When the router removes the GRE encapsulation, pops one or more labels and then swaps a label, it acts as an LSR. The LSR hashing for packets of a MPLS-over-GRE SDP or tunnel follows a different procedure, which is enabled automatically and overrides the LSR hashing option enabled on the incoming network IP interface (lsr-load-balancing {lbl-only | lbl-ip | ip-only | eth-encap-ip | lbl-ip-l4-teid}).
On a packet-by-packet basis, the new hash routine parses through the label stack and:
The new hash routine hashes on the SA/DA fields and the Layer 4 SRC/DST Port fields of the inner IPv4/IPv6 header.
If the GRE header and label stack sizes are such that the Layer4 SRC/DST Port fields are not read, it hashes on the SA/DA fields of the inner IPv4/IPv6 header.
If the GRE header and label stack sizes are such that the SA/DA fields of the inner IPv4/IPv6 header are not read, it hashes on the SA/DA fields of the outer IPv4/IPv6 header.