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Re: How to setup Jumbo Frames? NetBSD Dom0 and FreeBSD XENHVM

On 06/27/13 07:43, Manuel Bouyer wrote:
> On Thu, Jun 27, 2013 at 04:47:10AM +0000, Mike C. wrote:
>> Hi,
>> First, sorry if I'm asking something basic.
>> I have a re1 interface that supports jumbo frames (MTU up to 7422), the
>> card is set up correct, however I need a bridge for xen!
>> When I try to change the bridge mtu settings:
>> # ifconfig bridge0 mtu 7422
>> ifconfig: SIOCSIFMTU: Network dropped connection on reset
>> However ifconfig shows the mtu at 7422:
>> # ifconfig bridge0                                                        
>> bridge0: flags=0 mtu 7422
>> And the biggest problem comes when I try t start a domu... if the
>> bridge0 interface has a mtu different than 1500 I can't start the domu,
>> because the virtual interface creation fails with:
>> brconfig: add xvif5i0: Invalid argument
> I guess you could change the /usr/pkg/etc/xen/scripts/vif-bridge
> script to set the mtu of the xvif before adding it to the bridge.
> But I'm not sure that the netfront/netback (at last as implemented
> on NetBSD) supports MTU larger than 4k.

Forgot to mention I tried that...

While staring the domU I see
ifconfig xvif5i0 up
ifconfig: SIOCSIFMTU: Invalid argument
ifconfig: SIOCSIFMTU: Network dropped connection on reset (this is for
the bridge)

If I set the script to set the MTU to any value other than 1500 thats
what I get!

I tried 9000 last night and today with 4000, has you can see the bridge
mtu changes even though I see the "Network dropped connection on reset

---> bridge0: flags=41<UP,RUNNING> mtu 4000

I was under the impression that since Xen 4.1+ mtu of 9000 are
supported, at least I according to the change log it should:
"Fixes to properly support jumbo frames (mtu 9000) with vif-bridge script."

But perhaps NetBSD needs some specific patch for this...

NOTE: I'm running 4.2.2 compile from source following the instructions
at: http://wiki.xen.org/wiki/Compiling_Xen_From_Source_on_NetBSD.


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