within the specified period, then the BGP connection will be closed.

The negotiated holdtime value is the lesser of the values sent in the exchanged BGP Open messages. If a time of zero is specified, no keepalives will be sent. If a time of zero is received from the remote peer, then the holdtime must be configured to be zero in order for the peering session to become established.

Note: You cannot specify a holdtime value of 1 or 2. Attempting to do so will result in an error.

The negative form of this command, no neighbor timers, removes the configured values and returns this to its default values of 180 and 60 seconds, respectively. Note: Specifying a value for holdtime and keepalive in the no form of this command has no effect on the configuration. Thus, it is displayed above as optional.

Default

If neighbor timers is not specified, it is the same as if the user had specified the following:
(config-router-bgp)# neighbor [ip_address | group-name] timers 180 60

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures a keepalive value of 40 seconds and a holdtime value of 90 seconds for this peer.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 timers 40 90

(config-router-bgp)# exit

(config)#

neighbor ttl

Name

neighbor ttl - specifies time to live (TTL) value

Syntax

neighbor [ip_address | group-name] ttl ttl_num

no neighbor [ip_address | group-name] ttl ttl_num

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

ttl_num - an integer from 1 to 255 specifying either a number of seconds or a number of hops

Description

The neighbor ttl command is provided mainly for attempting to communicate with improperly functioning routers that ignore packets sent with a TTL value of 1. The ttl_num value has two units: seconds and number of hops. Either of these can be used. Note: Not all kernels allow the TTL to be specified for TCP connections.

Default

By default, Advanced Routing Suite sets the IP TTL for local peers to 1 and the TTL for non-local peers to the default kernel value.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures a TTL value of 5 for this peer.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 ttl 5

(config-router-bgp)# exit

(config)#

neighbor update-source

Name

neighbor update-source - specifies the IP address to be used on the local end of the TCP connection with the peer

Syntax

neighbor [ip_address | group-name] update-source source_addr

no neighbor [ip_address | group-name] update-source source-addr

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

source-addr - the local IP interface address

Description

Use neighbor update-source to specify the IP address to be used on the local end of the TCP connection with the peer. This is the address of a broadcast, NBMA or loopback interface and the local address of a point-to-point interface.

For external peers, the local address must be on an interface that is shared with the peer or with the peer’s gateway when a gateway is used. A session with an external peer will be opened only when an interface with the appropriate local address (through which the peer or gateway address is directly reachable) is operating. For internal peers, a peer session will be maintained when any interface with the specified local address is operating. In any case, an incoming connection will be recognized as a match for a configured peer only if it is addressed to the configured local address.

Default

The default update-source address is the IP address of a shared interface.

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example causes the TCP session to peer 1.2.3.4 to be established over the interface 4.3.2.1.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 update-source 4.3.2.1

(config-router-bgp)# exit

(config)#

Example 2

The following example causes the TCP session to be established over the shared interface.

(config)# router bgp 65535

(config-router-bgp)# no neighbor 1.2.3.4 update-source 4.3.2.1

(config-router-bgp)# exit

(config)#

neighbor use-med

Name

neighbor use-med - specifies whether MEDs will be used in routing computations

Syntax

neighbor [ip_address | group-name] use-med

no neighbor [ip_address | group-name] use-med

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

Description

By default, any MED (Multi_Exit_Disc) received on a BGP connection is ignored. If MEDs are to be used in selecting routes, the use-med option must be specified. When two routes to the same destination are received from different peers within the same peer-as, they could have different MEDs. When choosing between these routes, assuming that nothing else makes one preferable to the other (such as configured policy), the values of the differing MEDs are used to choose which route to use. In this comparison, the route with the lowest MED is preferred. Routes without MEDs are treated as having a MED value of zero unless "bgp bestpath med missing-as-worst" is configured on.

Default

If neighbor use-med is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# no neighbor [ip_address | group-name] use-med

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example causes BGP to pay attention to MED values received from this peer.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 use-med

(config-router-bgp)# exit

(config)#

Example 2

The following example causes BGP to ignore MED values received from this peer.

