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Re: Internet Backbone Index
From: "Jay R. Ashworth" <jra () scfn thpl lib fl us>
Date: Sun, 13 Jul 1997 19:44:06 -0400

On Sun, Jul 13, 1997 at 03:08:00PM -0800, Randy Bush wrote:
There is one significant difference between routed and switched backbones.
The hops on routed backbones can be seen by end users using tools such as
traceroute.  On switched backbones, the hops are still there, but can not be
seen by end users.  Hence the marketing perception is different though the
results are really the same.

Actually, from the IP packet's standpoint, no, the results aren't
necessarily the same.  It's unlikely, but possible, that a switched
mesh backbone could forward some packets that a routed one couldn't,
due to TTL issues.  

Didn't some older kernels set rediculously low TTLs on IP packets?

The router side could turn the argument.  "With a routed backbone, you can
actually SEE what is happening to your packets.  It is not a hidden unknown,
thus prone to failure you can not diagnose.  With routers you know it went
bad at nqu1.  With switches, it just went bad."

It's a problem I'd accept for this amount of debugging flexibility,
though.

Cheers,
-- jra
-- 
Jay R. Ashworth                                                jra () baylink com
Member of the Technical Staff             Unsolicited Commercial Emailers Sued
The Suncoast Freenet      "People propose, science studies, technology
Tampa Bay, Florida          conforms."  -- Dr. Don Norman      +1 813 790 7592


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