Explains MPLS TE adjacency support, including its integration with IS-IS, logical link operation for LSP tunnels, creation and advertisement of forwarding adjacencies, and technical prerequisites needed before configuring or verifying IS-IS behavior.
MPLS TE adjacency is a traffic engineering feature that
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enables a Label Switch Path (LSP) tunnel to operate as a logical link within an Interior Gateway Protocol (IGP) network using the Shortest Path First (SPF) algorithm,
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allows creation of forwarding adjacencies between routers in the same IS-IS level, even if the routers are several hops apart, and
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advertises TE tunnels as links with specific cost metrics, helping routers outside the TE domain calculate shortest paths for routing traffic.
MPLS TE adjacency support is considered in IS-IS SPF only if a two-way connectivity check is achieved. This check can be satisfied if the forwarding adjacency is bidirectional or if the head-end and tail-end routers of the MPLS TE tunnel are adjacent.
The MPLS TE adjacency support feature is available in IS-IS. For configuration instructions, see the MPLS Configuration Guide.