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E cohorting an_opportunity_for_telco_cdn_june10


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E cohorting an_opportunity_for_telco_cdn_june10

  1. 1. eCohorting - An opportunity for telco content delivery Ab stract: Telcos deploying content delivery networks for OTT, IPTV, Gaming and other services need to take into networks account the content traffic flowing over a P2P overlay network on their networks. Optimization of P2P traffic in a telco/ISP network can not only optimize P2P traffic flow over core and access networks b ut also help reduce peering costs with other ISPs, international b ackbone networks. NTSS CSU Furthermore, identification and localization of P2P traffic can lead to monetization opportunities for telco/ISPs. Monetization includes utilization of upload b andwidths in access networks, localized ad-insertions etc. Current article explores techniques to localize P2P traffic and seamlessly deploy Hyb rid CDN as a part of content strategy.Authors:Chitresh Markanda, Principal Consultant, CSU IP Network SolutionsPradip Pathak, Tech Lead, CSU IP Network SolutionsShruti Kapre, Sr. Technical Associate, CSU IP Network Solutions © Tech Mahindra Limited 2010
  2. 2. Table of ContentsIntroduction ............................................................................. 2Motivation ............................................................................... 2What is Localization of P2P traffic in an ISP network? ................ 3Utilizing P2P traffic localization via P4P in Hybrid CDN............... 4Benefits of localizing P2P traffic ................................................ 5Recommendations ................................................................... 6Referenc es.............................................................................. 6 1 © Tech Mahindra Limited 2010
  3. 3. IntroductionWith the emergence of peer-to-peer (P2P) technology along with user-generated content (UGC),Telco networks today face significant new challenges in achieving efficient and fair utilization ofnetwork resources. Existing P2P applications, while selecting peers do not tak e into accountnetwork topology. As a result, from the selected close peer-list, few peers appear within thesame ISP networks and few ac ross multiple ISP networks. P2P traffic routes through the corenetwork and multiple ISP networks and imposes high traffic cost to ISPs. Apart from high inter-ISP traffic cost, P2P traffic is not easily distinguishable and hence difficult to be monetized byISPs. Overall, ISPs suffer from bandwidth issues, revenue loss at peering points and end userssuffer from long delays in downloading content.To address this issue, several potential solutions have been suggested to localize P2P traffic i.e.having peers take into account network topology when selecting their clos e peers. This paperfocuses on e-Cohorting, which means to have a cohort of peers and to localize P2P contenttraffic in Hybrid-CDN architecture. H ere the word cohort means grouping of peers that havesimilar content needs.MotivationVideo and P2P content is increasing Internet bandwidth demands. Recent data [3] indicatesglobal internet bandwidth is growing at approximately 40% to 60% per year. Cisco projects 49%annual growth from 2007 to 2012 in overall Internet traffic, with 31% annual growth for P2P.Cisco estimated that 60% to 70% of P2P traffic is actually video [4].P2P traffic travers es multiple ISP networks and core networks, even though the same contentcould be retrieved from a much closer location. An article [5] showed that 99.5% of current P2Ptraffic (using ―eDonkey‖ in France) traversed national or international networks.Major ISPs including AT&T, Comcast, and Verizon Communications participated in the field trialscoordinated by Pando N etworks and Yale University during f all 2008 as an activity of the P4PWorking Group (P4PWG), a multi-industry initiative sponsored by the Distributed ComputingIndustry Association (DCIA). The results [9], [10] demonstrated improved performanc e for allcategories of users and for all participating ISPs, using cable, digital-subscriber-line (DSL), andfiber-to-the-home (FTTH ). The percentage of data delivered within each ISP increased from14% for normal P2P delivery to as much as 89% for P4P delivery. In addition, a majority (up to60%) of the internal data delivered using P4P was delivered within the same metro area.Another aspect is the upload concern. The ISP’s network is asymmetrically designed, where thebandwidth for download is more compared to upload. Due to rapid growth in user generatedcontents, there is a paradigm shift towards content sharing and distribution. T he momentarybandwidth requirement for upload could be better satisfied by P2P technology. This allows ISPto re-us e the existing infrastructure without installing additional hardware components.Hence a cohort of peers could be formed with P2P tec hnology underlying the overlay network toefficiently distribute the content. Combined with hybrid architecture and by localizing the P2Ptraffic, it not only decreases overall network operating costs but increases the download and2 © Tech Mahindra Limited 2010
