ATM Adaptation Layer 1. AAL1 is a specification for ATM networks that transmit data at a constant bit rate (CBR). AAL1 is useful for circuit-emulation applications.
ATM Adaptation Layer 2. AAL2 is a specification for ATM networks that transmit data at a variable bit rate (VBR) such as packetized audio and video signals.
ATM Adaptation Layer 3 and 4. AAL3/4 is similar to AAL2 except that it does not keep timing information intact through the network.
ATM Adaptation Layer 5. AAL5 is a specification for ATM networks that transmit data at a variable bit rate (VBR) that is specifically suited to LAN protocols.
Area Border Router. In OSPF, an ABR is a router that acts as the gateway between two areas.
Available Bit Rate. In ATM networks, a Quality of Service specification in which cells are delivered on a best-effort basis.
In wireless networking, the transmitter and receiver that acts as a hub for the BSS.
See ARP.
A Layer 3 concept in which the destination address specifies any of a set of possible specific destination devices. The network delivers the packet to one or more of these devices, but not necessarily to all of them.
A set of routable protocols developed by the Apple Computer Corporation.
See ABR.
Address Resolution Protocol. In TCP/IP networks, the ARP protocol provides the mechanism for devices to find Layer 2 MAC addresses associated with Layer 3 IP addresses.
In TCP/IP networks, a table maintained by each device correlating Layer 2 MAC addresses with their associated Layer 3 IP addresses. This table of information is stored locally on each device and is called the ARP Cache. See also ARP.
Advanced Research Projects Agency. ARPA is the research-and-development division of the US Department of Defense, which developed much of the core TCP/IP standards and set up the ARPANET.
An early predecessor to the modern public Internet. The ARPANET was the first large TCP/IP network. Devices in this network were addressed using the Class A address range 10.0.0.0. This address range, now unregistered, is sometimes called the ARPANET range. See also ARPA.
Autonomous System. In dynamic routing protocols, an Autonomous System is a region of a network that uses a single Interior Gateway Protocol.
Autonomous System Boundary Router. In dynamic routing protocols, an ASBR is a router that forms the gateway between two or more different Autonomous Systems.
American Standard Code for Information Interchange. A standard system for encoding character-based data using 8-bit bytes.
Asynchronous Transfer Mode. A network protocol in which very short "cells" of fixed size are relayed between switches over virtual circuits. ATM is capable of very high transfer rates and low latency. It is commonly used to emulate an Ethernet LAN by means of the LANE standard. See also LAN, LANE, and ELAN.
In ATM LAN emulation, the protocol that provides the ability to map Layer 2 MAC address information to Layer 3 IP addresses. See also ATM and ARP.
See AUI.
Attachment Unit Interface. In 10Mbps Ethernet, AUI provides a generic physical-layer specification that allows the connection of a transceiver to give the desired physical connection. See also MII and GMII.
See AS.
See ASBR.
See ABR.