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From: Mills@UDEL.EDU.UUCP
Newsgroups: mod.protocols.tcp-ip
Subject: Re:  network horror stories
Message-ID: <8703272058.a020394@Huey.UDEL.EDU>
Date: Fri, 27-Mar-87 20:58:56 EST
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Posted: Fri Mar 27 20:58:56 1987
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Rudy,

You are referring to what are called "hard-to-reach" (HTR) numbers. Clever
switches remember HTR prefixes in order to back congestion up towards the
source. Now consider doing the same thing in an IP gateway. All it has to
do is wiretap ICMP messages on the way back to the sender and cache the
information for awhile. You may remember the general reaction (horror)
in response to this suggestion some time back. Many consider wiretapping
ICMP messages something only a little less sinful than forwarding
redirects across gateways. Considering the almost universal practice
of ignoring ICMP error messages, perhaps your comment may spark a minor
change in that thinking.

Dave