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AI2524 Router Card User’s Manual
Page 8-14 August 1997
2524UM
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