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CS 447 Networks and Data Communication

Internet Routing Routing Algorithms and Protocols. CS 447 Networks and Data Communication. Department of Computer Science Southern Illinois University Edwardsville Fall, 2019 Dr. Hiroshi Fujinoki E-mail: hfujino@siue.edu. CS 447 Networks and Data Communication.

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CS 447 Networks and Data Communication

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  1. Internet Routing Routing Algorithms and Protocols CS 447 Networks and Data Communication Department of Computer Science Southern Illinois University Edwardsville Fall, 2019 Dr. Hiroshi Fujinoki E-mail: hfujino@siue.edu

  2. CS 447 Networks and Data Communication The Internet (or Internet Backbone) ISPs Long Distance Carriers Subscriber Loop Exchange Points Internet Organization/001

  3. BGP Routing Fundamentals  Disseminating membership information to other domains  Host reachability information CS 447 Network & Data Communication • BGP = Border Gateway Protocol • A protocol routers in the Internet use to exchange routing information Two type of routing information BGP manages: - Which host computers exist in which network domains - How each host computer in the Internet can be reached • The current BGP is “Version 4” (BGP-4) ROUTING/000

  4. SIUE Domain  Membership information (Network of SIUE) 146.163.0.0      146.163.255.255 146.163.1.5 Gateway Router ISP 146.163.0.0/16 Next-Hop Membership 146.163.1.5 146.163.0.0/16 CS 447 Network & Data Communication construct CIDR Prefix The Internet ROUTING/000

  5.  Host reachability information 146.163.0.0 146.163.255.255 146.163.1.5 Gateway Router ISP ISP ISP ISP ISP ISP ISP ISP 146.163.0.0/16 Next-Hop Membership 146.163.1.5 146.163.0.0/16 CS 447 Network & Data Communication SIUE Domain (Network of SIUE)      The Internet ROUTING/000

  6.  Host reachability information Next-Hop Membership AS PATH 146.163.1.5 146.163.0.0/16 LOCAL Next Hop AS PATH Destination 3004 146.163.0.0 7425 5895 701 10185 6020 912 105 146.163.255.255 146.163.1.5 Gateway Router 146.163.0.0/16 CS 447 Network & Data Communication “BGP UPDATE” message SIUE Domain (Network of SIUE) AS AS AS AS      AS AS AS AS BGP Routing Table LOCAL 146.163.0.0/16 146.163.1.5 AS = Autonomous System • Each AS has a unique AS-Number ROUTING/000

  7.  Host reachability information Next-Hop Membership AS PATH 24.151.1.9 146.163.0.0/16 5895 Next Hop AS PATH Destination 146.163.0.0 Router 24.152.1.9 146.163.255.255 146.163.1.5 Gateway Router 146.163.0.0/16 CS 447 Network & Data Communication SIUE Domain (Network of SIUE) 3004 7425 AS AS AS 5895 AS 701 10185      AS 6020 AS AS AS 912 105 5895 146.163.0.0/16 24.151.1.9 AS = Autonomous System • Each AS has a unique AS-Number ROUTING/000

  8.  Host reachability information Next-Hop Membership AS PATH 131.31.55.28 146.163.0.0/16 912 5895 Next Hop AS PATH Destination 146.163.0.0 Router 131.3.55.28 146.163.255.255 146.163.1.5 Gateway Router 146.163.0.0/16 CS 447 Network & Data Communication SIUE Domain (Network of SIUE) 3004 7425 AS AS AS 5895 AS 701 10185      AS 6020 AS AS AS 912 105 146.163.0.0/16 131.3.55.28 912 5895 AS = Autonomous System ROUTING/000

  9.  Host reachability information 912, 701, 3004, 5895 Next-Hop Membership AS PATH 18.210.1.5 146.163.0.0/16 Router 18.210.1.5 146.163.0.0 Next Hop AS PATH Destination 146.163.255.255 146.163.1.5 Gateway Router 146.163.0.0/16 CS 447 Network & Data Communication SIUE Domain (Network of SIUE) 3004 7425 AS AS AS 5895 AS 701 10185      AS 6020 AS AS AS 912 105 146.163.0.0/16 18.210.1.5 3004 701 912 5895 ROUTING/000