(config)# router bgp 65535

(config-router-bgp)# no neighbor 1.2.3.4 use-med

(config-router-bgp)# exit

(config)#

neighbor v4-gateway

Name

neighbor v4-gateway - configures an IPv4 intermediate destination by which packets are delivered to their ultimate destination

Syntax

neighbor [ip_address | group-name] v4-gateway gwv4_address

no neighbor [ip_address | group-name] v4-gateway gwv4_address

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

gwv4_address - the IPv4 address of the gateway specified in dotted-quad format

Description

A gateway is an intermediate destination by which packets are delivered to their ultimate destination. This command instructs Advanced Routing Suite to use a form of multi-hop EBGP.

If a network is not shared with this group, then this command specifies a router on an attached network to be used as the next hop router for routes received from this peer.

The gateway can also be used to specify a next hop for groups that are on shared networks. For example, you might use gateway to ensure that third-party next hops are never accepted from a given group by specifying that group’s address as its own gateway. The gateway specified must have consistent routing information to prevent routing loops. In most cases, the gateway is not needed.

Default

The neighbor v4-gateway command is not explicitly configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures address 192.168.1.1 as a gateway address for peer 1.1.1.1.

(config)# router bgp 64512

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# neighbor 1.1.1.1 remote-as 5

(config-router-bgp)# neighbor 1.1.1.1 v4-gateway 192.168.1.1

(config-router-bgp)# exit

(config)#

neighbor version

Name

neighbor version - specifies the BGP version number to use

Syntax

neighbor [ip_address | group-name] version num

Mode

BGP Router Configuration

Parameters

ip_address - the IP address of a BGP peer specified as a valid IPv4 address in dotted-quad format

group-name - the name of a BGP peer group specified as a string of characters. Note: If an invalid IP address is specified (for example 256.1.1.1), it will be read as a group name.

num - the BGP version number. Currently, this can only be 4.

Description

User neighbor version to specify the version of BGP you want to run on a peer group or peer. Because only version 4 is currently supported, there is no negative form of this command available.

Default

If neighbor version is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# neighbor [ip_address | group-name] version 4

Command History

NGC 2.2 - This command was introduced.

Examples

The following example configures BGP version 4 on peer 1.2.3.4.

(config)# router bgp 65534

(config-router-bgp)# bgp router-id 1.1.1.1

(config-router-bgp)# neighbor 1.2.3.4 remote-as 5

(config-router-bgp)# neighbor 1.2.3.4 version 4

(config-router-bgp)# exit

network

Name

network - specifies prefixes to be imported into BGP

Syntax

network (ipv4_address (mask net-mask))[route-map name]? [restrict]?

no network (ipv4_address (mask net-mask))[route-map name]? [restrict]?

Mode

BGP Router Configuration

Address Family Mode

Parameters

ipv4_address (mask net-mask) - specify an IPv4 address with an optional mask value. The ipv4_address and net-mask values are specified in dotted-quad format

route-map name - optionally specify a route map to apply policy to the prefix

restrict - optionally specify that the matching network range should not be advertised to other peers

Description

The network command is used to specify prefixes that should be imported into BGP. The negative form of this command removes configured network prefixes.

Note: Some competitors set the BGP ORIGIN attribute differently on routes configured via the static statement (origin incomplete) than via the BGP network statement (origin IGP). Advanced Routing Suite always sets origin incomplete. Use the Route Map command to modify the origin.

Default

Network prefixes are not configured by default.

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example imports the network 10.1.0.0 with a mask of 255.255.255.0 into BGP. Additionally, this network range will be advertised to other peers.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# network 10.1.0.0 mask 255.255.255.0 permit

(config-router-bgp)# exit

(config)#

See Also

Chapter 31 Route Maps

preference2

Name

preference2 - breaks a preference tie between two groups

Syntax

preference2 pref2

no preference2 pref2?

Mode

BGP Router Configuration

Parameters

pref2 - an integer between 0 and 255, inclusive

Description

The preference2 command breaks a preference tie between groups. Preferences are the first criteria of comparison for route selection. When a route has been learned from more than one group, the active route will be selected from the group with the lowest preference.

