Alcatel Speed Touch 591s, Technical User'S Manual

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Glossary
Speed Touch 591s Technical Practices GL-7
February 2001 90-8785-01
UDT unstructured data transfer
An unstructured data transfer is an AAL1 convergence sublayer procedure
where all payload and framing bits of an emulated circuit are carried on an
ATM VC.
UNI user-network interface
VC virtual circuit (frame relay)
A virtual circuit is a communications link that behaves like a dedicated
point-to-point circuit, even though it is not. Data packets are delivered to the
user in guaranteed sequential order, as if they were sent over a true
point-to-point circuit.
VCI virtual channel identifier
A VCI is a unique numerical tag that is defined by a 16-bit field in the ATM
cell header and identifies a virtual channel over which the cell is to travel.
VP virtual path
A VP is a logical communication channel that is available across a physical
cell relay interface and that can carry one or more virtual channels.
VPI virtual path identifier
A VPI is an 8-bit value used to identify an ATM path. The VPI is part of the
header of an ATM cell. The VPI is assigned on connection setup by the
devices at the two ends of a hop. Multihop VPCs use multiple VPIs to go
from source to destination. Each switch that the VPC traverses cross-
connects the VPC from one port and VPI to another port and VPI.