The way RIP uses holddown timer

[tcherkon]

According to different sources there're two opinions at how RIP uses holddown timer:

1. A router ignores ANY updates about failed network during holddown.

2. A router ignores only updates with worse metric than that it currently has.

What is right and what is wrong?

By the way, regarding second opinion: If a router had received poisoned route (with metric of 16), it starts holddown timer. So, what kind of updates that router ignores, if there's no metric worse than 16 (infinity)?

Thank you!

[ruwhite]

The way holddown works is that the router holds on to the route which it knows has failed, and remembers the old metric. It will ignore any updates with the same route and the same or worse metric until the holddown timer expires. The assumption is that if you receive an update with a worse, or the same, metric, it could be a "count to inifity" loop, and you need to break it.

Russ