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I-3 content-centric networking Taekyoung Kwon (TK) Some slides are from Van 1.

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Presentation on theme: "I-3 content-centric networking Taekyoung Kwon (TK) Some slides are from Van 1."— Presentation transcript:

1 i-3 content-centric networking Taekyoung Kwon (TK) Some slides are from Van 1

2 Why Content Networking (CN)? 2

3 Internet Original motivation for Internet is to share computing resources –Remote login, file transfer The Internet communication model is host-to- host conversations –An IP address indicates a host It has been successful for 40 years –TCP/IP has been so flexible for diverse host based applications 3

4 Why content networking (CN)? Internet traffic is already content-oriented –CDN, data center, web cache, redundancy elimination… –multimedia, web, P2P, IPTV… Users/applications care “what to receive” –They don’t care “from where or from whom” –So, host-based comm. model is outdated Storage cost is getting cheaper sharply –Compared to networking cost Other advantages of CN coming up later 4

5 Internet traffic breakdown 5

6 IP networking Host-centric design Lookup-by-name –Indirection (from name to locator) DNS –Host/link/DNS availability concern DNS is extendible and highly available –Distributed design –Thanks to caching Locators can be aggregated –Network prefix Currently almost 450k –Routing scalability is better than CN 6

7 Content networking (CN) Route-by-name –No indirection, better availability –Content name (or ID) is a routing entry –Huge scalability concern In-network caching Global-scale pure CN may not be feasible –At least billions of contents –Some aggregation may be possible E.g. hierarchical names like URLs Other merits such as authentication 7

8 Storage cost In-network storage 8

9 IP networking vs. CN Network prefix Content name DestinationNext Hop /16Router C Content NameNext Hop /a.com/b.jpgRouter C /a.com/b.jpg B: /a.com/b.jpg 9

10 Content name or ID Content names (Cnames) –May replace the IP addresses –Content identifiers (CIDs) Cname/CID design choices –Hierarchical vs. flat –Semantics vs. semantic-free Persistency Location independence –Variable length vs. fixed length examples –cnn.com/sports/news.avi –sonypictures.com/spiderman3.html –yahoo.co.kr/image/logo.jpg –0xF034BC….024A, E.g. hash of content data, name, public key –Or hybrid 10

11 Advantages of CN Better delivery efficiency –Multicast, mobility, QoS/QoE,… Caching at CN-capable routers –Shortest path to the (potentially cached) content Inter-ISP traffic reduction Web host provisioning –Server-less computing Policing –track the history of content requests Content authenticity –signature –Phishing and pharming are not possible 11

12 Where to put Cname? In TCP/IP –Application layer header E.g. HTTP, SIP Deep packet inspection –IP option header New L3 header –A clean slate approach 12

13 Content Centric Networking (CCN) Named Data Networking (NDN) 13

14 CCN “Networking Named Content,” ACM CoNEXT Van Jacobson –Palo Alto Research Center (PARC) NDN project at NSF 14

15 CCN Philosophy Solve the cognitive mismatch –User/app wants “what” –Network wants “who” –Mapping between two models requires a lot of convention and configuration (middleware, wetware) Users specify the objective No distinction between bits in a memory and in a wire Data security and integrity are the architectural foundation 15

16 CCN basics Content name –Hierarchical, variable-length, semantics No IP address Consumers send Interest Packets Content holders send back Data Packets Source: Van 16

17 CCN hourglass model Source: Van 17

18 A user wants some content Source: Van 18

19 Content is downloaded Content is cached! In-network caching Source: Van 19

20 Another user requests the same content Source: Van 20

21 Name tree Components Tree traversal to discover data Default traversal is LeftmostChild Relations: prev, next /parc.com/videos/WidgetA. mpg RightmostChild Source: Van 21

22 Source: Van 22 CCN forwarding

23 CCN: Strengths and Weaknesses Pros Better availability Better delivery Inter-ISP traffic Accountability, Policing Integrity Authentication Serverless computing Multicast Mobility Cons Huge scalability concern More in-network processing Potentially more signaling for routing 23

