Akihiro Motoki <amot...@gmail.com> wrote:
2016-04-18 15:58 GMT+09:00 Ihar Hrachyshka <ihrac...@redhat.com>:
Sławek Kapłoński <sla...@kaplonski.pl> wrote:
Hello,
What MTU have You got configured on VMs? I had issue with performance on
vxlan network with standard MTU (1500) but when I configured Jumbo
frames on vms and on hosts then it was much better.
Right. Note that custom MTU works out of the box only starting from
Mitaka.
You can find details on how to configure Neutron for Jumbo frames in the
official docs:
http://docs.openstack.org/mitaka/networking-guide/adv-config-mtu.html
If you want to advertise MTU using DHCP in releases before Mitaka,
you can prepare your custom dnsmasq config file like below and
set it to dhcp-agent dnsmasq_config_file config option.
You also need to set network_device_mtu config parameters appropriately.
sample dnsmasq config file:
--
dhcp-option-force=26,8950
--
dhcp option 26 specifies MTU.
Several notes:
- In Liberty, above can be achieved by setting advertise_mtu in
neutron.conf on nodes hosting DHCP agents.
- You should set [ml2] segment_mtu on controller nodes to MTU value for
underlying physical networks. After that, DHCP agents will advertise
correct MTU for all new networks created after the configuration applied.
- It won’t work in OVS hybrid setup, where intermediate devices (qbr) will
still have mtu = 1500, that will result in Jumbo frames dropped. We have
backports to fix it in Liberty at: https://review.openstack.org/305782 and
https://review.openstack.org/#/c/285710/
Ihar
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