From: Corey Hickey <bugfood-ml@fatooh•org>
To: Julian Anastasov <ja@ssi•bg>
Cc: Linux Netdev List <netdev@vger•kernel.org>
Subject: Re: strange routing issue--packets stop getting forwarded for a live connection
Date: Thu, 25 Aug 2011 20:50:03 -0700 [thread overview]
Message-ID: <4E5717EB.6030304@fatooh.org> (raw)
In-Reply-To: <alpine.LFD.2.00.1108211142180.1581@ja.ssi.bg>
On 2011-08-21 02:02, Julian Anastasov wrote:
>>>> 3. MTU size; 1500 on eth0 and 1406 on tun0. Bigger packets have been
>>>> transferred fine.
>>>
>>> Lower MTU, it can be PMTUD problem. At 04:50:24.112658
>>> I see 7801:9169 is 1420 bytes and no ICMP FRAG NEEDED is generated.
>>> May be these two regressions explain it:
>>>
>>> http://marc.info/?l=linux-netdev&m=131342172722536&w=2
>>>
>>> There are 2 fixes you can try or more recent kernel
>>> tree, for example 3.1-rc2 has the fixes.
>>
>> Many thanks for your reply--it looks like you're on to something. You
>> didn't specify which interface to lower the MTU on, so I tried them each
>> in turn, and found that lowering the MTU on the client machine to 1406
>> (matching tun0 on the router) did indeed solve the problem. That makes
>> sense in retrospect.
>
> I just wanted to note the difference in MTUs
> as a possible cause that triggers the problem. And after
> your confirmation I think the new/patched kernel should work
> without playing with MTUs.
I finally got a chance to test this, and the patched kernel works fine.
Thank you!
-Corey
prev parent reply other threads:[~2011-08-26 3:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-21 2:15 strange routing issue--packets stop getting forwarded for a live connection Corey Hickey
2011-08-21 6:35 ` Julian Anastasov
2011-08-21 8:12 ` Corey Hickey
2011-08-21 9:02 ` Julian Anastasov
2011-08-26 3:50 ` Corey Hickey [this message]
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