Hello, David Your comment was exactly correct!! I refer following blog. Then adjust MTU on the VM And current it's work well. http://techbackground.blogspot.kr/2013/06/path-mtu-discovery-and-gre.html Thank you for your comment. It was helpful to save my time. From: medberry at gmail.com [mailto:medberry at gmail.com] On Behalf Of David Medberry Sent: Tuesday, August 26, 2014 1:40 AM To: Taeheum Na Cc: openstack-operators at lists.openstack.org Subject: Re: [Openstack-operators] Iperf isn't work between VMs which are placed in other host What MTU are you using (try different ping sizes to see if this problem also occurs with large pings.) You will likely want to limit the vms to 1454 MTU and re-run your tests. Google for GRE OPENSTACK MTU for more info. On Mon, Aug 25, 2014 at 11:23 AM, Taeheum Na <thna at nm.gist.ac.kr<mailto:thna at nm.gist.ac.kr>> wrote: Hello, I tried to measure network performance BTW VM which connected through GRE tunnel. So, I configured neutron(ML2/GRE). Then I verified TCP performance between VMs which are placed on same host. But I could not make Iperf connection BTW VMs (on other host), but ping is ok. bellow things are current Security group configuration. I think that I allow all traffic which is needed to execute iperf. +-------------+-----------+---------+-----------+--------------+ | IP Protocol | From Port | To Port | IP Range | Source Group | +-------------+-----------+---------+-----------+--------------+ | udp | 1 | 65535 | 0.0.0.0/0 | | | tcp | 1 | 65535 | 0.0.0.0/0 | | | icmp | -1 | -1 | 0.0.0.0/0 | | +-------------+-----------+---------+-----------+--------------+ Do you have any comment? Regards Taeheum Na **************************************************** M.S. candidate of Networked Computing Systems Lab. School of Information and Communications GIST (Gwangju Inst. of Sci. and Tech.) E-mail: thna at nm.gist.ac.kr<mailto:thna at nm.gist.ac.kr> Phone: +82-10-2238-9424<tel:%2B82-10-2238-9424> Office: +82-62-715-2273<tel:%2B82-62-715-2273> _______________________________________________ OpenStack-operators mailing list OpenStack-operators at lists.openstack.org<mailto:OpenStack-operators at lists.openstack.org> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.openstack.org/pipermail/openstack-operators/attachments/20140826/e7dc479d/attachment-0001.html>