Subject: Re: middleboxes and Re: [tcpm] TCPx2

From: Mark Allman <[email-masked]>
Date: Thu, 11 May 2006 10:40:34 -0400

Joe:
> > There are different issues:
> > 
> > 	1. limitations of the reserved port numbers
> > 	2. the need for more port numbers in general
> > 
> > The thread I saw focused on #1; that's a function of the number of
> > reserved ports, and whether there's a separation of system vs. user
> > reserved ports.

Mark:
> What I have seen is "the lack of more than 16 bits is an issue"
> ... i.e., #2.  This is in the context of a big proxy of some sort.  I
> need to crystalize this a bit more, I understand.  I will.

The message below and more generally the thread it goes with indicates
that for some places the 16 bits is the problem, not the limitation of
reserved port numbers.

  http://www.mhonarc.org/archive/html/ietf/2005-07/msg00340.html

allman

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From: Joe Touch <[email-masked]>
Date: Thu, 11 May 2006 08:04:14 -0700

>   http://www.mhonarc.org/archive/html/ietf/2005-07/msg00340.html

Yes - 65,000 is too small, whether between proxies, between hops in
SMTP, or for (gasp) NATs. That's a reason to decouple service from port
number, or a reason to increase the number of source ports, but not to
increase them all.

Joe

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From: Joe Touch <[email-masked]>
Date: Thu, 11 May 2006 08:04:14 -0700

Joe

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From: Tim Shepard <[email-masked]>
Date: Thu, 11 May 2006 11:05:56 -0400

>   http://www.mhonarc.org/archive/html/ietf/2005-07/msg00340.html

If I understand that correctly, the things that are running out of
port numbers are proxies that have to have many simultaneous
connections open to particular (server, port) on behalf of their
clients.

Wouldn't it be simpler to give such boxes a few different IP addresses
that it can use to open connections from?  That'd work just fine.
Each additional IPv4 address you assign to the proxy box gives allows
an additional 65 thousand clients that can simultaneously have
connections open to some particular (server, port).

And with IPv6 the proxy could give itself additional addresses as
needed, a la rfc3041.  (And you can do IPv6 even if your ISP is not
offereing IPv6 by using rfc3056.)

			-Tim Shepard
			 [email-masked]

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From: Joe Touch <[email-masked]>
Date: Thu, 11 May 2006 08:09:59 -0700

Tim Shepard wrote:
> that it can use to open connections from? 

Simpler - and much more efficient, both in terms of packet and
congestion control - to fix the protocol that needs to open a connection
per exchange to keep the connection open and reuse it.

Joe

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From: Mark Allman <[email-masked]>
Date: Thu, 11 May 2006 11:35:26 -0400

> that it can use to open connections from?

That is a "solution" discussed in that thread.  I am not sure what
"simpler" is relative to in the above.

allman