Subject: Re: Questions about draft-lear-iana-no-more-well-known-ports-00.txt

From: Joe Touch <[email-masked]>
Date: Mon, 05 Jun 2006 22:33:57 -0700

Eliot Lear wrote:
> Jeff,
> 
>> Disclaimer - I wasn't even aware of this document before reading this
>> thread.  However, I have now read it, so feel prepared to comment.
> As it only just came out, you haven't missed much of a debate.
>> (1) The IANA is a group of adults, but it is no longer a group of
>>    protocol subject matter experts.  IMHO there is probably no need
>>    for IESG oversight of port number allocation, especially if we are
>>    eliminating the (artificial) scarcity of so-called well-known ports.
> 
> The point of the document is NOT really to deal with scarcity but to
> deal with an outdated process, and to attempt to encourage use of SRV
> records where appropriate, and to have some documentation for the port
> use. ...

SRV records are not equivalent to either assigned or mutually-negotiated
ports; they would require extra messages, extra round-trip times, and/or
extra services (DNS) beyond what is currently required.

There are other ways to reduce the limits of the current port space, as
well as to reduce the dual-registration of service names (which are
unique) and port numbers. See: draft-touch-tcp-portnames-00.txt

(FYI there is a pending update that includes more detail on the
difference between this and Tim Shepard's dynamic port reassignment
proposal from 2004)

Further discussion on this has already ensued on the TCPM WG mailing
list, whose archives may be a useful resource as well.

Joe

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From: Joe Touch <[email-masked]>
Date: Mon, 05 Jun 2006 22:33:57 -0700

Joe

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From: Eliot Lear <[email-masked]>
Date: Tue, 06 Jun 2006 08:15:27 +0200

Joe,
> extra services (DNS) beyond what is currently required.
Just to be clear, I am not suggesting that no assignments be done, but
that SRV records be used where appropriate.  If setup time or circular
dependencies are a concern, SRV records may not be appropriate.

Eliot

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From: Joe Touch <[email-masked]>
Date: Tue, 06 Jun 2006 07:39:08 -0700

> dependencies are a concern, SRV records may not be appropriate.

Right - I agree that assignments should not differentiate between privilege.

SRV records serve two purposes: to unload the fixed list from IANA (like
moving hosts.txt to the DNS did) and to allow local control over the map
between service name and port (which can allow more than 65,000 services
total).

The first use is fine, but overkill IMO for a list with 65,000 entries
at most. The second is a problem, for reasons explained in my I-D,
because it puts control over host service offerings in the hands of
whomever controls its DNS (e.g., another thing for ISPs to claim makes
you a commercial customer at commercial prices) and because it's
inefficient.

Joe