3.1.2 Controller Module Fault Tolerance
There are two dedicated slots, 18 and 19, provided for installing the controller
module. Once installed, the controller does not need to be configured. Since
the controller module is a critical component, it is recommended to have a
second controller module installed in the hub for backup purposes.
When two controller modules are installed in the hub, one is active and the other
will be a standby. Both the active and standby controller modules monitor and
modify the hub operating conditions such as temperature and power. This
redundant monitoring and control capability enables the standby controller
module to be ready to take over from the active controller module should the
active controller module fail.
When the standby controller module takes over from the active controller
module, all the installed modules perform a fast reboot. Fast reboot results in
all the 8260 modules equipped with onboard memory (NVRAM) to automatically
load the configuration stored there. This occurs regardless of the current DIP
switch settings on the modules. Fast reboot facilitates immediate resumption of
the hub activity following the failure of the active controller module and takeover
by the standby controller module. However, note that the takeover of the
operation by the standby controller module is disruptive to the operation of the
network and the users attached to the network.
Note: 8250 media modules do not have onboard memory to store configuration
information. Therefore, following a reboot due to the failure of the active
controller module, they will be configured by the DIP switch settings on the
module (in an unmanaged hub) or via the configuration stored in the
management module (in a managed hub).
If two controller modules are installed in a hub that is already powered up, the
first controller module to be installed becomes the active controller module and
the second controller module to be installed becomes the standby controller
module. This is regardless of the slot in which the controller modules are
installed. However, if two controller modules are installed in a hub that is not
yet powered up, the controller module installed in slot 18 becomes the active
controller module when the hub is subsequently powered up. Also, after a hub
is reset due to power outage, pressing the reset button on the active controller
module, or through 8260 DMM commands, the controller module in slot 18
becomes the active controller module and the controller module installed in slot
19 becomes the standby controller module.
3.1.3 Installing and Configuring the Fault Tolerant Controller Module
To install the controller module:
•Unpack the controller module from the shipping carton.
•Remove the blank faceplate from slot 18 and/or 19 depending on which slot
is for installation.
•Insert the controller module into the top and bottom board guides and slide it
into the hub until it is flush with the front of the hub.
•Tighten the two spring-loaded screws securely.
32 8260 Multiprotocol Intelligent Switching Hub