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Managed Gigabit Power Over Ethernet Switches

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ronjonp:
I'm going to be putting our VOIP phones on the same network as our computers and I'm worried that heavy network traffic will degrade call quality.
Does anyone have recommendations for a managed switch that would suit a small business for providing QOS to IP phones (that's not too difficult to configure) as well as gigabit connectivity to computers?

Thanks,

Ron

Keith™:
First off, I don't think you want to put the VOIP system on the same network ... you'll certainly cause lots of problems with traffic, you'll likely reduce call quality and you will certainly increase collisions thereby causing reduced network performance.

Now you can run everything through a single switch, but you should probably configure a different network and vlan for VOIP. It is all about configuring the switch properly. If you utilize a vlan for your VOIP network and then assign the ethernet ports on the switch to that particular vlan, you won't be competing for bandwidth since there won't be any regular network traffic in that particular vlan.

For a switch I'd suggest something like a Cisco SGE2000, it has 24 gigabit ethernet ports and can be rack mounted or stacked. It runs about $700. If you need more connectivity than that, the SGE2010 has 48 ports and costs about $1500, but you could simply stack two SGE2000 models if you can stand to lose two ports in the configuration. Configuration is managed through the CLI interface via telnet (after it is configured once) or though a console cable connected to a com port.

Also, you should keep in mind the 100m restriction on ethernet cables. While you *can* run them longer, you will experience traffic degradation.

There are lots of other considerations to think about, and you should be very careful about planning it out, othewise you will simply be throwing money away as you try to fix problems that crop up.

ronjonp:
Thanks for the reply Keith. I currently have a 24 port D-Llink DES1526. I was thinking of assigning the first 16 ports a High QOS (for the phones) and using the gigabit uplink port to daisy chain a Gigabit switch which would have normal QOS (for the network). Would this work? I only have 10 VOIP phones on the network and at most 3 will ever get used at a time. Will this small amount of concurrent use still cause the network issues you're talking about?

Thanks,

Ron

Keith™:
If you are only using 3 phones concurrently, you shouldn't experience any issues, however, I would still recommend configuring separate vlans for the phone system.

The switch you have supports multiple vlans, usually the default is vlan 1 which every port is a member of by default. You should create another vlan and assign Fa0/1 - Fa0/16 to the new vlan, this will prevent the switch from even sending traffic from other ports to this block of ports, therefore improving performance.

Once you have done that, make sure you put the phone system on a different network to prevent problems with someone misconfiguring an IP address on a computer. Knowing how many devices each network needs to support is key.

You need to support 10 VOIP phones. To minimize the number of network nodes wasted, you can subnet your existing network. Without knowing the exact layout and specifications of your network, it will be difficult to give you exact specifications.

I'd suggest for the computer network, assign IP addresses in this range (with 126 or fewer devices):
Network: 172.16.32.0
Netmask: 255.255.255.128
IP Range: 172.16.32.1 - 172.16.32.126 (172.16.32.127 is the broadcast address)

The phone network:
Network: 172.16.32.128
Netmask: 255.255.255.240
IP Range: 172.16.32.129 - 172.16.32.242 (172.16.32.243 is the broadcast address)

This will give you the best performance for the phone system and your computer network ... also, unless you specifically need to access the phone system from the computer network, I'd suggest you don't add a route between the two. You will still need to route the phone system to the internet though (or phone service provider).

Good luck

ronjonp:
Thanks Keith. Your reply is a bit beyond me right now but I'll do some reading to try and make sense of it.  :-)

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