Subject: [Ecrit] draft-ietf-ecrit-service-urn-02

From: Henning Schulzrinne <[email-masked]>
Date: Sun, 2 Apr 2006 21:10:51 -0400

I have submitted a new edition of the service URN draft to the I-D  
editor. Until it appears in the archives, you can find versions at

http://www.cs.columbia.edu/sip/draft/service/draft-ietf-ecrit-service- 
urn-02.html
http://www.cs.columbia.edu/sip/draft/service/draft-ietf-ecrit-service- 
urn-02.txt

The major changes are based on discussions in Dallas and the mailing  
list:

- removed the Accept-Contact mechanism; as discussed, the general  
idea is that the request-URI will be used as the marker for emergency  
calls and the actual PSAP URL will be inserted after the mapping has  
been performed via preloaded Route headers.

- simplified the mapping mechanism using S-NAPTR. I think this is now  
reasonably clean, while allowing a separate service resolution  
mechanism for each top-level service in each domain. The discovery of  
servers for LoST, for example, will obviously be discussed in the  
LoST document. I took the mailing list consensus to be that we wanted  
this extra level of indirection.

- addressed Jonathan's comments; some issues had become moot due to  
the removal of the Accept-Contact header and the rewriting of the  
NAPTR mechanism.

I believe that the precise description of how this works in SIP,  
e.g., the use of Route headers, belongs in the phone BCP, as it is  
fairly SIP-specific and does not define a new protocol mechanism but  
rather a "best current practice".

The draft is a bit fuzzy on how the NAPTR domain is determined.  
Currently, the draft simply talks about the "home domain" of the  
entity doing the resolution. I made this as a pragmatic choice, as it  
avoids having to define some kind of globally-valid NAPTR label. The  
phone BCP could discuss alternatives, such as using DHCP (to obtain  
the preference of the network provider) or SIP configuration (VSP).

Comments are appreciated.

Henning

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