Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual page 652

Understanding MPLS QoS
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Classification for MPLS-to-MPLS QoS
MPLS QoS at the ingress to P1 or P2 supports the following:
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MPLS QoS at the egress of P1 or P2 supports matching with the mpls experimental topmost command.
Classification at MPLS-to-MPLS Ingress Port
LAN port classification is based on the egress CoS from the PFC3B. OSM and FlexWAN interfaces
classify traffic using the match mpls experimental command. The match mpls experimental
command matches on the EXP value in the received topmost label.
Classification at MPLS-to-MPLS Egress Port
LAN port classification is based on the egress CoS value from the PFC3B. OSM and FlexWAN interfaces
classify traffic using the match mpls experimental command. The match mpls experimental
command matches on the egress CoS; it does not match on the EXP in the topmost label.
If the egress port is a trunk, the LAN ports and OSM GE-WAN ports copy the egress CoS into the egress
802.1Q field.
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Imposing an additional label—When imposing a new label onto an existing label stack, the PFC3B
maps the internal DSCP to the EXP value in the imposed label using the internal DSCP-to-EXP map.
It then copies the EXP value in the imposed label to the underlying swapped label. PFC3B assigns
the egress CoS using the internal DSCP-to-CoS global map. If the DSCP maps are consistent, the
egress CoS is based on the EXP value in the imposed label.
The PFC3B can mark in-profile and mark down out-of-profile traffic. After it marks the internal
DSCP, the PFC3B uses the internal DSCP-to-EXP global map to map the internal DSCP to the EXP
value in the newly imposed label. The PFC3B then copies the EXP in the imposed label to the
underlying swapped label. The PFC3B assigns the egress CoS using the internal DSCP-to-CoS
global map. Therefore, the egress CoS is based on the EXP in the imposed label.
Popping a label—When popping a label from a multi-label stack, the PFC3B preserves the EXP
value in the exposed label. The PFC3B assigns the egress CoS using the internal DSCP-to-CoS
global map. If the DSCP maps are consistent, then the egress CoS is based on the EXP value in the
popped label.
If EXP propagation is configured for the egress interface, the PFC3B maps the internal DSCP to the
EXP value in the exposed label using the DSCP-to-EXP global map. The PFC3B assigns the egress
CoS using the internal DSCP-to-CoS global map. If the DSCP maps are consistent, the egress CoS
is based on the EXP value in the exposed label.
Matching with the mpls experimental topmost command
The set mpls experimental imposition, police, and police with set imposition commands
Chapter 39 Configuring MPLS QoS
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