QoS Configuration

All user interactions with the QoS module are performed with the cpqos command.

The cpqos Command

The cpoqs command lets you manage the network Quality of Service on VSX Gateway.

To show QoS statistics:

cpqos stats [-u]

Parameter	Description
-u	Shows statistics for each CPU.

This command prints a line of statistics for each of the defined classes. Each line includes the following data columns:

Column	Value
rx	Number of bytes that arrived to this class since the last time statistics were presented
tx	Number of bytes that were transmitted from this class since the last time statistics were presented
drops	Number of bytes that were dropped from this class since the last time statistics were presented

Notes:

• Statistics values show byte counts, not packet counts
• Statistics values are reset after each query
• Statistics should be presented periodically with intervals of less than 1 minute.
• We recommend to use the watch command to periodically present these statistics

To show the QoS policy status:

cpqos status

To install the previously created QoS policy:

cpqos install

Note - This command also validates the overall integrity of the QoS policy. Once installed, the QoS policy remains installed even after the machine reboots.

To uninstall the previously installed QoS policy:

cpqos uninstall

Note - Once uninstalled, the QoS policy remains uninstalled even after the machine reboots.

To show the DiffServ classes defined in the QoS policy:

cpqos class show [-b]

Parameter	Description
-b	Shows DSCP values in 8 bits binary numbers.

To add new DiffServ class with specified name:

cpqos class add <class_name> prio <priority_value> type {llq | reg} [weight <weight_value>] dscp {default | <value[,value2[,value3...]]>}

Parameter	Description
add <class_name>	Unique class name.
prio <priority_value>	Priority value between 1-15. The lower the value, the higher the priority.
type {llq | reg}	Class Type: llq - low-latency reg - regular (weighted classes)
weight <weight_value>	This parameter is used only for classes of type reg. It determines the relative portion of the resources that the class will receive in relation to other weighted classes. Valid values are between 0 and 1000.
dscp {default | <value[,value2[,value3...]]}	The DiffServ code-points assigned to the class. Multiple DSCPs can be specified, separated by commas, with no spaces between values. Valid values are: default decimal numbers (not binary format) between 0 to 63 Notes: There can be only one class with a "default" DSCP. The default class is used for traffic without DiffServ marking (for example, tos=0), or traffic with DSCP values that are not assigned to any other class. If no class is used as "default", all 64 DSCP values must be assigned to the classes. A DSCP value cannot be assigned to more than one class.

To delete a specified DiffServ class name:

cpqos class del <class_name>

Note - Changes to the QoS policy will be are enforced only after the QoS policy is installed.

Notes:

• All commands return a zero value for success
• All commands return a non-zero value for failure
• Options and argument are case-sensitive

cpqos class add

This command adds a class with the following arguments:

Argument	Value
name	Unique name for the class
priority	Value between 1 and 15. A low value indicates a higher priority
type	"llq" for low-latency classes or "reg" for regular, weighted classes
weight	This value is used only for classes of type "reg". It determines the relative portion of the resources that the class will receive in relation to other weighted classes. Valid values are between 0 and 1000.
dscp	The DiffServ code-points assigned to the class. Multiple DSCP's can be specified, separated by commas, with no spaces between values. Values are in decimal (not binary format) with values from 0 to 63 or "default". There can be only one class with a "default" DSCP. The default class is used for traffic without DiffServ marking (e.g. tos=0) or traffic with DSCP values that are not assigned to any other class. If no class is used as "default", all 64 DSCP values must be assigned to the classes. A DSCP value cannot be assigned to more than one class.

Note - Changes to the policy with cpqos class add are enforced only after the policy is installed.

cpqos class del

This command deletes the class of the specified name. Changes to the policy with cpqos class del are enforced only after the policy is installed.

cpqos class show

This command shows the classes defined in the QoS policy.

cpqos install

This command installs the previously created QoS policy. It also validates the overall integrity of the policy. Once installed, the policy remains installed even if the machine reboots.

cpqos uninstall

This command un-installs the previously installed QoS policy. If un-installed, the policy will not be installed again when the machine boots.

cpqos stats

This command shows QoS statistics. cpqos stats prints a line of statistics for each of the defined classes. Each line includes the following data columns:

Column	Value
rx	Number of bytes that arrived to this class since the last time statistics were presented
tx	Number of bytes that were transmitted from this class since the last time statistics were presented
drops	Number of bytes that were dropped from this class since the last time statistics were presented

Note:

• [-u] option shows statistics separately for each CPU
• Statistics values are byte-counts, not packet counts
• Statistics values are reset after each query.
• Statistics should be presented periodically with intervals less than 1 minute.
• It is recommended to use the watch command to periodically present the statistics.

