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Re: Traffic engineering tools

  • From: Andrew Bender
  • Date: Tue Oct 26 14:07:42 1999

> From [email protected] Tue Oct 26 05:39:16 1999
> Date: Mon, 25 Oct 1999 22:13:35 -0700
> From: Tony Li <[email protected]>
> To: Alex P. Rudnev <[email protected]>
> Cc: Vadim Antonov <[email protected]>, [email protected], [email protected],
>      [email protected]
> Subject: Re: Traffic engineering tools
> Alex,
> You are absolutely correct.  A critically damped, dynamic traffic engineering system would provide benefits above and beyond that which can be derived in a static system.
> However, the dynamic system is non-trivial to construct.  As has been shown with routing protocols that react to dynamic changes, it is very easy to underdamp the system, with catastrophic results.
> I certainly believe that such dynamic systems are possible, and certainly folks with enough
> background in control theory could contribute wonderfully here.  However, the state of the art
> isn't quite there yet.  Sigh.
>                             "And that's the way it is..."
>                                                     - Walter Cronkite

Hear, hear! 

Beside simply solving the static minimization problem, decentralized
computation, and consideration of disjoint restoration paths are what I see to
be necessary prerequisites ( and arguably quite "interesting" ones ) for the
realization of dynamic TE.

Evading these is something that we seem to have succeeded at, as engineers. As
"easy" as it may be to prove the computational complexity of a problem, I find
offense instead in equating such a result with a decisive judgement on practical
tractability. I agree with Mr. Li that this is an approachable domain, although
many of its challenges remain areas of active interest.

The design of contemporary network elements suggests the unfortunate level of
attention this topic receives. Despite impressive improvements in datapath,
equipment control planes still seem to be sized / designed for maintenance of
traditional topologies with established methods. 1000MIPS* integer cores are
readily available in general purpose, commodity devices, and higher performance
is neither impractical nor unknown. 

The possibilities this suggests for performance headroom of control systems
should permit more serious consideration of practical solutions for dynamic TE
than is observed today, dispensing with easy reasons not to implement path
otimization or TE as a (semi-) automated, online function.

Andrew Bender
Total Network Solutions, Inc.

(* Yes, this metric is an arbitrary and somewhat bogus oversimplication)