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In This Section: |
The ICMP Router Discovery protocol is an IETF standard protocol that allows hosts running an ICMP router discovery client to learn dynamically about the presence of a viable default router on a LAN. It is intended to be used instead of having hosts wiretap routing protocols such as RIP. It is used in place of, or in addition to, statically configured default routes in hosts.
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Note - Only the server portion of the Router Discovery Protocol is supported. |
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Gaia implements only the ICMP router discovery server portion, which means that a Check Point router can advertise itself as a candidate default router, but it will not adopt a default router using the router discovery protocol.
The ICMP Router Discovery Service provides a mechanism for hosts attached to a multicast or broadcast network to discover the IP addresses of their neighboring routers. This section describes how you can configure a router to advertise its addresses by using ICMP Router Discovery.
The router discovery server runs on routers and announces their existence to hosts. It does this by periodically multicasting or broadcasting a router advertisement to each interface on which it is enabled. These advertisements contain a list of all the router addresses on a given interface and their preference for use as a default router.
Initially, these router advertisements occur every few seconds. They then fall back to every few minutes. In addition, a host can send a router solicitation, to which the router responds with a unicast router advertisement. However, if a multicast or broadcast advertisement is due in a moment, the router does not respond with a unicast advertisement.
Each router advertisement contains an advertisement lifetime field indicating the length of time that the advertised addresses are valid. This lifetime is configured such that another router advertisement is sent before the lifetime expires. A lifetime of zero (0) indicates that one or more addresses are no longer valid.
On systems that support IP multicasting, the router advertisements are sent by default to the all-hosts multicast address 224.0.0.1. However, you can specify the use of broadcast. All IP addresses configured on the physical interface are included in the router advertisement when:
When the router advertisements are sent to a net or subnet broadcast, only the address associated with that net or subnet is included.
To enable router discovery services:
The Add Interface window opens.
To disable router discovery service on an interface:
Router Discover Configuration parameters
Parameter |
Description |
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Interface |
The interface on which Router Discovery occurs. |
Enable Router Discovery |
Whether ICMP router discovery is running on the interface. After you enable ICMP router discovery, configuration options for the interface appear.
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Min. Advertise Interval |
The minimum time (in seconds) allowed between sending unsolicited broadcast or multicast ICMP Router Advertisements on the interface.
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Max. Advertise Interval |
The maximal time (in seconds) allowed between sending unsolicited broadcast or multicast ICMP Router advertisements on the interface.
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Advertisement Lifetime |
The lifetime (in seconds) of the advertisements sent from the interface.
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Advertise |
Whether the address should be advertised in the Router Advertisement packets. This applies to each address on the interface and not to the interface itself.
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Eligibility |
You can make an IP address ineligible as a default router address. A router address that is not to be used as a default router has a Preference of 0.
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Preference |
The level of preference of the IP address as a default router address, relative to other router addresses on the same subnet. The minimum value corresponds to Ineligible and indicates that the address is not to be used as a default router.
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Use the following Gaia Clish commands to configure router discovery properties for specific interfaces.
set rdisc interface <if_name>
<on | off>
adv-lifetime {<integer> | default}
advertise <ip_address>
{on | off}
preference {ineligible | <integer>}
max-adv-interval {<4-1800> | default}
min-adv-interval {<3-1800> | default}
Parameter |
Description |
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Whether to run ICMP router discovery on the interface. |
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The minimum time (in seconds) allowed between sending unsolicited broadcast or multicast ICMP router advertisements on the interface. |
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A value of 450 seconds. |
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The maximal time (in seconds) allowed between sending unsolicited broadcast or multicast ICMP router advertisements on the interface. |
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A value of 600 seconds. |
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The lifetime (in seconds) of the advertisements sent from the interface. An integer value between the configured value for the maximal advertisement interval and 9000. |
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A value of 1800 or 3 times the maximal advertisement interval. |
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Whether to advertise the specified IP address that is associated with the interface should be advertised in router advertisement packets. |
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Do not use the specified IP address as a default router. |
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The preferability of the specified IP address as a default router address relative to other router addresses on the same subnet. |
Use the following commands to monitor and troubleshoot your ICMP Router Discovery implementation.
show rdisc
interfaces
interface <if_name>
stats
summary
