MBGP—Capability Negotiation

BGP routers establish BGP sessions through the OPEN message
OPEN message contains optional parameters
BGP session is terminated if OPEN parameters are not recognised
New parameter: CAPABILITIES
- Multiprotocol extension
- Multiple routes for same destination

Configures router to negotiate either or both NLRI

If neighbor configures both or subset, common NRLI is used in both directions
If there is no match, notification is sent and peering doesn’t come up
If neighbor doesn’t include the capability parameters in open, session backs off and reopens with no capability parameters
- Peering comes up in unicast-only mode