Why does PacketShaper lose its settings right after configuration?

Products

• PacketShaper

Issue/Introduction

When I changed PacketShaper configuration settings using the command-line interface (Telnet or a direct console connection), it seems the changes were not applied after I turned the unit's power off and back on.

Resolution

Here is why this seems to happen from the CLI only: 

• There are two timer settings that must expire before changes are written to the non-volatile flash memory in the unit. Changes are only written when the timers fire. 
• The first timer fires at two seconds after the setting is changed. 
• If a change happens after the first timer, the change will not be written to flash until either the second timer fires at 60 seconds or the reset command is issued.

So, if you change settings after the first timer fires and you do a manual power cycle before the second timer fires, the most recent configuration changes are likely to be discarded. By waiting one minute after making configuration changes, the new settings will be written and the configuration will be current even with a power cycle.

This does not appear to happen from the browser interface because all the changes happen before the two-second timer expires. All changes are written correctly the first time. If you were to immediately make changes again, then power cycle, you should see the same behavior as the CLI.

The dual timers are in place to keep from "thrashing" the flash. These measures ensure efficient utilization of flash memory resources.