[ovs-discuss] Overlay Issues

[Lopez, James]

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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