Simplified Networking and Troubleshooting for K-12 Teachers

1. Simplified Networking and Troubleshooting for K-12 Teachers

2. AREN Topology • Multiple Star Network • Stars originate at the hub sites and hubs are connected by a North-South backbone • DS3/Partial OC-3 backbone • DS1 (T1) or Multiple T1 to clients • Multiple Internet access points (DS3+)

3. Example Client Site

4. Network Related Services The following services are currently offered by AREN to all clients at low or no cost - High speed Internet access - DNS hosting and management - Web hosting and server management - Email hosting and server management - Expert network consulting (LAN and WAN) - Content filtering -CIPA “Technology Protection Measure” - Router management and site monitoring - In state Quality of Service (QoS) configuration

5. What is a Computer Network? • Group of computers that are connected together and can communicate with each other in some way • Connections can be serial, parallel, bus, radio, satellite, phone, etc. • Can use Copper, Fiber-optics, Airwaves • Can speak many different “protocols”

6. Component Review What are they and what are their uses? • Computer • NIC • Printer • Hub/Switch • Router/CSU • Proxy Server • Email/Web Server

7. Simplified K12 Network Troubleshooting • Day 1 (Theory and equipment) • Introduction to Computer Networking (OSI) • Review of Common Components (show and tell) • Ethernet ins and outs (theory and hands-on) • Intro to TCP/IP addressing (don’t worry!) • DNS explained • Day 2 (It’s broken, what do I do?) • Quick review of Day 1 with any questions • The Internet is down! • My email doesn’t work! • I can’t print! • Where’s my network drive!?!? • I can’t join this domain! • Anything else y’all can throw at me  

8. OSI Reference Model • Layer 1 – Physical • Hardware interface, electrical signaling, transmission of raw bit stream. • Layer 2 – Data Link • MAC (hardware) addressing, frame type, topology, switching • Layer 3 – Network • Logical addressing, IP is here, host to host communication • Layer 4 - Transport • End to end delivery guarantees, port addressing, stream delineation

9. Physical Layer (Ethernet) • The “Big Phone Plug” • http://www.rabcomputers.com/resources/cablepinout.htm • http://www.aptcommunications.com/ncode.htm

10. Crimping Ethernet Cables • Show and tell time • No clip art available  • Practice checking cables by sight

11. More Ethernet Hardware

12. Ethernet Types (Flavors) • Ethernet • 10Base-2 (~200m, Coax) • 10Base-5 (500m, Coax) • 10Base-T (100m, Unshielded Twisted Pair = UTP) • 10Base-FL (2000m=2km, Multimode Fiber) • Fast Ethernet • 100Base-TX (100m over CAT5 UTP) • 100Base-FX (2000m=2km over MM Fiber) • Gigabit Ethernet • 1000Base-SX (300m over MM Fiber) • 1000Base-LX (550m over MM Fiber, 3000m over SM Fiber) • 10Gig

13. Ethernet: Classical (Data Link) • 10 Mbps • CSMA/CD • Carrier Sense Multiple Access with Collision Detection • Think CB radio (shared media, only used by one at a time) • Can be configured with cable, hubs, or switches • 1500 Byte Frames • MAC addresses • 08-00-46-4C-9C-B5 • 08:00:46:4C:9C:B5 • 0800:464C:9CB5

14. Common Ethernet Topologies

15. Limitations of Classical Ethernet • Distance limitations of UTP or Fiber • Network size limited by the 5-4-3 rule • just remember hosts cannot talk to each other if they are connected through more than 4 hubs or repeaters • One Broadcast Domain, One Collision Domain • collisions likely as number of hosts increases • Users generally don’t know about the 5-4-3 rule and just keep on adding hubs at random points

16. Ethernet: Current Baseline • Layer 2 switches (Ethernet, FastE, GigE) • Switching decisions are made based on MAC address • Segments network into separate collision domains • No more 5-4-3 rule • Broadcasts are still heard by all hosts (1 bcast domain) • Does not affect IP subnetting • 802.1p provides QoS and is essential in Voice/IP or VTC implementations

17. TCP/IP Protocol Suite(don’t worry about remembering this now) • IP = Internet Protocol • Responsible for core rules: addressing, routing, packet size etc • TCP = Transmission Control Protocol • Responsible for creating point to point communication over the connectionless Internet • UDP = User/Datagram Protocol • Provides port address resolution

18. IP Addresses • Each computer also must have an IP address. • This address is similar to the street address of a house in that each address is unique. • Schools are assigned a group of IP addresses. This similar to a zip code for a street address. • Example : 207.157.55.1 - 207.157.55.254 • IP addresses are written in dotted-decimal notation with the last number designating a particular computer*** 207.157.55.78 Points to machine with “street address” number 78 Points to the School’s “Zip Code”

