

RecFrom [email-masked] Fri May 12 16:53:33 2006
Date: Fri, 12 May 2006 13:50:50 -0700
From: Erik Nordmark <[email-masked]>
To: Fred Baker <[email-masked]>
Cc: [email-masked], [email-masked], David Woodhouse <[email-masked]>,
	Pekka Savola <[email-masked]>
Subject: Re: RFC3484 problem: scoping with site-locals/ULAs

Fred Baker wrote:
> So I have a dumb question.
> 
> Why not:
>     - use a DNS lookup that asks for all records (including A, MX, and 
> AAAA)
>     - open both a v4 and a v6 connection simultaneously
>     - accept the first to successfully open and shut down all others
> 
> Down sides: It gets all of the DNS data, which may be more than it 
> wanted to know, and it issues a second SYN-or-whatever, and in the worst 
> case one to each address. But it deterministically finds a solution that 
> works and gives the system the service it is looking for.
> 
> I the big picture, the problem with that behavior is what?

In the big picture, I think that's the direction we need to move.
But I don't think we want to have every application have that logic, 
since the logic might need to evolve over time (and needs to take into 
account Alain's example of umpteen different IP addresses - might want 
to stagger the attempts when there are lots of IP addresses to try.)

So instead I think we want to raise the abstraction layer for the 
applications by introducing a connect-by-name socket API so that the 
application just hands in the FQDN and the port number to which it wants 
to connect.

It isn't hard to come up with an initial cut of a connect-by-name 
implementation entirely as a library routine (using non-blocking sockets 
for the connect() system calls so that multiple can be outstanding and 
the same time.)

    Erik

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