MPLS Guide MPLS and RSVP-TE
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FRR Bypass Tunnel or Detour LSP SRLG Disjoint Configuration
• Create an SRLG-group (similar to creating an admin group).
• Link the SRLG-group to MPLS interfaces.
• Enable the strict option on the srlg-frr command, which is a system-wide
command that forces the CSPF calculation for every LSP path to take any
configured SRLG memberships into account.
• Configure primary FRR (facility backup or one-to-one backup) LSP paths. Each
PLR will create a bypass or detour LSP that will only avoid the SRLG
memberships configured on the primary LSP path egress interface. For one-to-
one backup, detour-detour merging is out of the control of the PLR. The PLR will
not ensure that the FRR detour will be prohibited from merging with a colliding
detour LSP. For facility backup, given that there are several bypass types to bind
to, the priority rules shown in Disjoint and Non-disjoint Paths are used.
Manually configured bypasses that do not use CSPF are not considered as possible
backup paths.
Figure 10 Disjoint Primary and Secondary LSPs
Secondary path taking SRLG_1 into account
Primary path
A-B
ABC D
EFH
G
J
B-C C-D
SRLG_1 SRLG_1 SRLG_1
Legend:
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