P2P Content Distribution for Multimedia Services in IMS-based Telco Environments

1. P2P Content Distribution forMultimedia Services inIMS-based Telco Environments Alex Bikfalvi, Jaime Garcia, Ivan Vidal, Francisco Valera

2. Overview: P2P and IMS? Multimedia Services • Peer-to-peer Technologies • … what is P2P (very brief)? • … why P2P? • … what content? • … how? • Next Generation Networks • … IMS & NGN? • … what is NGN/IMS? • … why IMS? • … how? Does make sense combining P2P and NGN (IMS) technologies? How can we do this? What services can benefit from P2P content distribution? What are the advantages for the telcos? But for the users?

3. Outline • (I) Multimedia services in today’s Internet • (II) IMS – a multimedia service platform • (III) P2P for multimedia content • (IV) A content distribution service for IMS

4. Part I: Multimedia Services Multimedia services in today’s Internet

5. The Internet... in 2004 • P2P traffic was 60% and rising • ISPs identified P2P as a major challenge in network design • It affects the QoS for all users • Mostly, file-sharing: BitTorrent, eDonkey, Kad, Gnutella Source: Cache Logic “P2P in 2005”

6. The Internet… in 2007 • Lately… the HTTP traffic is gaining the share back • … in terms of percentage of total traffic (not absolute value) Source: Magid Media Futures survey

7. The Internet… in 2007 and beyond • More than a third of the HTTP traffic is video streaming • YouTube is the most popular; counts for around 20% • That’s about 10% of all Internet traffic Source: Magid Media Futures survey • The (near)future… • Internet video, the new broadband “killer”application? • More“***Tube” service providers? • User generated content and commercial content

8. Video content distribution • Growing user demand • Increases bandwidth costs for the service providers • YouTube: ≈ 25 PB / month ≈ 1.2 M$ / month • Increases bandwidth demands for the ISPs • Consequences • (Popular) Service providers expect an increase in costs at the same quality of service • Deploying/contracting CDN capacity • ISPs need to provision new capacity to meet the demand • Only selling capacity is not a good business plan for telcos Service Provider Content Distribution Network Internet Service/Access Provider (Telco) Internet Service/Access Provider (Telco) Internet Service/Access Provider (Telco)

9. Part II: IMS & NGN IMS as a multimedia service platform for Next Generation Networks

10. The next generation… • … service oriented architectures • Telco keywords • Triple-play packages: voice & TV & Internet • Telcos don’t make most $$$ by selling bandwidth • Telcos → intermediary entities for service providers • Convergence: legacy networks → next generation (IP) Telco (Internet Access Provider) End-User Service Provider IP Core Network Common Management & Service & Control Functions xDSL PSTN Cable Cable GSM/3G PSTN xDSL GSM/3G

11. IP Multimedia Subsystem • A platform for IP multimedia services • Initially designed by 3GPP as an evolution of GSM/UMTS • Currently extended to many more access networks • Core of a Next Generation Network (TISPAN) Service Providers IP Multimedia Core Network Subsystem Service Layer Transport Control Functions Transport Layer IMS Gateways Legacy terminals Other Networks Core Network Access Networks 3GPPterminals IMS terminals Telco

12. IMS: the basics • Functional entities connected by standardized interfaces • Main purpose: creation of sessions to multimedia sessions • Most of them handle the signaling not the media Conferencing AS Application Servers IPTV AS Voice AS VoD AS Service Layer (Applications) P-CSCF Call Session Control Functions P-CSCF S-CSCF HSS P-CSCF I-CSCF Service Layer (IMS) UE UE Access Networks Access Networks UE UE User Equipments Core Network UE UE Access Networks Access Networks UE UE Transport Layer UE UE

13. IMS: session signaling • IMS uses SIP for session signaling • Like a handshake between parties, before multimedia data can be exchanged • Independent on transport layer (uses URIs to identify resources) • SIP network elements • User agents • Servers: proxies, registrars, redirect servers • In IMS the Call Session Control Functions are SIP servers • Proxy-CSCF: the local proxy server for an User Equipment • Interrogating-CSCF: the role of the registrar • Serving-CSCF: proxy server performing session control

