Prestige 645 ADSL Internet Access Router

 

 

computer equipment to digital transmission lines). The Channel Service Unit device connects

 

 

with the digital communication line and provides a termination for the digital signal. The

 

 

Data Service Unit device, sometimes called a digital service unit, is the hardware component

 

 

you need to transmit digital data over the hardware channel. The device converts signals

 

 

from bridges, routers, and multiplexors into the bipolar digital signals used by the digital

 

 

lines. Multiplexors mix voice signals and data on the same line.

 

 

 

DCE

 

Data Communications Equipment is typically a modem or other type of communication

 

 

device. The DCE sits between the DTE (data terminal equipment) and a transmission circuit

 

 

such as a phone line.

 

 

 

DHCP

 

Dynamic Host Configuration Protocol automatically assigns IP addresses to clients when

 

 

they log on. DHCP centralizes IP address management on central computers that run the

 

 

DHCP server program. DHCP leases addresses for a period of time which means that

 

 

addresses are made available to assign to other systems.

 

 

 

DNS

 

Domain Name System links names to IP addresses. When you access Web sites on the

 

 

Internet, you can type the IP address of the site or the DNS name. When you type a domain

 

 

name in a Web browser, a query is sent to the primary DNS server defined in your Web

 

 

browser’s configuration dialog box. The DNS server converts the name you specified to an

 

 

IP address and returns this address to your system. From then on, the IP address is used in all

 

 

subsequent communications.

 

 

 

Domain

 

The unique name that identifies an Internet site. Domain Names always have 2 or more parts,

Name

 

separated by dots. The part on the left is the most specific, and the part on the right is the

 

 

most general.

 

 

 

DRAM

 

Dynamic RAM that stores information in capacitors that must be refreshed periodically.

 

 

 

DSL

 

Digital Subscriber Line technologies enhances the data capacity of the existing twisted-pair

 

 

wire that runs between the local telephone company switching offices and most homes and

 

 

offices. There are actually seven types of DSL service, ranging in speeds from 16 Kbits/sec

 

 

to 52 Mbits/sec. The services are either symmetrical (traffic flows at the same speed in both

 

 

directions), or asymmetrical (the downstream capacity is higher than the upstream capacity).

 

 

DSL connections are point-to-point dedicated circuits, meaning that they are always

 

 

connected. There is no dial-up. There is also no switching, which means that the line is a

 

 

direct connection into the carrier’s frame relay, ATM (Asynchronous Transfer Mode), or

 

 

Internet-connect system.

 

 

 

DSLAM

 

A Digital Subscriber Line Access Multiplexer (DSLAM) is a network device, usually at a

 

 

telephone company central office, that receives signals from multiple customer Digital

 

 

Subscriber Line connections and puts the signals on a high-speed backbone line using

 

 

multiplexing techniques. Depending on the product, DSLAM multiplexers connect DSL

 

 

lines with some combination of asynchronous transfer mode ATM, frame relay, or IP

D

Glossary