Recommended cabling spec for voip

Discussion in 'VOIP' started by bob, Nov 24, 2004.

  1. bob

    bob Guest

    New building going in. 100 user VOIP system planned. Is Cat 6
    recommended or is the <1Gb speed on 5e adequate?


    bob, Nov 24, 2004
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  2. bob

    Mitel Lurker Guest

    Bob, VOIP will work over Cat-3. Obviously Cat-5 is what you should use.
    Cat-6 is a holy bitch to work with, I wouldn't wish it on my worst enemy.

    Note well... VOIP telephones require power. This can be either
    station-side via wall warts or centralized in the wiring closet. Most
    folks use a centralized approach since they often have UPS power available
    in the wiring closet(s). Therefore the additional pairs in a standard 4-pr
    cat5 data cable are needed. I mention this because I know some places
    where folks have cheated and patched 2 data circuits into the same 4-pr
    drop cable.

    Should you purchase a POE (Power Over Ethernet) LAN switch? Probably.
    Optionally purchase something like the PowerDsine 12 or 24 port inline
    power insertion unit.

    Any/all of your Etherswitches need to be capable of supporting 802.1p/q
    priority and VLAN tagging.

    Never connect a VOIP telephone to a hub.
    Never connect a VOIP telephone to a hub.
    Never connect a VOIP telephone to a hub.
    Never connect a VOIP telephone to a hub.
    Mitel Lurker, Nov 25, 2004
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  3. 5e will be adequate. Packets are packets, as far as the cable plant is
    concerned. You might want to consider the fact that POE might be in the
    offing, if you are doing a large roll-out of VOIP phones, and adjust the
    number of cable runs accordingly.
    Hammond of Texas, Nov 25, 2004
  4. bob

    stephen Guest

    some versions of power over ethernet use the spare 2 pairs, others send it
    over the ethernet pairs (lst time i checked, oth were part of the IEEE
    standard - but that was just before ratification).

    so - whether you need 4 pairs connected depends on the Voip PoE version.
    last time i priced these i could buy a new stackable switch with PoE at the
    same price as the power injector.

    Also, using a switch with built in PoE simplifies the wiring, and cuts down
    the rack space needed - both have been an issue for me before.

    so if you need to replace the ethernet switches anyway (to allow you to fit
    the new building while the old kit is still in the old place, or you need
    new for QoS support) - then check the system costs for the various ways you
    could do this.
    some switches also support QoS based on IP address, even if they are only
    layer 2 - e.g. Cisco and Nortel stackables. Using IP based QoS means you
    dont have to separate Voip traffic by VLAN (e.g. a PC softphone may not give
    you that option)
    works fine until you add data traffic and load the hub up......
    stephen, Nov 27, 2004
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