Problems with UDP frame size??

[Guus Sliepen]

On Thu, Mar 05, 2009 at 07:02:53PM -0500, Donald Pearson wrote:

[...]
> I removed the Compression line from the hosts files, and went back to the
> working UDP configuration that gave me 2MB/sec.
> 
> However the problem did not go away.  I say I think there is an IP/UDP frame
> size issue because the firewall software I use, SoftPerfect Personal
> Firewall, is reporting this error in it's logs when I try to do something
> like a file transfer.
> 
> I am able to ping between hosts with packet sizes up to 1417 bytes.
> 
> I did some testing with setting the PMTU value and setting PMTUDiscover =
> no, however it had no affect.

It seems there is a problem if both PMTUDiscovery and Compression is used.
Another problem is that both sides must have PMTUDiscovery = no, otherwise it
will still be enabled anyway. Michael Tokarev has also seen this problem. I'll
have a better look at the code and I'll try to reproduce it myself, and see if
I can fix it.

In the mean time, the workaround is to explicitly disable PMTUDiscovery and
Compression.

-- 
Met vriendelijke groet / with kind regards,
     Guus Sliepen <guus at tinc-vpn.org>
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