jin li, principal researcher (collaborators: cheng huang, keith ross) communication and...
TRANSCRIPT
Jin Li, Principal Researcher(Collaborators: Cheng Huang, Keith Ross)Communication and Collaboration Systems
Microsoft Research
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Introduction: Internet Video on the Rise
Internet Video is on the RiseVideo streams served increased 38.8% in 2006
to 24.92 billion (Source: AccuStream iMedia Research)
53 web-video startup in 2006 (US), $521M VC funding (Source: DowJones VentureOne)
Major studio goes into Web Video
$410M video ads revenue in 2006 and grow by 89% in 2007 (0.6% of $74B TV ad market, Internet ads $16.4B in 2006, expect to grow 19% in 2007) [source: Emarketer]
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Internet Video is Growing: in Popularity & Quality
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Apr. 2006 Dec. 2006 Up (%)
# of views (million) 41.1 64.7 57.4
# of users (million) 9.03 12.02 33.1
video quality evolution
popularity evolution
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Internet Video Delivery: Data Center vs. CDN vs. P2P
Just Build More Powerful Data Center?
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Data Center CapacityVHS quality video streaming: 500 kbps
(H.264)200,000 viewers = 100 Gbps
Data center capacity: Tera Grid (UIUC)30 petabyte of storage40 Gbps backbone: 80k video viewers
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CDN Is Not The Answer
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Akamai20,000 servers, 900 point of presence, 71 countries400Gbps bandwidthNetwork optimized for latency
Limelight25 point of presence, hundreds servers per
presence1,000Gbps bandwidth
Akamai+Limelight: 2.8 million viewers. Current TV audience
Olympics: 2.5 billion viewersEach viewer may have his/her own interest (different
sport event, athlete nationality, etc.)
Peer Assisted Delivery is the Way To Scale
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Economical to runSaves server/CDN bandwidth, disk I/O, CPU,
memoryRobust
no single point of failure in networkSuper-scalable
system capacity increases with number of nodes
peer resource
bandwidth
CPU
memory
harddrive
P2P Benefit Consumers: Better Video Quality, More Selection
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Case Study 1: On Demand Internet Video
Peer Assisted Delivery: Mode
File Sharing
broadcast On Demand Streaming(Interactive TV)
Live MessengerFolderShare
Groove
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Peer Buffer Map: File Sharing
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Peer 1
Peer 2
Peer 3
Peer 4
Peer 5
Peer 6
Peer Buffer Map: Broadcast
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Peer 1
Peer 2
Peer 3
Peer 4
Peer 5
Peer 6
Peer Buffer Map: On Demand
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Peer 1
Peer 2
Peer 3
Peer 4
Peer 5
Peer 6
MSN VoD Service
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Traces from the on-demand service of MSN Video9-month period: Apr. – Dec. 2006520M streaming requests59,000 unique videos
Peer-assisted VoD Model
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Guaranteed QoS: always available serverPerformance metric: server bandwidthPeers upload what / when they are
watchingconservative assumption
servers in data
centers/CDN
Peer Bandwidth
Download BW is measured by Windows Media Serverno accurate measurement
beyond 3.5MbpsUpload BW is inferred
Average upload: 500+ kbps
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DSL2 Cable Ethernet
Modem
ISDN
DSL1
Bandwidth Allocation Policies
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Assumptionspeers always start watching from beginningVoD: earlier peers upload to later peers
1st policy: no-prefetchingonly satisfy demand for smooth playback, do not
further build up the bufferused by commercial live streaming companies to offer
VoD
servers in data centers
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arrival
• ask• ask• ask• ask server
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Bandwidth allocation policies (2)
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Prefetching – to utilize remaining upload capacity2nd policy: water-leveling3rd policy: greedy
Lower boundallow later peers upload to earlier ones
no arrival order constraints
servers in data centers
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arrival
water-leveling:
greedy:
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Observations on Policies(Simulated: Peer Poisson Arrival)
Prefetching is crucial“free” to increase
video bitrate“balanced mode” is
most difficultS ≈ D
Greedy policy works bestlowest server loadvery close to bound
more available upload
Server BW Reduction – Two Videos
select top two most popular videos~800,000 views during April, 2006
significant server bandwidth reduction using peer assistance
less server BW even increase quality 3 times (@3x bitrate)22
gold stream silver stream
Server BW reduction – two videos
