BGP message types

BGP uses the following message types:

• Open—After establishing a TCP connection, BGP sends an OPEN message to establish a session to the peer.

• Update—BGP sends UPDATE messages to exchange routing information between peers. Each UPDATE message can advertise a group of feasible routes with identical attributes and multiple withdrawn routes.

• Keepalive—BGP sends KEEPALIVE messages between peers to maintain connectivity.

• Route-refresh—BGP sends a ROUTE-REFRESH message to request the routing information for a specific address family from a peer.

• Notification—BGP sends a NOTIFICATION message upon detecting an error and immediately closes the connection.