NB9/NB9W ADSL2+ VoIP Router
21
YML789 Rev1
CO
Central Office A circuit switch that terminates all the local
access lines in a particular geographic serving area; a
physical building where the local switching equipment is
found. xDSL lines running from a subscriber’s home con-
nect at their serving central office.
DHCP
Dynamic Host Configuration Protocol
DHCP automates
address assignment and management. When a computer
connects to the LAN, DHCP assigns it an IP address from
a shared pool of IP addresses; after a specified time limit,
DHCP returns the address to the pool.
DHCP relay
Dynamic Host Configuration Protocol relay. A DHCP relay
is a computer that forwards DHCP data between comput-
ers that request IP addresses and the DHCP server that
assigns the addresses. Each of the My ADSL Modem’s
interfaces can be configured as a DHCP relay. See DHCP.
DHCP server
Dynamic Host Configuration Protocol server. A DHCP
server is a computer that is responsible for assigning IP
addresses to the computers on a LAN. See DHCP.
digital
Of data, having a form based on discrete values ex-
pressed as binary numbers (0’s and 1’s). The data com-
ponent in DSL is a digital signal. See also analog.
DNS
Domain Name System. The DNS maps domain names
into IP addresses. DNS information is distributed hierar-
chically throughout the Internet among computers called
DNS servers. When you start to access a web site, a DNS
server looks up the requested domain name to find its
corresponding IP address. If the DNS server cannot find
the IP address, it communicates with higher-level DNS
servers to determine the IP address. See also domain
name.
domain name
A domain name is a user-friendly name used in place of
its associated IP address. For example, www.globespan.
net is the domain name associated with IP address
209.191.4.240. Domain names must be unique; their
assignment is controlled by the Internet Corporation for
Assigned Names and Numbers (ICANN). Domain names
are a key element of URLs, which identify a specific file at
a web site, e.g., http://www.globespan.net/index.html.
See also DNS.
download
To transfer data in the downstream direction, i.e., from
the Internet to the user.
DSL
Digital Subscriber Line A technology that allows both dig-
ital data and analog voice signals to travel over existing
copper telephone lines.
Ethernet
The most commonly installed computer network technol-
ogy, usually using twisted pair wiring. Ethernet data rates
are 10 Mbps and 100 Mbps. See also BASE-T,100BASE-T,
twisted pair.
