Can the production network be the testbed ?

The Akamai Network: A platform for high-performance Internet applicationErick Nygren, Jennifer Sun, Akamai TechnologiesVasileios Pappas, Akamai Technologies and University of MassachusettsACM SIGOPS 2010

Speaker : Conque, Kimcqkim@mmlab.snu.ac.kr# / 160OutlineIntroductionOverview of the Akamai platformAkamai HD network Conclusion# / 16IntroductionPossible risks of the current Internet for businessesReliabilityDesigned as best effort network, the Internet provides no guarantees on end-to-end reliabilitySingle one-hour outage can cause significant damage to brand reputation of e-commerce companiesPerformanceInherent limitation in the Internet makes difficult to achieve desired levels of performance for accessing the commercial sites e.g. application adoption and site conversion ratesLarge-scale distributed computing platform is neededFirst-pioneered one is the Akamai network

# / 16 . commercial network application , , , , scalability . , . IT , . Akamai network . 2Problem about performanceFor supporting web content and streaming media, current network has a limitationThe distance between server and end user becomes a bottleneck for video throughput

DistanceNetwork RTTTypical packet lossThroughput4GB DVD download timeLocal1.6 ms0.6 %44 Mbps12 min.Regional16 ms0.7 %4 Mbps2.2 hrs.Cross-continent48 ms1.0 %1 Mbps8.2 hrs.Multi-continent96 ms1.4 %0.4 Mbps20 hrs.[Fig] Effect of distance on throughput and download time# / 16 ?

Evaluation , origin server . 3Akamai networkOne of the world's largest distributed computing platforms Feature of the AkamaiDelivery network for evolving the business networkFirst pioneering the concept of Content Delievery NetworkReplicating and delivering content and applications at the edge of the Internet, close to the end users Virtual network for the existing InternetWorking over the existing Internet as-is

# / 16Akamai CDN (Content Delivery Network) Delivery network platform . web contents end point , middle mile, , intermediate links bottleneck . ( CDN .) Virtual networks internet client software .

4Benefits of AkamaiSpeed up remote user application performanceReduce server loadImprove application delivery reliabilityReduce bandwidth usage at main server datacenterImprove application security

[Fig] Global performance with and without Akamai*borrowed from ADCAP Network system`s site# / 16 end point content caching delivery network Akamai Application Performance , , .

5OutlineIntroductionOverview of the Akamai networkAkamai HD network Conclusion# / 16 , Caching . Akamai caching .6Resulting in traffic of:5.4 petabytes / day790+ billion hits / day 436+ million unique clients IPs / day

The Akamai EdgePlatform:

105,000+Servers1900+POPs78+Countries950+Networks750+ Cities

Backup Slides POP : Point of presence# / 167- caching edge server . edge server ISP . ISP , .

, . .

, Akamai , , EdgePlatform , , .

(Term) On the Internet, a point-of-presence (POP) is an access point from one place to the rest of the Internet(POP also stands for the e-mail Post Office Protocol; see POP3.) A POP necessarily has a unique Internet Protocol (IP) address. Your Internet service provider (ISP) or online service provider (such as AOL) has a point-of-presence on the Internet and probably more than one. The number of POPs that an ISP or OSP has is sometimes used as a measure of its size or growth rate.

Transport Sys.Anatomy of a delivery network

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End Users

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Contents?Mapping Sys.Data collection & analysisPull-based caching

# / 16 Edge server Caching .

Edge Origin server request . Edge server

, 1) CDN CP origin server .1-2) , Origin server . (, Push ) , Cache miss ,, push , .2) , origin server contents . (, Pull based .)3) , .

, CDN , Akamai , 'cache miss' 'Pull' .

end user cache label . cache label site URL request , edge server caching .

contents Mapping . =====================================[ ] Akamai network main stream . URL mapping system edge server IP . mapping system historical and current data . Edge server , Transport system . Transport system data content long-haul Internet , Static content caching .8Akamai`s Mapping systemMain parts of the mapping systemScoring system Creating current, topological map capturing the state of connectivity across the entire Internet Using equivalent classes of IP address and historic and real-time data like pings, traceroutes, and etc.Real-time mapping Creating actual maps used by the Akamai platform to direct end users based on the scored data

# / 16- Akamai mapping system , scoring system real-time mapping . - scoring system CP Content provider transport system , cluster end user . real-time mapping system end-user request , request , mapping edge server cluster .

