Subject: RE: [Sip] WGLC for draft-ietf-sip-target-dialog-01.txt

From: "Jean-Francois Mule" <[email-masked]>
Date: Sun, 14 Aug 2005 18:01:22 -0600

Jonathan,

   I have not followed this work closely so sorry if my comments are off-track, but here are 2 comments. 

--- 1. 
   The first comment is to consider aligning the aBNF grammar more strictly with the UAC/UAS behaviors on the remote-param and local-param.

   Sections 3 & 4 state that target-dialog should be authorized if both the remote-param and local-param are present (pending various conditions met). On the UAS, you even indicate the request for authorization MUST be ignored if both param are not provided (strong MUST).
Yet the grammar is much looser:
   Target-Dialog      =     "Target-Dialog" HCOLON call-id *(SEMI
                            td-param)
   td-param           =     remote-param / local-param / generic-param
   remote-param       =     "remote-tag" EQUAL token
   local-param        =     "local-tag" EQUAL token

Is there a reason for not making the grammar stricter to mandate both remote and local params? Or turning the question around, what would be examples when an authorization would be granted without both?
I understand the potential issues of msgs being rejected due to bad grammar vs. msgs being accepted while only the header could be ignored but it seems that an implementation using this new header should be strict when sending the header.

--- 2. IANA section and Header Field Parameters Sub-Registry
Per RFC3968, would it make sense to register the Target-Dialog header field parameters? 

Jean-François

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