Power shutdown / startup time, and DC power failure
Posted: Thu Jan 21, 2021 4:13 am
I have a DC site that has been running a little low on power lately thanks to the winter. I have used the power shutdown and startup times to shut down POE on a port that is not necessary, which powers an AP to relay for a single customer. This port shuts down at 0100 and powers up at 0700.
I realized, that, there's really no reason for the bridge/client radio which connects back to the main tower to be powered up either.
At 0054 I set this port to shut off at 0100, and turn back on at 0659.
I then noticed that the voltage was already rather low, and it dawned on me that when the switch powers off, it's going to lose it's NTP time sync once DC voltage is restored, and the whole shutdown / startup thing is going to be seriously out of whack.
So... now you see my dilemma. If I shut down the port for the bridge/client radio at 0100, and power goes off between 0100 and 0659... the switch will come back online with, what I can best tell, will be Dec 30, 5pm time settings, which means the POE would not be re-enabled for an additional 14 hours.
I cut it pretty close here:
Jan 21 00:59:54 UI: Port 2 Shutdown_Time: changed from '01:00' to ''
Jan 21 00:59:54 UI: Port 2 Startup_Time: changed from '06:59' to ''
So, before I try this again... Is my assumption correct, and using shutdown/startup timers a bad idea if power will go out during the shutdown window???
Or, is there some magic fail-safe in play that says "Hey, I just booted up and have no freaking clue what time it is, so I'm just going to enable power for now and see if I can grab a quick NTP sync to figure out what I need to be doing." ??
*EDIT* - I found this post: viewtopic.php?f=14&t=5926
"Say you set a watchdog up on Port 2 (where Port 2 is set to 24VH) and you want the watchdog to ping www.google.com and if it fails the "Enable Power" option is selected.
In this case, as long as the switch can ping www.google.com, Port 2 will actually be disabled until the watchdog fails. At which point the watchdog will enable it."
Does the watchdog take priority over a timer? Could I set the watchdog to ping upstream, and if it fails, enable the power to Port 2?
I realized, that, there's really no reason for the bridge/client radio which connects back to the main tower to be powered up either.
At 0054 I set this port to shut off at 0100, and turn back on at 0659.
I then noticed that the voltage was already rather low, and it dawned on me that when the switch powers off, it's going to lose it's NTP time sync once DC voltage is restored, and the whole shutdown / startup thing is going to be seriously out of whack.
So... now you see my dilemma. If I shut down the port for the bridge/client radio at 0100, and power goes off between 0100 and 0659... the switch will come back online with, what I can best tell, will be Dec 30, 5pm time settings, which means the POE would not be re-enabled for an additional 14 hours.
I cut it pretty close here:
Jan 21 00:59:54 UI: Port 2 Shutdown_Time: changed from '01:00' to ''
Jan 21 00:59:54 UI: Port 2 Startup_Time: changed from '06:59' to ''
So, before I try this again... Is my assumption correct, and using shutdown/startup timers a bad idea if power will go out during the shutdown window???
Or, is there some magic fail-safe in play that says "Hey, I just booted up and have no freaking clue what time it is, so I'm just going to enable power for now and see if I can grab a quick NTP sync to figure out what I need to be doing." ??
*EDIT* - I found this post: viewtopic.php?f=14&t=5926
"Say you set a watchdog up on Port 2 (where Port 2 is set to 24VH) and you want the watchdog to ping www.google.com and if it fails the "Enable Power" option is selected.
In this case, as long as the switch can ping www.google.com, Port 2 will actually be disabled until the watchdog fails. At which point the watchdog will enable it."
Does the watchdog take priority over a timer? Could I set the watchdog to ping upstream, and if it fails, enable the power to Port 2?