Re: [Xen-users] Problem MTU > 1500

[Stephan Seitz <s.seitz@xxxxxxxxxxx>]

Hi,

ok, I missed that part, that you're able to use jumboframes between dom0.
I'm sorry, but I don't know how bridges are created by XCP / XenServer. On recent Xen 4, the usual /etc/xen/scripts/network-bridge is somewhat
depricated. (Or simply doesn't work any longer ;-) without problems).
Most installations I've seen so far creating the bridges with onboard tools in /etc/sysconfig/network-scripts/... or /etc/network/interfaces.
During runtime only the vif's are created and removed, but not the bridges itself.
If(!) XCP does it the same way, you could try to find the script and/or configuration file where the bridge itself is been created.
As a short test, if it's worth the search, try ifconfig bridgename mtu 9000 and see if (and how long) this helps.

Maybe the XenServer forums are more helpful?

cheers,

Stephan

Am Montag, den 23.07.2012, 11:10 +0200 schrieb Mesut Donmez:
>     Hi,
>      
>     Thanks for your quick reaction.
>      
>     Yes I am sure for all the interfaces (intern as extern) the MTU is set to 9000 ans also the database for the vif/pif/network(bridges) shows me MTU 9000.
>     The strange thing is when I set everything to 9000 and start the guest the bridgeX shows me MTU=1500 ("ifconfig -a" command used ) even the vif/pif/network database (xe vif-param-list, xe pif-param-list, xe network-param-list commands used) are showing me MTU 9000.
>     And my NIC are able to send 9000 frames. Because what I mentioned before when I ping from the host to an extern interface I do not have problems.
>      
>     SO ra ra ra what do I wrong or is there still some other configure files in the host ot guest operating system which I did forgot???   
>     
>     
>     2012/7/20 Stephan Seitz <s.seitz@xxxxxxxxxxx>
> >         Hi,
> >         
> >         if you're sure, the interfaces are all set to 9k, i'ld expect your switch in between your
> >         hosts is not capable of / not cofigured for 9k frames.
> >         
> >         I'd only done 9k on  dom0 so far, but for having it available to domU I assume it needs to
> >         be set in a persistant way. If you change your vifX.X interfaces that would be gone
> >         if you shutdown/create your machine, wouldn't it?
> >         
> >         
> >         Am Freitag, den 20.07.2012, 10:44 +0200 schrieb Mesut Donmez: 
> >     
> > >             Hi, 
> > >               
> > >             I am using XCP version 1.5beta (1.4.90) with for the host the kernel version 2.6.32.12-0.7.1.xs1.4.90.530.170661xen en for the guests reh6.1 as operating system. 
> > >             When we  increase the MTU of the ethX, vifX and xenbrX to 9000 and also for other machines in our test envioranment and we give the command; ping -s 9000 <ip of extern machine> from the guest to an other machine 
> > >             wich is not on the same host we do not get any response. 
> > >             When we give the same command to an other guest on the same host the ping command succeeds. 
> > >             When we ping from the host to other machines outside the host the ping command is also succeeds. 
> > >               
> > >             Has somebody ideas what I am doing wrong? 
> > >               
> > >               
> > >               
> > >         
> >     
> > > _______________________________________________
> > > Xen-users mailing list
> > > Xen-users@xxxxxxxxxxxxx
> > > http://lists.xen.org/xen-users
> > >         
> >     
>

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