VLANS and VLANS over multiple sites

[HenryKrinkle]

Hi,

I have been looking after the physical side of a network for a while but the tcp/ip side is something new but exciting to me and I have a query about VLAN's that I hope somebody can help me along with.

I'm helping to manage a network spread over 4 sites, the 'core' consists of 3 switches on site 1, with 2 switches on each of the other 3 sites - all connected to the core with a fibre link.  It is one big network with a 22 bit subnet mask and my concern is that a problem on one site will spread across all switches.

Ive been looking into the concept of VLAN's to split the network up but have no kit to experiment with.  If I set up the switches with a VLAN for each site e.g

Site 1 - VLAN 100

Site 2 - VLAN 200

Site 3 - VLAN 300

Site 4 - VLAN 400

If all the servers are located on a switch on site 1, would I need to set up the ports they are attached to on all 4 VLANs?  Im just a bit confused as to how this fits together and would appreciate a couple of pointers.

H

[Chrisd131313]

Hi HenryKrinkle,

If you go with a VLAN on each site, you will then need to make sure you have layer3 functionality on each site to be able to route between the 4 VLANs - I am guessing you dont have a L3 device at each site?. This is a good method if you are looking at implementing some sort of dynamic routing. So it really comes down to what switches you are currently using on each site, do they have L3 capabilities, or are they all L2 and you have a firewall/single router that performs the routing for you that sits on one of the sites? I would hazard a guess that you have one single routing device as you have a flat /22 network.

If this is the case, and you don't have teh ability introduce any L3 devices then the best way would be to split things up by device type rather than geographical location. (Servers/Management/clients/wireless/etc) and then setup the routing on your routing device.

Hopefully this will give you some points :)