The 7705 SAR supports MPLS entropy labels on RSVP-TE and SR-TE LSPs, as per RFC 6790. The entropy label provides greater granularity for load balancing on an LSR where load balancing is typically based on the MPLS label stack.
If an ELI is found in the label stack, the entropy label is used as the hash result and hashing continues based on the configuration of label-only (lbl-only) or label-IP (lbl-ip) options. For information on the behavior of LSR hashing when entropy label is enabled, see LSR Hashing.
To support entropy labels on RSVP-TE and SR-TE LSPs:
the eLER must signal to the ingress node that entropy label capability (ELC) is enabled, meaning that the eLER can receive and process an entropy label for an LSP tunnel. Entropy labels are supported on RSVP-TE and SR-TE tunnels. Entropy labels are not supported on point-to-multipoint LSPs, BGP tunnels, or LDP FECs.
the iLER must receive the entropy label capability signal and be configured to enable the insertion of entropy labels for the spoke SDP, mesh SDP, or EVPN endpoint. Inserting an entropy label adds two labels in the MPLS label stack: the entropy label itself and the ELI.
At the eLER, use the config>router>rsvp>entropy-label-capability command to enable entropy label capability on RSVP-TE LSPs.
At the iLER, use the entropy-label command to enable the insertion of the entropy label into the label stack. The command is found under the following services and protocols:
Epipe and VPLS
config>service>epipe>spoke-sdp
config>service>epipe>bgp-evpn>mpls
config>service>vpls>spoke-sdp
config>service>vpls>mesh-sdp
config>service>vpls>bgp-evpn>mpls
IS-IS, OSPF, and MPLS
config>router>isis>segment-routing
config>router>ospf>segment-routing
config>router>mpls
For details on entropy labels, refer to the ‟MPLS Entropy Labels” section in the 7705 SAR MPLS Guide.