QoS Policy File

The QoS policy file is $FWDIR/database/qos_policy.C. The QoS policy file is created when the cpqos command is run for the first time.

Important - The QoS policy file should not be edited manually.

Use the cpqos class add/del commands to create entries. To maintain multiple QoS policies, rename the qos_policy.C file or copy it to another directory, and copy it back as $FWDIR/database/qos_policy.C when the policy needs to be enforced.

QoS Default Configuration

Default QoS configuration is set to "uninstall" (for example, not enforced).

Run the cpqos install or cpqos uninstall command to set the desired default configuration after boot.

Sample Differentiated Services Implementation

This section presents a sample differentiated services implementation. It includes examples for configuration, monitoring and statistics.

Sample Traffic Types

Traffic Type	Meaning...
Diamond	Real-time traffic (e.g. VOIP) which requires little bandwidth and is sensitive to latency and drops. This traffic is usually assigned to the EF (Expedited-Forwarding) PHB (Per Hop Behavior).
Platinum	Real-time traffic with low bandwidth requirements that is less sensitive to latency and drops than Diamond.
Gold	Traffic which is sensitive to drops
Silver	Traffic which is less sensitive to drops than Gold.
Bronze	Various types of traffic which require resource allocation. This traffic is usually assigned to the Best-Effort PHB.
Copper	High-volume traffic with a tendency to consume bandwidth

Configuration Guidelines

Your QoS policy should apply these guidelines:

• Diamond and Platinum classes should be defined as LLQ so they will have a lower latency then other classes
• Diamond should receive a higher priority than Platinum so it have even less latency and drops
• Gold should receive a higher priority than Silver so it will have fewer drops
• Copper resource consumption should be limited to about 10% of the available resource during periods of congestion
• Other traffic should receive about 45% of bandwidth when the traffic load is high

Configuration Examples

This example of the cpqos class add command creates classes for traffic of various types:

cpqos class add Diamond type llq prio 1 dscp 46 cpqos class add Platinum type llq prio 2 dscp 32 cpqos class add Gold type reg prio 3 weight 100 dscp 26 cpqos class add Silver type reg prio 4 weight 100 dscp 28 cpqos class add Bronze type reg prio 5 weight 200 dscp default cpqos class add Copper type reg prio 15 weight 50 dscp 10,12,14

Monitoring example shows previously defined classes:

[Expert@cpmodule:0]# cpqos class show class: Diamond priority: 1 type: llq weight: 0 DSCPs: 46 class: Platinum priority: 2 type: llq weight: 0 DSCPs: 32 class: Gold priority: 3 type: reg weight: 100 DSCPs: 26 class: Silver priority: 4 type: llq weight: 100 DSCPs: 28 class: Bronze priority: 5 type: llq weight: 200 DSCPs: default class: Copper priority: 15 type: reg weight: 50 DSCPs: 10,12,14

Statistics example shows statistics for the previously defined classes:

class   priority type     weight     rx         tx        drops Diamond   1       llq      0         2775        2650      0 Platinum  2       llq      0         1024        1020      105 Gold      3       reg      100       1775015     1773805   205 Silver    4       reg      100       1862437     1862336   550 Bronze    5       reg      200       3370033     2955120   3147 Copper    15      reg      50        1862437     762336    100689

From this statistical output, it is apparent that:

• In the Diamond class there were no drops.
• In the Platinum class there were a few drops, even though less traffic arrived classed as Platinum than did as Diamond.
• In the Gold class there were fewer drops than from the Silver class.
• In the Bronze class there were twice as many bytes transmitted than in the Silver and Gold classes, and four times as many bytes than there were in the Copper class.
• Most packets in the Copper class were dropped.