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Webcast-Catalyst9k
New Member

Bandwidth as it relates to IGRP Metric

Two T1 links between same two routers. Both links BandWidth set to 1544.

One link is unstable.

Protocols on both links are the same, IP and Vines.

Want the unstable link to carry very little (no) traffic only until the stable link goes down (if it ever does).

Show Serial Interface Documentation indicates the BandWidth parameter is used to compute IGRP Metrics only.

Does the computation follow consistently from BW to IGRP Metric?

Do I give my UNSTABLE link a BW of 1544; my STABLE link a BW of 768 (for example). Thanks in advance. MM

1 REPLY
New Member

Re: Bandwidth as it relates to IGRP Metric

The bandwidth is used for the metric but also for other purposes like the load ratio in show interfaces.

In the IGRP calculation the minimum bandwidth along a path is taken so you have to make sure that you don't have any routes with bandwidths smaller than you T1/768k link. To make the unstable link less preferable configure it a smaller bandwidth (like in your example). The stable link should stay at T1 BW.

Regards,

Mat

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