Very slow network speed using Tinc

[Guus Sliepen]

On Wed, Oct 23, 2013 at 05:21:01PM +0200, Florent Bautista wrote:

> > But... with Tinc 1.1 (git), I have a big MTU problem...
> >
> > Tinc does not seem to handle packets of 1500 bytes...
> >
> > ping -s 1400 is OK
> > ping -s 1500 is not OK.
> >
> > with 1.0.23, both were OK.
> >
> > 1469 bytes packet is OK, 1470 is not.
> >
> > Same parameters (defaults, except addresses of hosts).
> >
> > In logs, it does not seem to get errors but I can see that :
> >
> > Oct 23 15:46:16 host2 tinc.tincnetwork[8999]: Sending MTU probe length
> > 1518 to host1 (192.168.0.71 port 655)
> > Oct 23 15:46:16 host2 tinc.tincnetwork[8999]: Got type 2 MTU probe reply
> > 1518 from host1 (192.168.0.71 port 655)

Do you have jumbograms enabled on your physical network, or are the two VMs
running on the same machine connected by a virtual network?

That aside, tinc should handle that case, so that is definitely a bug. I'll try
to find out what is happening.

> > Interfaces are all MTU 1500...

Hm, but somehow tinc things that it can send packets with a payload up to 1518
bytes between the two hosts, and that is excluding the tunneling and encryption
overhead. On a real network with MTU set to 1500 tinc normally responds that
the PMTU is 1451 bytes.

-- 
Met vriendelijke groet / with kind regards,
     Guus Sliepen <guus at tinc-vpn.org>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 198 bytes
Desc: Digital signature
URL: <http://www.tinc-vpn.org/pipermail/tinc/attachments/20131023/a2356ac4/attachment.sig>