Comment 25 for bug 1075336

Ian,

Ian>veth_mtu (it's completely unclear why this needs a separate config option)

Please refer to the original review: https://review.openstack.org/#/c/27937/. Basically what I remember about this patch (too long ago for me) is that the MTU size adjustment was needed on Linux Kernel 2.6.x, not in 3.x. I don't know what kind of kernel issue caused the problem of packet dropping in 2.6.x when no mtu size was increased. So at that time my patch was a simple workaround that allows to increase mtu size on veth interfaces for a certain env, e.g., CentOS6 that uses 2.6.x. It means that some other env (e.g., Linux Kernel 3.x) didn't need this patch at all (I don't know this statement is still valid).

Ian>There are various settings that are relatively illogical and all need changing consistently. They also don't work universally.

I am with you, Ian.

It's interesting for me to see continuos complaints or issues about mtu size on overlay network tunnels. After providing my patch back then in June 2013, I expected some other issue of mtu size on tunnels, if any, would have been dealt with thereafter by someone else. Seems not though. Unfortunately, I have not been involved in other mtu size issues.

Ian, I would suggest you to provide a blue print to cope with all these mtu size issues in a consistent way.

But, still I am really curios if there is any real bug on tunnels right now regarding mtu size? Anyone who can please point out to me what bug report out there?