The Internet

1. The Internet What is the internet, and how does it work?

2. The Internet • What is the internet? • Internet hardware and connection • Internet infrastructure • A brief history of the Internet

3. The Internet • What is the internet? • Internet hardware and connection • Internet infrastructure • A brief history of the Internet

4. What is the internet? “The Internet is a massive network of networks, a networking infrastructure. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. Information that travels over the Internet does so via a variety of languages known as protocols.” Webopedia.com The internet is not: • The World Wide Web (WWW). The WWW is a way of accessing information over the internet • The physical media: this is just one component of the internet • The applications: again, this is just one component.

5. What is the internet? • From an application perspective, the internet • provides: • Communication • School, work, family, friends, spam… • Commerce • Amazon, ebay, travel, shopping, banking,… • Entertainment • Music, Movies, games, news, blog, … • Adventures • New applications, new techniques, millionaires!

6. Internet in 1969 UTAH SRI What was the link speed/bandwidth? UCSB UCLA

7. ARPANet in 1969 Internet UTAH SRI What was the link speed/bandwidth? UCSB 56 kbps UCLA

8. AS and IP address prefix UCDavis: 169.237/16 AS6192 Autonomous System: (System Administrative Domain) AS6192 is the routers in UC Davis UC Davis owns 169.237/16

9. 169.237.0.0/16 (less specific) 169.237.0.0/17 169.237.128.0/17 169.237.192.0/18 169.237.204.0/19 (more specific) BGP prefers more specific Address Prefix and Prefix Aggregation 8b.8b.8b.8b • Notation of network address prefixes 169.237.0.0/16 10101001111011010000000000000000 • Prefix aggregation/de-aggregation 11111111111111110000000000000000 Prefix Prefix length

10. 01100111.10110110.*.* 01100111.10110110.{0/1}*.* 00000000.00000000 00000000.00000001 ….. 111111111.111111110111111111.111111111 2^16 169.237.6.{0-255} NAT Network Address Translation

11. AS6192 UCDavis: 169.237/16 “BGP” • How would I let the whole world know about 169.237/16? • I announce that I owned 169.237/16 • More importantly, how would anybody else in the Internet know how to send (or route, forward) a IP packet to 169.237/16? • Others would know how to send packets to 169.237/16 Visualization and Monitoring of Network Traffic, Dagstuhl, Germany

12. Packet Forwarding UCDavis: 169.237/16 AS6192 AS11423 (UC) AS11537 (CENIC) AS513 an AS Path: 169.237/1651311537114236192 Visualization and Monitoring of Network Traffic, Dagstuhl, Germany

13. Peering ASes UCDavis: 169.237/16 AS6192 AS11423 (UC) AS11537 (CENIC) AS513

14. BGP Update: AS6192  AS11423 an AS Path: 169.237/16114236192 UCDavis: 169.237/16 AS6192 AS11423 (UC) AS11537 (CENIC) AS513

15. BGP Update: AS11423  AS11537 UCDavis: 169.237/16 AS6192 AS11423 (UC) AS11537 (CENIC) AS513 an AS Path: 169.237/1611537114236192

16. BGP Update: AS11537  AS513 UCDavis: 169.237/16 AS6192 AS11423 (UC) AS11537 (CENIC) AS513 an AS Path: 169.237/1651311537114236192

17. Packet Forwarding UCDavis: 169.237/16 AS6192 AS11423 (UC) AS11537 (CENIC) AS513 an AS Path: 169.237/1651311537114236192

18. AS Path and BGP Update • Prevent “packet routing loop” • Other attributes related to local policies

19. The Scale of the “Internet” • 31344Autonomous Systems • 294340 IP Address Prefixes announced • Every single prefix, and their “dynamics”, must be propagated to every single AS. • Every single AS must maintain the routing table such that it knows how to route the traffic toward any one of the 294340 prefixes to the right destination. • BGP is the protocol to support the exchange of routing information for ALL prefixes in ALL ASes. Visualization and Monitoring of Network Traffic, Dagstuhl, Germany

20. The “Internet” ASes Prefixes Visualization and Monitoring of Network Traffic, Dagstuhl, Germany

21. The “Internet” Visualization and Monitoring of Network Traffic, Dagstuhl, Germany

22. The “Internet” Visualization and Monitoring of Network Traffic, Dagstuhl, Germany

23. http://bgp.potaroo.net/cidr/ The “Internet”as June 7, 2004 • 17273 Autonomous Systems • >> 100K Routers • 136515 IP Address Prefixes announced

24. http://bgp.potaroo.net/cidr/ The “Internet”as September 26, 2005 • 1727320464 Autonomous Systems (+18%) • >> ??? Routers • 136515167138 IP Address Prefixes announced

25. The Scale of the “Internet” • 1727320464 Autonomous Systems (+18%) • 136515167138 IP Address Prefixes announced • Every single prefix, and their “dynamics”, must be propagated to every single AS. • Every single AS must maintain the routing table such that it knows how to route the traffic toward any one of the 167138 prefixes to the right destination. • BGP is the protocol to support the exchange of routing information for ALL prefixes in ALL ASes.

