You are right.  I got confused by Linux and other boxes that use 8472 for VXLAN... At the end of the day (and as far as I understand) IANA will assign a new well known port (in order to disambiguate between OTV and VXLAN) to draft-mahalingam-dutt-dcops-vxlan-03 as requested in Section 9 (IANA Considerations).  So, as you proposed: step1) the -T framework for VXLAN, step2) a new print-otv.c for port 8472, step3) make use of new assigned port in print-vxlan.c (when available).

Does it make sense?

useful links:
OTV
http://tools.ietf.org/html/draft-hasmit-otv-04

VXLAN
http://tools.ietf.org/html/draft-mahalingam-dutt-dcops-vxlan-03

thank you
Ciao
FF

PS
> Should this instead be an "OTV" parser, with a special case for "Overlay ID = 0" being VXLAN?
As far as I understand OTV it is possible to have Overlay ID == 0, so we cannot use it.