ADS Technologies SBG1000 D

139 SBG1000 User Guide

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Overview Installation Troubleshooting Contact FAQ Specifications Glossary License

Configuration: Basic Gateway TCP/IP Wireless Print Server USB

datagram In RFC 1594, a datagram is defined as “a self-contained, ind ependent entity of data carrying sufficient

information to be routed from the source to the destination computer witho ut reliance on earlier

exchanges between this source and destination computer and the transporting network.” For the most

part, it has been replaced by the term packet.

default route The route by which packets are forwarded when other routes in the routing table do not apply.

dB decibel

dBc Signal level expressed in dB relative to the unmodulated carrier level desired.

DBm A unit of measurement referenced to one milliwatt across specified impedance. 0dBm = 1 milliwatt

across 75 ohms.

dBmV Signal level expressed in dB as the ratio of the signal power in a 75-ohm system to a referenc e power

when 1 mV is across 75 ohms.

demodulation An operation to restore a previously modulated wave and separate the multiple signals that were

combined and modulated on a subcarrier.

DHCP A Dynamic Host Configuration Protocol server dynamically assigns IP address es to client hosts on an

IP network. DHCP eliminates the need to manually assign static IP addresses by “leasing” an

IP address and subnet mask to each client. It enables the automatic reu se of unused IP addresses:

The SBG1000 is simultaneously a DHCP client and a DHCP server.

•A DHCP server at the cable system headend assigns a public IP address to the SBG1000 and

optionally to clients on the SBG1000 LAN.

•The SBG1000 contains a built-in DHCP server that assigns private IP addresses to cl ients.

distortion An undesired change in signal waveform within a transmission mediu m. A nonlinear reproduction of

the input waveform.

diversity

antennas

Two identical antennas located a small distance apart to reduce multipath distortion and improve

wireless reception. Properly placed diversity antennas improve SBG1000 wireless reception.

DMZ A “de-militarized zone” is one or more hosts logically located between a private LAN and the Internet.

A DMZ prevents direct access by outside users to private data. (The term comes from the geographic

buffers located between some conflicting countries such as North and South Korea.) In a typical small

DMZ configuration, the DMZ host receives requests from private LAN users to access external web

sites and initiates sessions for these requests. The DMZ host cannot init iate a session back to the

private LAN. Internet users outside the private LAN can access only the DMZ hos t. You can use a

DMZ to set up a web server or for gaming without exposing confidential data.

DNS The Domain Name System is the Internet system for converting domain names to IP addresses. A

DNS server contains a table matching domain nam es such as Internetname.com to IP addresses

such as 192.169.9.1. When you access the world-wide web, a DNS serve r translates the URL

displayed on the browser to the destination website IP address. The DNS lookup table is a distributed

Internet database; no one DNS server lists all domain name to IP address matches.

DOCSIS The CableLabs Data-Over-Cable Service Interface Specification define s interface standards for cable

modems, gateways, and supporting equipment to deliver data between an HFC network and a

computer systems or television sets. To emphasize its use as a cable modem standard, DOCSIS is

now called CableLabs Certified Cable Modems. Euro-DOCSIS is DOCSIS ad apted for use in Europe.

domain name A unique name, such as motorola.com, that m aps to an IP address. Domain names are typically much

easier to remember than are IP addresses.

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