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VOIP 技術標準與發展趨勢 周勝鄰 博士 工研院電通所 E-mail: slchou@itri.tw Tel: 03-5915616 2003. 10

VOIP 技術標準與發展趨勢 周勝鄰 博士 工研院電通所 E-mail: slchou@itri.org.tw Tel: 03-5915616 2003. 10. Contents. Overview of VoIP System VoIP Technologies --- From H.323 to SIP SIP-based IP Multimedia Communication System ENUM for IP-PSTN Convergence Conclusion. VoIP 的過去. Born of VoIP Industry

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VOIP 技術標準與發展趨勢 周勝鄰 博士 工研院電通所 E-mail: slchou@itri.tw Tel: 03-5915616 2003. 10

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  1. VOIP技術標準與發展趨勢周勝鄰 博士工研院電通所E-mail: slchou@itri.org.twTel: 03-59156162003. 10

  2. Contents • Overview of VoIP System • VoIP Technologies --- From H.323 to SIP • SIP-based IP Multimedia Communication System • ENUM for IP-PSTN Convergence • Conclusion

  3. VoIP 的過去 • Born of VoIP Industry • VoIP Phone --- VocalTech 1995 • H.323 Standard for VoIP Industry • H.323 Proposed by ITU-T for Multimedia Communication over LAN in 1996 • Adopted Quickly and Widely by Industries • VoIP Gateway, Gatekeeper, Enterprise GW, IAD • Mainly Used in Enterprise, Toll-by-Pass Applications • Market Slow Down • Infrastructure Bottleneck --- Limitation of H.323 • New Technologies Developed • Users Hesitate to Buy H.323 Products • Vendors Invest Much in H.323

  4. VoIP 的現在 • New Technologies Ready • MGCP, MEGACO/H.248, SCTP/M3UA, SIP/SDP • IETF-like Protocols • New Products Developed • Most Upgraded from H.323 Products • Support New Technologies as well as H.323 • VoIP Infrastructure • Softswitch, Trunk GW, SS7 Signaling GW (SS7 over IP) • Market Re-Booming • IETF Technologies Dominate • SIP Telephony Being Widely Accepted • ENUM for IP/PSTN Convergence Being Developed • Softswitch vs. SIP • Softswitch: Mainly for Class 4/5 Switch Replacement • SIP: Provide Telephony from IP’s Point of View

  5. VoIP 的未來 • VoIP Infrastructure will Get Ready (How Soon ?) • ENUM for IP/PSTN Convergence • Product and Service Start to Boom • It’s Technologies Trend, Not Just for Cost Saving • Driving Force of NGN • Mandatory in Future All-IP Network • SIP Technologies Will Dominate • SIP Telephony/CO Signaling/Multimedia Service/3G • Key Technologies for IP/PSTN Convergence

  6. VoIP Applications • IP PBX • Softswitch • Application Server • Media Server • ENUM • 3G Softswitch • VoIP Mobile • VoIP Phone • Residential GW • Trunk GW • Enterprise • VoIP Gateway 97 99 02 05 • IP/PSTN • Convergence • All-IP • Networking • Toll By Pass • ITSP • Basic Service • Widely Deployment • New Services

  7. VoIP Services Applications • PSTN’s (Telecomm.’s) Point of View • Equip PSTN with VoIP Services • Original Voice Users • For Cost Saving, No Service Enhancement • Class 4/5 Switch Replacement with Softswitch • ISP’s (IP’s) Point of View • Enhance Data Network with VoIP Capability • Additional Voice Service to Original Data Users • Even Voice/Data Integrated Services • SIP Telephony + Application/Media Servers Incentive  Low Incentive  High

  8. VoIP Technologies--- From H.323 to SIP

  9. H.323 Terminal H.323 MCU Packet Based Network Packet Based Network H.323 Gateway H.323 Terminal H.323 Terminal H.323 Gatekeeper Guaranteed QoS LAN GSTN N-ISDN B-ISDN H.310 terminal operating in H.321 mode H.321 V.70 H.324 Speech Speech H.320 H.322 H.321 Terminal Terminal Terminal Terminal Terminal Terminal Terminal Terminal H.323 for VoIP • Has Been Adopted by Vendors for Years • Almost Current VoIP Products Support H.323 • Gateway • Gatekeeper • Terminal • MCU