  10.  Host reachability information 912, 701, 3004, 5895 Router 18.210.1.5 146.163.0.0 146.163.255.255 146.163.1.5 Gateway Router Gateway Router 146.163.0.0/16 CS 447 Network & Data Communication SIUE Domain (Network of SIUE) Next-Hop Membership AS PATH 18.210.1.5 146.163.0.0/16 3004 7425 AS AS AS 5895 AS 701 10185      AS 6020 AS AS AS 912 105 Next Hop AS PATH Destination 146.163.0.0/16 18.210.1.5 3004 701 912 5895 ROUTING/000

  11. Why do we need this field? Why do we need this field?  Host reachability information 912, 701, 3004, 5895 Router 18.210.1.5 146.163.0.0 146.163.255.255 146.163.1.5 Gateway Router Gateway Router 146.163.0.0/16 CS 447 Network & Data Communication SIUE Domain (Network of SIUE) Next-Hop Membership AS PATH 18.210.1.5 146.163.0.0/16 3004 7425 AS AS AS 5895 AS 701 10185      AS 6020 AS AS AS 912 105 Next Hop AS PATH Destination 146.163.0.0/16 18.210.1.5 3004 701 912 5895 ROUTING/000

  12.  Host reachability information 45.121.0.31 Router 18.210.1.5 146.163.0.0 Router 155.71.3.3 Next Hop AS PATH Destination 146.163.0.0/16 146.163.255.255 18.210.1.5 3004 701 912 5895 146.163.1.5 Gateway Router Gateway Router 146.163.0.0/16 CS 447 Network & Data Communication SIUE Domain (Network of SIUE) 3004 7425 AS AS AS 5895 AS 701 10185      AS 6020 AS AS AS 912 105 155.71.3.3 6020 105 912 5895 146.163.0.0/16 ROUTING/000

  13. CS 447 Network & Data Communication AS-PATH Destination Next Hop (Next-Hop Router) BGP Routing Table ROUTING/000

  14.  Host reachability information 45.121.0.31 Router 18.210.1.5 146.163.0.0 Router 155.71.3.3 Next Hop AS PATH Destination 146.163.0.0/16 146.163.255.255 18.210.1.5 3004 701 912 5895 146.163.1.5 Gateway Router Gateway Router 146.163.0.0/16 CS 447 Network & Data Communication SIUE Domain (Network of SIUE) 3004 7425 AS AS AS Default Gateway Address 5895 AS 701 10185      AS 6020 AS AS AS 912 105 155.71.3.3 6020 105 912 5895 146.163.0.0/16 ROUTING/000

  15.  Host reachability information Default gateway address makes sure your outgoing packets reach the gateway router in your network CS 447 Network & Data Communication ROUTING/000

  16. Concept of “peer” and “subscriber” in the Internet ISP A $ $ $ $ $ $ ISP B Different Types of AS’s X P R Z Q Y CS 447 Network & Data Communication • Tier-1 ISPs • Tier-2 ISPs • Tier-3 ISPs ROUTING/000

  17. Data Tx/Rv Service Data Tx/Rv Service Concept of “peer” and “subscriber” in the Internet Peer Subscribers Subscribers ISP A ISP B Different Types of AS’s X P R Z Y Q CS 447 Network & Data Communication Peer to other Tier-2 ISPs and subscriber to a Tier-1 ISP - those who have only “peer” connections with other ISPs • Tier-1 ISPs • Tier-2 ISPs - those who have both peer and subscriber connections - those who have only “subscriber” connection(s) with other ISPs • Tier-3 ISPs ROUTING/000

  18. Peer Subscriber Different Types of AS’s End users Tier-1 ISPs Tier-2 ISPs Tier-3 ISPs CS 447 Network & Data Communication ROUTING/000

