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We have a small network with two managed switches and two unmanaged (basic netgear 10/100) switches.

I would like to get to grips with VLAN's after creating another subnet. Currently we only have one subnet 192.168.1.0/24. I am planning on adding a test subnet of 192.168.5.0/24 and then adding that subnet to a new VLAN.

I was wondering, before I begin reading up on VLANs and how to configure them in the simplest form, if I can even use them on our network. The reason I am unsure is because one of the managed switches is maintained by BT (British Telecom) because of our IP phone system. I can't add VLAN information to this switch, and it's guaranteed that some workstations are connected either directly to that switch, or via an IP phone.

The switch I do have control over that's managed is a D-Link 3550, and we are using a Draytek Vigor 2820 router which supports VLANs.

So the question; if I setup a VLAN will it work if only the main router and one of the managed switches are 'aware' of the VLAN?

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Use port based VLAN's. –  Matt Mar 18 at 1:25

1 Answer 1

up vote 2 down vote accepted

You need to get a grip on where you're doing routing between VLANs first. If a router you have no control over is the default route for devices on 1.0/24 then you're going to have a tough time sending traffic over to the device be it L3 switch or router to get your traffic over to 5.0/24.

Now... because you have both phones and data on the same LAN now, you should be able to create a VLAN, call that VLAN101 for example and assign all existing ports on the switch you CAN manage to that VLAN. Now... create a second VLAN on the switch, let's call it VLAN105 and assign whatever port you want to that VLAN. If you assign that VLAN to an access port that has an unmanaged dummy switch, then all downstream devices will jump to that VLAN.

Just understand that each VLAN behaves like a separate switch, it has different properties and traffic will not pass from one VLAN to the other unless a L3 device is in place to permit that. Back in the day you created a trunk to a router, and a router performed this for you. Today even cheapo switches have L3 capabilities and can perform inter vlan routing. You need to look at the specifications of the switch, it sounds like your "router" can accept a trunk if it supports VLANs.

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and by the by, it sounds like your environment is too small to really need separate VLANs. Ideally voice traffic is placed into a separate VLAN and then either by VLANID or by QoS markings that traffic is given transmit priority. –  SpacemanSpiff Nov 17 '11 at 14:57
    
ok, I think I understand. Although I was thinking the reverse; leave all traffic on the default VLAN (I was under the impression that the switches that support VLAN's automatically put all traffic on a defauly VLAN?), and then add a second VLAN that is on the managed switch. Then connect the managed switch directly to the router and configure the VLAN on there. So then I have two managed switches - each connected to the router. I could then edit the router 'routes' to allow the VLANS to connect if I wanted? Does that make any sense? –  dannymcc Nov 17 '11 at 15:01
    
you'll also notice that some client-level devices support tagging as well, for instance your average intel or broadcom NIC driver for Windows lets you bust your local connection into separate "tagged" virtual nics. Lots of flexibility here, but I'd keep it simple. –  SpacemanSpiff Nov 17 '11 at 15:04
    
Does your router have ethernet ports available? –  SpacemanSpiff Nov 17 '11 at 15:13
    
then this is the easy way: i44.tinypic.com/30kc3mc.jpg –  SpacemanSpiff Nov 17 '11 at 15:19

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