363-206-208
Issue 5 June 2000
GL-1
Glossary
Numeric and Symbols
1+1
The 1+1 protection switching architecture protects against failures of the optical trans-
mit/receive equipment and their connecting fiber facility. One bidirectional interface (two
fibers plus associated OLIUs on each end) is designated "service", and the other is des-
ignated "protection". In each direction, identical signals are transmitted on the service
and protection lines ("dual-fed"). The receiving equipment monitors the incoming ser-
vice and protection lines independently, and selects traffic from one line (the "active"
line) based on performance criteria and technician/OS control. In 1+1 both service and
protection lines could be active at the same time.
1xN, 1x1
1xn protection switching pertains to circuit pack protection that provides a redundant
signal path through the DDM-2000 (it does not cover protection switching of an optical
facility; see "1+1"). In 1xn switching, a group of n service circuit packs share a single
spare protection circuit pack. 1x1 is a special case of 1xn, with n=1. In 1x1 only one is
active at a time.
A
ABN
Abnormal (status condition) indicated by an LED on the user panel. An abnormal condi-
tion, loopback, forced manual switch, etc., is initiated through a craft interface terminal
command.
ACO/TST
Alarm Cutoff and Test — The name of a pushbutton on the user panel. it retires an audi-
ble office alarm. It has other functions when used in combination with other pushbuttons
and controls.
Summary of Contents for DDM-2000 OC-12
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