Re: [Xen-users] XCP ethernet jumbo frames????

[Gémes Géza <geza@xxxxxxxxxxx>]

2010-09-21 00:27 keltezéssel, James Harper írta:
>> Hi,
>>
>> I have an XCP 0.5 box running a few DomUs some of the DomU's data is
>> stored at (clustered lvm volumes on) a Coraid etherdrive box which is
>> connected via an Ethernet cable to a dedicated card of the XCP box, for
>> which in the network config I' ve specified: MTU=9344: xe
>> network-param-list uuid=.... gives:
>> MTU ( RW): 9344
>> on the DomUs if I leave the MTU at 1500 (default settings) everything
>> works (slowly, but works). If I increase the MTU the aoe device appear
>> as expected, but the data on it becomes inaccessible, even just trying
>> to activate the lvm volume groups gives a bunch of IO errors at sector
>> 0, and so on.
>>
>> Please tell me what I'm doing wrong. Are jumbo frames expected et all to
>> work?
>>
>>     
> Does your network adapter really support jumbo frames?
> Is the network adapter on a bridge? (I'm unsure if Dom0 does AoE or if the 
> DomU's do)
> Are all the bridge interfaces set to 9344 MTU?
> Could tcp offload settings break any of this? (unlikely - AOE is not TCP)
>
> tcpdump might tell you what's going on.
>
> James
>   
The network adapter seems to be ok.
I've tried to do aoe at the DomU's.
I've set the network bridge's MTU at the bridge which is connected with
the Coraid box.

After some tcpdumping I've checked what the good old ifconfig would say
about my interfaces. Surprisingly while xe network... reports MTU=9344
ifconfig says it is at 1500 (the vifs attached to the bridge have 9344
), while xe pif... reports all interfaces to have MTU=1500 (I have an
other interface set at MTU=4200, which shows itself even with ifconfig
as having MTU=4200). I start to get really confused :-(

Cheers

Geza

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