24 Multiple copies CCN router IP router * No loop in CCN! Source: Van 24

25 CCN security In CCN, the content itself (not its container) is trusted –In TCP/IP, endpoints are authenticated Anypoint can retrieve the content from anywhere and validate it –Content is publicly authenticatable All content is digitally signed –Binding btw. name and the content itself Still PKI is needed 25

26 Signature in CCN Binding btw content name and payload is authenticated 26 Publisher’s private key Publisher’s public key digital Signature (encrypt) Name || Payload publisher Name || Payload || Signature Data packet signature anypoint digital Signature (decrypt) Name || Payload PKI Verify!

27 Interest packet Source: Udugama at Univ. Bremen 27

28 Data packet Source: Udugama at Univ. Bremen 28

29 CCN vs. Related Technologies (CDN, P2P, ICN) 29

30 Why CDN? For CPs! How do I get my content to my customer quickly, reliably, and accurately? How can I support 20 million hits per day? –Flash crowd Can I offload any server traffic? 30 * CP: content provider CDN: content delivery network

31 CDNs make content more available Push the content to the edge –Multiple places Load balance mirrored content Creative DNS solutions 31

32 First Point – DNS Selects from among several mirror sites operated by content provider 32

33 End User Akamai DNS Resolution Akamai High-Level DNS Servers 10 g.akamai.net 1 Browser’s Cache OS 2 Local Name Server 3 xyz.com’s nameserver 6 ak.xyz.com 7 a212.g.akamai.net Akamai Low-Level DNS Servers 12 a212.g.akamai.net xyz.com.com.net Root (Verisign) akamai.net8 select cluster select servers within cluster 33

34 With/without Akamai 34 Akamai operates over 73,000 servers in 70 countries in about 1,000 autonomous systems, which on any given day may handle upwards of 20% of traffic in 2010

35 Akamai vs. LimeLight (As of 2008) 35 Source: GridsLab at Univ. of Melbourne

36 Problems with legacy CDNs Current CDN models good for offloading content distribution Cache mostly located at exchange points –Colocation No benefit to access network operators –No traffic reduction –No revenue sharing 36 Source: Dirk Lab

37 telco CDN (or operator CDN) ISPs are not happy with “off-net” CDNs –Network control issues –Limited monetization chances 37 Source: Alcatel-Lucent

38 telco CDN: strengths Aka “On-net” CDN Optimize QoS/QoE –E.g. Deep caching Low cost –Same CDN infra for its own content and CP’s content –Cache OTT content (i.e. reduce traffic cost) Help CPs –Customize services depending on content portfolio New Biz models –In the content-to-customer chain Managed vs. OTT content E.g. Value-added service for CPs 38 * OTT: over the top

39 Recent changes in CDN: P2P CDNs P2P CDNs –Exploit user machines mostly –Little cost –Often copyright issues 39

40 Google Global Cache CP can be a CDN provider as well 40

41 Peer 1 popeye.mp4.torrent File popeye.mp4.torrent hosted at a (well- known) webserver The.torrent has address of tracker for file The tracker, which runs on a webserver as well, keeps track of all peers downloading file BitTorrent operations for “popeye.mp4” 41

42 Peer Tracker Addresses of peers 2 File popeye.mp4.torrent hosted at a (well- known) webserver The.torrent has address of tracker for file The tracker, which runs on a webserver as well, keeps track of all peers downloading file BitTorrent operations for “popeye.mp4” 42

43 Peer Tracker 3 Swarm File popeye.mp4.torrent hosted at a (well- known) webserver The.torrent has address of tracker for file The tracker, which runs on a webserver as well, keeps track of all peers downloading file BitTorrent operations for “popeye.mp4” 43

44 BitTorrent: Basic Idea Chop a file into many pieces Replicate DIFFERENT pieces on different peers as soon as possible As soon as a peer has a complete piece, it can trade it with other peers –Tit-for-tat Hopefully, a peer will be able to assemble the entire file at the end 44


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