Intelligent IGP Link Costing Algorithms?

William Charnock will at
Fri Jan 11 16:18:28 UTC 2002

For IGP metrics, I use a formula that goes like this:


Where m is the metric, d is the distance between the endpoints, l is the
latency, and s is the link speed (in Mbps)

Works well for us

William R. Charnock
Director Core Technology
Allegiance Telecom, Inc.
469.259.2260 (V)
469.259.9079 (F)

----- Original Message -----
From: "Joel Krauska" <jkrauska at>
To: <nanog at>
Sent: Thursday, January 10, 2002 11:49 PM
Subject: Intelligent IGP Link Costing Algorithms?

> Does anyone use intelligent algorithms for determining IGP costs?
> It's a widely academic topic on solving a NP-Hard problem, but
> I've found most providers tend to stick to simple functions
> based on RTT and link capacity.
> With bandwidth costs becoming more and more reasonable, it
> also seems to have been a simple "get bigger pipes" between
> point A and B solution.
> However, with budgets being tighter, I would assume some
> more thought has been put in to using more intelligent
> methods of traffic optimization.
> (briefly ignoring the MPLS TE "solution")
> An added twist appears to be that a full demand matrix
> is difficult to build without large systems of flow
> collection. I'm curious if the problem can easily be
> approached without full insight in to this data.
> (per link usage yes, but without end-to-end flows)
> I've seen a few modeling applications, but nothing that
> attempts to solve the general optimization problem.
> Thoughts?  Is there a need for something like this?
> Are there existing effective solutions?
> Thanks,
> Joel Krauska

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