CCNA 6.5 Distance-Vector Routing Protocols

• DVR protocol passes complete routing table contents to neighboring routers, which then combined the received routing entries with their own routing tables to complete the router's routing table
• Pinhole congestion (RIP) :

• Initial routing table with DVR (IP, Exit Interface, Hop Count):

• DVR - slow convergence time
• Converged routing tables:

• DVR keeps track of changes to internetwork by broadcasting periodic routing updates out all active interface
• Routing loops (counting to infinity) occur when every router isn't updated simultaneously
• Maximum hop - RIP up to 15 (solve routing loops)
• Splilt horizon enforce the rule that routing info cannot be sent back in the direction from which it was received (solve routing loops)
• Route poisoning assigns down network with hop counts of 16 or unreachable/infinite (solve routing loops)
• A holddown prevents regular update messages from reinstating a route that is going up and down (flapping)