Issue 9 October 1998
GL-1
Lucent Technologies
GLOSSARY
Numeric and Symbols
1+1
The 1+1 protection switching architecture protects against failures of the optical
transmit/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 designated "protection". In each direction, identical signals are
transmitted on the service and protection lines ("dual-fed"). The receiving equip-
ment monitors the incoming service 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 redun-
dant 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.