# DHCP reservations by MAC



## sda (Mar 6, 2015)

Hey guys/gals,

I'm looking with a little help with a issue. Our Windows server provides DHCP for the clients. One of our techs spend an enormous amount time configuring SIP phones from our network. What I'm hoping to accomplish is this:

I want to his phones, when they grab DHCP, to grab from a certain range (say 192.168.1.100- 150). Since all of his devices are from the same manufacturer, i was hoping to build a "filter":

Where if the MAC address matches, say: FE:12:22:*:*:* will pull DHCP from the above mentioned range. 

Hope what im asking makes sense, any help you have would be greatly appreciated.


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## CleaverX (Sep 27, 2012)

I understand what you are asking, but most admins usually put the phones on a different subnet. Especially if the phones use POE so the connection needs to come from dedicated switches, like Avaya for example.


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## sda (Mar 6, 2015)

In some cases we do a VLAN or the phones are on a completely different network. More often than not, the phones are on the same network, POE switches running everything.


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## zx10guy (Mar 30, 2008)

It's not about whether the VoIP phones are PoE capable or not. It's about needing to segregate the VoIP traffic from other traffic to ensure proper network availability and quality. Even though VoIP is not bandwidth intensive it is very sensitive with regards to amount of chatter on a particular LAN segment.

So best practices is always to have VoIP traffic on a dedicated VLAN or on a physically separate network. The use of a dedicated VoIP VLAN allows application of QoS to ensure call quality.


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## Stanr691 (Feb 15, 2015)

Agree...if you have phones and data on the same network, you're going to have call quality issues.

Vlan your switches and put the phones on a different subnet and vlan.


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## sda (Mar 6, 2015)

I understand what you all are saying about keeping your phone/data traffic on seperate LANs, subnets, etc...In a perfect world, and if the customer has the resources, it's the way to go.

I've been installing SIP/IP phones for years, and the selling point for most customers is that they do not have to invest in expensive VLAN capable switches, dual WAN routers, and dedicated cabling for their phones. A small business (10-15 phones, my average if I had to guess), can run perfectly fine on the data network. Some QoS tweaks, firewall issues aside.

Aside from all of that, this is for (more or less) a test bench situation on my own LAN. Is what I'm looking for in my original post possible on the server side?

Thanks guys


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## zx10guy (Mar 30, 2008)

I guess expensive is a relative term. But having a VLAN capable switch isn't expensive at all now a days. I have two 5 port GigE smart managed switches with VLAN capability purchased for under $100. Probably much less now. In the case of my Netgear 5 port smart switch, it even has a predefined voice VLAN.

While having your voice network coexist with regular production traffic can work, is it really best practices? We all agree that it is not. As stated above, VLAN capable switches are not that expensive. But I err on getting closer to ideal/best practices.


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