Symmetricom TimeProvider 1100 Reference Manual page 30

Chapter 2 TL1 Command Syntax and Description
The Firmware Download Process
After the file transfer completes, the IMC module validates the file (the system
remains locked against logins at this point). If the file is not validated, the unit
returns an error response and the IMC module returns to normal operation.
If the file is validated, the next step depends on which module is receiving the
upgrade.
If the upgrade file applies to the IMC module
If the upgrade file that was downloaded is valid and is for the IMC module, the flash
memory on the IMC module is reprogrammed and the IMC module is rebooted
using the new firmware.
The system outputs are not interrupted when the IMC module is upgraded. If the
process fails at any time, the upgrade process aborts and the IMC module returns to
normal operation using the existing version of firmware.
If the upgrade file applies to the IOC modules
If the upgrade file that was downloaded is valid and is for the IOC modules, the
system checks the following criteria to determine how to proceed with the upgrade
process:
It checks if the shelf contains two installed and communicating IOC modules
It checks if both IOC control loops are locked
It checks if both IOC modules are in service
It checks if both IOC modules are alarm free
It checks if one of the IOC modules is active
If the system determines that any of the above criteria are false, it reprograms the
IOC1 module's flash memory and reboots the module, then reprograms the IOC2
module's flash memory and reboots that module. If the shelf contains only one IOC
module, that module's flash memory is reprogrammed and the module is rebooted.
In these cases, the system outputs are interrupted for up to 30 minutes until the
upgraded IOC module enters Fast-Locked mode.
If the system determines that all of the above criteria are true, then the system
places the active IOC module in Standby mode, and the IOC module that was in
Standby mode is placed into Active mode. The system then reprograms the standby
IOC module's flash memory and reboots it. After the module reboots, the system
waits up to 30 minutes for its control loop to lock. After its control loop locks, the
system places it in Active mode and places the other IOC module in Standby mode.
The system then reprograms the standby IOC module's flash memory and reboots
it. In this case, the system outputs are not interrupted.
If at any time the above process fails for either IOC module, for example, if an IOC
module fails to transition from Standby to Active mode, the upgrade process aborts
and the IOC modules return to normal operation using the existing versions of
firmware.
30 TimeProvider TL1 Reference Guide 097-58001-01 Revision E – September 2006