On 14/03/16 10:26, Edward Cree wrote: > On 12/03/16 05:40, Alexander Duyck wrote: >> Well that is the thing. Before we can actually start tinkering with >> the outer header we probably need to make sure we set the DF bit and >> that it would be honored on the outer headers for IPv4. I don't >> believe any of the tunnels are currently doing that so repeating the >> IP ID would be the worst possible scenario until that is resolved >> since VXLAN tunneled frames can be fragmented while TCP frames cannot >> so we really shouldn't be repeating IP IDs for the outer headers. > So how do we progress with that? I'm presuming it's not as simple as > just patching the tunnel drivers to set DF if the inner packet has it, > as that could break existing setups. (I've heard that "but they're > already broken anyway" is not usually an acceptable argument.) Some > sort of configuration option on the tunnel (like we do with udpcsum)? ...and immediately I find out it already exists. (I guess I should have looked there first!) >From drivers/net/vxlan.c:2001: > else if (info->key.tun_flags & TUNNEL_DONT_FRAGMENT) > df = htons(IP_DF);
-Ed
