The user enables the use of the admin-group constraints in the association of a manual or dynamic bypass LSP with the primary LSP path at a Point-of-Local Repair (PLR) node using the following global command:
config>router>mpls>admin-group-frr
When this command is enabled, each PLR node reads the admin-group constraints in the FAST_REROUTE object in the Path message of the LSP primary path. If the FAST_REROUTE object is not included in the Path message, then the PLR reads the admin-group constraints from the Session Attribute object in the Path message.
If the PLR is also the ingress LER for the LSP primary path, then it just uses the admin-group constraint from the LSP or path level configurations.
Whether the PLR node is also the ingress LER or just an LSR for the protected LSP primary path, the outcome of the ingress LER configuration dictates the behavior of the PLR node and is summarized in Table: Bypass LSP admin-group constraint behavior.
| Ingress LER configuration | Session attribute | FRR object | Bypass LSP at PLR (LER/LSF) follows admin-group constraints | |
|---|---|---|---|---|
1 |
frr-object lsp>no propagate-admin group lsp>frr>propagate-admin-group |
Admin color constraints not sent |
Admin color constraints sent |
Yes |
2 |
frr-object lsp>propagate-admin-group lsp>frr>propagate-admin group |
Admin color constraints sent |
Admin color constraints sent |
Yes |
3 |
frr-object lsp>propagate-admin group lsp>frr>no propagate-admin-group |
Admin color constraints sent |
Admin color constraints not sent |
No |
4 |
No frr-object lsp>propagate-admin group lsp>frr>propagate-admin-group |
Admin color constraints sent |
Not present |
Yes |
5 |
No frr-object lsp>no propagate-admin group lsp>frr>propagate-admin-group |
Admin color constraints not sent |
Not present |
No |
6 |
No frr-object lsp>propagate-admin group lsp>frr>no propagate-admin-group |
Admin color constraints sent |
Not present |
Yes |
The PLR node then uses the admin-group constraints along with other constraints, such as hop-limit and SRLG, to select a manual or dynamic bypass among those that are already in use.
If none of the manual or dynamic bypass LSP satisfies the admin-group constraints or the other constraints, the PLR node requests CSPF for a path that merges the closest to the protected link or node and that includes or excludes the specified admin-group IDs.
If the user changes the configuration of the above command, there is no effect on existing bypass associations. The change only applies to new attempts to find a valid bypass.