Sr-Te Lsp Paths Using Explicit Sids - Nokia 7705 SAR-W Series Manual

MPLS and RSVP-TE
When the user attempts to change the max-sr-frr-labels parameter to a value that
results in a change to the computed FRR overhead, the IGP checks that all SR-TE
LSPs can properly account for the overhead based on the configuration of the LSP
max-sr-labels and additional-frr-labels values; otherwise, the change is rejected.
The FRR overhead is computed by the IGP and its value is shown in
The above LFA commands allow the user to enable the base LFA feature with the
loopfree-alternates command, and to add remote LFA with the remote-lfa
command and TI-LFA with the ti-lfa command. For more information, refer to the
"Segment Routing in Shortest Path Forwarding" section in the 7705 SAR Routing
Protocols Guide.

3.12.4 SR-TE LSP Paths Using Explicit SIDs

The 7705 SAR allows an explicit SID value to be configured for each hop in an
SR-TE LSP path. The SID value for an SR-TE LSP hop is configured using the
sid-label parameter under the config>router>mpls>path>hop context.
The sid-value parameter specifies an MPLS label value for that hop in the path.
The 7705 SAR supports a path computation method per LSP while allowing a
mix-and-match configuration for primary and secondary paths. For example, primary
and secondary paths can be different types: IP-to-hop paths or SID-based paths.
Note: For PCE delegation, the 7705 SAR only supports LSPs with a single path.
104
• 1 to 3 — the IGP LFA SPF widens the search to include a repair tunnel to a P
node that is connected to the Q nodes with zero to two hops for a total of three
labels maximum: one node SID-to-P node and two adjacency SIDs from the P
node to the Q node. If the P node is a neighbor of the computing node, its node
SID is compressed, meaning that up to three adjacency SIDs can separate the
P and Q nodes.
• 2 (default) — this corresponds to a repair tunnel to a non-adjacent P node that
is adjacent to the Q node. If the P node is a neighbor of the computing node, the
node SID of the P node is compressed and the default value of two labels
corresponds to two adjacency SIDs between the P and Q nodes.
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MPLS Guide
Table 7.
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