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[Xen-users] RE: [Xen-devel] Ethernet MTU

To: "'Molle Bestefich'" <molle.bestefich@xxxxxxxxx>
Subject: [Xen-users] RE: [Xen-devel] Ethernet MTU
From: "Sylvain Coutant" <sco@xxxxxxxxxx>
Date: Wed, 16 Aug 2006 15:00:29 +0200
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> > > That virtual interface should automatically have an MTU size of the
> > > underlying interface minus 4 bytes (for the VLAN tag).
> >
> > It should. It does not. It's usually not a problem
> 
> That's wrong.  Counted by the number of people on xen-users having
> problems with VLANs and MTUs, it is very much a problem.

Yes, because some network code in a Xen setup does not allow 1501 bytes 
packets. It should be possible to allow them in some way to keep a native 1500 
bytes mtu.


> Really?  If you pass off 100kB of TCP data to the IP layer, will it
> get split in correctly sized IP packets, but the fragment flag won't
> be set?

As far as I remember, yes. However, it's been a while I didn't coded sockets !


BR,

--
Sylvain COUTANT


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