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I'm ballparking the numbers here, but I have 50+ machines and around 30 hard VoIP devices. Unfortunately, 10 or so PCs use the 100Mb pass-through port from the VoIP phones and 2 PCs use softphones (+sales guys use softphones when out of the office over the VPN).

I have 2 switch locations with a couple gigabit Dell PowerEdge switches in each of them. Our building is very old, but before I started working here, it did get remodeled with Cat5e lines. If I need more ports where the PC's are sharing with it hardphones, I will be pulling them by myself.

I had kind of hoped to Vlan out VoIP from everything else, but we currently only average 10 concurrent calls throughout the day and some new lines may not be feasible. We write software here so our data traffic varies per user. I haven’t really looked at what the overall broadcast traffic is like.

I guess I am asking if I will see any improvement with subnetting now, or if i might as well leave it out of my planning until I have to do it.

I understand that this is a subjective question and am ready for answers that begin with - "That really depends on …"

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Why do you want to move VOIP traffic to separate VLAN at all ? Security ? Do you need it on this level ? – Vitaly Nikolaev Jul 8 '11 at 2:49
@Vitaly You would have it on a separate VLAN for both security and for QoS. – HostBits Jul 8 '11 at 12:31
you can mark packets for QOS on the phone. or you can simply mark all UDP > 10000 as RTP. That will solve QOS for small network with predictable traffic. As for Security... It depends on your needs. But in most setups I saw, this separation does not benefit security, Only bring complexity. Of course your situation can be different then both @CHeekaleak and Spaceman advises are good. – Vitaly Nikolaev Jul 8 '11 at 14:13

Best Practice would be to separate out the VoIP traffic to another VLAN. As for your requirement to use the pass-thru port, you should be able to specify a "voice" VLAN and a "data" vlan for each port. This way the phone will utilize the voice vlan and the PC connected to the pass-thru port will utilize the data vlan.

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The Dell PowerConnect switches most likely support LLDP-MED, which is used to basically help a phone find the "voice" vlan. If you do VLAN though at least one of these switches or perhaps a router with a trunk will be needed if there is a requirement to route IP traffic between said VLANs. What model PowerConnects are these?

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Two 2724s, a 2716, and a Linksys SR2016. There are also occasional 5-port switches living under developers desks for their test machines. – Desvio Jul 8 '11 at 0:58

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