Subject: cost of link changing

From: John Smith <[email-masked]>
Date: Fri, 16 May 2003 15:51:53 +0100

Hi,
I want to know if the cost of a link between two routers can change anytime because of
some Traffic Engg. module running or something?

Say this link gets congested then can i somehow increase the cost of this link so that
OSPF may take appropriate actions (choose an alternative lesser congested link, etc)? OR
does the cost once assigned to the link remain constant and unchanged unless the admin
actually changes it manually?

Thanks,
Smith

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From: Acee Lindem <[email-masked]>
Date: Fri, 16 May 2003 11:13:34 -0400

> some Traffic Engg. module running or something?

Hi John,

There is no provision for dynamically modifying the cost in base OSPF. For
traffic engineered paths, IGP metric is just one factor that may be considered.

> actually changes it manually?

In base OSPF, the cost will not change unless there is a configuration change (or
possibly an underlying link speed change). There was a fairly good proposal to
influence selection among equal-cost multipath routes based on congestion.
It was never standardized and I'm not sure if anyone has implemented it.

http://www.watersprings.org/pub/id/draft-ietf-ospf-omp-02.txt

Thanks,
Acee

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Acee