Routing Information Protocol (RIP)
Tables (vectors) “advertised” to neighbors every 30 s.
Counting-to-infinity problem:
- Simple configuration A->B->C. If C fails, B needs to update and thinks there is a route through A. A needs to update and thinks there is a route thru B.
- No clear solution, except to set “infinity” to be small (eg 16)
- Split-horizon: If A’s route to C is thru B, then A advertises C’s route (only to B) as infinity.
Slow convergence after topology change:
- Due to count to infinity problem
- Also information cannot propagate through a node until it recalculates routing info.