Advanced QoS policies

Overview

The adv-config-policy contains queue and policer configuration parameters that are not expected to be useful to most users. The policy only contains queue and policer child control parameters within a child-control node.

The parameters within the child-control node are intended to allow more precise control of the method that hierarchical virtual scheduling employs to emulate the effect of a scheduling context upon a member child queue or policer.

When a policy is created, it may be applied to a queue or policer defined within a sap-egress or sap-ingress QoS policy. It may also be applied to a queue or policer defined within an ingress or egress queue-group template. When a policy is currently associated with a QoS policy or template, the policy may be modified but not deleted (even if the QoS policy or template is not in use).

While the system maintains default values for the advanced configuration parameters, no default adv-config-policy exists.

For information about the tasks and commands necessary to access the CLI and to configure and maintain the router, see the Entering CLI Commands chapter in the 7450 ESS, 7750 SR, 7950 XRS, and VSR Classic CLI Command Reference Guide.

Port scheduler above offered allowance control

When the H-QoS algorithm within a port scheduler policy is configured to above-offered-allowance-control, it is possible to tune the distribution of unconsumed bandwidth for parented queues. This is achieved by applying an advanced configuration policy to the queue and configuring the following:

configure
  qos
    adv-config-policy
      child-control
        bandwidth-distribution
          above-offered-allowance
            unconsumed-agg-rate percent <percent-of-unconsumed-agg-rate>
            delta-consumed-agg-rate percent <percent-of-delta-consumed-agg-rate>
            unconsumed-higher-tier-rate percent <percent-of-unconsumed-higher-tier-rate>
            delta-consumed-higher-tier-rate percent <percent-of-delta-consumed-high-tier-rate>

When above-offered-allowance-control is enabled, both queues and schedulers use the default values. Default values of the percentages lists the default values for the percentages.

Table 1. Default values of the percentages

Parameter

Default Value

delta-consumed-agg-rate percent

20

delta-consumed-higher-tier-rate percent

5

unconsumed-agg-rate percent

100

unconsumed-higher-tier-rate percent

100

The percentage values can be tuned for parented queues by applying an advanced configuration policy to the queue with modified percent values.

See H-QoS algorithm selection, for information about the use of the parameters with the above-offered-allowance-control H-QoS algorithm.

Basic configurations

An advanced QoS policy must conform to the following:

  • Each advanced policy must have a unique policy ID.

  • Default values can be modified but parameters cannot be deleted.

Creating an advanced QoS policy

Configuring and applying advanced policies is optional. If no advanced policy is explicitly applied to a SAP or IP interface, then no default advanced policy is applied.

To create a new advanced policy, define the following:

  • a slope policy ID value. The system does not dynamically assign a value.

  • a description. The description provides a brief overview of policy features.

  • the child control parameters, which are intended to allow more precise control of the method that hierarchical virtual scheduling employs to emulate the effect of a scheduling context upon a member child queue or policer

The following displays an example of an advanced policy configuration:

ALA-7>config>qos# info
#------------------------------------------
echo "QoS Policies Configuration"
#------------------------------------------
...
        adv-config-policy "childPolicy1" create
            description "Test"
            child-control
                offered-measurement
                    add percent 30
                    granularity percent 30
                exit
                bandwidth-distribution
                    above-offered-cap percent 5
                    granularity percent 5
                exit
            exit
        exit
...
#------------------------------------------
ALA-7>config>qos# 

Applying advanced policies

Apply advanced policies to the following entities.

Queue group

Use the following CLI syntax to apply advanced policies to ingress queue groups.

config>qos queue-group-templates ingress queue-group group1 policer 1 adv-config-policy child1

Use the following CLI syntax to apply advanced policies to egress queue groups.

config>qos queue-group-templates egress queue-group group1 policer 1 adv-config-policy child1

SAP ingress

Use the following CLI syntax to apply advanced policies to an ingress SAP.

qos sap-ingress 11 policer 1 adv-config-policy child1 queue 1 adv-config-policy child1

SAP egress

Use the following CLI syntax to apply advanced policies to an egress SAP.

qos sap-egress 11 policer 1 adv-config-policy child1 queue 1 adv-config-policy child1

Default advanced policy values

The default policies cannot be edited or deleted. Advanced policy parameter defaults lists default advanced policy parameters.

Table 2. Advanced policy parameter defaults
Field Default

offered-measurement

high-rate-hold-time

0

time-average-factor

0

sample-interval

1

Service management tasks

This section discusses advanced QoS policy service management tasks.

Deleting QoS policies

Delete advanced policies from the following entities.

Queue group

Use the following CLI syntax to delete advanced policies from ingress queue groups.

config>qos queue-group-templates ingress queue-group group1 policer 1 no adv-config-policy

Use the following CLI syntax to delete advanced policies from egress queue groups.

config>qos queue-group-templates egress queue-group group1 policer 1 no adv-config-policy

SAP ingress

Use the following CLI syntax to delete advanced policies from an ingress SAP.

qos sap-ingress 11 policer 1 adv-config-policy child1 queue 1 no adv-config-policy

SAP egress

Use the following CLI syntax to delete advanced policies from an egress SAP.

qos sap-egress 11 policer 1 adv-config-policy child1 queue 1 no adv-config-policy

Copying and overwriting advanced policies

An existing advanced policy can be copied, renamed with a new policy ID value, or used to overwrite an existing policy ID. The overwrite option must be specified or an error occurs if the destination policy ID exists.

config>qos>copy {adv-config-policy} source-policy-id dest-policy-id [overwrite]

Editing advanced policies

Existing advanced policies and entries in the CLI or NMS can be edited. The changes are applied immediately to all services where this policy is applied. To prevent configuration errors, copy the policy to a work area, make the edits, then write over the original policy.