BGP (contd)
BGP sets up TCP connection between peers
- Exchange entire BGP table first
- Later exchanges only incremental updates
- Application (BGP)-level keepalive messages
# of paths proportional to number of AS
But, memory requirement: proportional to number of networks (one entry per network)
Path attributes: list of traversed AS and list of reachable networks
Interior and exterior peers: need to exchange reachability information among interior peers before updating intra-AS routing tables