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VLAN - when is using them prudent?


mattlandis
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We normally put out 5-20 handset phone systems. So far we have never used a VLAN and don't seem to have problems. When is it prudent to think about using VLAN?

 

Generally speaking, VLAN should always be used. It just makes sure than the voice infrastructure does not get interrupted for example if someone accidentially puts another DHCP server into the network and another device starts randomly packets that fills up the bandwidth. VLAN with a priority are a nice way to rule such simple network interruptions out.

 

The downside is that this is more work. Especially the provisioning becomes more difficult, especially if after a factory reset the phones get back into VLAN 0. And you have to set up a route from the VLAN into the regular LAN (if you want to be able to access the web interface of the phone) or from the VLAN into the internet if you want to make phone calls over the Internet.

 

You can have the PBX running in different VLAN with different IP addresses. This is very useful because you can have the user access the web interface from the regular VLAN 0 and you can have the phones access the PBX from the voice VLAN.

 

So if your priority is rock solid setup, I would recommend a VLAN.

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Generally speaking, VLAN should always be used. It just makes sure than the voice infrastructure does not get interrupted for example if someone accidentially puts another DHCP server into the network and another device starts randomly packets that fills up the bandwidth. VLAN with a priority are a nice way to rule such simple network interruptions out.

 

The downside is that this is more work. Especially the provisioning becomes more difficult, especially if after a factory reset the phones get back into VLAN 0. And you have to set up a route from the VLAN into the regular LAN (if you want to be able to access the web interface of the phone) or from the VLAN into the internet if you want to make phone calls over the Internet.

 

You can have the PBX running in different VLAN with different IP addresses. This is very useful because you can have the user access the web interface from the regular VLAN 0 and you can have the phones access the PBX from the voice VLAN.

 

So if your priority is rock solid setup, I would recommend a VLAN.

 

I appreciate that input.

 

Matt

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  • 2 weeks later...

A far more workable and easier solution on smaller LANS is to simply use managed switches that support a MAC learning/locking on all ports and once deployed LOCK all ports to prevent the reference to someone adding a DHCP server. Since some users may wish to have access to the Phone interface, you would then have to create a route for the to subnets on the different VLANS. More Work...

Since Many smaller installations will require a PC attached to a phone switch port, and not all phones will support VLANXXX for the Phone and VLANYYY for the PC Port. This gets complicated on layer2 switches and heaven forbid someone sticks a dumb switch in an office to get two usable ports as this will kill all your hard work. Your easiest and very reliable is as described above, and don't forget to learn and use all of the DSCP/QOS capabilities to ensure call quality.

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What switch do you use for these small installations?

 

Sorry for the slow reply - for the most part we try to stay agnostic on these boards in regards to brands.... But.... I'll admit we have a fair number of Linksys/Cisco SRW business series beginning with the 208P and up to and including STP stacks of the 224 and 248 series. All POE of course. However, many of these deployments were well before CISCO decided to whack the SRW series for competing with their other lines. The items are our immediate Radar are DLINK as a partner.

 

 

Cheers.

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