data collection and analysis system( source ( ) ), Communication and control system(status info, control msg, ),management portal(end-user / platform, app, content ) , system .9OutlineIntroductionOverview of the Akamai platformAkamai HD network Conclusion# / 16Delivery network for high performanceVideo-grade scalabilityCurrent network including datacenter and peering points is no longer sufficient to supportSolution, IP-layer multicasting is no more practical in realityStreaming performanceMulti dimensional and complex streaming performance need measurements for efficiencyStream availability, startup time, highest bitrate and effective bandwidth are a good metrics for optimizing the networkMonitoring infrastructure built by Akamai are measuring the metrics above# / 16 Cisco 2014 90 % traffic video , Youtube . video bandwidth , data center . , . IP layer multicast , multicasting backbone router content access control , time-shifting . Akamai network high-definition streaming network, HD Network . 11Edge ServerEdge ServerEdge ServerProcess of streaming CDNEncoderEntrypointSet reflectorSet reflectorSet reflectorEdge reflectorEdge reflectorEdge reflectorStreaming ServerStreaming ServerStreaming ServerMulticast CommunicationSubscribePublishSubscribePublishMapping to end users

Original FileSubscribePublish# / 16- HD network Akamai stream .- > > > , CDN . - entry point akamai server cluster edge server CDN . entrypoint edge server intermediate layer, , reflector , . reflector live stream multiple copy , edge server intermediate nodes . reflector publish-subscribe , edge reflector Set reflector reflector . Edge reflector request Set reflector publish , streaming . multicast communication . ** : edge reflector set reflector duplicate live stream cluster streaming server streaming server streaming End user .

streaming server streaming . 12Techs. for quality of streamingPacket loss recoveryCollecting traces of packet flows that were at least 1 h long, and spanning a lots of packetsBy using parity bits for single or multiple streams or using plain retransmission, they can reduce packets` loss rateAdaptive multipath transmissionReplicating packets originating from a particular entrypoint and sending across multiple set reflectors to a single edge region Modifying the streaming server to provide stream quality information to the edge reflectors# / 16 streaming CDN Akamai . packet loss recovery . CDN live streaming encoder edge server . streaming server streaming , packet loss recovery . () Transmission Control Protocol TCP , backoff Bandwidth throttling live stream , User Datagram Protocol UDP . loss recovery parity bit retransmission . 2. Multiple path single edge region adaptive multipath transmission . packet entry point set reflector single cluster of edge server . stream streaming server .

, stream , stream . streaming server stream quality edge reflector .13Techs. for quality of streamingPrebursting Delivering a stream to a server at a higher rate than the encoded rate for the first few seconds of the streaming session`s lifeAdvantagesReuse the retransmit buffers as the prebursting buffers Reduce buffering time

x 9# / 16 prebursting . encoded rate encoding . (retransmission ) encoding caching , prebursting . , . retransmission buffer prebursting buffer , buffering time , streaming . rebuffering minute , prebursting rebuffering 9 .14OutlineIntroductionOverview of the Akamai platformAkamai HD network Conclusion# / 16ConclusionAkamai network uses the cache functionality of edge node for improving the service of B2B networksAkamai has been providing their own technics for improving the end-to-end network performance, and now especially on the HD network for live streamingPacket loss recovery, multipath transmission, and prebursting

# / 1616Backup SlidesAkamai system`s design principleKey principle of the platform system designDesign for reliabilityEnsuring full redundancy of components, and building in multiple levels of fault tolerance, etcDesign for scalabilityHandling large volumes of resulting data and building components for supporting the increasing number of distributed machinesDesign for performanceImproving end user response times and the other metrics, such as cache hit rates and network resource utilization# / 16Akamai design principle . , data handling scalability , . Akamai edge server .17Using parity scheme across a single streamExample

Pros & cons

1011010- 1 0 1 1 0 1 0: even-parity codeward1- 1 0 1 1 0 1 1: odd-parity codeward01ProsConsNo additional storage and no added delayOdd numbers of bit errors are only detectedNo indication of which bits are in errorBackup Slides (1/3)# / 16Parity bit data even/odd parity bit bit block code 1 bit redundancy block code .

, bit 1 4 6bit data Even-parity 1 , 0 bit 1 ,Odd-parity 1 1 , bit 1 5, , .

bit error , . bit , odd-parity error . , , codeword bit .

delay , , block code .

18Parity scheme across multiple streamsArranging data bits into an array and compute parity along each row and columnAllowing us to both detect and correct the error

Pros & cons

1011001011100100100101010000001101101010000010001111ProsConsAvailable to correct a single-bit errorEasy to computeLimitation in correcting errorsCoding delay(Even parity)Backup Slides (2/3)# / 16 parity codes Parity codes rectangular codes .

code line-by-line .

7x7 even parity rectangular codes . bit transition (Column) parity bit error string , string bit even parity .

parity codes even/odd error , .

19Parity schemes considering single stream or multiple streams

Backup Slides (3/3)

In a single streamIn multiple streams# / 16 parity scheme bursty error multiple stream parity scheme . bursty streaming loss recovery . , . 20Backup Slides

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