Prestige 1600 Universal Access Concentrator

 

 

are divided into incoming and outgoing filters, depending on the direction of the packet relative

 

 

to a port. Data filtering can be applied on either the WAN side or the LAN side.

 

 

 

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.

 

 

 

Device Filter Rules

 

For Device rules, the Prestige treats a packet as a byte stream as opposed to an IP or IPX

 

 

packet. You specify the portion of the packet to check with the Offset (from 0) and the Length

 

 

fields, both in bytes.

 

 

 

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.

 

 

 

DLCI

 

For Frame Relay connections, DLCI (Data Link Connection Identifier) is a path number of a

 

 

portion of the PVC (the DLCI changes for each hop through the network). It is a logical identifier

 

 

with local significance only and is not the address of the destination.

 

 

 

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 Name

 

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

 

 

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 networks.

 

 

 

DTE

 

Originally, the DTE (data terminal equipment) was a dumb terminal or printer, but today it is a

 

 

computer, or a bridge or router that interconnects local area networks.

 

 

 

Dual Firmware Block

 

The Prestige 1600 employs a “dual firmware block structure” where one block is called the “main

Structure

 

block” and the other block is called the “backup block”. You can save the current firmware into

 

 

the backup block before you try to upload new firmware. If the firmware in the main block gets

 

 

corrupted, the Prestige will try to boot from the backup block automatically so the service will not

 

 

get interrupted.

 

 

 

E1

 

European basic multiplex rate which packs thirty voice channels into a 256 bit frame and

 

 

transmitted at 2.048 Mbps.

 

 

 

EIR (Excess

 

This is the burst capability of the connection, i.e., the maximum allowable data transfer rate.

Information Rate)

 

 

 

 

 

EMI

 

ElectroMagnetic Interference. The interference by electromagnetic signals that can cause

 

 

reduced data integrity and increased error rates on transmission channels.

 

 

 

Ethernet

 

A very common method of networking computers in a LAN. There are a number of adaptations

 

 

to the IEEE 802.3 Ethernet standard, including adaptations with data rates of 10 Mbits/sec and

 

 

100 Mbits/sec over coaxial cable, twisted-pair cable and fiber-optic cable. The latest version of

 

 

Ethernet, Gigabit Ethernet, has a data rate of 1 Gbit/sec.

 

 

 

FAQ

 

(Frequently Asked Questions) -- FAQs are documents that list and answer the most common

 

 

questions on a particular subject.

 

 

 

J

Glossary