The negative form of this command, no preference2, removes the configured value and returns this to its default value of 0. Note: Specifying a value for pref2 in the no form has no effect on the configuration. Thus, it is displayed above as optional.

Default

If preference2 is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# preference2 0

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example configures the global BGP preference2 value to be 20.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# preference2 20

(config-router-bgp)# exit

(config)#

Example 2

The following example removes the configured BGP preference2 value and reverts it back to its default value.

(config)# router bgp 65535

(config-router-bgp)# no preference2 20

(config-router-bgp)# exit

(config)#

redistribute

Name

redistribute - specifies routes to export to the current protocol

Syntax

redistribute protocol [route-map name]? {0,10}

no redistribute protocol [route-map name]?

Mode

BGP Router Configuration

Parameters

protocol - the protocol name whose routes you want to redistribute to the current protocol being configured. Valid protocols are aggregate, bgp, isis, kernel, ospf, ospf-ase, rip, ripng, and static.

route-map name - the name of a route map to apply to these routes. Specifying this is optional.

{0,10} - although this command can be given multiple times, it can only be given once for each of the configurable protocols. In other words, if a redistribute command is given for a protocol and route map, and then given again for the same protocol with a different route map, the second configuration overrides the first.

Description

Use the redistribute command to specify routes to export into the BGP. This command causes routes from the specified protocol to be considered for redistribution into BGP. Additionally, if a route map is specified, then routes from the specified protocol that match the named route map will be considered for redistribution into the current protocol. If the referenced route map has not yet been configured, then an empty route map is created with the specified name.

Note: Configuring this away from its default removes the implicitly configured default. You will have to go back and specify to redistribute BGP routes after the first redistribute configuration in order to export those routes.

Default

The default is to export BGP routes. Note that this is an implicit default that is wiped away with the first redistribute configuration.

Example

Example 1

In the following example BGP is configured to redistribute all RIP and RIPng routes.

(config)# router bgp 65535

(config-router-bgp)# redistribute rip

(config-router-bgp)# redistribute ripng

(config-router-bgp)# exit

(config)#

Example 2

In the following example, the route map set med is applied to OSPF routes and exported into BGP.

(config)# route map setmed

(config-route-map)# set med 20

(config-route-map)# exit

(config)# router bgp

(config-router-bgp)# redistribute ospf route-map setmed

(config-router-bgp)# exit

(config)#

Example 3

In the following example, route map "abc" is configured with the following match criteria:

If a route matches interface "fxp1", then communities specified in community "com-set-1" will be added to the route and the metric of the route will be set to 50.

(config)# route-map abc

(config-route-map)# match interface fxp1

(config-route-map)# set community-set com-set-1

(config-route-map)# set metric 50

(config-route-map)# exit

(config)#

This route map is then applied to static routes and exported into BGP.

(config)# router bgp 65121

(config-router-bgp)# redistribute kernel route-map abc

(config-router-bgp)# exit

See Also

"distribute-list"

router bgp

Name

router bgp - configures BGP on a router and specifies the router’s autonomous system number

Syntax

router bgp as_number

no router bgp as_number

Mode

Global Configuration

Parameters

as_number - an integer between 1 and 65535, inclusive

Description

The router bgp command enables BGP on a router. Because there is no default as_number, an autonomous system number must also be specified. The negative form of this command, no router bgp, disables BGP on a router.

Default

BGP is disabled by default.

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example configures the router to be a BGP speaker in AS number 65535.

(config)# router bgp 65535

(config-router-bgp)#

Example 2

The following example turns off BGP on the router.

(config)# no router bgp 65535

(config)#

show ip bgp

Name

show ip bgp - displays information about BGP routes installed in the BGP routing information base (RIB)

Syntax

show ip bgp [ip_address]? [prefix (longer-prefixes?)]

Mode

User Execution

Parameters

ip_address - optionally specify an IP address

prefix - optionally specify a prefix with an address and a mask length

longer-prefixes - if a prefix is specified, optionally specify to show routes matching the specified Network/Mask pair only

Description

Use the show ip bgp query to obtain information about BGP routes installed in the BGP RIB.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example returns BGP information for all BGP routes installed in the BGP RIB.

