User manual

Wide Bank 28 DS3 - Release 2.4 July 2004 2-17
Product Description
Controller and DS3 Redundancy
Controller and DS3 Redundancy
 Protection Modes ... 2-17
 Electronics Protection Mode ... 2-17
 Electronics and Network Protection Mode ... 2-19
 Operator-Initiated Switch ... 2-20
 Restoring to Original Status (Revertive Switching) ... 2-20
Protection Modes
The Wide Bank can be provisioned with one or two Controller cards and connections to one or two
DS3 lines to provide the following levels of protection:
 Electronics Protection – When provisioned with two Controller cards and only one DS3 line,
only the Controller cards can be protected.
 Electronics and Network Protection – When provisioned with two Controller cards and two
independent DS3 lines, both the Controller cards and the DS3 lines can be protected.
Electronics Protection Mode
In this mode there are two Controllers available to the Wide Bank but only one DS3 line.
The electronics mode of protection provides Controller card redundancy. Because there is only one
DS3 connected, there is no DS3 redundancy. The receive path from the DS3 line is simultaneously
applied to the receiver of both Controller cards (see Figure 2-8). This enables both Controllers to
monitor the condition of the DS3 line so both are continuously framed up to the incoming signal.
The controller-select signal disables the outputs of the low-speed receive paths on the standby
Controller and enables the low-speed receive paths on the active Controller. The active Controller’s
transmit signal is connected to the transmit path of the DS3 line through a relay, while the standby
is disconnected until a protection switch occurs.
The automatic redundancy mode is used to enable and disable protection switching. If arm is
enabled (arm on), and the redundancy control process determines the active Controller is
malfunctioning, or a maintenance switch is invoked (the switch command), a protection switch will
occur. This means that the active Controller relinquishes control to the secondary Controller. This
is done by enabling the standby Controller’s receive path and disabling the originally active
Controller’s low-speed receive path (controller-select signal) and switching the output paths so that
the transmit path of the DS3 line is connected to the standby Controller. Service interruptions (hits)
will be taken on both the DS3 and low-speed connections during this type of switch. However,
because the standby Controller is already framed up to the incoming signal, the hits are minimal.