Applying Custom MPLS EXP Classifiers to Routing Instances in Layer 3 VPNs

When you include the vrf-table-label statement in the configuration for a routing instance (as described in Filtering Packets in Layer 3 VPNs Based on IP Headers) but do not explicitly apply a classifier to the routing instance, the default MPLS EXP classifier is applied.

For PICs that are installed on Enhanced FPCs, you can apply a custom classifier to override the default MPLS EXP classifier for the routing instance. For detailed instructions, see the Junos Class of Service Configuration Guide. The following instructions serve as a summary:

1. Filter traffic based on the IP header by including the vrf-table-label statement at the [edit routing-instances routing-instance-name] hierarchy level:
   [edit routing-instances routing-instance-name]vrf-table-label;
2. Configure a custom MPLS EXP classifier by including the appropriate statements at the [edit class-of-service] hierarchy level. For instructions, see the Junos Class of Service Configuration Guide.
3. Configure the routing instance for CoS by including the routing-instances statement at the [edit class-of-service] hierarchy level:
   [edit class-of-service]routing-instances routing-instance-name {classifiers {exp (classifier-name | default);}}
4. Configure the routing instance to use the custom MPLS EXP classifier by including the classifiers statement at the [edit class-of-service routing-instances routing-instance-name] hierarchy level:
   [edit class-of-service routing-instances routing-instance-name]classifiers {exp classifier-name;}

To display the MPLS EXP classifiers associated with all routing instances, issue the show class-of-service routing-instances command.

Note: The following caveats apply to custom MPLS EXP classifiers for routing instances: An Enhanced FPC is required. Logical systems are not supported.