Quality of Service Guide Service Egress and Ingress QoS Policies
Edition: 01 3HE 11014 AAAC TQZZA 289
6.4.2.1.2 Service Egress QoS Policy Commands
sap-egress
Syntax [no] sap-egress policy-id [create]
Context config>qos
Description This command is used to create or edit a service egress QoS policy. The egress policy
defines the Service Level Agreement (SLA) for service packets as they egress on the SAP.
Policies in effect are templates that can be applied to multiple services as long as the scope
of the policy is template. The queues defined in the policy are not instantiated until a policy
is applied to a service.
A sap-egress policy differs from sap-ingress policies in the complexity of the QoS parameters
that can be defined. At ingress, policies determine queue mappings based on ingress DSCP
and dot1p criteria. Multiple queues can be created per forwarding class and each queue can
have different CIR or PIR parameters.
At egress, the policies are much simpler, since the forwarding class and in-profile or out-of-
profile determination is done at the original service ingress SAP. Egress SAP QoS policies
allow the definition of queues and the mapping of forwarding classes to those queues. Each
queue needs to have a relative CIR for determining its allocation of QoS resources during
periods of congestion. A PIR can also be defined that forces a hard limit on the packets
transmitted through the queue. When the forwarding class is mapped to the queue, a dot1p
value can optionally be specified. If specified, and the SAP has a dot1q or qinq encapsulation
type, the dot1p value will be used for all packets that egress on that forwarding class. If the
SAP is qinq-encapsulated, the qinq-mark-top-only command (under config>service) can
be used to specify which qtags will have their dot1p marked or re-marked with the specified
dot1p value. If the dot1p value is not specified, a dot1p value of 0 will be used. If the SAP is
null-encapsulated, the dot1p value has no meaning.
The sap-egress policy with policy-id 1 is the default sap-egress QoS policy and is applied to
service egress SAPs when an explicit policy is not specified or removed.
The factory default settings for sap-egress policy-id 1 define a single queue with PIR set to
the maximum value and a CIR set to 0. The single queue is the default queue and all
forwarding classes will map to it. Packets being tagged according to the defined SAP
encapsulation will have the dot1p bits set to 0 for the new tags being added. If the tag already
exists and the default sap-egress policy is being used, the dot1p bits are not changed.
Note: The ATM access egress shaping configuration in a SAP egress QoS policy is ignored
when that policy is assigned to an ATM SAP. The shaping of the egress cell stream is
controlled by the atm-td-profile command. If the atm-td-profile is not configured, the default
atm-td-profile is in effect. See the atm-td-profile command for more information.
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