  10. Challenges of H.323 • H.323 Was Originally Proposed for LAN Environment • Limitation Being Applied for VoIP Infrastructure Applications • Architecture is Too Simple • Single Gateway to Interact with PSTN/GSM • Suitable for Peer to Peer Communication • Protocol is Too Complex • Complicated Call Set-Up Signaling • Hard to Extend • Signaling Is Not Enough • Only DTMF is Specified • No SS7 Signaling Capability • Advanced Services are Limited • Interoperability is Still an Issue

  11. Gateway Decomposition H.323 GW MGC: Call Control, Call Routing, Service Selection,… Media GW Controller (MGC) Signaling GW (SG) SG Interface with SS7 and Translate to SS7 over IP MGCP MG Dedicate for Media Translation and Transportation SS7 Signaling Media GW (MG) Traffic

  12. IPDC 0.12 IPDC 1.0 Level3,... MGCP 1.0 MEGACO/H.248 SGCP IETF/ITU-T Telcordia MDCP AT&T May ‘98 Aug ‘98 Sept ‘98 Dec ‘98 Aug ‘00 Media Gateway Control IPDC: IP Device Control Protocol SGCP: Simple Gateway Control Protocol MEGACO: Media GAteway Control (IETF Working Group) MGCP: Media Gateway Control Protocol MDCP: Media Device Control Protocol

  13. MGCP/MEGACO/H.248 • Client-Server Architecture • Call Agent (Media Gateway Controller) • Call Control Server • Media Gateway • Dedicated for Media Transmission • Trunk/Access/Residential GWs • Signal Gateway • SS7 Interfacing MGC (CA) MGC (CA) SGW SGW MGCP/ MEGACO SS7 (ISUP) MGCP/ MEGACO SS7 (ISUP) CO RTP Streams Trunk GW Trunk GW Access GW/ IP-PBX/RGW MGCP IP phone IP phone

  14. MGC MGC SG SG ISUP/MGCP/SIP Interworking

  15. SIGTRAN Protocol Stack SS7 Protocol Stack OSI Layers MAP INAP INAP MAP Application Presentation Session TCAP TCAP ISUP ISUP SCCP SCCP Transport SCN Signaling Adaptation (M3UA, IUA, …) Network MTP Data Link Common Signaling Transport (SCTP) Physical IP SS7 over IP

  16. PSTN Softswitch System Architecture Enhanced Services Service APIs Application Server Media Server SIP SIP SIP SIP SOFTSWITCH SOFTSWITCH RTP RTP IP MGCP MGCP SCTP SCTP Media Gateway Signaling Gateway Media Gateway Signaling Gateway RTP RTP T1/PRI T1/PRI SS7 PSTN SS7

  17. Services, Applications & Features (Management, Provisioning and Back Office) PROPRIETARY Services & Applications Call Control & Switching Softswitch Call Control Open Protocols APIs Open Protocols APIs TransportHardware Transport Hardware What is A Softswitch ? Soft-Switched Circuit-Switched • Solutions are open standards-based products, and can come from multiple vendors. • Customers are free to choose best-in-class products to build their network. Open standards enable innovation and in the long run can reduce costs • Software, hardware and applications solutions typically come packaged in a single (proprietary) box. • Non-standard solutions are expensive to implement and leave little room for innovation.

  18. Gatekeeper/Billing/Internet Messaging Authentication/Directory/... SS7 SS7 Application Server ITG/IP-PBX SIP+ (?) SIP CoreBuilder 9000 IN/SCP Internet Telecom System MGC MGC VoIP Signaling Gateway SIP -T VoIP SG SCTP MGCP/ MEGACO IP Network RTP Streams Trunk Gateway Trunk Gateway PSTN

  19. GSM BSS HLR Gateway MSC/VLR Visited MSC/VLR PSTN PCU GPRS Gb Gn External Data Network Gi SGSN GGSN Wireless System --- From GSM to GPRS Always-On Wireless Packet Data Services

  20. Legacy Mobile Signaling Network Applications & Services Alternative Access Network SCP R-SGW CSCF Ms Multimedia IP Networks Mw Mh CAP CSCF HSS Mm Cx Mg Mr Gr Gi Gc MRF EIR Gi MGCF Gf T-SGW Iu Gi BSS/ GERAN GGSN TE MT SGSN Gn R Um Mc Gb A Gi Iu PSTN Legacy/External MGW TE MT UTRAN MGW Iu Nb R Uu Mc Mc Iu Nc GMSC Server MSC Server CAP C D CAP Applications & Services Signaling Interface HSS Signaling and Data Interface IP Multimedia in 3G All-IP System

