Computer Networking Part 1

1. Computer NetworkingPart 1 CS 1 Rick Graziani Cabrillo College Fall 2005

2. What is networking? • Communication! • An interconnection of computers and other devices including: • Client computers • Servers (computers) • Network Devices • Hubs and Switches • Routers • Firewall Rick Graziani graziani@cabrillo.edu

3. Most successful networking applications? Rick Graziani graziani@cabrillo.edu

4. What is in a network? Rick Graziani graziani@cabrillo.edu

5. What is a network? • A computer networkis a series of computers and other devices interconnected by communication paths. • Computer networks include: LANs and WANs http://www.albany.edu Rick Graziani graziani@cabrillo.edu

6. Ethernet LANs Rick Graziani graziani@cabrillo.edu

7. LAN – Local Area Network • LAN (Local Area Network) - A network connecting computers at a single site Rick Graziani graziani@cabrillo.edu

8. LAN – Local Area Network • A LAN: • Operates within a limited geographical area • Controlled by local administration • Allows local users to: • Share printers • Access local file servers with software and data • Access the Internet Rick Graziani graziani@cabrillo.edu

9. Ethernet LANs • The most common LAN technology is Ethernet. • Ethernet allows computers, printers, and other devices, “in the same network”, to be able to communicate. • For devices to be able to communicate with each other over an Ethernet network, they must be configured with: • IP Address and Subnet Mask on the same network • What??? (We will discuss this shortly) Rick Graziani graziani@cabrillo.edu

10. Creating an Ethernet Network • To start, your computer must have an Ethernet Network Interface Card (NIC). • Ethernet NICs have an RJ-45 interface or port. Rick Graziani graziani@cabrillo.edu

11. Creating an Ethernet Network • Hubs and Switches are used to connect computers, printers and other devices in the Ethernet LAN. Rick Graziani graziani@cabrillo.edu

12. Creating an Ethernet Network • Ethernet cables, i.e. Cat-5 or Cat-6 cables (Category 5, Category 6) are used to connect computers to the hubs and switches. • Cat-5 cable connects computer NIC to hub or switch. Rick Graziani graziani@cabrillo.edu

13. Creating an Ethernet Network Rick Graziani graziani@cabrillo.edu

14. Configuring IP (Internet Protocol) Rick Graziani graziani@cabrillo.edu

15. IP Configuration • To communicate with other computers on your network you need to properly configure: • IP Address (of your computer) • Subnet Mask (of your computer) • To communicate with computers outside your network you need to properly configure: • Default Gateway IP Address • To be able to use domain names, like www.cabrillo.edu, instead of IP addresses you need to properly configure: • DNS (Domain Name System) Server IP Address Rick Graziani graziani@cabrillo.edu

16. IP Configuration: IP Address & Mask I am part of the 192.168.1.0 network! • To communicate with other computers on your network you need to properly configure: • IP Address (of your computer) • Subnet Mask (of your computer) • IP – Internet Protocol • IP Address is the unique address of your computer on your network. • Subnet Mask is used by your computer to figure out what network it belongs to. • Analogy: • Name: RICKGRAZIANI • Mask: FFFFLLLLLLLL • The Mask tells us which part of RICKGRAZIANI is the first name (F) and which part is the last name (L). Rick Graziani graziani@cabrillo.edu

17. IP Configuration: Default Gateway • To communicate with computers outside your network you need to properly configure: • Default Gateway IP Address Rick Graziani graziani@cabrillo.edu

18. IP Configuration: Default Gateway • Default Gateway or Router: This is the device that connects your network to other networks, including the Internet. DSL or Cable Modem port that connects to your Internet Service Provider Switch ports that connect to computers on your LAN Rick Graziani graziani@cabrillo.edu

19. IP Configuration: Default Gateway • Any information that needs to be sent to IP Addresses outside your network is sent to the Default Gateway or Router. To the Internet 192.168.1.10 192.168.1.1 Rick Graziani graziani@cabrillo.edu

