Presentation is loading. Please wait.

Presentation is loading. Please wait.

August 31, 2007 P2P-TV SIGCOMM Peer-assisted VoD for set-top box based IP network Vaishnav Janardhan & Henning Schulzrinne Dept. of Computer Science.

Similar presentations


Presentation on theme: "August 31, 2007 P2P-TV SIGCOMM Peer-assisted VoD for set-top box based IP network Vaishnav Janardhan & Henning Schulzrinne Dept. of Computer Science."— Presentation transcript:

1 August 31, 2007 P2P-TV 2007 @ SIGCOMM Peer-assisted VoD for set-top box based IP network Vaishnav Janardhan & Henning Schulzrinne Dept. of Computer Science Columbia University New York, NY

2 August 31, 2007 P2P-TV 2007 @ SIGCOMM Overview Costs in providing video content DVRs Architecture –local DHTs and pre-fetching Challenges

3 August 31, 2007 P2P-TV 2007 @ SIGCOMM Economics of VoD Transit bandwidth $40/Mb/s/month ~ $0.125/GB US colocation providers charge $0.30/GB to $1.75/GB Netflix postage cost: $0.70 round-trip Typical PPV charges: $4/movie (7 GB)

4 August 31, 2007 P2P-TV 2007 @ SIGCOMM Cost for providing content cost distance possibly another step when crossing oceans within home within campus/AS (multiple L2s) same L2 switch (non-blocking) across provider boundaries

5 August 31, 2007 P2P-TV 2007 @ SIGCOMM Example: FiOS TV architecture Fiber Serving Office Serving Office Hub Office Super Headend Broadcast Video Voice, Data, IP TV Super Headend Serving Office Splitter Fiber J. Savage (Telecom ThinkTank), Nov. 2006 2 national super headends 9 video hub offices 292 video serving offices

6 August 31, 2007 P2P-TV 2007 @ SIGCOMM Verizons FTTP Architecture ONT Optical Network Terminal OLT Optical Line Terminal Optical Couplers (WDM) Voice & Data Downstream 1490 nm Upstream 1310 nm Voice, Data & Video 1490 nm, 1310 nm, 1550 nm 1x32 Optical Splitter EDFA Erbium Doped Fiber Amplifier Video 1550 nm Bandwidth & Services UpstreamDownstream Voice, Data & VOD at 622 Mbps Voice & Data at 155 to 622 Mbps Broadcast Video 1310 nm1490 nm1550 nm Analog TVDigital TV and HDTV 54 MHz864 MHz CENTRAL OFFICE CUSTOMER PREMISE Brian Whitton, Verizon

7 August 31, 2007 P2P-TV 2007 @ SIGCOMM Properties of DVRs Storage of 80-250 GB (Tivo 3) Probably on-line 24/7 already Often, directly connected to network (home gateway) May be owned by cable or DSL company

8 August 31, 2007 P2P-TV 2007 @ SIGCOMM (P2P) video variants Lots of variants - with very different requirements Modestart-up timeVCR controlscontent near VoDminutes - hours (~ BlockBuster) full, including skip ahead movies, UGC VoDsecondsfullmovies, UGC live streamingnoneTiVo-like (pause, rewind) news, sports

9 August 31, 2007 P2P-TV 2007 @ SIGCOMM VoD approaches WANLAN content provider Internet video (YouTube, Netflix,...) ISP-provided VoD end users Classical P2P (BitTorrent,...) this approach servers network

10 August 31, 2007 P2P-TV 2007 @ SIGCOMM VoD requirements short clips < 10 (long tail) feature-length Example: Superbad grossed $33M during August 17 weekend (in US) = roughly 3M viewers = roughly 1% of US population if VoD, each neighborhood has likely one copy 2 problems: –get initial copy to neighborhood multicast, OTA –distribute in neighborhood only viable for top 1000 content avoid Netflix queue avoid stocking 20,000 DVDs

11 August 31, 2007 P2P-TV 2007 @ SIGCOMM Assumptions Every P2P scheme needs to address those DRM is orthogonal –i.e., access to bits access to content –may not work if DRM assumes individualized content keying or fingerprinting Upstream bandwidth is sufficient to deliver >= 1 stream –true for modern FTTH and FTTC networks –if not, P2P systems only work if upstream > consumption if near-VoD, averaging interval may be whole day, rather than peak viewing period –but still need time to buffer content delay and no feedback on FF DVRs have spare capacity –likely true for PCs –may be optimistic for DVRs using LRU-style storage management –may be able to leverage content having been viewed by user –if owned by ISP, cheating problems disappears (no need for tit-for-tat) DVRs cant store all content –85,000 DVDs 595 TB

12 August 31, 2007 P2P-TV 2007 @ SIGCOMM Notes on cost shifting Servers vs. bandwidth Fixed vs. incremental costs –for VoD providers, each (peak) stream incurs additional cost –for end systems, generally $0 Bandwidth –providers - ~ peak usage –ISP - want to avoid paid (= non-local) traffic –users - may not care, but may be rate-limited or violate contract no cost impact as long as downstream >> upstream bandwidth e.g., Columbia severely limits student bandwidth –Quotas are 350M/hr download and 180M/hr upload (= 400 kb/s) not much extra upstream bandwidth left

13 August 31, 2007 P2P-TV 2007 @ SIGCOMM Example: Columbia University ratio 1.5 - not much upstream capacity left

14 August 31, 2007 P2P-TV 2007 @ SIGCOMM Regional Data Center Server services: DNS DHCP Chicago Dallas New York Los Angeles National Backbone Network architecture

15 August 31, 2007 P2P-TV 2007 @ SIGCOMM Architecture Try to find content locally (AS) –using a local (provider-internal) DHT by identifier –identify peer with available capacity –cf. Aggarwal (CCR 7/07) to identify candidate nodes If local, stream from peer –assume single server upstream bandwidth is sufficient –otherwise, piece together multiple servers –could use standard RTSP VCR controls Use extra upstream capacity for pre-fetching content –first, retrieve key frames and anchor points for fast-forward MPEG: 1/15th of frames –then, rest of video –handles bandwidth variability & releases server earlier for other uses If not local, contact ISP (caching) video server –e.g., RTSP redirect

16 August 31, 2007 P2P-TV 2007 @ SIGCOMM 5 sec 60 seconds Anchor point Anchor point Anchor point Seek point t (sec) Adjust to anchor point Pre-fetching

17 August 31, 2007 P2P-TV 2007 @ SIGCOMM Peer 1 [seed] Peer 2 [leech] Peer 4 [leech] Peer 3 [leech] Peer 5 [leech] Tracker Sliding Window modulePre-fetching module Pre-fetching

18 August 31, 2007 P2P-TV 2007 @ SIGCOMM Conclusion Need careful analysis of cost trade-off –P2P may only be optimal if you ignore network costs –compare to classical proxy architectures –clearly identify assumptions -- more than one P2P video Presented combination of different approaches –Locally popular content remains local –Mid-list content at end users –Long tail content at ISP –Back list at content provider What is the minimal set of tools and building blocks?

19 August 31, 2007 P2P-TV 2007 @ SIGCOMM Admission control DVR has small upload capacity –during busy time, may have > 50% DVR utilization Content replication converges to popularity But also hosts rare content only available once in network Allow client displacement –new client indicates rare content (last resort) –DVR tries to find alternative source for existing user –and serves new client


Download ppt "August 31, 2007 P2P-TV SIGCOMM Peer-assisted VoD for set-top box based IP network Vaishnav Janardhan & Henning Schulzrinne Dept. of Computer Science."

Similar presentations


Ads by Google