This section describes how MPLS OAM models the SR tunnel types.
An SR shortest path tunnel, SR-ISIS or SR-OSPF tunnel, uses a single FEC element in the target FEC stack TLV. The FEC corresponds to the prefix of the node SID in a specific IGP instance.
The following figure shows the format of the IPv4 IGP-prefix segment ID.
In this format, the fields are as follows:
IPv4 prefix
The IPv4 Prefix field carries the IPv4 prefix to which the segment ID is assigned. For an anycast segment ID, this field carries the IPv4 anycast address. If the prefix is shorter than 32 bits, trailing bits must be set to zero.
Prefix length
The Prefix Length field is one octet. It gives the length of the prefix in bits; allowed values are 1 to 32.
Protocol
The Protocol field is set to 1 if the IGP protocol is OSPF and 2 if the IGP protocol is IS-IS.
Both lsp-ping and lsp-trace apply to the following contexts:
SR-ISIS or SR-OSPF shortest path IPv4 tunnel
SR-ISIS IPv4 tunnel stitched to an LDP IPv4 FEC
BGP IPv4 LSP resolved over an SR-ISIS IPv4 tunnel or an SR-OSPF IPv4 tunnel; including support for BGP LSP across AS boundaries and for ECMP next-hops at the transport tunnel level