Re: [rohc] Sigcomp presence-specific dictionary
Miguel Garcia <Miguel.An.Garcia@nokia.com> Mon, 26 March 2007 11:46 UTC
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Date: Mon, 26 Mar 2007 14:46:07 +0300
From: Miguel Garcia <Miguel.An.Garcia@nokia.com>
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To: cco <cristian.constantin@iptel.org>
Subject: Re: [rohc] Sigcomp presence-specific dictionary
References: <45ED1706.8090504@nokia.com> <20070326100309.GB10477@shell>
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Hi Cristian: Thanks for your comments. Inline answers. cco wrote: > On Tue, Mar 06, 2007 at 09:23:50AM +0200, Miguel Garcia wrote: >> Hi. >> >> I have been working on a presence-specific static Sigcomp dictionary for >> SIP presence. The draft is addressed to the SIMPLE WG, which is working >> on SIP presence. But I want to make the ROHC WG aware of the draft and >> solicit comments. >> >> Until the draft is officially available, you can download a copy from: >> >> http://people.nokia.net/~miguel/drafts/pre/draft-garcia-simple-presence-dictionary-02.txt >> http://people.nokia.net/~miguel/drafts/pre/draft-garcia-simple-presence-dictionary-02.html > > cristian: hi! the section "1. Introduction" says at some point: > > "Sigcomp endpoints will announce the availability of > one or both dictionaries during the Sigcomp initialization phase." > > what exactly do you mean by "Sigcomp initialization phase"? sigcomp is > piggy-backed on SIP in this case and there is no explicit sigcomp > "signalling". "SigComp initialization phase" refers to when the endpoint has not received an acknowledgment from the other end that the other end has received the message containing the announcement about presence dictionary. Perhaps the text would be better phrased as: Sigcomp endpoints will initially announce the availability of one or both dictionaries until the other end acknowledges that it has received the announcement. > > on the other hand rfc3485, "The Session Initiation Protocol (SIP) and > Session Description Protocol (SDP) Static Dictionary for Signaling > Compression (SigComp)", defining a similar dictionary (sigcomp "local" state) > puts a requirement on the implementation of sigcomp stacks for sip: > > "The static dictionary is unique and MUST be available in all SigComp > implementations for SIP/SDP." > > (and the need for such a requirement is also explained in the rfc.) > why not having the same kind of req. in your draft? We were able to mandate the SIP dictionary for SigComp because they were created at the same time. However, nowadays, there are millions of deployed SIP endpoints that implement SigComp (and the SIP static dictionary), presence, and other services, that do not obviously implement the presence-specific dictionary that we are discussing here. So, obviously, we cannot assume that an implementation will have a built-in presence-specific dictionary, unless it is advertised. BR, Miguel > > bye now! > cristian -- Miguel A. Garcia tel:+358-50-4804586 Nokia Research Center Helsinki, Finland _______________________________________________ Rohc mailing list Rohc@ietf.org https://www1.ietf.org/mailman/listinfo/rohc