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QoS Overview
Access Egress QoS Policies
An access egress policy defines marking values for the traffic egressing towards the customer on
the access ports. Access egress QoS policies map forwarding class flows to marking values to use.
7210 SAS-X supports SAP-based egress marking and port-based egress marking on access ports.
Users have an option to turn on either sap-based marking or port-based marking using the
command 'sap-qos-marking' under the configure>port>ethernet>access>egress context. In SAP-
based marking the remark policy defined in the SAP egress policy associated with each SAP is
used to mark the packets egressing out of SAP if marking is enabled. In port-based marking, the
remark policy defined in the access-egress policy associated with the access port determines the
marking values to use for all the SAPs defined on that port. SAP-based marking is only supported
for L2 SAPs, i.e. SAPs configured in Epipe, VPLS and PBB (I-SAPs only) service. Port-based
marking is supported for L3 SAPs (i.e. SAPs configured in VPRN services), PBB B-SAPs and
other L2 SAPs configured on the port. The access egress policy is used only when port-based
marking has been enabled (i.e. sap-qos-marking is set to disable). More information on the CLI
command 'sap-qos-marking' is available in the 7210 SAS Interfaces guide.
The 7210 SAS-R6 supports SAP-based marking for access SAPs and port-based egress marking
on access ports. SAP-based marking is only supported for L2 SAPs, that is, SAPs configured in
Epipe and VPLS service. If user enables remarking in the SAP egress policy attached to the SAP,
then the remark policy configured in the policy is used to mark the packets egressing out of SAP. If
remarking is disabled in the SAP egress policy attached to the SAP, then remark policy configured
under the access-egress policy associated with the egress access port is used to mark all packets
egressing out of the L2 SAP configured on the access port. This is known as port-based marking.
Port-based marking is supported primarily for L3 SAPs (that is, SAPs configured in VPRN
services and IES services). In other words, SAP based marking is not supported for L3 SAPs.
Unlike 7210 SAS-X, on 7210 SAS-R6, no explicit CLI command is provided to choose between
port-based marking and SAP-based marking for L2 SAPs. The user can choose SAP based
marking by enabling remarking in the SAP egress policy attached to the L2 SAP or choose port
based marking by disabling remarking in the SAP egress policy attached to the SAP and enabling
remarking in the access-egress policy associated with the access port on which the L2 SAP is
configured.
NOTE: On 7210 SAS-R6, if remarking is enabled for the SAP egress policy and port based
marking is enabled, then for L2 SAPs, the values configured in the SAP egress policy is used. For
L3 SAPs the values configured in the access-egress policy is used.
NOTE: On 7210 SAS-R6, if remarking is disabled for the SAP egress policy and port based
marking is enabled, then IP DSCP values get marked even for the traffic egressing out of the L2
SAPs configured on the port. To avoid this, it is recommended to use only FC to dot1p values
when both L2 and L3 SAPs are configured on the same access port.
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7210 SAS-X and 7210 SAS-R6 OS Quality of Service Guide
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