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Old 07-08-2014, 11:11 AM   #1
fritz001
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Question POE Switch powering another switch ?


This may sound a noob question but I didn't find the right forum to ask.

So here is my question:

Soon I'll have a NETGEAR GS108P switch which has 4 POE ports.

I'd like to know if I can use one of those ports to poweron another switch which is not POE ( just a normal one) ??
 
Old 07-08-2014, 12:02 PM   #2
netnix99
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No, unfortunately, you cannot do this. Power over Ethernet (POE) is designed to power individual devices, not ANY device. POE provides a maximum of about 51 Watts (48 VDC) per port to power a device (i.e. VOIP phone). Most often, this is throttled down to about 16 watts (just what the phone needs) depending on the requirements of the device (could be a wireless Access Point instead, which requires more power).

I guess a simpler way of stating this might be that the 51 WATTS at a port would not be able to power a switch that requires a (apporimately) 350 Watt power supply in order to function.

*********************
I was looking at this in terms of a Cisco 3750 switch, hence the 350 W power supply; however, PoE is still not designed to power another switch... even if it is a smaller 8-port like your example...

Last edited by netnix99; 07-08-2014 at 12:04 PM. Reason: looked up requester's equipment
 
Old 07-08-2014, 12:15 PM   #3
fritz001
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Quote:
Originally Posted by netnix99 View Post
No, unfortunately, you cannot do this. Power over Ethernet (POE) is designed to power individual devices, not ANY device. POE provides a maximum of about 51 Watts (48 VDC) per port to power a device (i.e. VOIP phone). Most often, this is throttled down to about 16 watts (just what the phone needs) depending on the requirements of the device (could be a wireless Access Point instead, which requires more power).

I guess a simpler way of stating this might be that the 51 WATTS at a port would not be able to power a switch that requires a (apporimately) 350 Watt power supply in order to function.

*********************
I was looking at this in terms of a Cisco 3750 switch, hence the 350 W power supply; however, PoE is still not designed to power another switch... even if it is a smaller 8-port like your example...
Oh, much thanks

Somehow I'm better enlighten about how POE works,

However,

I do own another 5Port GB switch ( which based on official doc )

–Power adapter: 12W, 12V DC, 1A
–Maximum power consumption GS105: 3.5W

I'm wondering if such a device can be powered through PoE ?
 
Old 07-08-2014, 12:35 PM   #4
netnix99
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PoE powers devices FROM the switchport to the device. Switchports are not designed to allow power to COME IN and be distributed across the switch.
 
  


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