Address Translation
Feature that allows devices on an intranet to communicate to remote LANs using the IP address of a gateway.

ADSL
( Asymmetric Digital Subscriber Line ) is a technology for transmitting digital information at high bandwidth on existing phone lines to homes and businesses. ADSL is asymmetric in that it uses most of the channel to transmit downstream to the user and only a small part to receive information from the user. ADSL is generally offered at downstream data rates from 512 Kbps to about 6 Mbps. A form of ADSL, known as Universal ADSL or G.Lite, has been initially approved as a standard by the ITU-TS.

AO/DI
Always-On/Dynaimc ISDN used to allow the ISDN D-channel to offer a permanent low speed connection.

ARP
Address Resolution Protocol provides dynamic address mapping between an IP address and hardware address.

B channel
One of the two logical ISDN lines supplied by the service at a basic rate ISDN outlet.

BCP
Bridging Control Protocol is responsible for configuring, enabling and disabling the bridge protocol modules on both ends of the point-to-point link.

Bridging
Allows different LAN segments to communicate via PPP by creating a database of source and destination routes between networks.

CCP
Compression Control Protocol is responsible for configuring, enabling, and disabling data compression algorithms on both ends of the point-to-point link. It is also used to signal a failure of the compression/decompression mechanism in a reliable manner.

CHAP
Challenge Handshake Authentication Protocol is a login security protocol.

Community
Group of one or more management stations associated with an SNMP agent.

Compression
The compacting of files to save storage space and reduce the time it takes to transfer file.

Country Code
Each country has its own set of procedures and rules for ISDN. The Country Code is used to identify where the router will be installed so that this information can be included in the ISDN call setup information every time you make a call.

Datagram
The unit of transmission in the network layer (such as IP). A datagram may be encapsulated in one or more packets passed to the data link layer.

DHCP
Dynamic Host Configuration Protocol is the underlying protocol for network administration giving the network manager complete control over the distribution of configuration information.

DLCI
Data Link Connection Identifier is used to uniquely identify each virtual circuit at each Frame Relay interface.

DNS
Domain Name System is a distributed database system that establishes one or more name servers to maintain mappings between IP addresses and names.

Dotted-decimal notation
IP address that consists of four non-negative integers, called octets, separated by periods. Example: 127.95.16.12

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 (DSL) 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 Internet Protocol networks. DSLAM enables a phone company to offer business or homes users the fastest phone line technology (DSL) with the fastest backbone network technology (ATM).

Dynamic route
A route determined on a per connection or session basis by routing protocols such as RIP or OSPF. These routes are stored only in memory and are lost during a power failure, for example.

Ethernet
Ethernet is the most widely-installed local area network technology. Specified in a standard, IEEE 802.3, Ethernet was originally developed by Xerox and then developed further by Xerox, DEC, and Intel. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. The most commonly installed Ethernet systems are called 10BASE-T and provide transmission speeds up to 10 Mbps. Devices are connected to the cable and compete for access using a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol.

Fast Ethernet
Fast Ethernet or 100BASE-T provides transmission speeds up to 100 megabits per second and is typically used for LAN backbone systems, supporting workstations with 10BASE-T cards. Gigabit Ethernet provides an even higher level of backbone support at 1000 megabits per second (1 gigabit or 1 billion bits per second).

Filter
A program or feature that lets users sort through data by specifying selection criteria.

Frame
The unit of transmission at the data link layer. A frame may include a header and/or a trailer, along with some number of units of data.

Frame Relay
A network access protocol for bursty data applications that is characterized by four important features: high transmission speed, low network delay, high connectivity and efficient bandwidth use.

FTP
File Transfer Protocol is an application that transfers files between systems.

G.Lite
G.Lite is the informal name of what is expected to be the standard way to install ADSL (Asymmetric Digital Subscriber Line) service. Also known as Universal ADSL, G.Lite makes it possible to have Internet connections to home and business computers at up to 1.5 Mbps (millions of bits per second) over regular phone lines.

