One has to be careful about interpreting the results in this paper.
The results hold only if:
1. All demands are equal (stems from the formulation)
2. All link capacities are equal (a fact hidden in half a sentence)
If link capacities are different it is clear their results do not hold
even if all demands are the same.
I did not attempt to check the correctness of their claim
when the above two assumption hold.
Yuval
-----Original Message-----
From: Van Jacobson [mailto:van@packetdesign.com]
Sent: Fri, March 23, 2001 4:21 AM
To: irtf-rr@puck.nether.net
Subject: interesting Infocom paper on traffic engineering via routing
metrics
There's a paper in this year's Infocom that manages to prove MPLS is
unnecessary for traffic engineering. It shows that for *any* set of
LSPs, it is possible to compute a set of routing link metrics that
result in exactly the same traffic flow. This is slightly surprising
since for N nodes there are typically O(N^2) LSPs but only O(N) links so
there's a huge difference in information content between the two
approaches. But their development shows that the problem is so
conditioned by flow balance contraints (ie., all the flow that enters a
node must leave it) that O(N) parameters (the link metrics) are
sufficient to completely specify the solution.
If anyone's interested, the paper is available at:
http://infocom.ucsd.edu/papers/744-2798113708.pdf
- Van
-- Yuval Shavitt Dept. of Electrical Engineering - Systems Tel Aviv University, Tel Aviv 69978, Israel Tel: +972 3 640 8659 Fax: +972 3 640 7095 URL: http://www.eng.tau.ac.il/~shavitt
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