BGP - Border Gateway Protocol (2)
3 types of routing between BGP routers
- intra-autonomous system routing
- inter-autonomous system routing
- pass-through autonomous system routing
BGP operation
- maintains routing tables (lists all physical paths to a particular network)
- transmits routing updates (routers send the portion of their routing tables that have changed)
- bases routing decisions on routing metrics
- keeps information about global topology of network
Types of BGP messages (version 4)
- open messages (open BGP communication session)
- update message (provides routing updates to other BGP systems; TCP )
- notification message (sent when error occurs)
- keep-alive message - notify BGP peers that a device is still alive)