This feature provides operations with the ability to manually enter the link members of SRLG groups for the entire network at any SR OS which needs to signal LSP paths (for example, a head-end node).
The operator may explicitly enable the use by CSPF of the SRLG database. In that case, CSPF does not query the TE database for IGP advertised interface SRLG information.
Note, however, that the SRLG secondary path computation and FRR bypass/detour path computation remains unchanged.
There are deployments where the SR OS interoperates with routers that do not implement the SRLG membership advertisement via IGP SRLG TLV or sub-TLV.
In these situations, the user is provided with the ability to enter manually the link members of SRLG groups for the entire network at any SR OS which needs to signal LSP paths, for example, a head-end node.
The user enters the SRLG membership information for any link in the network by using the interface ip-int-name srlg-group group-name command in the config>router>mpls> srlg-database>router-id context. An interface can be associated with up to 5 SRLG groups for each execution of this command. The user can associate an interface with up to 64 SRLG groups by executing the command multiple times. The user must also use this command to enter the local interface SRLG membership into the user SRLG database. The user deletes a specific interface entry in this database by executing the no form of this command.
The group-name must have been previously defined in the srlg-group group-name value group-value command in the config>router>if-attribute. The maximum number of distinct SRLG groups the user can configure on the system is 1024.
The parameter value for router-id must correspond to the router ID configured under the base router instance, the base OSPF instance or the base IS-IS instance of a specific node. Note however that a single user SRLG database is maintained per node regardless if the listed interfaces participate in static routing, OSPF, IS-IS, or both routing protocols. The user can temporarily disable the use by CSPF of all interface membership information of a specific router ID by executing the shutdown command in the config>router>mpls> srlg-database> router-id context. In this case, CSPF assumes these interfaces have no SRLG membership association. The operator can delete all interface entries of a specific router ID entry in this database by executing the no router-id router-address command in the config>router>mpls> srlg-database context.
CSPF does not use entered SRLG membership if an interface is not listed as part of a router ID in the TE database. If an interface was not entered into the user SRLG database, it is assumed that it does not have any SRLG membership. CSPF does not query the TE database for IGP advertised interface SRLG information.
The operator enables the use by CSPF of the user SRLG database by entering the user-srlg-db enable command in the config>router>mpls context. When the MPLS module makes a request to CSPF for the computation of an SRLG secondary path, CSPF queries the local SRLG and computes a path after pruning links which are members of the SRLG IDs of the associated primary path. Similarly, when MPLS makes a request to CSPF for a FRR bypass or detour path to associate with the primary path, CSPF queries the user SRLG database and computes a path after pruning links which are members of the SRLG IDs of the PLR outgoing interface.
The operator can disable the use of the user SRLG database by entering the user-srlg-db disable in command in the config>router>mpls context. CSPF then resumes queries into the TE database for SRLG membership information. However, the user SRLG database is maintained
The operator can delete the entire SRLG database by entering the no srlg-database command in the config>router>mpls context. In this case, CSPF assumes all interfaces have no SRLG membership association if the user has not disabled the use of this database.