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Apply MPLS EXP Classifiers for Explicit-Null Labels

When you configure MPLS explicit-null labels, label 0 is advertised to the egress router of an LSP. When label 0 is advertised, the egress router (instead of the penultimate router) removes the label. Ultimate-hop popping (UHP) ensures that any packets traversing an MPLS network include a label. For more information about explicit-null labels and UHP, see the MPLS Applications User Guide.

When you configure MPLS explicit-null labels with an MPLS EXP classifier, the MPLS EXP classifier can be different from an IPv4 or IPv6 classifier configured on the same logical interface. In other words, you can apply separate classifiers for MPLS EXP, IPv4, and IPv6 packets per logical interface.

Configure an MPLS EXP classifier for explicit-null labels:

  1. Create the MPLS EXP classifier.
  2. Specify the name of a predefined classifier to include in this configuration.
  3. Define a classification of code point aliases for the classifier.

Apply the MPLS EXP classifier to the logical interface:

  1. Specify the physical and logical interface names on which you want to apply the classifier.

  2. Specify the classifier type and name you want to apply to the interface.

Note:

When a packet with a single label is received, if the label is an explicit-null label (0 or 2), the label is popped first, making the EXP information no longer available. The subsequent packet classification is based on the IPv4/IPv6 payload. To preserve the MPLS classification of the packet, set [explicit-null-cos inet|inet6] at the [edit forwarding-options] hierarchy level. This option makes the packet classification based on the MPLS EXP value rather than on the payload.

Related Documentation

Change History Table

Feature support is determined by the platform and release you are using. Use Feature Explorer to determine if a feature is supported on your platform.

Release
Description
18.1
Starting with Junos OS 18.1R1, PTX Series routers with third-generation FPCs (FPC3) support [explicit-null-cos inet|inet6] at the [edit forwarding-options] hierarchy level. This option makes the packet classification based on the MPLS EXP value rather than on the payload, thus preserving the MPLS classification of the packet.