  21. VoIP Network Applications & Services (OSA Platform) Multimedia Sub-Core Network (VoIP) CSCF MGCF HSS MGF Gm Alternative Access Network GGSN SGSN Gm PSTN/GSM GPRS Backbone IP Network SIP in 3G All-IP System Gm: Interface between UE and CSCF -Over GPRS Data Bearer Service - Based on SIP (RFC 2543) Protocol - For Application Level Signaling * Register to CSCF * Call Orgination/Termination * Supplementary Services

  22. SIP-based IP MultimediaCommunication System

  23. SIP Request SIP Response Redirect Server RTP Media Stream Proxy Server Location Server Proxy Server Proxy Server User Agent Client(Caller) User Agent Server(Callee) SIP Telephony System

  24. Session Initiation Protocol • Session Initiation Protocol • SIP is HTTP-like, Text-based Client-server Protocol (client-to-client is possible) • To Establish, Modify and Terminate Multimedia Sessions or Calls • Be able to Integrate Voice, Video and other Interactive Communication Services with Instant Messaging and Presence • Original RFC 2543 --- Feb, 1999 • Newest RFCs --- July, 2002 • RFC 3261 SIP: Session Initiation Protocol • RFC 3262 Reliability of Provisional Response in Session Initiation Protocol (SIP) • RFC 3263 Session Initiation Protocol (SIP): Location SIP Servers • RFC 3264 An Offer/Answer Model with Session Description Protocol (SDP) • RFC 3265 Session Initiation Protocol (SIP)-Specific Event Notification

  25. SIP Attributes • User Agents • End Systems Acting on Behalf of a User • Clients(UAC) to initiate a SIP request and servers(UAS) to receive the request and return responses • Servers • Proxy Server Relay Call Signaling • Redirect Server • Registrar Server: User Locations Tracking (Like HLR in GSM) • Naming & Addressing • SIP URL, e-mail like: user@host • Examples • Sip:patrik@example.com • Sip:Jackie@176.7.6.1

  26. SIP Operation in Proxy Mode

  27. SIP Operation in Redirect Mode

  28. Protocol Format INVITE sip:pgn@example.se SIP/2.0 Via: SIP/2.0/UDP science.fiction.com From: Fingal <sip:ffl@fiction.com> To: Patric <sip:pgn@example.se> Call-ID: 1234567890@science.fiction.com Cseq: 1 INVITE Subject: lunch at La Empenada? Content-Type: applcation/sdp Content-Length: … SIP Header v=0 o=ffl 53655765 2353687637 IN IP4 123.4.5.6 s=Chorizo c=IN IP4 science.fiction.com m=audio 5004 RTP/AVP 0 3 5 a=rtpmap:0 PCMU/8000 Payload: MIME type (SDP)

  29. Applications R S V P SDP/SDPng RTP/ RTCP HTTP SMTP SIP RTSP SAP TCP/SCTP TCP/UDP UDP IPv4/IPv6 with Mobility, DiffServ and Multicast SIP in IP Multimedia Architecture • Common Addressing, user@domain • (URI & URL) • Text-based and Encoding Format • Same Request-Response Model, • and Response Codes • MIME for Flexible Payload • DNS for Address Mapping Easy to Do Integrated Services by Combining more than One Protocols

  30. SIP-Based Services • Internet Telephony • Well-Recognized IP Telephony System • Instant Messaging • Exchange of Content between Participants in Real-time • Presence • Subscription to and notification of changes in the comm. State of a users • Currently worked by SIMPLE WG in IETF • Click-to-Call from an Electronic Document • ‘SIP as tag’ Contained in Document • Transport of MIME in SIP Signaling • Reference to Web/WAP Pages, mail, pictures • Interactive Games with SIP Signaling

  31. Rich Call with SIP • Before the Call • Dynamic Phone Book • Click-to-Talk • During Call Establishment • Sending a Rich Clip, which Can be • A Picture with Call Subject, or • Special Ringing Tone • During the Call • Document Sharing • Information Push • During Session Tear-Down • (same as Call Establishment) • After the Call • Be Able to Send Instant Message

