Hi guys , hit a bit of a strange bug at a customer in the week.I don’t think the Mikrotik device is at fault here , but just leaving this here in case someone else runs into this problem.
From what I can tell the culprit seems to be the switch incorrectly identifying the type/class of POE device connected to it.
The customer uses Dell 1524P and Dell 1548P switches in their locations linked up to Mikrotik RB2011UiAS-RM’s (various bugfix released tested 6.34-6.39.3 @ rb fw 3.33/3.41) which we use either as fiber converters or as a termination points for wireless Ubnt or Mikrotik wireless P2P radios and do shaping etc.The 2011 is powered up via a power brick usually connected to to UPS.
Problem
During a coldboot with a ethernet cable is run from the Dell switches to port 1 on the Mikrotik RB2011UiAS-RM’s,the RB2011UiAS-RM’s blue light on the bottom left corner will flicker for a very short amount and then switch off.The unit will then fail to boot.If the ethernet lead is removed and re-inserted the unit will then boot up ok using the regular power provided from the power brick.What I have noticed on the Dell switch when the unit fails to boot up , the switch picks up the RB2011UiAS-RM as an available POE Class0 400mw device via the cli tools . I have tried ports 1-24/48 on these switches and all of the ports seem to do the same.I cannot replicate this issue on Netgear,DLink or HP switches we have lying around the office.
console#show power inline gigabitethernet 1/0/1
Port Powered Device State Priority Status Class Power[mW]
Gi1/0/1 auto Low On Class0 400
Overload Counter… 0
Short Counter … 0
Denied Counter… 0
Absent Counter… 0
Invalid Signature Counter… 0
Output Volts… 52
Output Current… 9
Temperature… 37
console#show power inline
Gi1/0/1 auto Low On Class0 400
Temporary Workaround/Resolution
A) On the port connecting towards the RB2011UiAS-RM , issue a #power inline never command to turn off POE on the port.This is the most favorable in our case as we have autoconfig scripts we use to program eth1
or
B) Insert cable into ETH2 rather than ETH1. No POE-In available on this port , but in our case we’d have to redo or reprogram a couple of our RSC scripts.
Hope this helps someone.