Jumbo frame support on xn0 in AWS EC2

[Bradley T. Hughes]

Howdy!

I started off posting a question to freebsd-cloud@ about what would be necessary to get jumbo frame support on xn0 in a FreeBSD VM running in AWS EC2. I was advised to post my question to a wider audience (hence the cross post).

Here was my original question:

The AWS EC2 Instance Types documentation[1] says that the MTU for the network interfaces is dependent on the instance type. A post on the AWS forums[2] by an AWS representative states that the MTU configuration is available via DHCP.

I noticed that all of our T2 instances running FreeBSD have an MTU of 1500. After searching around a bit, I found this patch[3]. I get the same results when running the reproduction steps in EC2, despite ifconfig(8) saying it's using an MTU of 9001.

I'm wondering if the patch in 187094 is what's needed to make the xn0 interface on our FreeBSD instances use jumbo frames?

Thanks in advance :)

[1] http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-types.html
[2] https://forums.aws.amazon.com/thread.jspa?threadID=143674
[3] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=187094

--
Bradley T. Hughes
bradleythughes at fastmail.fm