IBM SG24-4817-00 manual Glossary, 285

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Glossary

A

AAL (ATM Adaptation Layer). The layer that adapts user data to/from the ATM network by adding/removing headers and segmenting/reassembling the data into/from cells.

AAL-5 (ATM adaptation Layer 5). One of several standard AALs, AAL-5 was designed for data communications and is used by LAN Emulation and classical IP.

ABR (Available Bit Rate). ATM Forum Service category in relation to traffic Management on ATM networks. Use bandwidth available in the running network after other traffic utilizing guaranteed bandwidth services has been serviced.

ARP (Address Resolution Protocol). IP ARP translate network addresses into hardware addresses, LE ARP translates LAN destinations into ATM addresses.

asynchronous. Any two events that are not tied together exactly in time are said to be asynchronous.

ATM (asynchronous transfer mode). A transfer mode in which the information is organized into cells. It is asynchronous in the sense that the recurrence of cells containing information from an individual user is not necessarily periodic.

ATM layer. The layer in the protocol model which relays cells from one connection to another.

ATM peer-to-peer connection. A virtual channel connection (VCC) or a virtual path connection (VPC).

ATM user-to-user connection. An association established at the ATM layer to support communication between two or more ATM service users (that is, between two or more next higher layer entities or between two or more ATM entities). The communication over an ATM layer connection may be either bidirectional or unidirectional. The same virtual channel identifier (VCI) is used for both directions of a connection at an interface.

ATM layer link. A section of an ATM layer connection between two active ATM layer entities (ATM entities).

ATM link. A virtual path link (VPL) or a virtual channel link (VCL).

B

Broadcast. A value of the service attribute ªcommunication configurationº, which denotes unidirectional distribution to all users.

BCM (Broadcast Manager). An IBM extension to LAN Emulation designed to limit the effects of broadcast frames

BUS (Broadcast and Unknown Server). A LAN emulation Service component responsible for the delivery of multicast and unknown unicast frames.

C

cell header. ATM layer protocol control information.

CBR (Constant Bit Rate). ATM Forum Service category in relation to traffic Management on ATM networks. Includes anything where a continuous stream of bits at a predefined constant rate is transported through the network.

cell loss priority. A control descriptor in each ATM cell header which indicates the relative importance of the cell. If set to zero it should not be discarded, if set to one it may be discarded.

CIP (Classical IP). An IETF standard for ATM-attached devices to communicate using IP.

CIPC (Classical IP Client). A classical IP component that represents users of the classical IP Subnet.

CAC (connection admission control). The set of actions taken by the network at the call setup phase (or during call re-negotiation phase) in order to establish whether a virtual channel/virtual path connection can be accepted or rejected (or a request for re-allocation can be accommodated). Routing is part of connection admission control actions.

congestion control. The set of actions taken to relieve congestion by limiting its spread and duration.

connection oriented. Communication where there is a connection provided between sender and receiver, which must be maintained for data to be transferred.

connectionless service. A service which allows the transfer of information between service users without the need for end-to-end call establishment procedures.

constant bit rate service. A type of telecommunication service characterized by a service bit rate specified by a constant value.

 Copyright IBM Corp. 1996 285