Re: [dccp] port numbers and DCCP

[Mark Handley <M.Handley at cs.ucl.ac.uk>]

On 11/16/05, Eddie Kohler <kohler at cs.ucla.edu> wrote:

> DCCP connections may make use of well known port numbers, as in TCP
> and UDP, although the Service Code may lessen this requirement
> somewhat.  IANA SHOULD maintain registrations for well-known DCCP
> port numbers using similar mechanisms as for TCP, UDP, and SCTP.
> When a port number is not explicitly reserved for DCCP,
> implementations SHOULD use any existing registration for UDP.
> However, implementers are encouraged not to rely on this fallback,
> and explicitly reserve well-known ports as they are used.

I agree it's better to take this track.  Question: should it be
required to register a Service Code together with a well-known port? 
I think probably yes.

Which leads to the question of whether there's one well-known port per
service code, or one service code per well-known port, or something
else.  In other words, is the mapping one-to-one,  or one-to-many, and
if it's one-to-many, which way round?

Simplest would be to start out one-to-one, and see how this evolves in reality.

 - Mark