  32. SIP for Instant Messaging • Integration of Messaging, Presence, and Session-oriented Communication • RFC 3428 --- SIP Extension for Instant Messaging • SIP MESSAGE Method --- Pager-mode IM • For small IM Exchange • Carry IM on Signaling Channel --- Big Overhead • Pager-mode vs. Session mode Instant Messaging • Pager-mode --- Each message is independent of any other message • Session-mode --- IMs are associated with a media session established by SIP INVITE method • Message Session Relay Protocol (MSRP) --- IETF Draft • Support Session-mode IM between Endpoints

  33. SIP for IP Convergence • In 3G and NGN, the Focus Shift towards to All-IP Paradigm • IP Transport, IP Mobility and VoIP (e.g. SIP) Protocol • SIP Has Been Adopted by 3GPP for Session Signaling • SIP Telephony System Has Been Well Accepted • With SIP, Service Creation is Fast and Easy • IP Protocols vs. Telecom Protocol, like IN • Be able to Integrate Most IP-based Services • Service Mobility and Personal Reachability • By SIP and IPv6 Mobility

  34. ENUM for IP-PSTN Convergence

  35. ENUM 101 • What is ENUM (RFC 2916)? • Make Telephone Number Become a Domain Name in Internet • Importance of ENUM • Mechanism for IP/PSTN Convergence • Global ENUM Activities • IETF, ITU-T, US ENUM Form, Europe, … • ENUM Trials: More Than 10 Countries • Different Kinds of ENUM • Public ENUM: Future Vision • Carrier ENUM: Enhance MMS/SMS Services • Enterprise ENUM: Enhance Enterprise Telecomm Service

  36. What is ENUM ? Problem: How to Address (or Locate) a User in IP Telephony World or PSTN/VoIP Integrated Network ? ENUM is a Mechanism to Translate an E.164 Number into A List of URI (Service@Host) So that An IP User Can be Accessed by E.164 Number. ENUM Mechanism E.164 Number URI(Service@Host) Domain Name System (DNS)

  37. What is ENUM ?

  38. What is ENUM ?

  39. ENUM Domain

  40. .arpa ENUM DNS Hierarchy . Tier 0 (RIPE) 6.8.8.e164.arpa -> ns1.t1.com ns2.t1.com ns1.t1.com/ns2.t1.com 2.6.8.8.e164.arpa -> ns1.t1a.com; ns2.t1a.com 6.6.8.8.e164.arpa -> ns1.t1b.com; ns2.t1b.com Tier 1 ns1.t1a.com/ns2.t1a.com ns1.t1b.com/ns2.t1b.com ... ... 4.3.2.1.4.9.3.2.2.6.8.8.e164.arpa -> ns1.t2.biz; ns2.t2.biz 4.3.2.1.8.9.2.6.6.8.8.e164.arpa -> ns1.t2.org; ns2.t2.org ns1.t2.biz/ns2.t2.biz Tier 2 (Designated by the end user) 4.3.2.1.4.9.3.2.2.6.8.8.e164.arpa -> NAPTR RRs (ldap URL) Tier 3 (Depending on the application) ldap URL LDAP DB Source: James Yum, Neustar

  41. SIP Proxy ENUM Scenario Enum Record $ORIGIN 6.1.6.5.1.9.5.3.6.8.8.e164.arpa. IN NAPTR 100 10 “u” “sip+E2U” “!^.*$!sip:slchou@itri-sip-proxy.org.tw!” IN NAPTR 102 10 “u” “tel+E2U” “!^.*$!tel:+886910961527!” IN NAPTR 102 10 “u” “mailto+E2U” “!^.*$!mailto:slchou@itri.org.tw!” E-Mail Server DNS ENUM Server 3 SIP Phone 3 IP Network 5 2 Signal Gateway Media Gateway IAD • User Dial Tel. No • ENUM Query, get 3 URIs • Make SIP Call, No Answer • Make Mobile Call, Fail • Connect to E-Mail Softswitch 4 1 Dial:03-5915616 0910961527

  42. ENUM Scenario (cont.) • User Make Call to E.164 Number: 03-5915616 • Softswitch Translates the E.164 Number to Query Input to ENUM Server: • 6.1.6.5.1.9.5.3.6.8.8.e164.arpa and gets a list of URIs returned • The Softswitch Processes the 1st URI Record, • Query DNS to get the IP Address of Host: itri-sip-proxy.org.tw • Make SIP Call to SIP Phone of slchou through SIP Proxy • SIP Phone Does not Answer • The Softswitch Processes the 2nd URI Record, • Make PSTN Call Through Gateway to 0910961527 • 0910961527 Does not Answer • The Softswitch Processes the 3rd URI Record, • Query DNS to get the IP Address of Host: itri.org.tw • Connect the Caller E-Mail Server SMTP Protocol • Caller Leave the E-Mail Message