14. IMS: session signaling example alice@atlanta.com @ 10.0.0.45 bob@biloxi.com @ 130.4.1.45 • A SIP example: alice@atlanta.com 10.0.0.45 atlanta.com 10.0.0.1 biloxi.com 130.4.1.1 bob@biloxi.com 130.4.1.45 DNS DNS Query: SRV _sip.biloxi.com DNS Response: 130.4.1.1 INVITE sip:bob@biloxi.com INVITE sip:bob@biloxi.com Request Message Status Message 200 OK 200 OK ACK sip:bob@biloxi.com ACK sip:bob@biloxi.com

15. IMS: session signaling example • Session description protocol (SDP) alice@atlanta.com bob@biloxi.com Session Negotiation INVITE sip:bob@biloxi.com SDP: IP, port, codec INVITE sip:bob@biloxi.com SDP: IP, port, codec 183 Session Progress SDP: IP, port, codec 183 Session Progress SDP: IP, port, codec 200 OK 200 OK ACK sip:bob@biloxi.com ACK sip:bob@biloxi.com

16. IMS: session signaling example • In IMS each users has a dedicated SIP server: • In the access (visited) network: the P-CSCF • In the home network: the S-CSCF • Each network has a I-CSCF (the role of the registrar) visited1.com atlanta.com biloxi.com visited2.com alice@atlanta.com pcscf.visited1.com scscf.atlanta.com biloxi.com scscf.biloxi.com pcscf.visited2.com bob@biloxi UE P-CSCF S-CSCF I-CSCF S-CSCF P-CSCF UE INVITE INVITE INVITE INVITE INVITE INVITE 200 OK 200 OK 200 OK 200 OK 200 OK 200 OK

17. IMS applications • The S-CSCF perform service control based on user’s service profile • Used to implement application servers • Example: IPTV application server srv.atlanta.com:5999 RTSP/UDP alice@atlanta.com pcscf.atlanta.com scscf.atlanta.com iptv.atlanta.com UE P-CSCF S-CSCF AS INVITE iptv@atlanta.com INVITE iptv@atlanta.com INVITE iptv@atlanta.com Service Control 183 Session Progress SDP: srv.atlanta.com:5999 RTSP/UDP 183 Session Progress SDP: srv.atlanta.com:5999 RTSP/UDP 183 Session Progress SDP: srv.atlanta.com:5999 RTSP/UDP

18. Part III: P2P Multimedia Content Distribution P2P technologies for multimedia content The architecture of an IMS content distribution service

19. Content distribution technologies • What are IMS/NGN advantages? • Multiple transport technologies • Use of broadband and quality-of-service • Separated service and transport functions • Generalized mobility • However… media (especially video) streaming is extremely expensive • Applications target a lot of receivers • We need support at the transport layer • What are the options? • IP multicast • Content distribution network • Peer-to-peer Media Server IMS IMS Terminals (set-top boxes)

20. Case study: video streaming • What are IMS/NGN advantages? • Multiple transport technologies • Use of broadband and quality-of-service • Separated service and transport functions • Generalized mobility • However… media (especially video) streaming is extremely expensive • Applications target a lot of receivers • We need support at the transport layer • What are the options? • IP multicast • Content distribution network • Peer-to-peer Media Server IMS IMS Terminals (set-top boxes)

21. Case study: video streaming • What are IMS/NGN advantages? • Multiple transport technologies • Use of broadband and quality-of-service • Separated service and transport functions • Generalized mobility • However… media (especially video) streaming is extremely expensive • Applications target a lot of receivers • We need support at the transport layer • What are the options? • IP multicast • Content distribution network • Peer-to-peer Media Server IMS IMS Terminals (set-top boxes)

22. Case study: video streaming • What are IMS/NGN advantages? • Multiple transport technologies • Use of broadband and quality-of-service • Separated service and transport functions • Generalized mobility • However… media (especially video) streaming is extremely expensive • Applications target a lot of receivers • We need support at the transport layer • What are the options? • IP multicast • Content distribution network • Peer-to-peer Media Server IMS IMS Terminals (set-top boxes)

23. P2P issues • P2P looks fine… but: • Peers may have an unpredictable behavior • Resources (bandwidth, delay) may not be adequate • We need uplink resources as well • However,in NGN/IMS: • Some peers may be considered stable (e.g. set-top boxes) • Resources are known and reserved • Once reserved, they are guaranteed Fan-out: 3 Fan-out: 2 Fan-out: 2

