Power over ethernet / inline power to Cisco 7960 IP phone

Discussion in 'VOIP' started by Bernie, Feb 9, 2004.

  1. Bernie

    Bernie Guest

    Dear all,

    I am testing an Orinoco AE 12 Port DC Injector which looks like an OEM
    PowerDsine 4012 and I am trying to connect some Cisco 7960 IP phones
    to it via inline power. To plug an ethernet cable straight between the
    POE hub and the phone did nothing. So after some search at Cisco's web
    site (http://www.cisco.com/en/US/products..._guide_chapter09186a00800b607e.html#wp1003764)
    and other documents and specs readings, I switched lines 4&5 with 7&8
    and vice versa of the cable (just to reverse polarity, without really
    knowing what '+48 Volts return' and '+48 Volts source' at the Cisco
    page above means...) - and now some relais (?) sound click-click
    inside the IP phone can be heard, but the phone still doesn't work.

    My guess is that Cisco uses its own propritary way, but I am not

    Any help would be appreciated!

    Thanks, Bernie
    Bernie, Feb 9, 2004
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  2. Bernie

    Jerry Guest

    You are right, Cisco use its own L2 propritary protocol CDP for
    detecting the any direct connected Cisco device (i.e. Cisco IP phone,
    router, switch, etc).

    A in-line powered switch will send a little bit of power and CDP to its
    neighbor (FE) to detect any Cisco IP phone, if the phone response, the
    switch send DC power to the phone for boot up process.
    Jerry, Feb 10, 2004
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  3. Bernie

    Bernie Guest

    Thanks, Jerry, for your answer!

    I found at http://www.powerdsine.com/Documentation/SelectionGuide/SelectionGuide.pdf
    that there exists a simple passive splitter to connect an Cisco IP
    phone to the PowerDsine 6000 midspan series. This splitter is sold
    e.g. at http://hardwarecentral.dealtime.com/xKW-PD-PS-401/NS-1/linkin_id-3013120/GS.html
    - it looks like an ethernet adaptor with some crossed internal
    connections (they wouldn't sell an adaptor with all lines linked
    one-to-one, would they? ;-) ) My test injector device seems to be a
    PowerDsine from the 4000 series. (4012 w/ 12 ports)

    So the two questions are: 1. cable layout of this adaptor? (just 4/5
    switch with 7/8?) and 2. is the 4012 cabable of serving Cisco's Ip
    phones with that adaptor?

    Thanks, Bernie
    Bernie, Feb 10, 2004
  4. Bernie

    Jerry Guest


    Tell you the truth, I am not sure about this product from PowerDsine and
    the wiring. I know that Cisco sell something call Power Patch Pannel,
    what it does is the ethernet connection from the switch will connect to
    the power patch pannel, and the Cisco IP phone will connect to the power
    patch pannel. Since this is also a Cisco product, (I think) CDP is also
    installed on the power patch pannel.

    When I am doing the VoIP project, I found that the cost of the power
    patch pannel is not much different from replace the switch to a Cisco
    in-line powered switch (w/ all the port cap. I have). And we decided to
    buy power-cube from Cisco to power the phone for the user instead (of
    course, the user shouldn't unplug the power-cube from the outlet). My
    thinking was if I am going to replace switch to in-line powered later on
    (within the next 2 yr), I also have the cube on the user's desk as the
    backup power source.

    Jerry, Feb 14, 2004
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