How does "Power-Over-Ethernet" work?

Discussion in 'VOIP' started by Ramon F Herrera, Nov 18, 2005.

  1. 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
     
    Ramon F Herrera, Nov 18, 2005
    #1
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  2. "Ramon F Herrera" <> 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.
     
    Doug McIntyre, Nov 18, 2005
    #2
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  3. Ramon F Herrera

    R-Guy Guest

    "Doug McIntyre" <> wrote in message
    news:437e406f$0$30641$...
    > "Ramon F Herrera" <> 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
     
    R-Guy, Nov 19, 2005
    #3
  4. Ramon F Herrera

    Jeff Little Guest

    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" <>
    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
     
    Jeff Little, Nov 19, 2005
    #4
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