Traffic Engineering (fwd)

Eric Germann ekgermann at
Thu Sep 18 21:16:13 UTC 1997

At 04:31 PM 9/18/97 -0400, Sean M. Doran wrote:
>Perhaps you could explain to me how you can find the
>shortest path between A and B using ping times, traceroute
>hop counts, and AS_PATHS observed at C, assuming that
>traffic between A and B is not exchanged through C?

You're not trying to find it between A and B.  A connects to B, but B has
every intention of redirecting to C1, C2, or C3, etc.

If B can communicate with some measurement tool on Cx, they can all report
back on their "connectivity" to A.  B can then redirect A to the "best" Cx
node.  If the results are inconclusive, round robin it.  If B had knowledge
of BGP and AS's, maybe it wouldn't have to decide on distance but instead
search for a Cx which was nearest to B in the AS_PATH.  The premise being
it may be better to pick a Cx nearest me in my upstream, as opposed to
driving it through some overloaded exchange point.

Granted, ping tends to get dropped on the floor at overloaded points, and
traceroute probably isn't a) too much better b) probably blocked in some
(most) cases, but are there any better alternatives?  Anyone know of some
reasonably available methods for measuring end to end "performance" which
are almost universally implemented?

Kind of making do with what we have.

#Included junk

>From Network World

Olympic effort could be much more 
By Marc Myers


     If you, like me, are among the six million people that have succumbed 
to the temptation of visiting IBM's Olympics Web site (http://www., don't feel bad for having wasted company time. Just 
tell your boss that you are reviewing one of the most phenomenal 
technological feats of the decade: a worldwide network constructed in just 
15 months.
     The project - though it has run into some technical snags during the 
early going - demonstrates how much can be accomplished when an immutable 
deadline is accompanied by a virtually unlimited budget. IBM provided a $40 
million sponsorship, but the company's actual expenses probably exceeded $1 
     The Internet setup utilizes two primary RS/6000 SP2 multiprocessing 
servers, one of which hums away on 52 processors in Southbury, Conn., while 
its buddy chugs along on 16 processors in Hawthorne, N.Y. Mirror servers 
run in Asia, Europe and the U.S. IBM developed new load-balancing software 
as part of its Web Object Manager that optimizes traffic, automatically 
finding and tapping the most available servers. Other aspects of the system 
- including the Global Shared Data Center - are so secret that we don't 
even know where they operate from.
     For surfers who are into the Olympics, the services offered are 
superlative: You can get game results almost as fast as the major networks, 
download images and flicks of the world's greatest athletes and shop for 
official Olympic products.
     But what I find most appealing about this system is that it was built 
so quickly and with such creativity.
     What if IBM decided that this was something that could be done more 
than once?

[snip ...]

Eric Germann				Computer and Communications Technologies
ekgermann at			Van Wert, OH 45891
					Phone:	419 968 2640			Fax:	419 968 2641

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