select top two most popular videos~800,000 views during April, 2006
significant server bandwidth reduction using peer assistance
less server BW even increase quality 3 times (@3x bitrate)23
gold stream silver stream
P2P @3x
Server BW reduction – all videos
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12,000+ videosserver bandwidth
reduction in all categories1.23Gbps 36.9Mbps (97%)1.23Gbps 770Mbps
@3X bitrate (38%)April 2006
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Locality Aware P2P Delivery
P2P Traffic Today
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1999 to present: fueled by Napster, KaZaA, eDonkey and BitTorrent
CacheLogic ResearchInternet Protocol Breakdown 1993 - 2006
Internet Traffic on the Rise
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Internet traffic trend: grow at a compound monthly average of 7.4% in 2006
Internet traffic d
oubles per y
ear
Traffic at Amsterdam Internet Exchange (AMS-IX)
Locality to the Rescue
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Internet HierarchyASISP POPHome/corporationBranch office of a corporation
Delivery content in a locality aware fashionBeyond ISP aware delivery
Internet : Grand View
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Impact on ISPs
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Tier 1 ISP
Tier 2 ISP
AS
sibling
peering
peering entityboundary
sibling entityboundary
transit
Tier 2 ISP
AS AS AS
Economics of ISP relationships sibling relationship
several ISPs belong to same org
peering relationship mutual beneficial free
agreement (to certain extent)
transit relationship one ISP pays another
Inside ISP
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ISP POP (Point of Presence)
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Inside Home/Branch Office
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neighborhood
home corporation
Branchoffice
Identify Peers Locality
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Information usedExternal IP addressInternal IP addressSubnet mask
Peer localityISP (AS)ISP POPHome/corporationCorporate branch office
Peers are considered closer if they are in a smaller common neighborhood
MAP External IP Address to AS
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Identify POP
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POP neighborhoodIdentify one peer that is directly connected to
the Internet at some point of timeCollect its external IP address and the subnet
maskInfer the subnet neighborhood where other
peers belong, even if they are not directly connected to the Internet
Below POP
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Home/corporation neighborhoodAll peers with the same external IP address
Corporation branch officeAll peers with the same external IP address,
and on the same internal subnet (based on subnet mask)
Locality Aware Topology Building
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Preferentially link peers within the same ISP neighborhoodSay if we need to establish 20 connections
We assign 50% of links to be within branch office neighborhoodIf there are less peers than the allocated links,
we simply put the unused links back to the pool
We then assign 50% of unused links to be within home/office neighborhood
The next 50% of unused links are assigned within POP neighborhood
The next 50% of unused links are assigned within AS neighborhood
The rest of the links are used for cross-AS connections
Example
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Scenario Neighborhood Branch office Home/corporation
ISP AS Outside AS
1 Total peers 20 80 0 900 9000
Connected peers 10 5 0 3 2
2 Total peers 0 10 100 1000 9000
Connected peers 0 10 5 3 2
3 Total peers 0 2 0 1000 9000
Connected peers 0 2 0 9 9
Locality Aware P2P Scheduling
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Preferentially deliver content to peers within closer neighborhoodPropagate neighborhood availability
informationExchange with a outside peer preferentially
content that is not available in the neighborhood
Preliminary Result: ISP Friendly
Without ISP-friendlyMuch more cross
sibling than peering boundary
Significant crossing boundary traffic
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Without ISP-friendly
Preliminary Result: ISP Friendly
Pure ISP-friendly1 video 5000+
separate distributionsstill surprising
reductions but unnecessarily conservative
ISP could help by sharing information
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svr rate (Mbps)
no P2P
sibling partition
peering partition
silver 39.0 19.6 15.8
top 10 295.2 90.3 75.1
cut cross boundary traffic completely
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Conclusions
Conclusion
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Peer assisted delivery is the way to go for mass content delivery over the worldPeer assistance can significantly reduce
server bandwidth requirementDemonstrated in real world for file sharing &
broadcastShown in our work for on demand streaming
Locality aware P2P delivery is the way to scale