Hi everybody
It's basically possible to use a higher MTU than 1500 but with some
constraints. We have a setup for using MTU 5000 for our domUs.
The procedure is as follows:
- enable MTU 5000 on the physical interface of dom0
- enable MTU 5000 on the interface of domU
- after domU startup, enable MTU 5000 at the virtual interface (vif)
of that domU in dom0
- the Xen bridge still shows MTU 1500. The MTU cannot be set for
bridges but afaik they also don't care about MTU size.
The constraints are:
- MTU 5000 doesn't work between two domUs inside the same dom0
- MTU 5000 doesn't work reliable between two domUs inside different
dom0s (may be issue with our iptables setup?!)
- MTU 5000 works reliable between domUs and physical servers
I hope this helps you.
It would be very nice to see native jumbo frame support in Xen in the
future. We currently use Xen-3.2.0 but I also couldn't find anything
related to this topic in the Xen-3.3.0 changelog. So I filled a bug
at: http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1341
Kind regards
Reto Gantenbein
On Mar 7, 2008, at 10:54 AM, Pasi Kärkkäinen wrote:
On Thu, Mar 06, 2008 at 04:24:25PM +0000, Gareth Bult wrote:
Hi,
After failing to make Jumbo frames work on my Xen installation, I
read that Xen doesn't support Jumbo Frames.
What did you actually do/configure when you tried jumbo frames?
Is this really true?
I'm not sure.. I have never really tried jumbo frames with Xen..
I assume first you need to configure your ethX (pethX) devices to
use 9000
bytes mtu.. and then your bridge devices to use 9000 mtu too.
After that you need to configure your ethX devices in domU to use
9000 mtu.
Is that enough? Has someone tried this?
-- Pasi
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