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en | Hardware Installation Procedure for Redundant System Configuration Utilizing LTC
34
8901 Series CPU
With this in place, data coming from the in-use CPU will go to all other ports on both switches.
This allows the video bays to be connected to any port on either switch (except port 1 or 2,
which is reserved for the System Controller PC).
The LAN switches are extremely reliable, but the system should be designed to minimize the
impact of a switch failure. If a single port on a switch fails, only the bay connected to that port
will be lost. If an entire switch fails, all bays connected to that switch will fail.
Thus, it is advisable to divide critical cameras and monitors to bays connected to different
switches, ensuring that no more than half of these signals will be lost in the event of a switch
failure.
The LTC 8901 Series CPU bay provides separate LAN connections for the primary CPU and
backup CPU. The LTC 8900 system was designed so that each CPU board always thinks that it
is controlling the system. Thus both CPUs send control data to the LAN switches. To prevent
conflicts, the System Controller disables the LAN switch port 1 for the CPU that is not in use.
For example, when the primary CPU is controlling the system, LTC 8945/93 LAN switch port 1
for the backup CPU is disabled.
The System Controller uses LAN connections into port 2 of the switches to control and
monitor these switches. If a switch failure is detected (either a complete failure or a failure of
the CPU port, i.e., port 1), automatic switch-over will occur.
6.1.5
Video Bay Redundancy Considerations
The LTC 8900 system was designed to provide redundancy for critical components. Careful
system design ensures that tolerance of single point failures is maintained. For example, if a
single output bay is used in the system and the data receiver board in the bay fails, the entire
system will fail (this is true for the LTC 8900 system as well as the competitors systems).
When fault-tolerance is critical, the system designer should always specify at least two output
bays. This allows critical camera signals to be distributed between the bays.
To support this redundancy concept for smaller systems, the LTC 8901 Series configuration
tables may be programmed with logical camera and monitor numbering. An example of the
non-redundancy/redundancy concept is shown in the following two figures. Both figures
showa 256 x 64 system.
In the first configuration, a worst case failure in either the output or input bay could disable
the entire system.
In the second configuration, logical monitor numbering was used to unconfigure monitor
outputs 33-64, and renumber monitor outputs 65-96 as logical monitor numbers 33-64. Logical
monitor renumbering is configured using the Allegiant Server software. Refer to the software
manual for details.
2015.01 | 10.6 |
Installation Manual
LTC 8900 Series
Bosch Security Systems, Inc.
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