AIS AI2524 user manual Disable Holddown, Enforce a Maximum Network Diameter, System designer

AI2524 Router Card User’s Manual

work performance, however, so ensure that you make all metric ad- justments carefully.

Note:	Because of the complexity of this task, we recommend that
	you only perform it with guidance from an experienced
	system designer.

To adjust the IGRP metric weights, type this command in router con- figuration mode:

metric weights tos k1 k2 k3 k4 k5

By default, the IGRP composite metric is a 24-bit quantity that is a sum of the segment delays and the lowest segment bandwidth (scaled and inverted) for a given route. For a network of homogeneous media, this metric reduces to a hop count. For a network of mixed media (FDDI, Ethernet, and serial lines running from 9600 bps to T1 rates), the route with the lowest metric reflects the most desirable path to destination.

Disable Holddown

When the Cisco IOS software learns that a network is at a greater dis- tance than was previously known, or it learns the network is down, th route to that network is placed in holddown. During the holddown pe- riod, the route is advertised, but incoming advertisements about that network from any router other than the one that originally advertised the network's new metric will be ignored. All devices in an IGRP au- tonomous system must be consistent in their use of holddowns. To dis- able holddowns with IGRP, type this command in router configuration mode:

no metric holddown

Enforce a Maximum Network Diameter

The Cisco IOS software enforces a maximum diameter to the IGRP network. Routes whose hop counts exceed this diameter are not adver- tised. The default maximum diameter is 100 hops. The maximum di- ameter is 255 hops.

To configure the maximum diameter, type this command in router configuration mode:

metric maximum-hops hops

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