Switch resource?



  • right now out company has about 30 PC's on it's network.
    about half are connected to a cheap (unmanaged) 24 port gigabit switch.
    the rest are connected via a second cheap (unmanaged) 24 gigabit switch connected to the first.
    I have an older 24 Port Managed switch not being used now.

    We may need to switching to POE switches soon for a phone system. At this point I'm not sure that we need gigabit. Is there a good resource that I can read to help me make this decision, or a better forum I can post the specifics in?

    I'm really trying to see If I need gigabit or 100 Meg, Managed or Unmanaged.
    I know I am going to need POE, and VLan support.



  • Managed vs unmanaged depends on your environment.  I'd suggest that, if you can afford it, managed is a better choice in a commercial setup.

    Given the cost difference between Gbit and 100Mb, there's little point in only going with 100Mb switches.



  • When it comes to managed PoE switches, it seems that gigabit is about 3 times more expensive than 100MB.

    What should I look for in a switch other than just Vlan support and POE?



  • Gigabit and PoE are exclusive.
    For gigabit to work you need 8 wires (4 pairs).
    For 100mbit to work you need 4 wires (2 pairs).
    PoE uses the 2 unused pairs of 100mbit to transmit up to 15W.

    The reason why PoE capable gbit switches are so expensive is because the switch first has to check if the attached device is a PoE device and then run in 100mbit mode and connect a power supply to the unused pairs.
    Or if the device doesnt require power it has to disconnect the power supply from the now used pairs and set the PHY into gbit mode.



  • Are the phones going to use separate network jacks or are you planning on using the phones that have the switch inside to pass the data through to the computer? If your using the phones with the built-in switch the majority of them are only 10/100 unless you are purchasing the higher end phones which have gigabit switches inside. Just something to think about because if the phones only support 10/100 then a gigabit switch is not gaining you anything.



  • @GruensFroeschli:

    The reason why PoE capable gbit switches are so expensive is because the switch first has to check if the attached device is a PoE device and then run in 100mbit mode and connect a power supply to the unused pairs.
    Or if the device doesnt require power it has to disconnect the power supply from the now used pairs and set the PHY into gbit mode.

    This is not correct. Ethernet always uses an isolation transformer which will remove any DC components from the signal; the power is pulled off before this, and the signal passes just fine to the PHY. At least 802.3af works fine with 1000baseT, you can see this if you have phones with built in GigE switches running on PoE.

    NetGear has some decent PoE GigE smart switches that will cost about 1/4 per port (~$1400 for 48 ports) as much as a fully managed L3 HP (~$4500 for 48 ports - the lowest model that can do GigE and PoE). Similar NetGear stuff for 10/100 is about half the price of the Gig gear; the gap is about the same but much larger in dollars on the HP side. I assume the Cisco situation is similar. FWIW I've got a few NetGear PoE switches out there and haven't had any problems with them, and they do offer a lifetime warranty (though not nearly as good as HP's). Obviously not as nice to use, but they're a good compromise for a cash-strapped small business.



  • Interresting. Will have to check up on this.
    The last PoE capable gbit switch i used (noname brand, not sure what switching unit behind) could only run PoE/100mbit OR gbit.
    But this is already a few years ago, so i assume improvements have been made :)

    Edit: It seems the taskforce to specify PoE over gbit completed their work in 2003 and their work is included in the specification since version 802.3af-2003.


  • Banned

    The Cisco 7940G should do the trick….:)

    @rsw686:

    Are the phones going to use separate network jacks or are you planning on using the phones that have the switch inside to pass the data through to the computer? If your using the phones with the built-in switch the majority of them are only 10/100 unless you are purchasing the higher end phones which have gigabit switches inside. Just something to think about because if the phones only support 10/100 then a gigabit switch is not gaining you anything.


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