1. CS 447 Networks and Data Communication Department of Computer Science Southern Illinois University Edwardsville Fall, 2015 Dr. Hiroshi Fujinoki E-mail: hfujino@siue.edu Internet Routing Routing Algorithms and Protocols

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

3. CS 447 Network & Data Communication ROUTING/000 BGP Routing Fundamentals BGP = Border Gateway Protocol A protocol routers in the Internet use to exchange routing information Two type of routing information BGP manages:  Membership information  Host reachability information - 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)

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

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

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

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

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

9. CS 447 Network & Data Communication  Host reachability information SIUE Domain (Network of SIUE) 146.163.0.0 146.163.255.255 146.163.0.0/16      Gateway Router 146.163.1.5 AS 5895 701 912 10185 3004 6020 105 7425 Destination Next Hop AS PATH Router 18.210.1.5 ROUTING/000 Next-Hop Membership 18.210.1.5146.163.0.0/16 AS PATH 5895 912, 701, 3004, 146.163.0.0/16 18.210.1.53004 701 912 5895

10. CS 447 Network & Data Communication  Host reachability information SIUE Domain (Network of SIUE) 146.163.0.0 146.163.255.255 146.163.0.0/16      Gateway Router AS 5895 701 912 10185 3004 6020 105 7425 Destination Next Hop AS PATH 146.163.0.0/16 18.210.1.53004 701 912 5895 Router 18.210.1.5 Next-Hop Membership 18.210.1.5146.163.0.0/16 AS PATH ROUTING/000 5895 912, 701, 3004, Gateway Router 146.163.1.5

11. CS 447 Network & Data Communication  Host reachability information SIUE Domain (Network of SIUE) 146.163.0.0 146.163.255.255 146.163.0.0/16      Gateway Router AS 5895 701 912 10185 3004 6020 105 7425 Destination Next Hop AS PATH 146.163.0.0/16 18.210.1.53004 701 912 5895 Router 18.210.1.5 Next-Hop Membership 18.210.1.5146.163.0.0/16 AS PATH ROUTING/000 5895 912, 701, 3004, Gateway Router 146.163.1.5 Why do we need this field?

12. CS 447 Network & Data Communication  Host reachability information SIUE Domain (Network of SIUE) 146.163.0.0 146.163.255.255 146.163.0.0/16      Gateway Router AS 5895 701 912 10185 3004 6020 105 7425 Destination Next Hop AS PATH 146.163.0.0/16 18.210.1.53004 701 912 5895 Router 18.210.1.5 ROUTING/000 Gateway Router 146.163.1.5 Router 155.71.3.3 146.163.0.0/16 155.71.3.36020 105 912 5895 45.121.0.31

13. CS 447 Network & Data Communication ROUTING/000  Host reachability information Destination Next Hop (Next-Hop Router) AS-PATH

14. CS 447 Network & Data Communication  Host reachability information SIUE Domain (Network of SIUE) 146.163.0.0 146.163.255.255 146.163.0.0/16      Gateway Router AS 5895 701 912 10185 3004 6020 105 7425 Destination Next Hop AS PATH 146.163.0.0/16 18.210.1.53004 701 912 5895 Router 18.210.1.5 ROUTING/000 Gateway Router 146.163.1.5 Router 155.71.3.3 146.163.0.0/16 155.71.3.36020 105 912 5895 45.121.0.31 Default Gateway Address

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

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

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

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

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

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

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

23. CS 447 Network & Data Communication ROUTING/000 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!

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

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

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

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

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

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

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

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