  19. Different Types of AS’s CS 447 Network & Data Communication • Tier-1 ISPs (“settlement free” networks) - The ISPs who do not pay to any other ISPs for Internet connection - The ISPs that are guaranteed to be able to reach every host in the Internet - The interconnection of Tier-1 ISPs forms “the Internet core” • Tier-2 ISPs - The ISPs that pay to Tier-1 ISP(s) to connect to the Internet (a Tier-2 ISP is a customer of a Tier-1 ISP) - Customers of a Tier-2 ISP are Tier-3 ISPs - A Tier-2 ISP can have a peer connection to other Tier-2 ISPs • Tier-3 ISPs - The ISPs that do not have any peer connection (subscriber connection only) - Customers of a Tier-3 ISP are “end users” ROUTING/000

  20. Tier-1 ISPs Carrier Names Degree of Connectivity ASN CS 447 Network & Data Communication There are only nine Tier-1 ISPs in the world AOL Transit Data Network (ATDN) AS-1668 74 1382 AT&T AS-7018 AS-3549 499 Global Crossing (GBLX) Level 3 AS-3356 753 Verizon Business (formerly UUNET) AS-701, 702, 703 1452 NTT Communications (formerly Verio) 254 AS-2914 Qwest AS-209 828 AS-3561 SAVVIS 295 Sprint Link AS-1239 880 All Tier-1 ISPs, except GBLX and NTT are headquartered in the US ROUTING/000

  21. Tier-2 ISPs Carrier Names Subscribed Tier-1 ISP ASN CS 447 Network & Data Communication Major Tier-2 ISPs in the Internet (partial list) AS-3491 PCCW Global (formerly BTN) SAVVIS Verio Cogent Communications AS-174 GBLX, SAVVIS AS-4436 nLayer France Telecom AS-5511 Sprint Link Tiscali International AS-3257 Sprint Link SWIPNet Sprint Link AS-1257 Telecom Italia Sparkle AS-6762 Sprint Link AS-14361 HopOne Internet Level-3, AT&T Mzima Networks AS-25973 Level-3, SAVVIS ROUTING/000

  22. Source: http://www.grc.com/dos/theinternet.htm Coverage of a Tier-1 ISP Coverage of a Tier-2 ISP Coverage of a Tier-3 ISP You (your PC) is here! CS 447 Network & Data Communication ROUTING/000

  23. Source: http://www.grc.com/dos/theinternet.htm CS 447 Network & Data Communication ROUTING/000

  24. Source: http://www.grc.com/dos/theinternet.htm Coverage of a Tier-1 ISP CS 447 Network & Data Communication ROUTING/000

  25. ISP AS Difference between “ISP” and “AS” ISP A ISP B AS-701 Internet CS 447 Network & Data Communication • ISP = commercial concept A network recognized in terms of business and law • AS = technical concept A network recognized by the Internet routing protocol (BGP) • Owned by a company X • Legally recognized as a property owned by X • A network recognized by BGP ROUTING/000

  26. Difference between “ISP” and “AS” ISP AS-701 AS-702 AS-703 CS 447 Network & Data Communication • ISP = commercial concept A network recognized in terms of business and law • AS = technical concept A network recognized by the Internet routing protocol (BGP) Is it possible for an ISP owns multiple AS’s? ROUTING/000

  27. Difference between “ISP” and “AS” ISP A ISP B ISP C AS CS 447 Network & Data Communication • ISP = commercial concept A network recognized in terms of business and law • AS = technical concept A network recognized by the Internet routing protocol (BGP) Is it possible for an AS owned by multiple ISPs? ROUTING/000

  28. Peer Subscriber Different Types of AS’s End users Tier-1 ISPs Tier-2 ISPs Tier-3 ISPs CS 447 Network & Data Communication ROUTING/000

  29. Peer Subscriber Different Types of AS’s End users Tier-1 ISPs Tier-2 ISPs Tier-3 ISPs CS 447 Network & Data Communication IXP = Internet eXchange Point IXP ROUTING/000

  30. CS 447 Network & Data Communication Major IXPs in the world http://www.bgp4.as/internet-exchanges ROUTING/000

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