> show ip bgp

Network Next Hop R Metric LocPref Path
1.2.3.4/24 192.165.251.1 u 9 100 201 202

1.2.3.5/24 192.165.251.1 u 10 100 201 202

Field Descriptions

The following table describes the fields that appear in the BGP Query.

Table 13‑1 BGP Query Fields

show ip bgp instance

Name

show ip bgp instance - shows current BGP instance information

Syntax

show ip bgp instance

Mode

User Execution

Parameters

none

Description

Use the show ip bgp instance query to obtain summarized information about the current BGP instance.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example shows information about the current BGP instance.

> show ip bgp instance

Instance ID is 0

show ip bgp neighbors

Name

show ip bgp neighbors - displays information about the state of BGP’s IPv4 peering sessions

Syntax

show ip bgp neighbors [ipv4-address]?

Mode

Privileged Execution

Parameters

ipv4-address - optionally enter an IPv4 address to view information for only the specified neighbor

Description

Use the show ip bgp neighbors query to obtain detailed information about the state of BGP’s peering sessions. You can optionally specify an IPv4 address. When you do so, the output of the query will display information for the specified address.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example shows detailed information about all BGP peering sessions.

# show ip bgp neighbors

BGP neighbor is 10.11.31.32, remote AS 65534
BGP version is 4, remote router ID 10.133.10.32
Negotiated version is 4
TTL is 0
holdtime is 180
restart-time is 0
Restarting: no
Current state is "Established"
Last state was "OpenConfirm"
Last event was "RecvKeepAlive"
Last error code was 0
Last error subcode was 0
Local address is 10.11.31.31
Local AS is 65535
Local router ID is 192.168.11.31
Capabilities:
Multicprotocol IPv4 Unicast: no
Graceful Restart IPv4 Unicast: no
Multiprotocol IPv4 Multicast: no
Graceful Restart IPv4 Multicast: no
Route Refresh: no
Send End-of-RIB messages: no
Dynamic Capabilities: no

BGP neighbor is 10.11.31.33, remote AS 65533
BGP version is 4, remote router ID 192.168.11.33
Negotiated version is 4
TTL is 0
holdtime is 180
restart-time is 0
Restarting: no
Current state is "Established"
Last state was "OpenConfirm"
Last event was "RecvKeepAlive"
Last error code was 0
Last error subcode was 0
Local address is 10.11.31.31
Local AS is 65535
Local router ID is 192.168.11.31
Capabilities:
Multiprotocol IPv4 Unicast: no
Graceful Restart IPv4 Unicast: no
Multiprotocol IPv4 Multicast: no
Graceful Restart IPv4 Multicast: no
Route Refresh: no
Send End-of-RIB messages: no
Dynamic Capabilities: no

show ip bgp orf

Name

show ip bgp orf - displays ORF-related information for all peers or for a specific peer

Syntax

show ip bgp orf ip_address?

Mode

User Execution

Parameters

ip_address - optionally specify the IPv4 address of a peer for which you want ORF information returned

Description

Use the show ip bgp orf query to view ORF-related information for a single peer or for all peers.

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

In the following example, ORF information for all peers is displayed.

> show ip bgp orf

ORFs for peer 1.2.3.4
prefix 10.0.0.0/8 ge 8 le 8 deny
community 200:300
extcommunity rt 192.168.10.2:500
ORFs for peer 2.2.2.2
community 202:302
community 400:500

Example 2

In the following example, ORF information is returned for peer 2.2.2.2 only.

> show ip bgp orf 2.2.2.2

ORFs for peer 2.2.2.2
community 202:302
community 400:500

Field Descriptions

The following table describes the fields that appear in the BGP ORF Query.

Table 13‑1 BGP ORF Query Fields

show ip bgp paths

Name

show ip bgp paths - displays BGP AS Path information

Syntax

show ip bgp paths

Mode

User Execution

Privileged Execution

Parameters

none

Description

Use the show ip bgp paths query to view AS Path information.

