The autonomous system number and router ID configured in the VPRN context only applies to that particular service.
The minimal parameters that should be configured for a VPRN BGP instance are:
Specify an autonomous system number for the router. See Configuring Global VPRN Parameters.
Specify a router ID - If a new or different router ID value is entered in the BGP context, then the new values takes precedence and overwrites the VPRN-level router ID. See Configuring Global VPRN Parameters.
Specify a VPRN BGP peer group.
Specify a VPRN BGP neighbor with which to peer.
Specify a VPRN BGP peer-AS that is associated with the above peer.
VPRN BGP is administratively enabled upon creation. Minimally, to enable VPRN BGP in a VPRN instance, you must associate an autonomous system number and router ID for the VPRN service, create a peer group, neighbor, and associate a peer AS number. There are no default VPRN BGP groups or neighbors. Each VPRN BGP group and neighbor must be explicitly configured.
All parameters configured for VPRN BGP are applied to the group and are inherited by each peer, but a group parameter can be overridden on a specific basis. VPRN BGP command hierarchy consists of three levels:
the global level
the group level
the neighbor level
For example:
config>service>vprn>bgp# (global level)
— group (group level)
— neighbor (neighbor level)
The local-address must be explicitly configured if two systems have multiple BGP peer sessions between them for the session to be established.
For more information about the BGP protocol, refer to the 7450 ESS, 7750 SR, 7950 XRS, and VSR Router Configuration Guide.