  43. ITU-T ENUM Activities • ITU-T Study Group 2 • Interim Procedures for Use of the ARPA Domain • Approved in May, 2002 • Interim procedures for delegation of E.164 country codes into ARPA domain before Approval of E.A-NUM • RIPE-NCC is Authorized by ITU-TSB to Perform such Delegation at this Stage • http://www.ripe.net/enum/instructions.html

  44. Tier-0 Top Level Domain (TLD) • The Choice of Common Designated Domain fir ENUM Tier-0 is Undecided and is Proving Controversial • ARPA as ENUM TLD is Controlled by IETF and Operated by RIPE-NCC • US and some other countries, ISOC/IAB/IETF Support IETF Conclusion • European Union, France and Germany Proposed ITU-TSB as the Operator for ENUM • China, France, Germany, Syria and Spain Objected to ARPA as TLD for political reason  to reinforce the infrastructure of Internet governance • E.A-ENUM Recommendation • “Principle and procedures for the administration of E.164 Country codes for registration into the Domain Name System” • TLD is open • ITU-TSB is the ENUM Tier-0 Administrator

  45. IETF ENUM Activities • Telephone Number Mapping (ENUM) WG • RFC 2916, “E.164 number and DNS” • RFC 2915, “The naming authority pointer (NAPTR) DNS resource record”, August, 2000 • RIPE-NCC • Related ENUM Activities after RFC 2916 • Update RFC to reference the DDDS • RFC2916bis,”The E.164 to URI DDDS Application” • ENUM Administrative and Operational Prtocedures • Registration and Provisioning Procedures, Validation and Authentication of Data • Operational Privacy, Security Issues and Procedure • IETF Liaison with ITU-T SG2 • New Issues Being Considered: • Extent Same URI in RFC 2916 for Different Service • e.g., 2 SIP URIs but one for voice and one is instant messaging • SIP vs. ENUM Services, e.g., distinction the location provided by SIP and ENUM • Adding Presence as an ENUM service • Extension of ENUM service ‘tel’ URI • Location Number Portability, using DNS as the source • Extensible Provisioning Protocol (EPP) in PROVREG WG, IETF

  46. European Forums • ETSI • “ENUM Administration in Europe”, May, 2002 • 3 Level architecture: ENUM Tier-0, Tier-1, and Tier-2 • Refers to e164.arpa as TLD, but accommodate different selection by ITU-T in the future • Permit the Deployment of ENUM in roots alternative to “.” • A threat to universal resolvability of DNS controlled by ICANN • Important Principles for Each European National Implementation of ENUM: • ENUM end user must be the assignee of an E.164 • Integrity of ENUM data shall not be compromised • Administration requirements for different number types and managements of E.164 Numbering Plan • Must be compliant to ITU-T Recommendation and IETF technical specification • Stable and secure ENUM Environment • Conformity with national data protection and privacy laws • Accord with national regulatory requirements • Don’t affect existing network functions, such as LNP • Opt-in ENUM service for end users

  47. US ENUM Forum US ENUM Forum (General Session) External Communications Group Legal Experts Group Architecture and Infrastructure Provisioning Security and Privacy Interworking Applications

  48. Current ENUM Trials 16 ENUM Request Approved: AC, AE, AT, BR, CN, DE, HU, IO, NL, PL, RO, SE, SH, UK, NeuStar, VISIONng/INFONOVA

  49. Taiwan ENUM Activities • ENUM Forum Taiwan • Formed by TCA Coordination • TWNIC, CCL, TL, III, Operators, … • SIP/ENUM Trial Project • Coordinated by ENUM Forum Taiwan • Sponsors: IDB, DGT, CCL, NTP & NBEN, TWNIC, Operators, NICI, IPv6 Task Force, ISP, … • Duration: 2003.1 --- 2003.12 • DGT’s Activities • 法令研究 • 爭取 886 國碼之使用權 • 贊助Trial Project

  50. Taiwan SIP/ENUM Trial Project

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