[Openstack-operators] VXLAN and jumbo frames: performance gains and configuration options

Gustavo Randich gustavo.randich at gmail.com
Mon Dec 14 21:34:10 UTC 2015


Scenario: Kilo / VXLAN / DVR

Networking installation documentation mentions that when using tunneling
protocols, ideally, we could use jumbo frames on the physical network, but
then describes a "conservative" approach which is to decrease the MTU size
of the guests' interfaces (i.e. to 1454), using DHCP.

In my current installation, which is the 'conservative' one (guest
MTU=1454, host MTU=1500) , I'm getting these approximate iperf rates:

   tenant network, guest to guest same host = 9.5 GB/sec
   tenant network, guest to guest different host = 1.4 GB/sec

My questions are:

   - Should there be any performance gains if I opt for guest MTU = 1500,
and physical/host MTU = 1550 / 1600 / 9000?

   - Which Neutron / ML2 plugin configuration parameters should I modify
(in addition to changing physical interfaces' MTU), in order to specify an
MTU greater than 1500 in the physical network that contains my tenant

   - Anyone knows of a Neutron installation procedure or guide covering the
jumbo frames approach?

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