Understanding the Layers of the Internet & Dial-up Networking

1. The Internet

2. Internet Tiers • Internet is built in layers • 9 Tier One computing centers in US • Many Tier Two providers connected to Tier Ones • Lots of Tier Threes connected to Tier Twos • If one link breaks, there are other routes from A to B

3. TCP/IP • The language of the Internet • Provides many services • Hypertext Transport Protocol (HTTP) is one service, FTP is another • We connect to Internet using TCP/IP through Internet Service Providers (ISPs)

4. Dial-up Connections • Hardware: Modem or ISDN Terminal Adapter • Software: Microsoft’s Dial-up Networking (DUN) • Uses PPP – Point to Point Protocol (your point to another modem)

5. Modems • Modulator/Demodulator: to convert digital signals to analog to run over phone lines

6. UARTs • Universal Asynchronous Receiver/Transmitter • Converts parallel data to serial data to parallel data • External modems do not have UARTs (they use serial port, which has UART) • Internal modems have on-board UART • 16550A is today’s UART

7. BAUD • Technically, it is one cycle per second (same as Hertz) • Max baud rate over phone lines (actually phone switches) is 2400 baud • It’s 56 Kbps, not 56 baud or 56 K baud • 33.6 Modem is 14 bits x 2400 Baud

9. Standards Server • V.90 is 56K down and 33.6 up • V.92 is 56K down and 48 upload • All of this over perfect phone wires and to an equal modem on the other end • FCC limit is 54Kbps • Best actual use is 48K down and 28K up (I got 32K max.) Me

10. Flow Control • Also called Handshaking. • Local flow control between modem and COM port • Software uses special characters; XON/XOFF; slower mode • Hardware uses extra wires; RTS/CTS • End-to-end flow control is between modems which is handled by the modems

11. Connections • Internal • ACR (Advanced Commication Riser) – AMD • CNR (Communications Network Riser) – Intel • PCI slot • PCI-e slot • External • Serial port • USB port

12. Dial-up Networking • Network and Sharing Center applet • Will need to know ISP phone number, account name and password • Use Point-to-Point Protocol (PPP) • Make sure there is dial tone on line in use • Make sure dial tone is plugged into Line port • “No Carrier Detect(ed)” is no connection to a modem on the other end

13. ISDN • Integrated Services Digital Network • Up to 64 Kbps by going digital all the way to your house over Bearer (B) channel • D channels carry setup and configuration at 16 Kbps • Can get two B channels for 128Kbps in Basic Rate Interface (BRI) • Can get 23 B’s and a D for 1.544Mbps – T1

14. xDSL • Asynchronous (ADSL) is 2Mbps down and 128-768 Kbps up • Synchronous (SDSL) has same up and down speed – but costs • Connect filters on all jacks except the one to DSL modem • NIC setup is usually just DHCP now • Have to be within two miles of CO 2M 56K 2 miles

15. Cable • RG-6 or RG-59 cable to modem; RJ-45 connector and UTP to computer (CAT 5e) • 6-100 Mbps down and 1-10 Mbps up • Got a bad rap at first due to many people sharing a cable; fiber optic backbone now

16. Fiber • Fiber-to-the-Node (FTTN) • Runs from provider to box in neighborhood • Box is connected to your home by coax or UTP • Fiber-to-the-Premises (FTTP) is fiber all the way to you • Verizon’s FTTP is called FiOS

17. Satellite • Used to require a dial-up modem for upload traffic • Dish now handles both up and down • In theory, allows you to be way out in the bush and still connect • 500 Kbps down and ~50Kbps up

18. Networking Revisited • The “language” of the Internet is TCP/IP. • Have to have an IP address • “Upstream” of you is likely a router that hands out IP address when your modem is turned on • DHCP can supply much more than just IP address

19. Routers • Lots to choose from at Fry’s • Provide firewall between you and Internet • NAT – Network Address Translation: private IP’s inside and one IP outside (public) • Provides DHCP service also

