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Cell Relay Retreat>MPLS-OPS Archive>month:2003-Nov> msg00104



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CR algorithm

  • From: nbwaite@attglobal.net
  • Date: Fri, 28 Nov 2003 11:59:02 -0500 (EST)
  • Resent-Date: Fri, 28 Nov 2003 12:32:43 -0500
  • To: mpls-ops@mplsrc.com

Bhavesh Modi:

Saw your post with:

>    I have 2 questions:
>
>    1. Which are the constraints that are specified ( other
>    than bandwidth ) generally to determine a constrait based
>    route?
>
>    2. Which are the algoriths generally used for determinig
>    a constraint based route?

If the constraints are severe enough, then the problem can get
complicated.  In particular, the problem can be in the class
parts of the research community call 'NP-complete' where 'NP'
abbreviates 'non-deterministic polynomial'.  NP-complete
theory is an extensive topic with some unsolved problems:  In
practice, large NP-complete problems tend to be challenging to
solve, but generally attacks can be successful.  For such
attacks, it is possible to use manual or simple methods, but
it is fair to say that the most powerful attacks are via
'integer optimization'.

As bad as this can be for operations, for design it is worse
because (1) there is much more to design than to operations
(getting solutions for operations is a special case of
design), (2) in operations mostly we just want a solution
using existing deployments while in design we are saying how
to spend money, and (3) operations is concerned mostly with
just the short term while in design we want to consider the
longer term and its uncertainties.

Norman B. Waite, Ph.D.
Network Architectonics
9 Fox Run
Wappingers Falls, NY 12590
nbwaite@attglobal.net
845-227-7821

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