調査と解説

セッション確立のための基本的なシーケンスは図 ??? に記述したが，3GPP における資源要求からポリシーの決定までふくむシーケンスの例を図 1 にしめす (TS 24.228 [3GP 06c] の Figure 5.3.1-1)． ここでは P-CSCF と PDF がまとめて記述されているが，P-CSCF は図 2 においては AF に相当し，この間は Gq インタフェース (Diameter 準拠) によってつながれる．

この例においてはセッション確立の第 2 フェーズ (12.～18.) において GPRS 固有の機能 (12. GPRS: Activate PDP Context など) を使用している． また，TS 23.207 [3GP 06e] (Annex D) には RSVP をこの機能とあわせて使用する例も記述されている．

図 1　ポリシーの決定をふくむセッション確立シーケンス

図 ??? における SIP メッセージの例は TS 24.228 などに記述されているが，TS 24.228 に記述されたおおくの例は未完のままである． (ほぼ) 完成されているひとつの INVITE 要求の例 (Table 7.2.2.1-1) を図 2 にあげ，UPDATE要求の例 (Table 7.2.2.1-19) を図 3 にあげる． 太字の部分が RFC 3312 [Cam 02] にしたがって QoS 条件を指定している． この例においては，UPDATE 要求が太字の部分それぞれの最初の行の “none” と “sendrecv” をのぞけば INVITE 要求の内容をエコーしているだけであり，図 1 のシーケンスが非常に冗長であることがわかる．

INVITE tel:+1-212-555-2222 SIP/2.0
Via: SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7
Max-Forwards: 70
Route: <sip:pcscf1.visited1.net:7531;lr;comp=sigcomp>, <sip:scscf1.home1.net;lr>
P-Preferred-Identity: "John Doe" <sip:user1_public1@home1.net>
P-Access-Network-Info: 3GPP-UTRAN-TDD; utran-cell-id-3gpp=234151D0FCE11
Privacy: none
From: <sip:user1_public1@home1.net>;tag=171828
To: <tel:+1-212-555-2222>
Call-ID: cb03a0s09a2sdfglkj490333 
Cseq: 127 INVITE
Require: precondition, sec-agree
Proxy-Require: sec-agree
Supported: 100rel
Security-Verify: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; spi-c=98765432; spi-s=87654321; port-c=8642; port-s=7531
Contact: <sip:[5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp>
Allow: INVITE, ACK, CANCEL, BYE, PRACK, UPDATE, REFER, MESSAGE
Content-Type: application/sdp 
Content-Length: (…)

v=0
o=- 2987933615 2987933615 IN IP6 5555::aaa:bbb:ccc:ddd
s=-
c=IN IP6 5555::aaa:bbb:ccc:ddd 
t=0 0
m=video 3400 RTP/AVP 98 99
b=AS:75
a=curr:qos local none
a=curr:qos remote none
a=des:qos mandatory local sendrecv
a=des:qos none remote sendrecv
a=rtpmap:98 H263
a=fmtp:98 profile-level-id=0
a=rtpmap:99 MP4V-ES
m=audio 3456 RTP/AVP 97 96
b=AS:25.4
a=curr:qos local none
a=curr:qos remote none
a=des:qos mandatory local sendrecv
a=des:qos none remote sendrecv
a=rtpmap:97 AMR 
a=fmtp:97 mode-set=0,2,5,7; mode-change-period=2
a=rtpmap:96 telephone-event
a=maxptime:20

UPDATE sip:[5555::eee:fff:aaa:bbb]:8805;comp=sigcomp SIP/2.0
Via: SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7
Max-Forwards: 70
Route: <sip:pcscf1.visited1.net:7531;lr;comp=sigcomp>, <sip:scscf1.home1.net;lr>, <sip:scscf2.home2.net;lr>, <sip:pcscf2.visited2.net;lr>
P-Access-Network-Info: 3GPP-UTRAN-TDD; utran-cell-id-3gpp=234151D0FCE11
From: <sip:user1_public1@home1.net>;tag=171828
To: <tel:+1-212-555-2222>;tag=314159
Call-ID: cb03a0s09a2sdfglkj490333
Cseq: 129 UPDATE
Require: sec-agree
Proxy-Require: sec-agree
Security-Verify: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; spi-c=98765432; spi-s=87654321; port-c=8642; port-s=7531
Content-Type: application/sdp
Content-Length: (…)

