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Configuring the Entropy Label for LSPs

 

The insertion of entropy labels for an LSP enables transit routers to load-balance MPLS traffic across ECMP paths or Link Aggregation groups using just the MPLS label stack as a hash input without having to rely on deep packet inspection. Deep packet inspection requires more of the router’s processing power and different routers have differing deep-packet inspection capabilities.

To configure the entropy label for an LSP, complete the following steps:

  1. On the ingress router, include the entropy-label statement at the [edit protocols mpls labeled-switched-path labeled-switched-path-name] hierarchy level or at the [edit protocols mpls static-labeled-switched-path labeled-switched-path-name ingress] hierarchy level. The entropy label is added to the MPLS label stack and can be processed in the forwarding plane.

    Note

    This is only applicable for RSVP and static LSPs.

  2. On the ingress router, you can configure an ingress policy for LDP-signaled LSPs:

    Configure the ingress policy at the [edit policy-options] hierarchy level:

    The following shows an example of an entropy label ingress policy.

  3. (Optional) By default, routers that support the pushing and popping of entropy labels are configured with the load-balance-label-capability statement at the [edit forwarding-options] hierarchy level to signal the labels on a per-LSP basis. If the peer router is not equipped to handle load-balancing labels, you can prevent the provider edge (PE) router from signaling the entropy label capability by configuring the no-load-balance-label-capability statement at the [edit forwarding-options] hierarchy level.

Transit routers require no configuration. The presence of the entropy label indicates to the transit router to load balance based solely on the MPLS label stack.

Penultimate hop routers pop the entropy label by default.

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