  4. 4. uploads of the content.What is Localization of P2P traffic in an ISP network?Localization of P2P traffic provides information about peers, which enables them to chooseneighbors, not randomly but close to themselves in the underlying network topology.Researchers have investigated and proposed several approaches to reduce P2P traffic by sharingunderlying network information with P2P applications. The objective is that P2P client s houlduse underlying network information to choos e their close peers more efficiently. This reducescore network congestion and significantly increases download s peed for P2P applications.In following paragraphs, we survey few existing approaches for P2P traffic optimization wherenetwork layer information is shared with P2P applications to improve P2P neighbor s election.Path Selection Service: A decentralized approach of conveying network layer information to P2Pclients is propos ed in [6]. The paper [6] focuses on the Ono project where the peer selection isbased on path selection service. It reuses information provided by content delivery networks forclose peer selection using existing infrastructure of CDN to mi nimize download latency. CDNredirection method is used to direct the clients to CDN replica servers. The whole idea is basedon the concept that if two client are s ent to same CDN replica server they are likely to be locatedclose to each other on the network topology. Here close is in the respect of the CDNs point ofview and not nec essarily the ISPs.As per Figure-1, Ono-enabled Peer periodically looks up a list of CDN names to determineredirection behavior and encodes this information as ratio maps. The request routing system inthe CDN triggers distanc e measurements (RTT) between the replica s erver and the peer’s localDNS server. The peer is redirected to the best replica server and updates its redirection ratiomap. Ono-enabled peers exchange ratio maps at connection handshake. The close peerselection is based on the cosine similarity of the ratio map between two peers. Figure- 1: Ono project 3 © Tech Mahindra Limited 2010
  5. 5. Operator provided topological information : The P4P Working Groups (P4PWG) research projecthas developed a framework [7] that allows ISPs to convey network information to P2Papplications. The framework of P4P project is interface centric. It mandates the networkoperator to host an iTracker. This iTracker serves as the portal to be used by P2P applicationswithin the network provider’s network to acquire network layer information through theexposed REST interfac es. For track er-less P2P system, this iTracker directly communicates withP2P client and for track er-bas ed P2P system, iTracker communicates with P2P client throughApplication Tracker (AppTracker). By configuring the iTracker, network provider logically groupsits network and computes the pDistance between the peers. pDistance is a metric repres entingnetwork information or preference between PIDs (Partition-ID – provider defined logical groupof networks) This pDistance is computed based on routing policies, topology information, inter-ISP cost agreements, etc. Thus P4P allows ISP to secure its network from the disruption byabstracting the detailed network information. At the time of close peer selection, P2P clientqueries iTracker to retrieve the pDistance between the selected peers. Based on the pDistance,P2P client reduces the s elected peer-list that serves the content with reduced network cost andimproved download speed. For the selection of good reduc ed peer list, P4P client could selectintra-PID peers, then intra-ISP peers and then inter-ISP peers. H ere, the objective is to have anISP preference for better clos e peer selection not necessary close but rather efficient routeselection to minimize traffic cost. Figure- 2: P4P in Hybrid CDNUtilizing P2P traffic localization via P4P in Hybrid CDNVideo distribution on a typical c ontent delivery network faces significant challenges to meetpeak demand. The content distribution could be through (a) download, (b) progressivedownload and (c) live stream. For live content distribution during peak demand (e.g. majorsport events), the existing network infrastructure needs to meet this additional bandwidth4 © Tech Mahindra Limited 2010