v=0
o=- 2987933615 2987933617 IN IP6 5555::aaa:bbb:ccc:ddd
s=-
c=IN IP6 5555::aaa:bbb:ccc:ddd
t=0 0
m=video 3400 RTP/AVP 98
b=AS:75
a=curr:qos local sendrecv
a=curr:qos remote none
a=des:qos mandatory local sendrecv
a=des:qos mandatory remote sendrecv
a=rtpmap:98 H263
a=fmtp:98 profile-level-id=0
m=audio 3456 RTP/AVP 97 96
b=AS:25.4
a=curr:qos local sendrecv
a=curr:qos remote none
a=des:qos mandatory local sendrecv
a=des:qos mandatory remote sendrecv
a=rtpmap:97 AMR
a=fmtp:97 mode-set=0,2,5,7; mode-change-period=2
a=rtpmap:96 telephone-event
a=maxptime:20

参考文献

• [3GP 06c] 3rd Generation Partnership Project (3GPP), “Technical Specification Group Core Network and Terminals; Signalling Flows for the IP Multimedia Call Control Based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 (Release 5)”, 3GPP TS 24.228 V5.14.0, December 2005.
• [3GP 06e] 3rd Generation Partnership Project (3GPP), “Technical Specification Group Services and System Aspects; End-to-end Quality of Service (QoS) Concept and Architecture (Release 6)”, 3GPP TS 23.207 V6.6.0, September 2005.
• [Boe 03] Bohm, W. and Braun, P., “Policy Based Architecture for the UMTS Multimedia Domain”, 2nd IEEE Int’l Symposium on Network Computing and Applications (NCA 2003), pp. 275-285, April 2003.
• [Cal 03] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and Arkko, J., “Diameter Base Protocol”, RFC 3588, IETF, September 2003.
• [Cam 02] Camarillo, G., Marshall, W., and Rosenberg, J., “Integration of Resource Management and Ses-sion Initiation Protocol (SIP)”, RFC 3312, IETF, October 2002.
• [Cha 03] Chakravorty, R., Pratt, I., and Crowcroft, J., “A Framework for Dynamic SLA-based QoS Control for UMTS”, IEEE Wireless Communications, Vol. 10, No. 5, pp. 30-37, October 2003.
• [Mam 00] Mameli, R. and Salsano, S., “Integrated Services over DiffServ Network Using COPS-ODRA”, draft-salsano-issll-is-ds-cops-00, Internet Draft, IETF, August 2000.
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• [Ngu 03a] Nguyen, T. M. T., Boukhatem, N., and Puiolle, G., “COPS-SLS Usage for Dynamic Policy-Based QoS Management over Heterogeneous IP Networks, IEEE Network, Vol. 17, No. 3, pp. 44-50, May-June 2003.
• [Ngu 03b] Nguyen, T. M. T., Boukhatem, N., El Mghazli, Y., Charton, N., Hamer, L.-N., and Pujolle, G., “COPS-PR Usage for SLS Negotiation (COPS-SLS)”, draft-nguyen-rap-cops-sls-03, Internet Draft, IETF, July 2002.
• [Sal 00] Salsano, S., “COPS Usage for Outsourcing DiffServ Resource Allocation”, draft-salsano-issll-cops-odra-00, Internet Draft, IETF, February 2000.
• [Sal 02a] Salsano, S. and Veltri, L., “QoS Control by Means of COPS to Support SIP-Based Applica-tions”, IEEE Network, Vol. 16, No. 2, pp. 27-33, March-April 2002.
• [Sal 02b] Salsano, S., “COPS Usage for DiffServ Resource Allocation (COPS-DRA)”, draft-salsano-cops-dra-00, Internet Draft, IETF, May 2002.
• [Zhu 03a] Wei Zhuang, Yung-Sze Gan, Kok-Jeng Loh, and Kee-Chaing Chua, “Policy-Based QoS Architecture in the IP Multimedia Subsystem of UMTS”, IEEE Network, pp. 51-57, May-June 2003.
• [Zhu 03b] Wei Zhuang, Yung-Sze Gan, Kok-Jeng Loh, and Kee-Chaing Chua, “Policy-Based QoS-Management Architecture in an Integrated UMTS and WLAN Environment”, IEEE Communications Magazine, Vol. 41, No. 11, pp. 118-125, November 2003.