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<p class="MsoNormal">And you will need switch settings to match that MTU.<o:p></o:p></p>
<p>-----Original Message-----<br>
From: rdo-list-bounces@redhat.com [mailto:rdo-list-bounces@redhat.com] On Behalf Of Dan Sneddon<br>
Sent: Friday, January 29, 2016 4:17 PM<br>
To: rdo-list@redhat.com<br>
Subject: Re: [Rdo-list] Slow network performance on Kilo?<br>
<br>
On 01/27/2016 12:30 PM, Erich Weiler wrote:<br>
> Hi Y'all,<br>
> <br>
> I've seen several folks on the net with this problem, but I'm still <br>
> flailing a bit as to what is really going on.<br>
> <br>
> We are running RHEL 7 with RDO OpenStack Kilo.<br>
> <br>
> We are setting this environment up still, not quite done yet. But in <br>
> our testing, we are experiencing very slow network performance when <br>
> downloading or uploading to and from VMs. We get like 300Kb/s or so.<br>
> <br>
> We are using Neutron, MTU 9000 everywhere. I've tried disabling GSO, <br>
> LRO, TSO, GRO on the neutron interfaces, as well as the VM server <br>
> interfaces, still no improvement. I've tried lowing the VM MTU to<br>
> 1500, still no improvement. It's really strange. We do get<br>
> connectivity, I can ssh to the instances, but the network performance <br>
> is just really, really slow. It appears the instances can talk to <br>
> each other very quickly however. They just get slow network to the <br>
> internet (i.e. when packets go through the network node).<br>
> <br>
> We are using VLAN tenant network isolation.<br>
> <br>
> Can anyone point me in the right direction? I've been beating my head <br>
> against a wall and googling without avail for a week...<br>
> <br>
> Many thanks,<br>
> erich<br>
> <br>
> _______________________________________________<br>
> Rdo-list mailing list<br>
> Rdo-list@redhat.com<br>
> https://www.redhat.com/mailman/listinfo/rdo-list<br>
> <br>
> To unsubscribe: rdo-list-unsubscribe@redhat.com<br>
<br>
To use jumbo frames with Neutron, you first need to make sure that all layers have the same MTU: bridge, interface, VLAN, and bond (if applicable).<br>
<br>
Check these settings on both Controllers and Computes:<br>
<br>
In /etc/nova/nova.conf, edit or create this line:<br>
network_device_mtu=9000<br>
<br>
In /etc/neutron/plugins/openvswitch/ovs_neutron_plugin.ini:<br>
veth_mtu = 9000<br>
<br>
That will increase the MTU on the virtual Ethernet adapter to. You can get away with an MTU here that matches the wire in Neutron VLAN mode.<br>
In VXLAN you'd want this value to be 50 bytes less than the MTU on the wire.<br>
<br>
You also want to check the DHCP options in the file /etc/neutron/dnsmasq-neutron.conf on all controllers:<br>
dhcp-option-force=26,9000<br>
<br>
You can also try setting that last option to 1400, that will limit the VM MTU, but if things speed up then you know you've got a bottleneck somewhere (like a less-than 1500-byte MTU somewhere in the path of VLAN traffic).<br>
<br>
-- <br>
Dan Sneddon | Principal OpenStack Engineer<br>
dsneddon@redhat.com | redhat.com/openstack<br>
650.254.4025 | dsneddon:irc @dxs:twitter<br>
<br>
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To unsubscribe: rdo-list-unsubscribe@redhat.com<o:p></o:p></p>
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