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Date: Wed, 04 May 2005 16:53:38 +0200
From: Andre Oppermann <andre@freebsd.org>
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To: Bruce M Simpson <bms@spc.org>
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Subject: Re: cvs commit: src/sys/netinet tcp_subr.c
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Bruce M Simpson wrote:
> 
> On Wed, May 04, 2005 at 01:48:44PM +0000, Andre Oppermann wrote:
> >   Log:
> >   If we don't get a suggested MTU during path MTU discovery
> >   look up the packet size of the packet that generated the
> >   response, step down the MTU by one step through ip_next_mtu()
> >   and try again.
> 
> Yay! Now I really need to sit down and sort out the gre(4) PMTU story.

What's the problem there?

> Of course a more generic way of doing this might be good, e.g. a generic
> PMTU callback for each protocol which needs to exchange this information
> with the IP/ICMP layer.

There is.  Look into ip_icmp.c:icmp_input().

-- 
Andre