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Re: Here's a new idea:

Tal -

One of the objectives the group stated was to test for powerablity on the 
same wires as the power would be provided. In addition, it is desirable 
that the powering and thus the testing be done in such a manner that the 
signal carrying capability of the wire pairs not be compromised (this it to 
allow it to work with 1000BaseT. Could your scheme meet these two requirements?

Bob Bell

At 02:27  4/30/2000, Tal Weiss wrote:

>Hi all,
>Since this is my first contribution to the forum and I'm not sure that this
>email forwarding system works, I'll be brief.
>I read the different discovery process approaches and I want to offer
>something completely different!
>All of the proposals in the forum are analog by nature, and lack in
>I was able to construct a digital "power-identity-chip", costing less than
>1$, to be implemented inside the powered-IP-phone. This was done using
>off-the-shelf parts.
>The chip is powered remotely from the switch using 5 Volts (a simple 5K
>pull-up resistor does the trick).
>The power-enabled-switch polls the line for "power-identity-chip" (this can
>be done across wires 4,5 or 7,8) and when a phone is attached the chip is
>found (CRC protected communication, of course).
>This chip then tells the switch what it's power requirements are! (Voltage,
>which wires, power, MAC address and so on...)
>The power-enabled-switch then applies the correct power using the correct
>This approach has been tested in the lab and works using different cabling
>schemes from more than 200 meters!
>No false alarms and no misses.
>I know this is different than all the other approaches mentioned above, but
>it works so well I couldn't resist sharing.
>If more information is needed I'll be glad to supply it!
>Tal Weiss
>Congruency Ltd.
>23 Hasivim St.
>POB 7813
>Petah-Tikva 49170, Israel
>Email:  tal@xxxxxxxxxxxxxx
>Phone:  972-3-9212322-218
>Fax  :  972-3-9210757

Bob Bell
Cisco Systems Inc.