For nonstandard PHBs, the mapping is similar to AFn mapping. Red color maps to
011, yellow maps to 010, and green maps to 001.
Tasks to perform static configuration and signaled mapping between the EXP bits
and the PHB of traffic include the following sets of tasks:
â– Configuring Static EXP-to-PHB Mapping on page 305
â– Signaled Mapping for RSVP-TE Tunnels on page 305
â– Preference of per-VR Versus per-LSP Behavior on page 308
Configuring Static EXP-to-PHB Mapping
You can configure static EXP-to-PHB mapping at the per-VR level, only for LSPs that
do not have specific policies attached (by either per-LSP configured mapping or
signaled mapping). The configured mapping applies regardless of label distribution
protocol, BGP. LDP, or RSVP-TE.
The PHB of incoming packets is determined from the EXP bits by the match values
set with the mpls match exp-bits command.
The EXP bits of outgoing packets are determined from the PHB by the mtach values
set with the mpls match traffic-class command.
To configure static EXP-to-PHB mapping:
1. Set a combination of traffic class and color for incoming traffic that matches the
specified EXP bits value in the shim header.
host1(config)#mpls match exp-bits 1 set traffic-class bronze color red
You can repeat the command to support the eight possible EXP bit values.
2. Set the EXP bits in the shim header of outgoing traffic that matches a particular
combination of traffic class and color.
host1(config)#mpls match traffic-class gold color green set exp-bits 7
You can repeat the command to support up to 24 combinations: eight traffic
classes supported on the router times three colors.
Signaled Mapping for RSVP-TE Tunnels
For signaled mapping between EXP and PHB, policies apply the EXP bits matching
and setting on a per-LSP basis rather than a per-VR basis. Signaled mapping applies
only when RSVP-TE is the label distribution protocol.
When traffic is mapped onto the ingress router of the LSP, the EXP bits are set
according to a policy attached to the LSP. The policy corresponds to the EXP-to-PHB
mapping defined for the LSP. Typically, the policy sets the EXP bits differently
according to classifier lists that match on internal class/color information or on a
user packet class associated with a packet.
Configuring Static EXP-to-PHB Mapping â– 305
Chapter 3: Configuring MPLS
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