Glossary
Glossary-56
255-700-166
PacketStar
®
PSAX 6-Port DS1 IMA Module User Guide
, Issue 1
Release 7.0
UPC
usage parameter control. Network actions used to monitor
and control traffic at the end system. UPS detects negotiated
parameters violations, and it can take appropriate action to
protect against malicious or unintentional misbehavior. Its
actions include cell tagging and cell discarding.
uplink
The connectivity between an ATM border node and an upn-
ode.
upnode
In ATM, the border node’s outside neighbor in the common
peer group. The upnode must be a neighboring peer of one of
the border node’s ancestors.
usage parameter control
See UPC.
user network interface
See UNI.
user-to-network (UNI) Implementa-
tion Agreement
See FRF.1
UTC
Universal Time Coordinate. The new term for Greenwich
Mean Time. See GMT.
UTP
unshielded twisted pair. A pair of wires that is twisted so as to
minimize the crosstalk with other pairs of wires in the same
cable (which are twisted at a slightly different rate) but not
shielded.
V
V ac
volt, alternating current
V dc
volt, direct current
V.35
A standard module used for communication between a net-
work access device and a packet network. It provides clocking
19.2 Kbps to 4.0966 Mbps.
validation
The checking of data for correctness or for compliance with
applicable standards, rules, and conventions.
variable bit rate
See VBR.
variable bit rate - real time
See VBR-RT
variable bit rate- non-real time
See VBR-NRT.
VBR
variable bit rate. A voice service over an ATM switch which
provides only as much bandwidth as voice conversations
need at any moment (making bandwidth “elastic”). The
remaining bandwidth is dynamically allocated to other ser-
vices. VBR be divided into VBRnrt (variable bit rate, nonreal
time) and VBRrt (variable bit rate, real time). See also VBR-
NRT, and VBR-RT.