  6. 6. requirement that typically last for short duration. Henc e, smart hybrid integration between P2Pand a CDN can be combined to form Hybrid solution that gives high efficiency during peakconnections with reduc ed bandwidth cost. To get control of P2P traffic, P4P shall play a majorrole that shall not only localize the traffic but shall give additional benefits to network providerto generate revenue by distributing localized advertisement content on the existing networkinfrastructure with minimal operational cost.Figure- 2 depicts how P4P could be utilized in Hybrid CDN. The proposed approac h suggeststhat network provider can host Local Ad-Server for the localized advertisement content. As P4Pprovides a benefit of logical grouping of networks, Local Ad-Server could be hosted based onthe logical grouping of networks along with the iTracker. The streaming server at the edgeneeds to be made more intelligent for the insertion of cue points in the live streams. These cuepoints shall later be used by P2P client to identify them during rendering of live streams andcan request the Local Ad-Server for the advertisement contents. P2P client will now receiveboth the streams i.e. live content stream and advertisement content stream. P2P client could beenhanced with additional intelligenc e to effectively switch between both the streams s eamlesslywhich shall enable P2P users to view advertisements inters persed in the live content.Benefits of localizing P2P trafficLocalizing P2P traffic enables network providers (ISPs) to reduce network congestion andmonetize the traffic. The benefits include: 1. To manage peak demand: Localizing P2P traffic in Hybrid CDN architecture enables network provider to manage peak bandwidth demand which lasts for a short duration. For any hosted sport event e.g. Olympics, network provider could effectively distribute the content with the existing infrastructure and P2P technology. H ence for such kind of rare events the network provider does not have to add additional hardware components into their existing infrastructure. 2. Reduced inter-network bandwidth and ISP traffic cost: Enables P2P client to choos e close peers within the ISP networks thereby retrieving the content from the local or close by network avoiding multiple intra-ISP traffic cost. This significantly reduces the load on the core network and network congestion in the ISP networks. 3. Better performance of P2P application: By serving the content from the loc al or intra-ISP network, the P2P clients gets better download s peed in the loc alized network. 4. To efficiently manage the network: For P4P, an ISP has to logic ally group their networks while configuring iTracker. This enables ISP to provide limited network information and abstracts the network details to prevent any further disruption, thereby managing network efficiently. 5. Regional Ad-insertion: By localizing P2P traffic, network provider could generate additional revenue by localized advertisement insertion along with efficient distribution of regional content. 5 © Tech Mahindra Limited 2010
  7. 7. RecommendationsTelcos and ISPs can offer peer enabled s ervices as a part of their CDN offerings. This will benefittelco/ISPs both in terms of rapidly scaling a content service as well as reduce abus e of otherISP/telco peering arrangements by content providers . Moreover, identification, management andoptimization of P2P traffic as a part of CDN strategy would also provide many monetizationopportunities including loc alized ad-insertions, monetization of upload bandwidth in accessnetworks. Henc e, it is recommended to include localized P2P as part of hybrid CDN strategy.References[1] White Paper - Hybrid CDNs Leveraging the Best of Both Worlds,[2] Distributed Computing Industry Association (DCIA),[3] Minnesota Internet Traffic Studies (MINTS) data,[4] Cisco, ―Cisco visual networking index —forecast and methodology. 2007–2012,‖ 525/ns537/ns705/ns827/white_ paper_c11-481360_ns827_Networking_Solutions_White_Paper.html[5] L. Plissonneau, J.-L. Costeux, and P. Brown, ―Detailed analysis of eDonkey transfers onADSL,‖ 0- 7803-9455-0/06, IEEE, 2006.[6] D. R. Choffnes and F. E. Bustamante, ―Taming the Torrent: A practical approach to reducingcross-isp traffic in peer-topeer systems,‖ ACM SIGCOMM Computer Communications Review(CCR), vol. 38, no. 4, pp. 363–374, Oct. 2008.[7] R. Alimi, D. Pasko, L. Popkin, Y. Wang, and Y. Yang,―P4P: Provider Portal for P2P Application,‖Internet Engineering Task Force, Internet-Draft draft-p4p-framework-00, Nov. 2008, work inProgress. [Online]. Available:[8] Research article - Bandwidth Reduction via Localized Peer-to-Peer (P2P) Video. Available:[9][10] © Tech Mahindra Limited 2010