Re: [tae] New draft: announcing the supported transports via DNS

[Caitlin Bestler <[e-mail]>]

On Sep 18, 2009, at 12:07 PM, Dan Wing wrote:

> Can you enumerate those requirements, or shall we just throw things  
> at the
> wall?  This goes back to Caitlin's post
> <http://www.ietf.org/mail-archive/web/tae/current/msg00114.html> which
> suggested we take a step back and look at what we want.  I'm all for  
> doing
> that.  This list has been too quiet, so we wrote a straw man.  I  
> take it you
> don't like the straw man because it's trying to cover the DNS use- 
> case, and
> your use-case is IP address literals, and your use-case can incur  
> additional
> round trip(s) to learn which transport protocols the server supports.


Any non-directory based solution is going to run the risk of having an  
extra
message required to setup the connection/association. That suggests to  
me
that the solution set should include a directory based method, I'm  
just not sure
that DNS is appropriate for service-specific information.

I think the following objectives need to be met for any probe-based  
solution:

1) Must add no additional messages when the default protocol is  
selected.
2) TCP must be a valid default protocol.
3) There may be a case for adding UDP to that set for RTTP.
4) It should be capable of learning when a given client/server pair is  
blocked
     from using Transport X by some middle-box. Note: this is  
something a
     directory-based solution probably cannot do.,




--
Caitlin Bestler
[e-mail]
http://www.asomi.com/CaitlinBestlerResume.html