Drawing power from PoE without Ethernet
Cisco's PoE switches and routers will power remote devices that show a certain &quot;power signature&quot; called MPS.

Directly from Cisco's &quot;Troubleshooting Power Over Ethernet&quot; application note:
&quot;The switch uses maintain power signature (MPS) to detect the continued presence of a powered device after detection and after power is applied. As long as a power signature is present, the switch provides PoE.
The powered device must maintain its power signature to maintain a PoE feed from the switch. PoE is typically removed within 500 milliseconds after the switch no longer detects a power signature. All disconnect methods occur at the physical layer.&quot;
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/software/troubleshooting/g_power_over_ethernet.html#pgfId-1010244