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From: brady@DCN9.ARPA.UUCP
Newsgroups: mod.protocols.tcp-ip
Subject: Re:  UDP vs. ICMP dest unreachable messages
Message-ID: <8702121123.AA09025@DCN9.ARPA>
Date: Thu, 12-Feb-87 06:23:14 EST
Article-I.D.: DCN9.8702121123.AA09025
Posted: Thu Feb 12 06:23:14 1987
Date-Received: Sun, 15-Feb-87 00:00:15 EST
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I came in on this discussion a little late, so pardon me if I'm 
a little off topic...

> The problem with this is that there are often transient routing 
> problems.  If you try again, things might actually work.  Until 
> the core gets more reliable, I would rather retry. Indeed for a 
> while we intentionally broke our TCP code so that it would keep 
> trying when it got destination unreachable, instead of aborting 
> the connection.  This helped us keep connnections up to certain 
> hosts.

If you adopt this practice, you negate the purpose of the message. 
So why is it sent in the first place? In the long run, ignoring 
control messages like these could undermine any sort of development
on the internet, particularly in relation to gateway to gateway 
communications. It may seem that some benefit is gained in certain
instances from ignoring unreachable messages. But if there is to 
be a "standard" protocol, such a change would have to be beneficial
(or at least non-detrimental) to the majority of the cases. I believe
that in most cases, the control messages are a necessary factor in 
the control of needless congestion across an already strained internet.


							-Sean