Subject: Re: PMTUD blackhole detection
To: None <>
From: Darren Reed <>
List: tech-net
Date: 05/01/2001 19:45:15
In some email I received from, sie wrote:
> >> 	on PR 12790, I posted a simple patch for TCP PMTUD blackhole detection.
> >> 	if there's no ack for a while, the patch will do the following:
> >[...]
> >
> >What if there is no ACK, but ICMP unreachable errors that are not
> >"need fragmentation" - will they reset the timer (I think they should) ?
> 	i did not change that part of the codepath.  icmp unreachables will
> 	be counted, and if the count reaches maximum, the connection will
> 	be terminated.

That's not what I was asking.

What I meant was, if you are waiting at most time X for an ACK before
disabling PMTU, if you get an ICMP host unreachable at X/2, will PMTU
still be disabled after time X or will it wait until time X + X/2 ?