[ovs-dev] [PATCH] Document GRE port options.

[Ben Pfaff]

It looks good to me.

I would probably put double quotes or some other kind of marking around
"ICMP destination unreachable - fragmentation needed" because I had to
read that part a few times.

Also, understanding this description requires a great deal of background
knowledge.  I'm not sure that the uninitiated will be able to learn much
from it.  Perhaps some references, e.g. to where one can find out more
about OpenFlow flows, the Nicira extensions to OpenFlow flows and
actions, and to GRE in general, would help.