Chapter 6: WAN Technologies Flashcards Preview

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Flashcards in Chapter 6: WAN Technologies Deck (16)
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Packet Switching

Circuit Switching

Provides communication pathways between two endpoints and manages how data flows between them

Messages broken into packets which are assigned source, destination, and intermediate node addresses because they do not use the same path or route to get to intended destinations

Requires a dedicated physical connection between sending and receiving devices; Well suited for public switched telephone network (PSTN) and Integrated Services Digital Network (ISDN); Guaranteed rate of transfer



Enables the transmission of voice and data over the same physical connection; Faster than regular modem connections but special phone line required (costly)


T-carrier lines

High-speed dedicated digital lines that can be leased from telephone companies; Always open, always available; Can support voice and data transmissions and are often used to create point-to-point networks

T1: Create point-to-point dedicated digital communication paths and commonly used for connecting LANs; Also known as DS1


T3: Dedicated circuits that provide high capacity and generally are used by parge companies, ISPs and long distance companies; Also known as DS3



Synchronous Optical Network (SONET)

A fiber-optic WAN technology that delivers voice, data, and video at speeds starting at 51.84 Mbps; Main purpose was to create a standardized access method for all carriers within the newly competitive U.S. market and to unify different standards around the world


Optical Carrier (OCx) levels

A new system that defined data rates created from SONET

OC-3: 155.52 Mbps
OC-12: 622.08 Mbps


Dense wavelength-division multiplexing (DWDM)

Replaces SONET/SDH regenerators with erbium doped fiber amplifiers (EDFAs) and can also amplify the signal and enable it to travel a greater distance


Coarse wavelength-division multiplexing

Method commonly used with television cable networks; Relaxed stabilization requirements (Different speeds for download than upload)


Frame relay

A WAN protocol that operates at the physical and data link layers of the OSI model. Enables data transmission for intermittent traffic between LANs and between endpoints in a WAN; Packet-switching technology that uses variable-length packets; Can be used on 56Kbps, T1, T3, and ISDN lines


Asynchronous Transfer Mode

Packet-switching technology suited for a variety of data types such as voice, data, and video; Uses cells that are 53 bytes long (fixed-length packets), can operate more efficiently than variable-length packets


Summary of WAN technologies

Pg. 186-187


Multiprotocol Label Switching

Used in high-performance-based telecom networks; Technology that uses short path labels to direct data from one node to another; Labels used to identify shorter virtual links between nodes instead of endpoints; Supports ATM, Frame Relay, DSL, T1, and E1


Digital Subscriber Line (DSL)

Asymmetric DSL (ADSL)

High-Rate DSL (HDSL)

An Internet access method that uses a standard phone line to provide high-speed Internet access

High data rate in only one direction; Fast download speeds but slower upload speeds

Provides a bidirectional high-data-rate service that can accommodate services such as videoconferencing that require high data rates in both directions


DSL Troubleshooting Practices

Physical Connections
Protocol Configuration


Cable Internet Access

ExamAlert: A cable modem generally is equipped with a medium-dependent interface crossed (MDI-X) port, so you can use a straight through UTP cable to connect the modem to a system

Always-on Internet access method available in areas that have digital cable television; Connectivity achieved through cable modem; Coaxial connection for connecting to the provider's outlet and an unshielded twisted pair (UTP) connection for connecting directly to a system or to a hub, switch, or router



A form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telephone line


Public Switched Telephone Network

ExamAlert: If money is a major concern, the PSTN is the method of choice for creating a WAN.

The entire collection of interconnected telephone wires throughout the world; The modern PSTN is largely digital with analog connections existing primarily between homes and local phone exchanges