Re: [Sipping] Requesting the publication of cc-transfer

[Alan Johnston <[e-mail]>]

Hi Ian,

Thanks for your comments on the draft.  We will fix the issues you raise 
below.  We will check the other Replaces tags to ensure they are correct.

Thanks,
Alan

Ian Elz (CV/ETL) wrote:
> I have been reading through this draft as much of what is included must
> be considered for the b2bua draft.
>
> I have a couple of NITS:
>
> Section 1 refers to the Refer method and the Replaces header but there
> is no mention in the draft of the Referred-By header. While this is
> optional it may be worth showing the use of the Referred-By header in
> one of the examples.
>   
Section 8 shows the use of Referred-By, but we can mention it in Section 
1 as well.
> Section 5 3rd paragraph references section 5.2. This should now read
> 6.2, there has been another section added.
>
> In some Figures where you use the Replaces= you show the replaced dialog
> as 'dialog2' (Figure 9) and in others it is just '2' (Figures 6,7 & 8).
>
> I have an observation about Section 7.2. While this shows that either
> party in this scenario can become the transferee I am unsure how this
> hides information about the Transfer Target (performing the transfer in
> this case). The INVITE, as shown in Figure 6, will reveal the
> information about the Transfer Target to the Transferee. If you wish to
> show information hiding perhaps an example should include Privacy
> headers.
>
> There appears to be an issue with the To-tag and From-tag in the
> Replaces headers.
>
> Let me use Figure 6 as an example.
>
>               Transferor           Transferee             Transfer
>                    |                    |                  Target
>                    |                    |                    |
>          dialog1   | INVITE/200 OK/ACK F1 F2                 |
>                    |<-------------------|                    |
>          dialog1   | INVITE (hold)/200 OK/ACK                |
>                    |------------------->|                    |
>          dialog2   | INVITE/200 OK/ACK F3 F4                 |
>                    |---------------------------------------->|
>          dialog2   | INVITE (hold)/200 OK/ACK                |
>                    |---------------------------------------->|
>          dialog3   | REFER (Target-Dialog:1,                 |
>                    |  Refer-To:sips:Transferee?Replaces=1) F5|
>                    |---------------------------------------->|
>          dialog3   | 202 Accepted       |                    |
>                    |<----------------------------------------|
>          dialog3   | NOTIFY (100 Trying)|                    |
>                    |<----------------------------------------|
>          dialog3   |                    |            200 OK  |
>                    |---------------------------------------->|
>          dialog4   |         INVITE (Replaces:dialog1)/200 OK/ACK F6
>                    |                    |<-------------------|
>
> In this example you have shown F1 and F2 where F2 is:
>
>   F2 200 OK Transferor -> Transferee
>
>   SIP/2.0 200 OK
>   Via: SIP/2.0/TLS 192.0.2.4;branch=z9hG4bKnas432
>   To: <sips:[e-mail]>;tag=31431
>   From: <sips:[e-mail]>;tag=7553452
>   Call-ID: 090459243588173445
>   CSeq: 29887 INVITE
>   Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY
>   Supported: replaces, gruu, tdialog
>   Contact: <sips:[e-mail];grid=723jd2d;gruu>
>   Content-Type: application/sdp
>   Content-Length: ...
>
> You have then used the Call-Id, To-tag and From-tag from this
> transaction to specify the Replaces values in the REFER/Replaces in F5
> as:
>
> ?Replaces=090459243588173445%3Bto-tag%3D31431%3Bfrom-tag%3D7553452
>
> The Replaces header in F6 is shown with the same to-tag and from-tag:
>
> Replaces: 090459243588173445;to-tag=31431;from-tag=7553452
>
> This is not in agreement with the contents of RFC 3891 Replaces header
> which states in Section 3:
>
>                                                    The User Agent Server
>    (UAS) matches the to-tag and from-tag parameters as if they were tags
>    present in an incoming request.  In other words, the to-tag parameter
>    is compared to the local tag, and the from-tag parameter is compared
>    to the remote tag.
>
> As the initial INVITE of dialog1, dialog to be replaced, is from the
> Transferee to the Transferor the local-tag for the Transferee is 7554542
> and the remote-tag is 31431.
>
> This means that in a Replaces header directed towards the Transferee to
> replace dialog1 the tags should be as follows:
>        To-tag=7554542
>        From-tag=31431
>
> Thus in F6 the Replaces header should be:
>
> Replaces: 090459243588173445;to-tag=7553452;from-tag=31431
>
> Which means that the Replaces contained in the Refer-to in F5 should be:
>
> ?Replaces=090459243588173445%3Bto-tag%3D7553452%3Bfrom-tag%3D31431
>
> Which is as if the Transferor is sending a Request directly to the
> Transferee.
>
> I have not checked the other examples to see if the same mistake has
> been made in these examples.
>
> Ian Elz
>
> Office: + 44 24 764 35256
> gsm: [phone]
> [e-mail]
>
> -----Original Message-----
> From: Gonzalo Camarillo [mailto:[e-mail]] 
> Sent: 30 August 2007 13:05
> To: sipping
> Cc: Mary Barnes
> Subject: [Sipping] Requesting the publication of cc-transfer
>
> Folks,
>
> now that the GRUU mechanism is stable, Alan has put together a new 
> revision of the cc-transfer draft that is ready for publication.
>
> http://www.ietf.org/internet-drafts/draft-ietf-sipping-cc-transfer-08.tx
> t
>
> Please, have a look at this draft and let us know if you have comments. 
> We intend to request its publication in a couple of weeks.
>
> Thanks,
>
> Gonzalo
>
>
>
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>   



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