23. Connection Sharing • Internet Connection Sharing – allows sharing of (dial-up) connection • Broadband (DSL and Cable): use router between modem and PCs • Firewalls can prevent peer-to-peer networking isp pc1 router pc2 modem pc3

25. WWW • World Wide Web (HTTP) • Runs on port 80 • HTTPS runs on port 443 • Servers run special software (IIS)

26. Page 1006

27. Internet Explorer • Internet Options in Control Panel or Tools menu in Explorer • Internet Options has no effect outside of IE • General tab: home page, browsing history, searching • Security tab: Zones for Internet, local intranet, trusted sites and restricted sites • Privacy tab: Cookies and pop-ups • Content tab: What will or will not display • Connections tab: Set up connection to Internet, connect to VPN, proxy server • Programs tab: Settings for browser and add-ons • Advanced tab: Accessibility, browsing, international and security

29. Proxy Server • A LinkSys router operates at Layer 3 of OSI model (Network layer) • PS operates at layer 7 – Application layer • You request the PS to request a web page

30. Email • Email address: <name>@<server> • Need account name, password, POP3 server name and SMTP server name • Should come from your ISP • Have to use your ISP’s outgoing mail (SMTP) server – even for other accounts • Get a “throw away” account (free) at Yahoo or Hot Mail or Google • Ports: POP3=110; IMAP=143; SMTP=25

31. More Mail • When the system does all the configuration for you, that is called Integrated commercial provider email configuration • Windows 10 uses Microsoft account, sets up mail; this is called live sign in

32. FTP • File Transfer Protocol • Ports 20 and 21 • You use FTP to download my PowerPoint decks; I use it to upload decks • User name and password sent in clear text; don’t use important password

33. Telnet and SSH • Telnet to remotely control a server/router • Clear text, again • Port 23 • SSH = Secure Shell; port 22 • Entire connection is encrypted; looks like Telnet

34. SFTP • FTP running through an SSH tunnel • Can get a dedicated server and client for this

35. VoIP • Voice over IP • Phone calls over the network • Works with DSL to cable to satellite • Skype is completely proprietary – now owned by Microsoft • Low latency (time for packet to get there) is important • Adapter is built into the cable modem from Time Warner

36. Remote Desktop • Programs that allow you to run another computer • Also called Terminal Emulation or VNC • We will do this, both Remote Assistance and Ultra-VNC (virtual network computing)

37. Virtual Private Network • An encrypted tunnel requires endpoints with dedicated IP addresses; server at one end and client at the other • Can be a dedicated box (router) • Point-to-point Tunneling Protocol (PPTP) • Employee to home office; Routing and Remote Access Service (RRAS) on server • Remote gets address on LAN

38. LDAP • Lightweight Directory Access Protocol • Used to do anything with Active Directory

39. SNMP • Simple Network Management Protocol • Enables remote query and remote configuration of just about anything on a network, provided it is SNMP-capable

40. SMB • Server Message Block • Tools that get PC’s names around the network • NetBIOS names are gone; SMB is the reason that Network can show you all the computers on you network • SAMBA, from IBM, runs on big iron, emulates SMB

41. No Connectivity • Rule out the network issue(s) first • Ping the URL; should get an IP address and successful ping; no IP means DNS issue • “Repair” connection • Try another DNS server 8.8.8.8 or 8.8.4.4 or 4.2.2.2

42. Limited Connectivity • The dreaded APIPA address: 169.254.x.x • Means no DHCP server is working (check/restart router)

43. Local-only Connectivity • Could be a router problem (I had to get a new one) • If no external (WAN) IP address it’s time to call ISP

44. Slow Transfer Speed • It’s a bandwidth issue; similar to traffic on the freeway • Buy more bandwidth? • QoS = Quality of Service; can limit usage by application, IP address and others; find it on router’s configuration

45. Safe Surfing • Need firewall – either Windows, router or third party • Need antivirus – either pay for it (Norton) or free download (AVG Free) • Need antispam software (Ad-Aware, Spybot Search and Destroy) • Watch what you click on!!!!