ATM Glossary
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A set of ATM Forum specifications that enables you to bridge LANs over an ATM backbone, creating a
single virtual network or ELAN. The ATM Forum has defined LANE 1.0 and will finalize LANE 2.0 in
March 1997.
LAN EMULATION NETWORK-TO-NETWORK INTERFACE (LNNI)
A LANE 2.0 standard that will define the interface between two LANE servers within the same virtual
network, or ELAN.
LAN EMULATION USER-TO-NETWORK INTERFACE (LUNI)
A LANE standard that specifies the components needed to connect two LANs using an ATM backbone, to
create one virtual network, or ELAN.
LATENCY
The time that lapses between the point at which an end station seeks access to the transmission medium and
the point at which the end station receives that access.
MULTIPROTOCOL OVER ATM (MPOA)
An ATM Forum standard that enables you to route protocols from traditional LANs over an ATM backbone.
MPOA contrasts with LANE, which enables you to bridge protocols but does not provide routing.
NETWORK-TO-NETWORK INTERFACE (NNI)
A generic term that describes the interface between two switches on a switched network.
NEXT HOP ROUTING PROTOCOL (NHRP)
A protocol being developed by the IETF that will add routing capabilities to Classical IP over ATM.
OPEN SYSTEMS INTERCONNECTION (OSI) MODEL
A seven-layer networking model developed by the International Standards Organization (ISO). The OSI model
is a guideline for developing standards to enable dissimilar network computing products to communicate.
PERMANENT VIRTUAL CIRCUITS (PVCS)
Virtual circuits that the network supervisor or ATM service provider sets up when configuring the ATM
network. Bandwidth is always reserved for the virtual circuit, whether the PVC is in use or not, so PVC's are
always available for immediate use.
PHYSICAL LAYER
The lowest layer of the ATM model, roughly corresponding to the OSI physical layer. Standards for the ATM
model's physical layer, like those for the OSI model's physical layer, specify how to send bits over the
transmission medium.
PRIVATE NETWORK-TO-NETWORK INTERFACE (PNNI)
An ATM Forum standard that defines the interface between two switches on an all-ATM network. It enables
switches to distribute routing information.
QUALITY OF SERVICE PARAMETERS
Parameters that specify how many cells can be lost during a transmission, how long it can take for cells to
reach their destination, and how much the amount of time between cells can vary. Quality of Service
parameters are used to determine the quality of service a given virtual circuit will provide.
SERVICE CATEGORIES
Classes of service that are used to provide different levels of service for different types of traffic. ATM service
categories are CBR, VBR, UBR, and ABR.
SWITCH
