Lucent Technologies DDM-2000 OC-3, Руководство по установке

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GLOSSARY
Issue 9 October 1998 GL-21
U
UAS
Unavailable Seconds. In performance monitoring, the count of seconds (1) in
which a signal is declared failed or, (2) in which, 10 consecutively severely errored
seconds (SES) occurred, until the time when 10 consecutive non-SES occur.
Unidirectional
A protection switching mode in which the system at each end of an optical span
monitors both service and protection lines and independently chooses the best
signal (unless overridden by an equipment failure or by an external request, such
as a forced switch or lockout). In a system that uses unidirectional line switching,
both the
service and protection lines may be active simultaneously, with one line
carrying traffic in one direction and the other line carrying traffic in the other direc-
tion. The K1 and K2 bytes in the SONET line overhead are used to convey to the
far-end which line the near-end receiver has chosen, so that an "active" indication
may be made at the far-end.
UPD/INIT
A pushbutton on the user panel.
V
VF
Voice Frequency
VLSI
Very Large Scale Integration — Refers to very complex state of the art integrated
circuits.
VM
Violation Monitor — A mode of the DS3 circuit pack in which it will monitor but not
remove P-bit parity violations on the DS3 signal received from the fiber.
VMR
Violation, Monitor, and Removal — A mode of the DS3 circuit pack in which it will
monitor and remove P-bit parity violations on the DS3 signal received from the
fiber.
VT
Virtual Tributary — A structure designed for transport and switching of a sub DS3
payload.
VT1.5
A 1.728 Mb/s virtual tributary