Understanding BGP neighbors

BGP neighbors are routers forming TCP connection for exchanging BGP updates. They are also called BGP Peers or BGP Speakers.

There are two types of BGP relationship:

  • IBGP (Internal BGP)
  • EBGP (External BGP)

BGP Databases

Neighbor table

  • a list of all configured BGP neighbors
  • neighbor has to be manually configured using neighbor command
  • we have lots of variations regarding neihborship like internal bgp neighbors, external neighbors, neighborship using loopbacks, route reflectors, peer groups, etc…
  • #sh ip bgp summary
  • #sh ip bgp neighbors

BGP forwarding table/database

  • A list of networks known by BGP, along with their paths and attributes
  • #sh ip bgp

IP routing table

  • List of best paths to destination networks
  • sh ip route