[ovs-discuss] Overlay Issues

[Jesse Gross]

I'm not sure that I exactly understand your test setup. Performance is
fine if you go from the hypervisor but is 1.5G (85% reduction on 10G)
if it is between VMs and tunneling is used in both cases?

It sounds like the lack of offloading could be a problem (I believe
those NICs support VXLAN offload but the kernel and OVS versions are
too old) but that probably isn't the issue if tunneling works fine
from the hypervisor directly.

On Mon, Apr 28, 2014 at 2:42 PM, Lopez, James <jlopez at io.com> wrote:
> Normal setup is
>
> 1500 on the VM
> 9000 on br-tun
> 9000 on the nic
>
> Best I can tell there shouldn’t be fragmentation am I missing something ? I have even taken the Guest MTU down to 1400 Just to be sure with no change.   thanks for the help Jesse.
>
>
> Keep in mind VM-VM on the same node is 10Gig  with a 1500 Byte MTU so it's not the guest OS that needs tuned I wouldn't think,.
>
> -----Original Message-----
> From: Jesse Gross [mailto:jesse at nicira.com]
> Sent: Monday, April 28, 2014 2:32 PM
> To: Lopez, James
> Cc: discuss at openvswitch.org
> Subject: Re: [ovs-discuss] Overlay Issues
>
> On Mon, Apr 28, 2014 at 1:37 PM, Lopez, James <jlopez at io.com> wrote:
>> Team,  I am working through an issue with OVS and tunneling.  My setup
>> consist of 2 nodes running Ubuntu 12.04 LTS  / KVM / OVS 1.10 and the
>> Mellanox Connect X3 , and 2 nodes running Ubuntu 12.04 LTS  / KVM /
>> OVS 1.10 and the Mellanox Connect X3 Pro.  Currently  I am seeing an
>> 85% reduction of throughput VM-VM using iperf vs the same iperf test
>> running on the nodes br-tun to br-tun…  ConnectX3 and ConnectX3 Pro
>> show the exact same results , also although VXLAN performance is
>> slightly better it still shows the same 85% reduction.
>>
>>
>>
>> I can clear this up by adjusting the MTU’s
>>
>>
>>
>> 7000 on the VM
>>
>> 8000 on the br-tun
>>
>> 9000 on the nic
>>
>>
>>
>> Is this expected behavior ?  Any help is greatly appreciated.
>
> Yes, if there is fragmentation then that will greatly reduce performance.
>
>
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