Convergence is when all routers agree on the network topology after a change. Until complete, packets may be dropped or misrouted.
Convergence involves:
Detecting the topology change
Propagating information to other routers
Recalculating best paths
Updating routing tables
Factors affecting convergence time:
- Protocol timers (hello/dead intervals)
- Network size and complexity
- Number of alternative paths
During convergence, you may see temporary routing loops or black holes.