Slow Neutron Network on Outbound Nova-Docker Instance Traffic

asked 2015-08-14 16:20:14 -0500

Nastooh gravatar image

On a multi-node Kilo, running gre, I am getting very low network bandwidth on Docker 1.6.2 instances. Did a number of tests to narrow down the problem area. The following is the list of well behaved network connections, i.e., reported bandwidth is in par with the actual NIC, which is 1Gb/s:
1- Nova host to Nova host
2- Docker Nova host to arbitrary Nova VM/Docker instance, via public address
3- Neutron host to Nova Docker instance (through qrouter/qdhcp name spaces)
4- Nova Docker instance to Nova Docker instance, on the same host
5- Docker host to Nova Docker instance, on the same host (through host's name space)
6- Nova VM instance to Nova Docker instance

The problem is in outbound traffic generated from Nova Docker instance. Here, bandwidth from Nova Docker instance:
A- To a physical host, on the same public network, drops to around 8Mb/s
B- To another instance, VM or Docker, using either floating or private address, drops to 1Mb/s

I am using nc to measure bandwidth:
Tx: time dd if=/dev/zero bs=1M count=1K | nc -vvn $IP $PORT
Rx: nc -ln $PORT

Tried mtu 1700 and 3000 on Docker host, to no avail.
Any thoughts?

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What is the MTU on your physical NICS? In an environment with a standard 1500 byte MTU, you have to reduce the size of the instance MTU (in this case, your Docker containers) to allow space for the tunneling metadata. E.g., set your container MTU to 1450 and see if you still see the same issue.

larsks gravatar imagelarsks ( 2015-08-14 20:10:49 -0500 )edit