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-   -   PoE in network (https://www.linuxquestions.org/questions/linux-newbie-8/poe-in-network-800785/)

jonaskellens 04-08-2010 08:38 AM

PoE in network
 
To implement VoIP-phones that work with PoE, I need some understanding on how to implement the PoE-switch.

If this is the network :

router -- switch1 -- switch2 -- IP-phone

can I then connect a PoE-switch to switch 1 and will the IP-phone get the PoE-signal ??

In other words : is it possible to place a PoE-switch somewhere in the network and that al the PoE-clients get the signal ?? Also when there are non-PoE switches in between ??

Thanks for making this understandable.

KodaK 04-08-2010 10:12 AM

POE is only on the ports provided by the POE switch. It's not actually transmitted over Ethernet, and you're far from the first to be confused by this. It should be called Power over Twisted Pair. You need a physical connection from the POE port to the phone.

jonaskellens 04-08-2010 10:26 AM

So there can never be a network element in between a PoE source and a PoE destination, only a network cable ?!

In many companies, the network is expanded by putting a series of switches. So am I correct that when 1 IP-phone is in one end of the office, and an other IP-phone is in the other far end of the office... 1 PoE-switch will not do to provide both ??

salasi 04-08-2010 12:29 PM

thanks, KodaK...I hadn't seen where the confusion had come from.

The device providing the power (ie, the PoE box) can only be connected to the device to be supplied with the power by the cable. The cable can be relatively long, but you can never, never, never put any other network box in the way, and get the power to the end item, unless it is that other box that does the PoE thing...in which case, the argument changes to the second box and the end user item and only a cable, and nothing else between the two.

jonaskellens 04-08-2010 01:05 PM

I understand now. Thank you !


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