20. IP Configuration: DNS • To be able to use domain names, like www.cabrillo.edu, instead of IP addresses you need to properly configure: • DNS(Domain Name System) Server IP Address 207.62.87.54 Rick Graziani graziani@cabrillo.edu

21. IP Configuration: DNS • You could use IP Addresses when accessing other computers, but we would rather use names (domain names). Rick Graziani graziani@cabrillo.edu

22. IP Configuration: DNS • Computer networks only understand IP Addresses such as: • 66.94.230.47 • Computer networks do not understand domain names such as: • www.yahoo.com • A domain name is a name that is entered into a computer (e.g. as part of a website or other URL, or an email address) and then looked up in the global [Domain Name System] which informs the computer of the IP address(es) with that name. (Wikipedia.com) • People are better with names than numbers, so we would rather use names when: • Accessing a web page: www.yahoo.com • Emailing a friend: Rick.Graziani@cabrillo.edu • DNS (Domain Name System) servers (computers) are used to translate domain names to IP Addresses. Rick Graziani graziani@cabrillo.edu

23. IP Configuration: DNS Hey, 207.62.87.54, what is the IP Address for www.yahoo.com? It is 66.94.230.47 Hey, 66.94.230.47, please send me your web page. Yahoo Web Server Here, 192.168.1.10, here is my web page. Rick Graziani graziani@cabrillo.edu

24. IP Configuration: DNS • The details of how DNS works. • If your DNS server does not know the answer, it will find out for you. Rick Graziani graziani@cabrillo.edu

25. How do I view/edit this information on my computer? Rick Graziani graziani@cabrillo.edu

26. How do I view/edit this information on my computer? 3. TCP/IP, Properties Left click 1. Right click 2. Right click Rick Graziani graziani@cabrillo.edu

27. How do I view/edit this information on my computer? Rick Graziani graziani@cabrillo.edu

28. Setting the IP Configuration Information • IP information can be configured: • Statically • Dynamically • Using a DHCP (Dynamic Host Configuration Protocol) Server Rick Graziani graziani@cabrillo.edu

29. IP Configuration: Static Configuration • Static configuration is when the user or administrator of the computer configures the IP Address, Subnet Mask, Default Gateway and DNS Server information. Rick Graziani graziani@cabrillo.edu

30. IP Configuration: Dynamic Configuration • Dynamic configuration is when the IP Address, Subnet Mask, Default Gateway and DNS Server information is obtained automatically from a DHCP (Dynamic Host Configuration Protocol) Server. Rick Graziani graziani@cabrillo.edu

31. IP Configuration: Dynamic Configuration I’m booting up, if there is a DHCP Server out there, I need my IP Configuration Information! DHCP Server Here is your IP Address, Subnet Mask, IP Address for the Default Gateway (router), and IP Address for the DNS Server! Rick Graziani graziani@cabrillo.edu

32. The Internet and TCP/IP Rick Graziani graziani@cabrillo.edu

33. What is the Internet? • The Internet was originally designed by DARPA (Defense Advanced Research Projects Agency) in response to the U.S.S.R. launching Sputnik, the first satellite. • Out of this came the Internet, a way for computers to communicate from different parts of the world. • These computers can be any type of computer using any type of operating system, as long as they are using the protocol TCP/IP. Rick Graziani graziani@cabrillo.edu

34. What is TCP/IP? What is a protocol? • A protocol is nothing more than an agreement or rules to govern a way of communicating. • The sender and receiver, and everyone in between, must agree on the rules, the protocol. The actual letter (data) is inside (encapsulated) the envelope. Rick Graziani graziani@cabrillo.edu

35. What is TCP/IP? What is a protocol? • Protocol: An agreed form of communications. Rick Graziani graziani@cabrillo.edu

