From mboxrd@z Thu Jan  1 00:00:00 1970
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
In-reply-to: Your message of "Wed, 01 Jun 2011 21:23:48 EDT."
	<37aa028227cbf68318c2703b7c6bf5ae@ladd.quanstro.net>
References: <3c94c382decb6fec1b6fe5df7b29da66@ladd.quanstro.net>
	<alpine.OSX.2.00.1106011811560.26468@haldir.orthanc.ca>
	<37aa028227cbf68318c2703b7c6bf5ae@ladd.quanstro.net>
Date: Wed,  1 Jun 2011 18:42:24 -0700
From: Bakul Shah <bakul@bitblocks.com>
Message-Id: <20110602014224.198F4B827@mail.bitblocks.com>
Subject: Re: [9fans] icmp unreachable messages sometimes dropped
Topicbox-Message-UUID: ea3fa8b2-ead6-11e9-9d60-3106f5b1d025

On Wed, 01 Jun 2011 21:23:48 EDT erik quanstrom <quanstro@quanstro.net>  wrote:
> On Wed Jun  1 21:18:26 EDT 2011, lyndon@orthanc.ca wrote:
> > > i didn't have time to fully debug this situation today, but i
> > > noticed that on some hosts, icmp unreachable messages do not
> > > terminate the connection, though snoopy did see the icmp packet.
> >
> > Nor should they.  A temporary routing flap is no reason to arbitrarily
> > tear down a viable TCP connection.  Instead, tell the application and let
> > it decide what to do.
>
> this was on initial connection.  plan 9 ignores icmp unless it's waiting for
> the initial response.

SHOULD abort a connection for destination unreachable codes
2-4, but not for codes 0, 1 & 5. See rfc1122 2.4.3.9.