19. IP Subnet Masking Network = 207.157.55 Host = 78 Network = 207.157 Host= 55.78 207.157.55.78 255.255.255.0 207.157.55.78 255.255.0.0

20. Default Gateway The “Default Gateway” refers to the device that provides connectivity to (or towards) the rest of the world

21. Static vs. DHCP • Static addressing • Each computer is “hard coded” with IP configuration. • IP address never changes (Static) • DHCP addressing • Dynamic Host Configuration Protocol • Computer automatically obtains IP address by sending broadcast query to the network

22. Internet Settings

26. Static/DHCP Demonstration

27. Private Addressing (RFC1918) • Addresses that have no meaning to Internet routers • These addresses are often used by school systems instead of public routable addresses • Computer’s with these types of addresses must access the Internet through either proxy servers or translation devices From RFC1918: The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private internets: 10.0.0.0 - 10.255.255.255 (10/8 prefix) 172.16.0.0 - 172.31.255.255 (172.16/12 prefix) 192.168.0.0 - 192.168.255.255 (192.168/16 prefix)

28. Network Address Translation (NAT) • RFC1918 addresses can be translated into routable public addresses • PAT=Port address translation • A single “real” address can be used to provide Internet access to thousands of computers using private addresses • Exercise for the student: What is our “Real” address? • (http://www.avl.lib.al.us/whatweknow.phtml)

29. Network Address Translation (NAT)

30. Proxy Server Instead of NAT • Unlike NAT no address translation is used • Client computer requests web page • Proxy server retrieves web page and then passes page to client • Protocols supported can be limited • Some proxy servers only allow web access • No telnet, ftp, chat, email, etc….

31. Proxy Server

32. Proxy Settings

35. DNS: Making English out of Numbers(DNS = Domain Name Service) • IP addresses are hard to remember for humans, so IP names are much more useful. • A computers IP address can be associated with an IP name. • IP Names use a dotted notation, for example www.foxnews.com • Using the same address analogy, the Linden k12 network has been assigned a domain name (“zip code”) of linden.k12.al.us. All computers are also given a host names that are the “street addresses”. www.linden.k12.al.us Host name (“Street Address”) Domain Name (“Zip Code”)

36. DNS Tree

37. Routing 101

38. Traceroute – Tool of the Gods

39. Traceroute – no DNS (fast)

40. Troubleshooting at last! Commands you must know and love: ping (the daddy of them all) traceroute (tracert in Microsoft land) ipconfig (ipconfig /all for details) ipconfig /release (ipconfig /renew) winipcfg (for Win95) nslookup (not available in Win9x)

41. Interactive Command Review

42. The Internet is Down ! This is a very generic statement and generally means that folks can’t get to web sites with their browser (Internet Explorer and/or Netscape).

43. The Internet is Down ! Step 1: Check link light and Ethernet cable - if no link check cable - check hub/switch lights and power Step 2: Confirm IP is configured on host and address is valid - check with ipconfig (or winipcfg) Step 3: Ping Default Gateway - find Gateway using ipconfig (or winipcfg) Step 4: Ping school proxy server and/or NAT device Step 5: if all of the above is fine ping and trace to 129.66.12.151 Step 6: if all of the above is fine ping and trace to www.asc.edu Step 7: if all of the above is fine ping and trace to 149.149.11.7 Step 8: if all of the above is fine ping and trace to www.tntech.edu

44. My Email Doesn’t work ! Step 1: Confirm that you have access to other Network resources (web, ftp, telnet, etc.) Step 2: Check email server configuration in email client (method varies by client) Step 3: Can you receive email from outside school system? Step 4: Can you receive email from inside school system? Step 5: Can you send email to addresses outside system? Step 6: Can you send email to addresses inside system?

45. I Can’t print! (Network Printer) • Is the printer “online”? • Confirm that you have access to other Network resources (web, ftp, telnet, etc.) • If IP address of printer or print server is known, try to ping it. • If printer attached to a computer, can you print from that computer?

46. I Can’t print! (Local Printer) • Is the printer “online”? • Is the printer out of paper? Ink? • What message(s) are you getting from the driver? • Is the local driver software still installed?

47. Can’t “see” anything in Network Neighborhood (no access to network shares) Step 1: Confirm that you have access to other Network resources (web, ftp, telnet, etc.) Step 2: Did you authenticate into the local domain (hitting cancel at login is not a good idea) Step 3:Is the share reached via Network Neighborhood or a pre-mapped drive letter? Step 4: Can you ping the share name? Step 5: Can you ping the IP address of the file server?

48. I can’t get this “&*#ing” computer to join the domain! New Computer: 1) You must be an administrator to add a computer to a domain. Existing Computer that worked previously: 1) Confirm that you have access to other Network Resources (web, ftp, telnet, etc.) 2) Do you have a valid domain username/password?