srlg-disjoint

Use this command to set how to avoid the Shared Risk Link Groups (SRLGs) of a protected primary.

A fast-reroute or secondary path for an LSP that is disjoint from the primary ensures that a single point of failure on a particular link does not bring down both the primary and secondary paths in the LSP.

 

  • The SRLG option configured in RSVP-TRUNK mode (see the secondary-priority srlg-disjoint command) takes higher preference than the option configured in RSVP router mode (this command).

  • For one-to-one protection, when both “primary fast-reroute node-protection” and “srlg-disjoint preferred” commands are configured, detour path selection occurs in the following order:

    • Find a path for “Node protection along with SRLG protection”; if no path is found, then

    • Find a path for “Link protection along with SRLG protection”; if no path is found, then

    • Find a path for “Node protection without SRLG protection”; if no path is found, then

    • Find a path for “Link protection without SRLG protection”.

• When SRLG disjointness is configured on a PLR, auto-bypass tunnels are created using the SRLG constraints of the outgoing interface for the protected LSP. If the SRLG values on that interface are updated, a new auto-bypass tunnel reflecting the revised SRLG set is created and used to protect the LSPs. The previous auto-bypass tunnel is marked invalid and is removed after all protected LSP references to that tunnel are cleared.

Use the no form of this command to not avoid the SRLGs of a protected interface.

Command Syntax

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srlg-disjoint (forced|preferred)
no srlg-disjoint

Parameters

forced

The router does not create the secondary or backup tunnel unless it avoids SRLGs of the primary-path/protected-interface.

preferred

With two explicit paths, the first explicit path tries to avoid the SRLGs of the primary-path/ protected interface. If that does not work, the secondary or backup tunnel uses the second path (which ignores SRLGs).

Default

None

Command Mode

Router RSVP mode

Applicability

This command was introduced before OcNOS version 1.3.

Example

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#configure terminal 
(config)#router rsvp 
(config-rsvp)# srlg-disjoint forced