HDSL
The earliest variation of DSL to be widely used has been HDSL (High bit-rate DSL), which is used for wideband digital transmission within a corporate site and between the telephone company and a customer. The main characteristic of HDSL is that it is symmetrical: an equal amount of bandwidth is available in both directions. For this reason, the maximum data rate is lower than for ADSL. HDSL can carry as much on a single wire of twisted-pair as can be carried on a T1 line in North America or an E1 line in Europe (2,320 Kbps).

Hops
Number of nodes the data must pass through before it reaches its destination. This value is used to determine the most efficient route.

Host name
Name or alias for a system.

HTTP
Hypertext Transfer Protocol that enables communication between World Wide Web browsers and servers.

ICMP
Internet Control Message Protocol describes a method for communicating error messages and other transmission information.

InARP
Inverse Address Resolution Protocol describes a method for resolving a protocol address when the hardware address is already known.

IP
Internet Protocol is a connectionless, unreliable datagram service that serves as the base for a number of different protocols, defines the basic unit of transmission across the Internet and defines the Internet address scheme.

IP address
Internet Protocol address assigned to a computer according to its Internet network. The address is 32-bit number grouped into four sets of eight bits (octets). See dotted-decimal notation.

IPCP
Internet Protocol Control Protocol is responsible for configuring, enabling, and disabling the IP protocol modules on both ends of the point-to-point link.

IPX
Internet Packet Exchange is a Novell protocol designed for the exchange of IP packets between dissimilar networks.

IPXCP
Internet Packet Exchange Control Protocol is responsible for configuring, enabling, and disabling the IPX protocol modules on both ends of the point-to-point link.

ISDN
Integrated Services Digital Network. A hierarchy of digital switching and transmissions systems. The ISDN provides voice, data and image in a unified manner. ISDN consists of two digital transmission (B) channels and one signaling (D) channel.

ISDN Operator Type
Also known as the ISDN switch type, identifies the signaling for each country or region. If you are unsure of your ISDN Network Operator, contact your ISDN service provider.

ITU-TS
The ITU-T (for Telecommunication Standardization Sector of the International Telecommunications Union) is the primary international body for fostering cooperative standards for telecommunications equipment and systems.

LCP
Link Control Protocol is a PPP protocol used to negotiate the encapsulation format options, handle varying limits on sizes of packets, authenticate the identity of its peer on the link, determine when a link is functioning properly and when it is defunct, detect a looped-back link and other common mis-configuration errors, and terminate the link. For more information, refer to RFC1570 PPP LCP Extensions.

Login ID
Name that the user enters to login to the system. The system uses it to uniquely identify the user.

MRU
The Maximum Receive Unit is sent to inform the peer that the implementation can receive larger packets, or to request that the peer send smaller packets.

NNTP
Network News Transport Protocol is used to transfer news across the Internet.

NTP
Network Time Protocol is used to synchronize time between computers on the Internet.

Octet
Number that represents the unsigned value of an 8-bit byte. The decimal number `255' represents the maximum value of an unsigned 8 bit byte. See dotted-decimal notation.

Packet
A group of binary digits, including data and control signals, which is switched as a switched as whole unit. A packet is usually mapped to a frame; the exceptions are when data link layer fragmentation is being performed, or when multiple packets are incorporated into a single frame.

PAP
Password Authentication Protocol is a login security protocol.

Password
Next security check after the login ID, the password is used a verification of the user logging in.

POP3
Post Office Protocol version 3. An e-mail protocol used to retrieve e-mail from a service provider's machine for dial-up accounts. Most people refer to POP with its version number to avoid confusing it with a point of presence.

PPP
Point-to-Point Protocol allows a computer to use the TCP/IP protocols to be directly connected to the Internet using a standard voice telephone line and a high-speed modem.

Protocol
A specification that describes the rules and procedures so that computers can communicate.

PVC
Permanent Virtual Circuit. A permanent connection between two devices.

RARP
Reverse Address Resolution Protocol is a method of mapping the physical Ethernet address to the IP address of the host.

