Re: [dispatch] draft-jesske-sipping-etsi-ngn-reason-04; why encapsulation is problematic

[<[e-mail]>]

Adam wrote:
> S/MIME for a general purpose network suffers from the classical key 
> distribution problem. It's not used for the same reason encrypted
email 
> is not used (except among the geek community).
> 
> But you're not talking about general purpose networks.
> You're talking about tightly constrained networks with PSTN gateways 
> that are either all within a single administrative domain, or that 
> communicate with each other through bilateral agreements. In these 
> circumstances, key distribution is no more difficult a problem than IP
> address assignment. It's a simple matter of configuration.
In theory, S/MIME should be doable in an administrative domain. It's the
lack of implementations that troubles me. 
 
Adam wrote:
> B2BUAs will break whatever they break. Until someone sits down and 
> documents their behavior, we can't really do too much to work around 
> their behavior. It's the same problem we're having all over the place 
> (identity, MSRP ACM, etc). There's no point in talking about something

> as nebulous as B2BUA behavior.
Sure. I was referring to an argument made (not by Adam) in the meeting. 

Adam wrote:
> While many UAs won't be able to ignore the multitype body (aside: this

> is sad -- email clients all can), you'd be hard pressed to find one
that 
> can't understand multipart that also won't respond to a multipart body

> in a request with a 415.
Right, but connection setup times are already a concern now, without the
extra transaction to reject multipart content.

Adam wrote:
> At one point, you said "IMS." I don't think you'll find an IMS client 
> that has any hope of receiving a UDP SIP message -- show me an INVITE
on 
> the terminating side of an IMS network that is somehow smaller than
1500 
> bytes, and I'll be shocked into silence. TCP is a foregone conclusion.
The universal deployment of IMS may take some time. Until that glorious
day, we may have networks that would profit from the Reason header and
don't have big SIP messages. 

Wolfgang