How does "Power-Over-Ethernet" work?
 

As we all know, 100BT uses 2 pairs, one for Tx, one for Rx.

One of the reason they were able to squeeze 1GB on Ethernet was by
using all 8 conductors.

So, if I have a Gigabit LAN with VoIP phones, how is the power
delivered to the SIP phones if all conductors are used already?

TIA,

-Ramon

Re: How does "Power-Over-Ethernet" work?
 

"Ramon F Herrera" <ramon@conexus.net> writes:
>As we all know, 100BT uses 2 pairs, one for Tx, one for Rx.

>One of the reason they were able to squeeze 1GB on Ethernet was by
>using all 8 conductors.

>So, if I have a Gigabit LAN with VoIP phones, how is the power
>delivered to the SIP phones if all conductors are used already?


The standard specifies several modes, one of which is shared signal
and power, but I haven't seen anybody run in this mode. All I've seen
is power over the unused pins after the two ends negotiate what mode
they'll be in.

Most often, you get 10/100 and PoE connections. Gigabit has to be
handled seperately out to the desktop.

Re: How does "Power-Over-Ethernet" work?
 

"Doug McIntyre" <merlyn@geeks.org> wrote in message
news:437e406f$0$30641$892e0abb@auth.newsreader.oct anews.com...
> "Ramon F Herrera" <ramon@conexus.net> writes:
>>As we all know, 100BT uses 2 pairs, one for Tx, one for Rx.
>
>>One of the reason they were able to squeeze 1GB on Ethernet was by
>>using all 8 conductors.
>
>>So, if I have a Gigabit LAN with VoIP phones, how is the power
>>delivered to the SIP phones if all conductors are used already?
>
>
> The standard specifies several modes, one of which is shared signal
> and power, but I haven't seen anybody run in this mode. All I've seen
> is power over the unused pins after the two ends negotiate what mode
> they'll be in.
>
> Most often, you get 10/100 and PoE connections. Gigabit has to be
> handled seperately out to the desktop.
>
>
>
>
This box does POE on 1000base-T according to 802.3af:
http://www.phihong.com/assets/pdf/PSA20U.pdf

Re: How does "Power-Over-Ethernet" work?
 

Evening Ramon;

More info than you probably wanted to know:

http://www.poweroverethernet.com/

Jeff


On 18 Nov 2005 11:04:13 -0800, "Ramon F Herrera" <ramon@conexus.net>
wrote:

>As we all know, 100BT uses 2 pairs, one for Tx, one for Rx.
>
>One of the reason they were able to squeeze 1GB on Ethernet was by
>using all 8 conductors.
>
>So, if I have a Gigabit LAN with VoIP phones, how is the power
>delivered to the SIP phones if all conductors are used already?
>
>TIA,
>
>-Ramon