ADTRAN 1000R Series

Command Reference Guide Global Configuration Mode Command Set

Now consider a route that was learned and does not receive an update for 180 seconds. The route is

marked for deletion, and even if it was l earned on an interface, a poisoned (metric =16) route should be

sent by itself immediately and during the next two update cycles with the remaining normal split horizon

update routes. Following actual deletion, the poison reverse update ceases. If an update for a lea rned

route is not re ceived for 180 seconds, the rou te is marked for d eletion. At that point, a 120-second garba ge

collection (GC) timer is started. During the GC timer period, expiration updates are sent with the metric for

the timed-out route set to 16.

If an attached interface goes down, the associated route is immediately (within the same random

five-second interval) triggered. The next regular update excludes the failed interface. This is the so-called

first hand knowledge rule . If a gateway has first hand knowled ge of a route failure (conn ected interfaces) or

reestablishment, the same action is taken. A triggered update occurs, advertising the route as failed

(metric = 16) or up (normal metric) followed by the normal scheduled update.

The assumption here is that if a gateway missed the triggered update, it will eventually learn from another

gateway in the standard convergence pr ocess. This conserves bandwidth.

RIP-Related Definitions:

Route A description of the path and its cost to a network.

Gateway A device that implements all or part of RIP (a router).

Hop A metric that provides the integer distance (number of inte r ven in g ga te wa ys) to a

destination ne tw or k ga teway.

Advertisement A broadcast or multicast packet to port 520 that indicates the route for a given

destination ne tw or k.

Update An advertisement sent on a regular 30-second interval including all routes

exclusive of those learned on an interface.