Open Stack

Hi Tangqing,

This is a well-known problem, it is because GRE/VxLan 's packet header use
some bytes, length of data packet should reduced.
You can get refer to bellow pages:
http://www.chriscowley.me.uk/blog/2014/03/31/openstack-neutron-performance-problems/
https://ask.openstack.org/en/question/25947/openstack-neutron-stability-problems-with-openvswitch/
https://openstack.redhat.com/forum/discussion/302/quantumneutron-and-ip-packet-mtus-questions-answers-and-suggestions/p1

Hope it helps,
Damon

2014-10-27 9:18 GMT+08:00 Li Tianqing <jazeltq at 163.com>:

> Hello,
>     Right now, we test neutron under havana release. We configured
> network_device_mtu=1450 in neutron.conf,
>    After create vm, we found the vm interface's mtu is 1500, the ping,
> ssh, is ok. But if we scp large file between vms
>    then scp display 'stalled'. And iperf is also can not completed.
>    If we configured vm's mtu to 1450, then iperf, scp all is ok.
>    If we iperf with -M 1300, then the iperf is ok too.
>    The vms path mtu discovery is set by default. I do not know why the vm
> whose mtu is 1500 can not send large file.
>
>
> Thanks.
>
>
>
>
> --
> Best
>     Li Tianqing
>
>
>
> _______________________________________________
> OpenStack-dev mailing list
> OpenStack-dev at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstack.org/pipermail/openstack-dev/attachments/20141027/e01b5a23/attachment.html>