Class Based Forwarding (CBF) is not supported together with Weighted ECMP in LoR.
If both weighted ECMP and class-forwarding are configured under LDP, then LDP uses weighted ECMP only if all LSP next hops have non-default-weighted values configured. If any of the ECMP set LSP next hops do not have the weight configured, then LDP uses CBF. Otherwise, LDP uses CBF if possible. If weighted ECMP is configured for both LDP and the IGP shortcut for the RSVP tunnel, (config>router>weighted-ecmp), then weighted ECMP is used.
LDP resolves and programs FECs according to the weighted ECMP information if the following conditions are met.
LDP has both CBF and weighted ECMP fully configured.
All LSPs in ECMP set have both a load-balancing weight and CBF information configured.
weighted-ecmp is enabled under config>router.
Subsequently, deleting the CBF configuration has no effect; however, deleting the weighted ECMP configuration causes LDP to resolve according to CBF, if complete, consistent CBF information is available. Otherwise LDP sprays over all the LSPs equally, using non-weighted ECMP behavior.
If the IGP shortcut tunnel using the RSVP LSP does not have complete weighted ECMP information (for example, config>router>weighted-ecmp is not configured or one or more of the RSVP tunnels has no load-balancing-weight) then LDP attempts CBF resolution. If the CBF resolution is complete and consistent, then LDP programs that resolution. If a complete, consistent CBF resolution is not received, then LDP sprays over all the LSPs equally, using regular ECMP behavior.
Where entropy labels are supported on LoR, the entropy label (both insertion and extraction at LER for the LDP label and hashing at LSR for the LDP label) is supported when weighted ECMP is in use.