Cisco 7604 Configuration Manual page 737

Chapter 42 Configuring PFC3BXL or PFC3B Mode MPLS QoS
MPLS to IP
PFC3BXL or PFC3B mode MPLS QoS supports these capabilities at the MPLS-to-IP edge:
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This section provides information about the MPLS-to-IP MPLS QoS classification. Additionally, this
section provides information about the capabilities provided by the ingress and egress modules.
Classification for MPLS-to-IP
The PFC3BXL or PFC3B assigns the internal DSCP (internal priority that the PFC3BXL or PFC3B
assigns to each frame) based on the QoS result. The QoS result is affected by the following:
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There are three different classification modes:
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For information about recirculation, see the
Note
For incoming MPLS packets on the PE-to-CE ingress, the PFC3BXL or PFC3B supports MPLS
classification only. Ingress IP policies are not supported. PE-to-CE traffic from the MPLS core is
classified or policed on egress as IP.
OL-4266-08
Option to propagate EXP value into IP DSCP on exit from an MPLS domain per egress interface
Option to use IP service policy on the MPLS-to-IP egress interface
Default trust EXP value
Label type (per-prefix or aggregate)
Number of VPNs
Explicit NULL use
QoS policy
Regular MPLS classification—For nonaggregate labels, in the absence of MPLS recirculation, the
PFC3BXL or PFC3B classifies the packet based on MPLS EXP ingress or egress policy. The
PFC3BXL queues the packet based on COS derived from EXP-to-DSCP-to-CoS mapping. The
underlying IP DSCP is either preserved after egress decapsulation, or overwritten from the EXP
(through the EXP-to-DSCP map).
IP classification for aggregate label hits in VPN CAM—The PFC3BXL or PFC3B does one of the
following:
Preserves the underlying IP ToS
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Rewrites the IP ToS by a value derived from the EXP-to-DSCP global map
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Changes the IP ToS to any value derived from the egress IP policy
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In all cases, egress queueing is based on the final IP ToS from the DSCP-to-CoS map.
IP classification with aggregate labels not in VPN CAM—After recirculation, the PFC3BXL or
PFC3B differentiates the MPLS-to-IP packets from the regular IP-to-IP packets based on the ingress
reserved VLAN specified in the MPLS decapsulation adjacency. The reserved VLAN is allocated per
VRF both for VPN and non-VPN cases. The ingress ToS after recirculation can be either the original IP
ToS value, or derived from the original EXP value. The egress IP policy can overwrite this ingress ToS
to an arbitrary value.
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
Understanding PFC3BXL or PFC3B Mode MPLS QoS
"Recirculation" section on page 24-4.
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