26. Chain Reaction • Removing/creating one AS  updating the routes for possibly a large number of prefixes • Removing/creating one prefix  updating the routing table for possibly a large number of ASes

27. Global Failure • AS7007 falsely de-aggregates 65000+ network prefixes in 1997 and the east coast Internet was down for 12 hours. 169.237/16 142.7.6/24 204.5.68/24 …. AS6192 AS11423 (UC) Black Hole AS11537 (CENIC) AS513

28. Value 1 Value 2 ... Value N UPDATE Message Format • Eight type of Path Attributes • ORIGIN • AS_PATH • NEXT_HOP • MULTI_EXIT_DISC • LOCAL_PREF • ATOMIC_AGGREGATE • AGGREGATOR • COMMUNIY_ATTRIBUTE AS_PATH for prefix D COMMUNITY_ATTRIBUTE (32 bits value) <AS1, AS2, … ASn>

29. The Internet • A network of networks • Millions of connected devices, or hosts • Infrastructure: wire, fiber, radio, satellite,… • Traffic controllers: routers,… • Protocols: languages for sending and receiving messages: TCP/IP, ftp, http,…

30. The Internet • What is the internet? • Internet hardware and connection • Internet infrastructure • A brief history of the Internet

31. Hardware on the host:Network Interface Card: NIC • Physically connects a computer to the network • What is device driver? • NIC comes with different drivers for different types of operating systems. • A driver is the software that allows the operating system to communicate with the network interface card.

32. The MAC address: a unique signature • When a NIC is manufactured, the card is given a unique hardware address. • It never changes.

33. Internet Infrastructure • How to connect a host to the outside network (the “last mile” problem): • home network • Phone line (modem, ADSL) • Cable • Institution network • Ethernet,… • Mobile access network • Wireless router,…

34. Google’s solution: TiSP (April’s fool) http://www.google.com/tisp/install.html

35. Home connection: The Modem Digital data - 10101010101 Telephone line Analog data • Dialup via modem: • up to 56 Kbps • Cannot use internet connection and phone at the same time

36. Home connection: ADSL • ADSL: Asymmetric Digital Subscriber Line • up to 1 Mbs upstream (today typically < 256 Kbs) • Up to 8 Mbs downstream (today typically < 1 Mbs) • Distance is a factor (the further you are from the active router, the worst your connection is; ADSL is good in cities)

37. Home connection: Cable • - Computer attached to cable network through a cable modem. • Up to 1Mbs upstream and 10 Mbs downstream • Cable is shared by nearby houses: risk of congestion

38. Home connection: Powerline • Powerline Communication (PLC): • use the existing electricity network for voice and data transmission • Superpose an analog signal to the AC current • Ubiquitous, cheap to setup • High risk of interference

39. Home connection: the different cables • Twisted pair • RJ45 connector • Coaxial cable • BNC connector • Fiber optic cable • A cable for each length: • Optic > coaxial > Twisted pair

40. Institution Network • Most institutions have their own network: Local Area Network (LAN). They are based on either: • Ethernet • It is the most popular architecture used to build networks. • It is the least expensive and easiest to setup • Popular in universities and research institutes • Token-ring architecture • It was developed by IBM in 1984. • They are popular in large organizations, such as banks and insurance companies. • Others: AppleTalk, …

41. Institution Network: the Ethernet Local Area Network (LAN) Ethernet cables

42. Ethernet: CSMA/CD (Carrier Sense Multiple Access with Collision Detection) Two computers send data at the same time A collision occurs Random time: 427ms Random time: 123ms Both computers send a “jam” signal Each computer wait a random time prior to sending data again http://www.thebryantadvantage.com/

43. Ethernet Hubs and Switches • Both devices allow multiple computers to be connected to the internet through a single entry point • Hubs are passive: they do not monitor traffic nor do they check for collision • Switches are active: they are small computers with a CPU. They act as “cops” and control traffic.

44. Wireless Networks • Host is connected to the router by shared wireless access through a base station or “access point” • Wireless LANS: • 802.11b (WiFi): 11 Mbps, 2.4 GHz ISM band (ISM: Industrial, Scientific and Medical) • 802.11g: 54 Mbps, 2.4 GHz ISM band • 802.11a: 54 Mbps, 5 GHz ISM band • 802.11n: 100 Mbps

45. Wireless Transmission • Using radio wave: • no physical wires • Use electromagnetic wave as a carrier • Suffer from environmental effects (obstructions) • However…they are great to go around obstacles for physical cables (mountains, …) • Examples: • terrestrial microwaves • Wide area (cellualr networks) • Satellites

46. The Internet • What is the internet? • Internet hardware and connection • Internet infrastructure • A brief history of the Internet

47. Internet Infrastructure • To communicate over the Internet, the computers must: • have a way to address one another. • use a common language or a protocol to organize the exchange of messages. • Addressing: • defines where to deliver the messages • Protocol: • specifies exact format, order of messages sent and received among network entities, and actions taken on message transmission and receipt. • .

48. Internet Infrastructure • Internet has a large collections of protocols organized in a layer model. • Application: enables the user, whether human or software, to access the network. • Transport: responsible for source-to-destination (end-to-end) data transfer. • Network: responsible for routing packets from source-to-destination across multiple networks. • Data link: responsible for data transfer between neighboring network elements. • Physical: coordinates the functions required to transmit a bit stream over a physical medium.

49. Internet Infrastructure Moobilenet MoobilenetX

50. Internet Infrastructure TCP/IP: • A protocol is a collection of rules for formatting, ordering, and error-checking data sent across a network. • In 1974, Vincent Cerf and Robert Kahn developed the Transmission Control Protocol (TCP) which was further split into the Internet Protocol (IP) and TCP in 1978. • In 1982, DoD adopted TCP/IP as the standard protocol in the Internet. • Because the significance of TCP/IP in the history of the Internet, Cerf and Kahn are considered to be the Fathers of the Internet.