Appendix C
8-1
8. Appendix C: 1 : 1 Line Protection
Introduction
Among the many applications of the Loop-V 4200-9, an IAD (integrated access device) is 1:1 or 1:N line
protection. 1:1 line protection exists when the system is set up so that a backup line (or lines in the case of
1:N) will be switched into service if the working line fails. In such a case, it must be switched in at each end
of the line. The 1:1 line protection function exists only for E1 and T1 cards.
In the diagram below, working ports and protection ports are directly connected to the Time Slot Interchange
(TSI). Signal paths are clearly marked in bold lines.
The protection function is set up but is not in use because the lines at the working ports are functioning
properly. For example, the line at working Port A is connected to the line at working Port J.
In the example below, a line failure has occurred at Port A. The protection function has kicked in and the
system has switched to protection port B as shown below.
A
B
D
C
H
E
F
K
J
Working Port
Protection Port
Working Port
Working Port
Working Port
Protection Port
Protection Port
Protection Port
T.S.I.
TS 01-10
TS 11-20
TS 21-30
