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Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 42 Configuring PFC3BXL or PFC3B Mode MPLS QoS
Understanding PFC3BXL or PFC3B Mode MPLS QoS
Note For information on recirculation, see the “Recirculation” section on page 24-4.
The PFC3BXL or PFC3B propagates the EXP value if all interfaces in the VPN have EXP propagation
enabled.
The following PE MPLS QoS features are supported:
• General MPLS QoS features for IP packets
• Classification, policing, or marking of CE-to-PE IP traffic through the VPN subinterface
• Per-VPN QoS (per-port, per-VLAN, or per-subinterface)
LSRs at the MPLS Core
This section provides information about MPLS QoS features for LSRs at the core (MPLS-to-MPLS) for
MPLS and MPLS VPN networks. Ingress features, egress interface, and PFC3BXL or PFC3B features
for Carrier Supporting Carrier (CsC) QoS features are similar to those used with MPLS to MPLS
described in the next section. A difference between CsC and MPLS to MPLS is that with CsC labels can
be imposed inside the MPLS domain.
MPLS to MPLS
PFC3BXL or PFC3B mode MPLS QoS at the MPLS core supports the following:
• Per-EXP policing based on a service policy
• Copying the input topmost EXP value into the newly imposed EXP value
• Optional EXP mutation (changing of EXP values on an interface edge between two neighboring
MPLS domains) on the egress boundary between MPLS domains
• Microflow policing based on individual label flows for a particular EXP value
• Optional propagation of topmost EXP value into the underlying EXP value when popping the
topmost label from a multi-label stack.
The following section provides information about MPLS-to-MPLS PFC3BXL or PFC3B mode MPLS
QoS classification. Additionally, the section provides information about the capabilities provided by the
ingress and egress modules.
Classification for MPLS-to-MPLS
For received MPLS packets, the PFC3BXL or PFC3B ignores the port trust state, the ingress CoS, and
any policy-map trust commands. Instead, the PFC3BXL or PFC3B trusts the EXP value in the topmost
label.
Note The PFC3BXL or PFC3B mode MPLS QoS ingress and egress policies for MPLS traffic classify traffic
on the EXP value in the received topmost label when you enter the match mpls experimental command.
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