Harris Intraplex STL-160 Series Installation & Operation Manual page 37

2 – Functional Description
Table 2-6. Failure Switching Precedence: Non-Revertive Line Redundancy and Backup Line
Backup Line Status
Good
Good B
Soft B
Hard B
P = Primary Line is active
B = Backup Line is active
NC = No Change (current state)
Detection times for line failures depend on the nature of the failure conditions. The total time to switch
to line protection after the start of any Hard Failure condition does not exceed 500 milliseconds,
including detection time and re-frame time, unless a switching delay time has been selected (the SDLY
group in the LRDN menu on Table 4-23).
You can select from a range of available line switching delays. The selected delay begins when a line
failure condition is detected. If the condition persists throughout the delay period, the line is switched.
The programmable switching delay values are
● 0 seconds.
● 0.5 seconds.
● 1 seconds.
● 10 seconds.
You can manually force line switching via the front panel switches or ISiCL command. If a line switch
is forced manually, the system reverts according to normal failure switching precedence. For a
permanent manual switch, set line redundancy mode to OFF before initiating the manual switch.
2.1.4.7 Manual Switching for Line Failure
If a line failure condition occurs and is later cleared but the control is not reverted to the primary CM-
5RB common module (CM), you can manually switch by
● Removing and reinstalling the primary CM.
● Manually switching at the front panel display (MRDN >> PRIM).
2.1.4.8 Line Redundancy Revertive Operation
You can configure line redundancy for revertive or non-revertive switching separately for line and
module redundancy. If you select revertive switching for line redundancy, operation returns to the
primary line after a user-programmable delay at the conclusion of the primary line failure. You can
program this delay to
● 10 seconds
● 1 minute
● 5 minutes
Reversion to the primary line only occurs if the primary is in "Good" condition or in better condition
than the backup.
If you select non-revertive switching, operation returns to the primary line if manually forced via the
front panel switches, by using ISiCL commands, or if the primary line becomes "better" than the
backup line (Tables 2-5 and 2-6). Figure 2-10 shows T1 signal flow after a line switch operation to the
backup line. In this state, both transmit and receive T1 traffic flows through the backup CM.
Harris Corporation
Intraplex Products
ACS-160 Series & STL-160 Series T1 Multiplexer Installation & Operation
Soft Hard
P P
NC P
B NC
Version 2.11, August 2011
2-15