Cisco Cisco SG200-26P 26-port Gigabit PoE Smart Switch ユーザーガイド

Consider the following when connecting switches capable of 
supplying PoE:

The PoE models of the switches are PSE (Power Sourcing 
Equipment) that are capable of supplying DC power to 
attaching PD (Powered Devices). These devices include VoIP 
phones, IP cameras, and wireless access points. The PoE 
switches can detect and supply power to pre-standard 
legacy PoE Powered Devices. Due to the support of legacy 
PoE, it is possible that a PoE switch acting as a PSE may 
mistakenly detect and supply power to an attaching PSE, 
including other PoE switches, as a legacy PD. 

Even though PoE switches are PSE, and as such should be 
powered by AC, they could be powered up as a legacy PD 
by another PSE due to false detection. When this happens, 
the PoE switch may not operate properly and may not be 
able to properly supply power to its attaching PDs. 

To prevent false detection, you should disable PoE on the 
ports on the PoE switches that are used to connect to PSEs. 
You should also first power up a PSE device before 
connecting it to a PoE switch. When a device is being falsely 
detected as a PD, you should disconnect the device from the 
PoE port and power recycle the device with AC power 
before reconnecting its PoE ports.

Verify the managing computer requirements in the product release notes.

To access the switch by using the web-based interface, you must know 
the IP address the switch is using. The switch uses the factory default IP 
address of 192.168.1.254 by default.