Subject: [rohc] AD comments on draft-ietf-rohc-sigcomp-sip-05

From: Magnus Westerlund <[email-masked]>
Date: Thu, 29 Mar 2007 13:47:47 +0200

Hi,

I have now reviewed the SigComp draft and a have a few comments.

1. Section 3.

    Additionally, it must support the SIP/SDP static dictionary, as
    specified in [RFC3485], and the mechanism for discovering SigComp
    support at the SIP layer, as specified in [RFC3486].

Shouldn't the "must" in the above sentence be "MUST"?

2. Section 5. Last paragraph:

Should it for any reason not be desirable to set up
    more than one TCP connection to a SIP implementation, but the
    flexibility to send both compressed and uncompressed SIP messages be
    required, the compressor can set up a SigComp-structured connection
    and send any uncompressed SIP messages using the well-known shim
    header.

What is "SigComp-structured connection"? A reference to where this is 
specified might be a good idea.

Cheers

Magnus Westerlund

IETF Transport Area Director & TSVWG Chair
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From: Miguel Garcia <[email-masked]>
Date: Thu, 29 Mar 2007 15:23:56 +0300

> Shouldn't the "must" in the above sentence be "MUST"?

That "MUST" is already written in RFC 3485 and RFC 3486, respectively, 
so, in my opinion, the "must" is correct, especially since the text 
refers to both canonical specifications RFC 3485 and RFC 3486.

/Miguel
-- 
Miguel A. Garcia           tel:+358-50-4804586
Nokia Research Center      Helsinki, Finland

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From: Magnus Westerlund <[email-masked]>
Date: Thu, 29 Mar 2007 15:10:16 +0200

> refers to both canonical specifications RFC 3485 and RFC 3486.

Now you get me confused. Isn't this document the one intended to be the 
root document for anyone implementing sigcomp for SIP? In that case it 
seems necessary for this document to have a normative statement saying 
that you shall implement RFC 3485 and RFC 3486. It doesn't matter if 
these document are within themselves saying what feature to implement.

Cheers

Magnus Westerlund

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From: Miguel Garcia <[email-masked]>
Date: Thu, 29 Mar 2007 16:16:41 +0300

> these document are within themselves saying what feature to implement.

Yes and no. I don't think it makes sense to have two equal normative 
statements in different documents, a technique commonly known as 
overspecifying. Remember that no matter whether you have 
draft-ietf-rohc-sigcomp-sip-05 or not, the MUST implement RFC 3485 and 
3486 remain in their respective documents.

Thus, I am fine with the current wording. It could be rewording in 
different words, for example: "Notice that RFC 3485 and RC 3486 already 
mandate the implementations.... " But this is just a matter of taste.

BR,

       Miguel

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From: Magnus Westerlund <[email-masked]>
Date: Thu, 29 Mar 2007 16:07:12 +0200

> mandate the implementations.... " But this is just a matter of taste.

Okay, based on that wording in RFC 3485 and 3486 can't be changed I am 
fine with the current wording.

What about question 2?

Cheers

Magnus Westerlund