When the node operates as an LER and forwards unlabeled packets over an endpoint policy, the spraying of packets over the multiple NHGs of type direct or over the resolved next hops of a single NHG of type indirect follows prior implementation. Refer to the 7450 ESS, 7750 SR, 7950 XRS, and VSR Interface Configuration Guide.
When the node operates as an LSR, it forwards labeled packets matching the ILM of the binding label over the label-binding policy. An MPLS packet, including a MPLS-over-GRE packet, received over any network IP interface with a binding label in the label stack, is forwarded over the primary or backup next hop of either the single NHG of type indirect or of a selected NHG among multiple NHGs of type direct.
The router performs the following procedures when spraying labeled packets over the resolved next hops of a NHG of resolution type indirect or over multiple NHGs of type direct.
The router performs the GRE header processing as described in MPLS-over-GRE termination if the packet is MPLS-over-GRE encapsulated. Refer to the 7450 ESS, 7750 SR, 7950 XRS, and VSR Router Configuration Guide.
The router then pops one or more labels and if there is a match with the ILM of a binding label, the router swaps the label to implicit-null label and forwards the packet to the outgoing interface. The outgoing interface is selected from the set of primary or backup next hops of the active policy based on the LSR hash on the headers of the received MPLS packet.
The hash calculation follows the method in the user configuration of the command lsr-load-balancing {lbl-only | lbl-ip | ip-only} if the packet is MPLS-only encapsulated.
The hash calculation follows the method described in LSR Hashing of MPLS-over-GRE Encapsulated Packet if the packet is MPLS-over-GRE encapsulated. Refer to the 7450 ESS, 7750 SR, 7950 XRS, and VSR Interface Configuration Guide.