Device Communications Restored - False reading

DCIM_Support · ‎2020-07-05

I had several devices that were offline due to a power outage. At almost exactly 8:00pm last night, all six devices alerted that the communications were restored and they appeared fine in DCE, even though the locations were still out of power and unpingable. I tried to do a device scan and rebooting the server and it still showed that it was up. Why might this happen?

DCIM_Support · ‎2020-07-05

Hi Mike,

Although I've seen issues where a device might show the wrong state, I can't say that I've seen it be communications restored while the device is not available. Add to that the fact that you've got 6 devices doing this, it's even more strange.

If you right click the device and show sensor values, do they show as values or unplugged?

Keep in mind a ping or web interface may not be available while SNMP is. Of course you do need network connection but there may be a little more troubleshooting that you can do if the devices are still inaccessible.

If you're running DCE 7.6 or higher, go to the web page of the server. Click on status and under additional information, select SNMPwalk. Can you retrieve any SNMP values from any of the devices using this feature?

If you right click and request a scan and it remains online when you know for sure it is not, perhaps you can run a packet capture to see if DCE is actually sending anything out and receiving anything back.

If the devices are back up and running at this point, we'll be hard pressed to troubleshoot what may have happened. If they're on line you can try disconnecting one from the network and see if you can replicate but I'm thinking that is time consuming and might not replicate the issue....you can try though.

Again, I've never seen what you're describing so you'd have to do testing while it's in this state to figure anything out.

Steve

See Answer In Context

DCIM_Support · ‎2020-07-05

Hi Mike,

Although I've seen issues where a device might show the wrong state, I can't say that I've seen it be communications restored while the device is not available. Add to that the fact that you've got 6 devices doing this, it's even more strange.

If you right click the device and show sensor values, do they show as values or unplugged?

Keep in mind a ping or web interface may not be available while SNMP is. Of course you do need network connection but there may be a little more troubleshooting that you can do if the devices are still inaccessible.

If you're running DCE 7.6 or higher, go to the web page of the server. Click on status and under additional information, select SNMPwalk. Can you retrieve any SNMP values from any of the devices using this feature?

If you right click and request a scan and it remains online when you know for sure it is not, perhaps you can run a packet capture to see if DCE is actually sending anything out and receiving anything back.

If the devices are back up and running at this point, we'll be hard pressed to troubleshoot what may have happened. If they're on line you can try disconnecting one from the network and see if you can replicate but I'm thinking that is time consuming and might not replicate the issue....you can try though.

Again, I've never seen what you're describing so you'd have to do testing while it's in this state to figure anything out.

Steve

DCIM_Support · ‎2020-07-05

Thanks Steve - before I had a chance to do any of this, powered was restored to all sites. After the sites came back up, I have not been able to replicate this scenario unfortunately. I hate to chalk it up to being a fluke, but that appears to be what it was. Thanks again for your response.

DCIM_Support · ‎2020-07-05

No problem. If you unplug a device now and you can't replicate the issue, I don't know where to go from there either. Glad it's working now though.

DCIM_Support · ‎2020-07-05

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