peer assisted vod for set top box based ip network l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Peer-assisted VoD for set-top box based IP network PowerPoint Presentation
Download Presentation
Peer-assisted VoD for set-top box based IP network

Loading in 2 Seconds...

play fullscreen
1 / 19

Peer-assisted VoD for set-top box based IP network - PowerPoint PPT Presentation


  • 349 Views
  • Uploaded on

Peer-assisted VoD for set-top box based IP network. Vaishnav Janardhan & Henning Schulzrinne Dept. of Computer Science Columbia University New York, NY. Overview. Costs in providing video content DVRs Architecture local DHTs and pre-fetching Challenges. Economics of VoD.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Peer-assisted VoD for set-top box based IP network' - birch


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
peer assisted vod for set top box based ip network

Peer-assisted VoD for set-top box based IP network

Vaishnav Janardhan & Henning Schulzrinne

Dept. of Computer Science

Columbia University

New York, NY

P2P-TV 2007 @ SIGCOMM

overview
Overview
  • Costs in providing video content
  • DVRs
  • Architecture
    • local DHTs and pre-fetching
  • Challenges

P2P-TV 2007 @ SIGCOMM

economics of vod
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)

P2P-TV 2007 @ SIGCOMM

cost for providing content
Cost for providing content

cost

across provider boundaries

possibly another step when crossing oceans

within campus/AS

(multiple L2s)

same L2 switch

(non-blocking)

distance

within home

P2P-TV 2007 @ SIGCOMM

example fios tv architecture

Broadcast Video

Voice, Data, IP TV

Voice, Data, IP TV

Serving

Office

Fiber

Fiber

Super

Headend

Hub

Office

Serving

Office

Splitter

Serving

Office

Super

Headend

Example: FiOS TV architecture
  • 2 national super headends
  • 9 video hub offices
  • 292 video serving offices

J. Savage (Telecom ThinkTank), Nov. 2006

P2P-TV 2007 @ SIGCOMM

verizon s fttp architecture
Verizon’s FTTP Architecture

CUSTOMER PREMISE

Voice & Data Downstream 1490 nm

Voice, Data & Video 1490 nm, 1310 nm, 1550 nm

OLT

Optical Line Terminal

ONT

Optical Network Terminal

Optical Couplers (WDM)

Optical Splitter

Upstream 1310 nm

Video 1550 nm

1x32

CENTRAL OFFICE

EDFA

Erbium Doped Fiber Amplifier

Bandwidth & Services

Upstream

Downstream

1310 nm

1490 nm

1550 nm

Voice & Data at 155 to 622 Mbps

Voice, Data & VOD at 622 Mbps

Broadcast Video

54 MHz

864 MHz

Analog TV

Digital TV and HDTV

Brian Whitton, Verizon

P2P-TV 2007 @ SIGCOMM

properties of dvrs
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

P2P-TV 2007 @ SIGCOMM

p2p video variants
(P2P) video variants
  • Lots of variants - with very different requirements

P2P-TV 2007 @ SIGCOMM

vod approaches
VoD approaches

network

servers

P2P-TV 2007 @ SIGCOMM

vod requirements
VoD requirements

short clips < 10’

(long tail)

  • 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

feature-length

  • avoid Netflix queue
  • avoid stocking 20,000 DVDs

P2P-TV 2007 @ SIGCOMM

assumptions
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 can’t store all content
    • 85,000 DVDs  595 TB

P2P-TV 2007 @ SIGCOMM

notes on cost shifting
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

P2P-TV 2007 @ SIGCOMM

example columbia university
Example: Columbia University

ratio 1.5 - not much upstream capacity left

P2P-TV 2007 @ SIGCOMM

network architecture
Network architecture

Los Angeles

New York

Chicago

National Backbone

Dallas

Regional Data Center

  • Server services:
  • DNS
  • DHCP

P2P-TV 2007 @ SIGCOMM

architecture
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

P2P-TV 2007 @ SIGCOMM

pre fetching
Pre-fetching

Adjust to anchor point

Adjust to anchor point

t (sec)

5 sec

5 sec

5 sec

Seek point

Anchor

point

Anchor

point

Seek point

Anchor

point

60 seconds

60 seconds

60 seconds

P2P-TV 2007 @ SIGCOMM

pre fetching17

Tracker

Peer 3

[leech]

Peer 5

[leech]

Peer 1

[seed]

Peer 2

[leech]

Peer 4

[leech]

Sliding Window module

Pre-fetching module

Pre-fetching

P2P-TV 2007 @ SIGCOMM

conclusion
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?

P2P-TV 2007 @ SIGCOMM

admission control
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

P2P-TV 2007 @ SIGCOMM