An option to configure a main Class Type (CT) and a backup CT for the primary path of a Diff-Serv TE LSP is provided. The main CT is used under normal operating conditions, for example, when the LSP is established the first time and when it gets re-optimized because of timer based or manual resignal. The backup CT is used when the LSP retries under failure.
The use of backup Class Type (CT) by an LSP is enabled by executing the config>router>mpls>lsp>primary>backup-class-type ct-number command at the LSP primary path level.
When this option is enabled, the LSP uses the CT configured using the following commands (whichever is inherited at the primary path level) as the main CT:
config>router>mpls>lsp>class-type ct-number
config>router>mpls>lsp>primary>class-type ct-number
The main CT is used at initial establishment and during a manual or a timer based resignal Make-Before-Break (MBB) of the LSP primary path. The backup CT is used temporarily to signal the LSP primary path when it fails and goes into retry.
Note that any valid values may be entered for the backup CT and main CT, but they cannot be the same. No check is performed to make sure that the backup CT is a lower CT in Diff-Serv Russian-Doll Model (RDM) admission control context.
The secondary paths of the same LSP are always signaled using the main CT as in existing implementation.