UPD/INIT
A recessed push-button on the SYSCTL faceplate.
UPSR
Unidirectional Path Switched Rings
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V
VAC
Volts Alternating Current
VDC
Volts Direct Current
Virtual Tributary (VT)
A structure designed for transport and switching of sub-STS-1 payloads. There are currently
four sizes: VT1.5 (1.728 Mb/s), VT2 (2.304 Mb/s), VT3 (3.456 Mb/s), and VT6 (6.912 Mb/s).
VM
Violation Monitor
VMR
Violation Monitor and Removal
VoIP
Voice over Internet Protocol
VT
Virtual Tributary
VT-G - Virtual Tributary Group
A 9-row by 12-column SONET structure (108 bytes) that carries one or more VTs of the same
size. Seven VT groups (756 bytes) are byte-interleaved within the VT-organized STS-1
synchronous payload envelope
VT1.5
Virtual Tributary 1.5 (1.728 Mb/s)
VT1.5 Tributary
A SONET logical signal with a data rate of 1.728 Mbps. In the 9-row structure of the STS-1
SPE, a VT1.5 occupies three columns. VT-structured STS-1 SPEs are divided into seven VT
groups. Each VT group occupies twelve columns of the 9-row structure and, for VT1.5s,
contains four VTs per group.
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G L O S S A R Y
G L - 2 8
Lucent Technologies
365-372-333 R2.1
Issue 4, June 2005