On Mon, 4 Nov 2002, Steve Francis wrote:

> Date: Mon, 04 Nov 2002 09:00:47 -0800
> From: Steve Francis <[EMAIL PROTECTED]>
> To: Agent Drek <[EMAIL PROTECTED]>
> Cc: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
> Subject: Re: MTU problems ...
>
> The problem below (which is still a problem in FreeBSD, but one that
> will be rarely encountered) was caused by a load balancer in front of
> the BSD boxes, that did not NAT part of the ICMP unreachable message
> payload to the BSD's address. (The ICMP includes part of the original
> datagram that caused the problem, and the load balancer did not
> translate the sequence numbers, I think.)  Its still a BSD problem (I'd
> say) as if BSD hears the ICMP and reduces its MSS, it should not resend
> the original packet at a size > MSS.
>
> So this could be your issue if your ISP is forcing all your traffic
> through a proxy that does the same thing.
>
> A workaround would be disable PMTU-discovery.
>

hi,

I didn't notice the pr until now:
http://www.freebsd.org/cgi/query-pr.cgi?pr=42137

In my case the "load balancer" is something at the telco that is probably
aggregating a bunch of stuff at the dslam. Thus I can't really fix the
bad router, and there is no option of going somewhere else.

I think I want something like:

net.inet.tcp.stupid_router_in_front_of_me_mtu_hack->1

but that may not be what I need. Is it rude to send mail to that same
pr? should I try and harvest more info first?

disabling path mtu discovery just cause the problem to happen faster
for me :(

cheers,

--
   Derek Marshall

Smash and Pow Inc > 'digital plumber'
http://www.smashpow.net


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