RIP
Routing Information Protocol is a popular interior gateway protocol that classifies routers as active and passive.

SAP
Service Advertising Protocol is a Novell routing protocol used with RIP.

SDSL
Symmetric Digital Subscriber Line is similar to HDSL with a single twisted-pair line, carrying 1.544 Mbps (U.S. and Canada) or 2.048 Mbps (Europe) each direction on a duplex line. It's symmetric because the data rate is the same in both directions.

Security level
Hierarchical classification level that represents sensitivity of information.

Server
Computer that can distribute services or resources. Service Application port number such as FTP, NNTP, etc.

Session
A logical connection between two devices.

SMTP
Simple Mail Transfer Protocol is used to exchange messages between two mail transport agents.

SNMP
Simple Network Management Protocol lets administrators efficiently manage, monitor and maintain local or remote TCP/IP-based computer networks. A host receiving an SNMP trap must be configured so it can respond to the trap.

SPID
Service Profile Identifier used in North America to identify the services and features the ISDN switch provides for ISDN devices. An ISDN service provider normally allocates a unique SPID (SPID1 and SPID2) for each ISDN B Channel.

Static route
A predefined route to a specific network and/or device such as a host. These routes are stored in FLASH and are recoverable.

STP
Spanning Tree Protocol is used between bridges to detect and logically remove any redundant paths generated during the Bridge database creation process

Sub-network mask
Means of modifying the structure of an IP address by using some of the bits allocated for the host address as extra network address bits. In a mask, `255' means an exact match, and `0' means any number. The sub-network mask depends on the class of Internet addresses and the number of bits you wish to use as extra network address bits. For example, a class B address is normally made up of a 16 bit of network address and a 16 bit host address with a mask of 255.255.0.0. If the mask is changed to 255.255.255.0, the network address is increased in size to 24 bits and the host address is decreased to 8 bits.

T1
The T1 carrier is the most commonly used digital line in the United States, Canada, and Japan. In these countries, it carries 24 pulse code modulation signals using Time-Division Multiplexing at an overall rate of 1.544 megabit per second. T1 lines use copper wire and span distances within and between major metropolitan areas. A T1 outstate System has been developed for longer distances between cities.

TCP
Transmission Control Protocol is a connection oriented, full duplex, reliable end to end transmission protocol.

TEI
Terminal Endpoint Identifier is used with ISDN to identify a device when more than one device share the same connection (similar to a telephone extension).

Telnet
A terminal-emulation protocol that allows Internet users to remotely log onto a host computer using a Telnet program.

TFTP
Trivial File Transfer Protocol is used to transfer files.

Timeout
A `timeout' is what happens when two computers are `talking' and one computer fails to respond. The other computer keeps on trying for a specified period of time, but eventually `gives up'.

Trap
Exceptional condition notification sent by SNMP.

UDP
User Datagram Protocol. A connectionless, unreliable Internet protocol.

URL
Universal Resource Locator. An addressing scheme used to link resources via the World-Wide Web.

Van-Jacobson compression
Provides software based compression of TCP headers for the purpose of increasing the efficiency of communication over low speed serial links.

VDSL
Very high data rate Digital Subscriber Line is a developing technology that promises much higher data rates over relatively short distances (between 51 and 55 Mbps over lines up to 1,000 feet or 300 meters in length). It's envisioned that VDSL may emerge somewhat after ADSL is widely deployed and co-exist with it. The transmission technology (CAP, DMT, or other) and its effectiveness in some environments is not yet determined. A number of standards organizations are working on it.

World-Wide Web
A hypermedia-based system for accessing Internet resources.

X.25
The X.25 protocol, adopted as a standard by the Consultative Committee for International Telegraph and Telephone (CCITT), is a commonly-used network protocol. The X.25 protocol allows computers on different public networks (such as CompuServe, Tymnet, or a TCP/IP network) to communicate through an intermediary computer at the network layer level. X.25's protocols correspond closely to the data-link and physical-layer protocols defined in the Open Systems Interconnection (OSI) communication model.