LDP LER ECMP is not supported.
LDP LSR ECMP is only supported on 7210 SAS-T, 7210 SAS-Mxp, 7210 SAS-R6, 7210 SAS-R12, 7210 SAS-Sx/S 1/10GE, and 7210 SAS-Sx 10/100GE.
This feature performs load balancing for LDP-based LSPs by having multiple outgoing next-hops for a specified IP prefix on ingress and transit LSRs.
An LSR that has multiple equal cost paths to a specified IP prefix can receive an LDP label mapping for this prefix from each downstream next-hop peer. As the LDP implementation uses the liberal label retention mode to retain all the labels for an IP prefix received from multiple next-hop peers.
Without ECMP support (only for LDP LSR LSPs on 7210 SAS), only one of these next-hop peers will be selected and installed in the forwarding plane. The next-hop peer selection algorithm looks up the route information obtained from the RTM for this prefix and finds the first valid LDP next-hop peer (for example, the first neighbor in the RTM entry from which a label mapping was received). If, for some reason, the outgoing label to the installed next-hop is no longer valid ( for example, if the session to the peer is lost or the peer withdraws the label) a new valid LDP next-hop peer will be selected out of the existing next-hop peers and LDP will reprogram the forwarding plane to use the label sent by this peer.
With ECMP support, all the valid LDP next-hop peers, those that sent a label mapping for a specified IP prefix, will be installed in the forwarding plane. In transit LSR, an ingress label will be mapped to the next hops that are in the RTM and from which a valid mapping label has been received. The forwarding plane will then use an internal hashing algorithm to determine how the traffic will be distributed amongst these multiple next-hops, assigning each ‟flow” to a particular next-hop.
For more information about the hash algorithms at transit LSR, see ‟LAG and ECMP Hashing” in the 7210 SAS-Mxp, R6, R12, S, Sx, T Interface Configuration Guide.