Count to Infinity Problem With Distance-Vector Routing Protocols
Posted on 2011-03-08
I'm revising for my Cisco CCNA. I understand the general concept of count-to-infinity, but I have a problem with it: It was my understanding that routing tables only updated themselves if they were sent updates with routes that were shorter than that already stored. With the count-to-infinity scenario, the routing metric will always be bigger than that currently stored in the table, so the router shouldn't update the routing table to include it. How then, does the metric ever rise to infinity? And if this isn't the case (i.e. routers update regardless of metric values), surely the routing table can't be described as "a table containing the shortest known paths to different networks"?