[IMS Tech] SIP-I vs BICC
James Grayland
Dear all,
Following the conversations concerning SIP-I vs BICC and the interesting document sent by Victor, I would like to ask the expert members of the forum some additional questions;
1) What are the fundamental difference between SIP-I ITU-T Q.1912 + ANSI T1.679 (not including the fact one will carry ITU-T + national variants of ISUP and one ANSI ISUP)
2) Are there devices that allow interworking of ITU-T Q.1912 with white book ISUP and ANSI T1.679 with ANSI ISUP?
3) Is there a danger that we end up with national variants of SIP-I? If so are any of the national bodies already working on this?
Regards
James
-----Original Message-----
From: imstech...@imsforum.org [mailto:imstech...@imsforum.org] On Behalf Of Victor Pascual Ávila
Sent: 21 July 2008 18:00
To: ims...@imsforum.org
Subject: [IMS Tech] IMS-CS User plane interworking
Hello,
please, let me present the following scenario: Interworking between BICC over SCTP/IP and IM CN subsystem.
In 3GPP TS 29.163 version 6.11.0 Release 6 (Interworking between the IP multimedia Core Network and Circuit Switched networks), Section 8 (User Plane Interworking), Subsection 8.1 (Interworking between IM CN subsystem and bearer independent CS network) I can read:
"8.1.1.5: Even when the IM-MGW bridges compatible codec configurations between the Nb and Mb interfaces, the IM-MGW shall perform translation between the frame formats defined for the two interfaces, since all codec configurations have different framing procedures fot the two interfaces".
Mb--[IM-MGW]--Nb
In case both Nb and Mb interfaces are using the services of a RTP/UDP/IP transport, is it really necessary to perform such a translation? Hence, could the media gateway be eliminated at the interworking point?
In [1] I can read: "the media packet framing protocols used by BICC and SIP are different. BICC uses the 3GPP specific IuFP framing protocol while SIP framing is based on IETF specifications. Since IuFP is specific to 3GPP BICC, it is not as widely deployed as IETF based framing. Even the ITU version of BICC uses the IETF framing. The IuFP framing used by BICC introduces a protocol layer above the RTP which duplicates some of the RTP functions; as a result, the IuFP framing is not as efficient as strict IETF. Furthermore, IuFP framing is not supported by SIP; therefore, when interworking between existing SIP networks (e.g., IMS or NGN), additional media resources are required to provide the framing conversion. In contrast, when IETF framing is used in both peering networks, it becomes possible to eliminate the media gateway at the interworking point."
[1] http://www.3gamericas.org/pdfs/3G_Americas_SIP-I_White_Paper_August_2007-FINAL.pdf
Could anybody point out the real interworking problems between IuFP and IETF framing?
Any help will be appreciated,
--
Victor Pascual Ávila