24. Trees vs. meshes • Trees • Mimic multicast • Each peer selects a parent peer • The content/stream can be divided and sent across several trees • Meshes • A peer obtains pieces from any available peer • There is not a strict relationship: child-parent • Instead peers can collaborate in sharing pieces

25. Where P2P? • P2P media vs. P2P signaling • Until now we discussed P2P in media plane • What is P2P signaling? • Discovery of other peers using a P2P protocol • For trees: a structured protocol (DHT) to find a parent • For meshes: an unstructured protocol to find other peers • With P2P signaling • The functionality is distributed • No need of a central entity

26. Part IV: A P2P Content Distribution Service for IMS (work in progress)

27. Incentives for P2P • IMS network capabilities • Smart IMS devices as peers: residential gateways, set-top boxes • Transport: quality of service, resource reservation • Telco policies: using capacity that is physically available but not paid for by the user • Advantages • All advantages of IMS: AAA, mobility, QoS • Performance improvement goals • Reduce load on core network / service provider • Keep most of the traffic in the access network • The telco controls the network • P2P in a managed environment → optimizations • Business model • Service providers → Telco → Users

28. Why such a service? • Video content may be the new killer app, but… • … other services can benefit from P2P too (conferencing, software distribution) • … even video may have different requirements (IPTV ≠ VoD) • Content Distribution Service Provider • Intermediary between the Multimedia Content Service Provider and IMS + transport layer • Makes the content distribution transparent for the MCS • Hides the specifics of the media content to the IMS/transport The Content Distribution Service is intended as an adaptation layer between the multimedia content and the mechanism (P2P or otherwise) used for content distribution

29. The idea Multimedia Services Content Distribution Service AS AS AS AS IMS Transport Network UE UE UE UE UE UE

30. The idea: IPTV simple example • IPTV client • Needs the address, port of a host delivering the video • We call this host the content serving host UE alice@atlanta.com IPTV client CDS client cds.atlanta.com INVITE cds@atlanta.com SDP: provider=iptv3, ch=5 connect(ch5) AS INVITE cds@atlanta.com SDP: provider=iptv3, ch=5 183 Session Progress SDP: peer IP, port, protocol, codec 183 Session Progress SDP: peer IP, port, protocol, codec 200 OK 200 OK return IP, port, … ACK cds@atlanta.com ACK cds@atlanta.com

31. The infrastructure • Different topologies for P2P • P2P between UEs (same/different access networks) • P2P between Edge Servers/Distribution servers Content Distribution Service IMS AS AS AS AS Multimedia Services Edge/Distribution Servers P2P P2P P2P P2P User Equipment (IMS terminals)

32. Business model Third Party Service Providers Trust Relationship Pays for the services retaining a % IMS CDS Provider Service Packager Transport Provider P2P streaming enabled network User-Network Interface Pay for data transport and third-party services Set-top boxes Users Telco

33. Case Study: IPTV • Content: TV channels • Number of pieces of content: relatively low (hundreds) • Requirements • Access time very important (channel switching) • Low delay of live content (limited caching) • Constant streaming (no interruptions) • Design criteria • P2P signaling not an option: latency too large • Fast discovery of the content serving host (centralized, AS-based) • The edge server may improve performance – maybe P2P signaling is an option here?

34. Case Study: Video-on-Demand • Content: published clips / user generated content • Number of pieces of content: high (very high) • Requirements • Initial access time not critical • Distributed content: caching/storage part of design • Constant streaming after video started • Design criteria • P2P signaling could be essential (a lot of content to index) • Redundancy • P2P protocol can be optimized (no tit-for-tat)

35. …other applications • Other endeavors … telcos might pursuit • Distributed computing • Distributed storage • Delay tolerant transfers • Content distribution with social networking

36. Conclusions

37. Conclusions • P2P content distribution in IMS = P2P in a managed network • Does it make sense? • Bulk of the Internet traffic: P2P and video • Telcos don’t make money from selling bandwidth • IMS/NG is the right platform for telcos • P2P in the transport layer could be a cost-effective approach • TISPAN began working in this direction (first draft Nov ‘08) • But • Although 3GPP is pushing IMS standardization… • … deployment in near future is uncertain