Command History

NGC 2.3 - This command was introduced.

Examples

The following example is a query for AS Paths.

> show ip bgp paths

Refcount Metric Path
5 0 IGP (Id 2)
12 0 Incomplete (Id 1)

show ip bgp peer-group

Name

show ip bgp peer-group - displays information about BGP peer groups

Syntax

show ip bgp peer-group [name]?

Mode

User Execution

Parameters

name - optionally specify the name of a peer group

Description

Use the show ip bgp peer-group query to obtain BGP peer group information. If a name is not specified, then information about all BGP peer groups is displayed.

Command History

NGC 2.2 - This command was introduced.

Examples

The following example returns information for all BGP peer groups.

> show ip bgp peer-group

BGP peer-group is abc
BGP version 4
For address family: IPv4 Unicast
BGP neighbor is abc, peer-group external, members:
192.168.100.1
192.168.100.2

Field Descriptions

The following table describes the fields that appear in the BGP Peer Group Query.

Table 13‑1 BGP Peer Group Query Fields

show ip bgp summary

Name

show ip bgp summary - shows summarized BGP information

Syntax

show ip bgp summary

Mode

User Execution

Parameters

none

Description

Use the show ip bgp summary command to view summarized BGP information, including the router ID and the local AS number.

Command History

NGC 2.2 - This command was introduced

Examples

The following example shows a request for summarized BGP information.

> show ip bgp summary

BGP router identifier 65.247.36.97, local AS number 4

>

timers bgp

Name

timers bgp - specifies global keepalive and holdtime values for BGP

Syntax

timers bgp keepalive_value holdtime_value

no timers bgp [keepalive_value holdtime_value]?

Mode

BGP Router Configuration

Parameters

keepalive_value - the time, in seconds, between keepalive messages with a value range between 0 and 4,294,967,295, inclusive

holdtime_value - the time, in seconds of the BGP Hold Timer with a value of 0 or a value between 3 and 65535, inclusive

Description

The BGP keepalive timer will be set to one-third of the negotiated holdtime by default. The keepalive value specifies the number of seconds that will elapse between keepalive messages.

The holdtime value specifies the number of seconds to use when negotiating a peering session. If Advanced Routing Suite does not receive a keepalive, update, or notification message within the specified period, then the BGP connection will be closed. The negotiated holdtime value is the lesser of the values sent in the exchanged BGP Open messages. If a time of zero is specified, no keepalives will be sent. If a time of zero is received from the remote peer, then the holdtime must be configured to be zero in order for the peering session to become established.

Note: You cannot specify a holdtime value of 1 or 2. The value can be 0 or at least 3.

The negative form of this command, no timers bgp, removes the configured values and returns this to its default values of 180 and 60 seconds, respectively. Note: Specifying a value for keepalive and holdtime in the no form of this command has no effect on the configuration. Thus, it is displayed above as optional.

Default

If timers bgp is not specified, it is the same as if the user had specified the following:

(config-router-bgp)# timers bgp 60 180

Command History

NGC 2.2 - This command was introduced.

Examples

Example 1

The following example sets the BGP keepalive value to 30 seconds and the holdtime value to 90 seconds. Notice that the values have positional significance. The keepalive value must appear first, and the holdtime value must appear second.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# timers bgp 30 90

(config-router-bgp)# exit

(config)#

Example 2

The following example removes the user-configured timer values and returns these to their defaults.

(config)# router bgp 65535

(config-router-bgp)# no timers bgp

(config-router-bgp)# exit

(config)#

trace file

Name

trace file - specifies the file to receive tracing information, the size of the file, whether to overwrite existing files, and the maximum number of files allowed

Syntax

trace file file_name [no-timestamp || overwrite]?

no trace file file_name [no-timestamp || overwrite]?

Mode

BGP Router Configuration

Parameters

file_name - specifies the name of the file to receive the tracing information. Note that the file name is not specified in quotes.

no-timestamp - specifies that a timestamp should not be prepended to all trace lines

overwrite - specifies to begin tracing by appending or truncating an existing file

Description

The trace file command is associated with each protocol, so that information pertaining to a single protocol can be written to its own file. For BGP, the trace file command in BGP Router Configuration Mode specifies a file for tracing of all BGP events. The negative form of this command disables this tracing. The specific events that are traced are controlled by the trace flag command.