36. TCP/IP Transmission Control Protocol / Internet Protocol • TCP/IP is a suite of protocols. • IP (Internet Protocol) is used for sender and receiver addressing. • Every computer on the Internet or a network must have an IP address to communicate. Source IP Address: 192.168.1.10 Destination IP Address 66.94.230.47 This is known as an “IP Packet” Rick Graziani graziani@cabrillo.edu

37. Source IP Address: 192.168.1.10 Inside envelope: Request for web page Destination IP Address: 66.94.230.47 192.168.1.10 66.94.230.47 Yahoo Web Server Source IP Address: 66.94.230.47 Inside envelope: Web page Destination IP Address: 192.168.1.10 Rick Graziani graziani@cabrillo.edu

38. Pinging another computer (FYI) Rick Graziani graziani@cabrillo.edu

39. Connecting Networks with Routers • The Internet, or simply the Net, is the publicly accessible worldwide system of interconnected computer networks. • Routers are network devices that connect two or more networks together. • Routers connect networks. Rick Graziani graziani@cabrillo.edu

40. Rick’s IP Packet Analogy… • Routers only need to care about where they send the packet next. • “What is the next-hop router I need to send this packet to?” Rick Graziani graziani@cabrillo.edu

41. Connecting Networks with Routers Rick Graziani graziani@cabrillo.edu

42. DSL or Cable Modem: No Router • Routers can help protect your DSL or Cable Modem Network. 204.180.205.1 Public Address Hacker can only get to public address and not private address DSL or Cable Modem Rick Graziani graziani@cabrillo.edu

43. DSL or Cable Modem: With a Router • The router is between your computer (LAN) and your DSL Modem. • The router is between you and the Internet. Internet Rick Graziani graziani@cabrillo.edu

44. DSL or Cable Modem: With a Router When using NAT (Network Address Translation, the Router helps hide your network from attackers. 192.168.1.10 Private Address 204.180.205.1 Public Address Internet Hackers can only get to public addresses and not private addresses Rick Graziani graziani@cabrillo.edu

45. Networks: Bandwidth and Connections • Local Area Networks • DSL • Cable Modem • Leased Lines • Modems Rick Graziani graziani@cabrillo.edu

46. Bandwidth • Bandwidth - The amount of information that can flow through a network connection in a given period of time. • Usually measured in bits per second (bps) • bps: bits per second • Kbps: thousands of bits per second • Mbps: millions of bits per second Rick Graziani graziani@cabrillo.edu

47. Bandwidth LANs: 10 Mbps or 100 Mbps (or more) Connection to ISP (Internet Service Provider) Note: Bandwidth depends up provider, location, and service plan. • DSL: • Download: 600 Kbps to 1.5 Mbps (or more) • Upload: 256 Kbps (or more) • Cable Modem: • Download: 600 Kbps to 3.0 Mbps (or more) • Upload: 256 Kbps (or more) • Telephone Modem: • Up to 53 Kbps • Leased Lines • T1: 1.5 Mbps • T3: 44.736 Mbps Rick Graziani graziani@cabrillo.edu

48. Connection to ISP: DSL • DSL (digital subscriber line) is a very high-speed connection that uses the same wires as a regular telephone line. Rick Graziani graziani@cabrillo.edu

49. DSL: From HowStuffWorks.com • Advantages of DSL: • You can leave your Internet connection open and still use the phone line for voice calls. • The speed is much higher than a regular modem • DSL doesn't necessarily require new wiring; it can use the phone line you already have. • The company that offers DSL will usually provide the modem as part of the installation. • But there are disadvantages: • A DSL connection works better when you are closer to the provider's central office. • The connection is faster for receiving data than it is for sending data over the Internet. • The service is not available everywhere. Rick Graziani graziani@cabrillo.edu

50. Connection to ISP: Cable Modem • A cable modem is a special type of modem that is designed to modulate a data signal over cable television infrastructure. Rick Graziani graziani@cabrillo.edu