Network+ Certification (Outline) - Chapter 12: Remote network access

This chapter includes contents: Types of remote network connections, public switched telephone network (PSTN), modems, modem communications, configuring a modem, Virtual Private Network (VPN) communications,...
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Network+ Certification (Outline) - Chapter 12: Remote network access Chapter 12, Remote Network Access|1| Chapter Overview A. Using Remote Connections B. SLIP and PPP C. WAN Technologies Chapter 12, Lesson 1 Using Remote Connections 1. Remote Networking A. Connecting to a remote network using a modem or other device is not very different from connecting to a LAN. 1. From the network layer up, a remote connection is no different from a direct LAN connection, but the data-link and physical layers can take several different forms. B. Modems and other wide area networking devices can function as network interfaces, just as network interface adapters do.|2| C. Remote network connections can take several forms, including 1. Computers to Internet service providers (ISPs) 2. Computers to private networks 3. Computers to computers 4. Networks to networks 2. Connection Types|3| A. Public Switched Telephone Network (PSTN) 1. Technical name for the standard voice telephone system 2. Also known as the Plain Old Telephone Service (POTS) 3. Analog, circuit-switched network 4. Works with asynchronous modems to transmit data between computers at almost any location 5. Typically uses copper-based, twisted-pair cable with RJ-11 jacks a. RJ-11 connectors have four (or sometimes six) pins, rather than the eight pins in the RJ-45 connectors used by LANs.|4, 5| 6. Modems a. A modem (modulator/demodulator) is required to convert a computer’s digital signals to the analog signals used by PSTN. b. At the other end of the connection, another modem converts the analog signals back to digital. c. Early modems used proprietary communication protocols, requiring the same manufacturer’s modems at each end of the connection. d. Today, organizations such as the International Telecommunication Union (ITU) develop specifications for the communication, compression, and error-detection protocols that modems use when generating and interpreting analog signals. (1) The ITU was formerly known as the Comité Consultatif International Télégraphique et Téléphonique (CCITT). e. V.90 is the current industry-standard modem communication protocol. (1) V.90 defines the 56-Kbps data transfer mode that most modem connections use today. 7. PSTN advantages a. No special service installation is required. b. No special equipment is required except modems and a PSTN line. c. Portable systems can dial into a network from any location. 8. Disadvantage: using PSTN frequently over long distances can be expensive. 9. PSTN connections are relatively slow. a. The maximum speed for a connection with two modems is 33.6 Kbps. b. 56-Kbps connections require one of the devices to have a digital connection to the PSTN. c. PSTN connections can vary in quality, depending on the age and condition of the equipment and the location of the modems. 10. Leased lines are permanent, dedicated PSTN connections between two locations. a. Advantages of leased lines (1) Higher speeds (2) Available in analog or digital form (3) More consistent quality of service b. Disadvantages (1) Less flexible than standard PSTN modem connections (2) More expensive than standard PSTN connections|6| 11. Configuring a modem a. Most modems today support the Plug and Play standard. b. Modems typically need an interrupt request (IRQ) and an input/output (I/O) port to communicate with the computer. (1) For external modems, the IRQ and I/O port are assigned to the serial port used to connect the modem to the computer. (2) Internal modems plug into a bus slot, and you configure the modem itself to use a specific COM port. c. Serial ports use a chip called a universal asynchronous receiver- transmitter (UART) to manage the communications of the device connected to the port. (1) For today’s high-speed modems, you should always use a 16550 UART. B. Virtual private networks 1. A VPN is a connection between a remote computer and a server on a private network that uses the Internet as its network medium.|7| 2. VPN communications2 Outline, Chapter 12 ...