The no-timestamp option disables the pre-pending of a timestamp to all lines written to the trace file. The default is to prepend a timestamp to all lines written to a trace file.

The overwrite option specifies whether to start tracing by truncating or appending to an existing file.

Note: These options are not cumulative across multiple commands. Consider the following example:

(config-router-bgp)# trace file /var/log/bgp.log no-timestamp

(config-router-bgp)# trace file /var/log/bgp.log max-files 10

The option given in the second command completely replaces that given in the first. In order to specify both no-timestamp and max-files 10, they must be entered on the same line as follows.

(config-router-bgp)# trace file /var/log/bgp.log
max-files 10 no-timestamp

Default

BGP tracing is turned off by default.

Command History

NGC 2.2 - This command was introduced.

Examples

In the following example, BGP tracing is written to the file "/var/tmp/bgp.log". No timestamp will display at the beginning of the trace lines.

(config)# router bgp 65535

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# trace file /var/tmp/bgp.log no-timestamp

trace flag

Name

trace flag - specifies BGP-specific tracing options as well as options that are common across all protocols

Syntax

trace flag ( [ route | normal | state | policy | task |
timer | all | aspath ]) | ( [ packets | open |
update | keepalive | notify ] [ send | receive |
send-receive ]? [detail?] )

no trace flag ( [ route | normal | state | policy | task |
timer | all | aspath ]) | ( [ packets | open |
update | keepalive | notify ] [ send | receive |
send-receive ]? [detail?] )

Mode

BGP Router Configuration

Parameters

Flags common to all protocols:

[ route | normal | state | policy | task | timer | all ] - These tracing flags are common to all protocols. They cannot be associated with a send, receive, or send-receive action item. Similarly, you cannot specify to show detailed information when tracing these flags. These flags are defined as follows:

• route - trace routing table changes for routes installed by this protocol or peer
• normal - trace normal protocol occurrences. Note: Abnormal protocol occurrences are always traced.
• state - trace state machine transition in the protocol
• policy - trace the application of protocol and user-specified policy to routes being imported or exported
• task - trace system interface and processing associated with this protocol
• timer - trace timer usage by this protocol
• all - turns on all trace flags. Note: When issuing a show command, the output will display all the trace flags rather than this all keyword.

GP-specific flags that do not allow associated actions:

• [ aspath ] - The following BGP-specific flags cannot be associated with the send, receive, send-receive, and detail action items. These flags are defined as follows:
• aspath - traces AS Path messages
• GP-specific flags that allow associated actions:
• [ packets | open | update | keepalive | notify ] - The following BGP-specific flags can be associated with the send, receive, send-receive, and detail action items. These flags are defined as follows:
• packets - trace all BGP packets
• open - trace BGP Open packets
• update - trace BGP Update packets
• keepalive - trace BGP Keepalive packets
• notify - trace BGP Notification messages
• [ send | receive | send-receive ]? - optionally specify whether to limit the tracing to packets sent, received, or both
• [detail?] - optionally specify to use a more verbose format when displaying information about the contents of packets instead of one or two lines

Description

Use the trace flag command to specify tracing flags for BGP tracing. Each flag must reside on its own configuration line. For example, you cannot specify to trace both open and keepalive packets in the same command.

Default

The default is for no flags to be explicitly configured.

Command History

NGC 2.2 - This command was introduced.

Examples

In the following example, trace flags specify that both the sent and received update and keepalive messages are traced in detail. This tracing information will be written to the file /var/tmp/bgp.log.

(config)# router bgp 65525

(config-router-bgp)# bgp router-id 1.2.3.4

(config-router-bgp)# trace file /var/tmp/bgp.log

(config-router-bgp)# trace flag update send-receive detail

(config-router-bgp)# trace flag keepalive send-receive detail

(config-router-bgp)# exit

(config)#