VLAN is the logical segmentation of a switch network whereby users with common requirement are grouped together, independent of physical location. A typical example of this grouping is found in a banking system where staffs are grouped on the basis of the type of work they do e.g. Sales dept., Marketing dept., Finance dept.…etc.
Each VLAN is its own broadcast domain, and by default interVLAN communication is impossible. This is a very good security measure as it prevent say, for example people in sales department from prying into the activities of those in the finance department and vice versa.
However, VLANs can be made to communicate with each other if a layer 3 device like a router or a switch capable of layer 3 function e.g. Cisco 3560, is introduced into the network. A layer 3 device brings flexibility into the network, it allow us to choose who and who should communicate, and which resources a user must have access to.
Creating a VLAN on a switch is easy, giving the VLAN a name is even more fun. So let’s create and name our VLAN on a Cisco switch. And before I proceed, know that VLAN 1 is the default VLAN on a switch and can’t be changed, deleted or renamed. See what I mean:
Let’s create others,
The show VLAN command is used to view the VLANs we’ve just configured
So we’ve created VLANs, what’s next is to assign each VLAN an IP address. Each VLAN is a separate network and the addressing scheme need to reflect this.
VLAN 1 – 192.168.1.0
VLAN 2 – 192.168.2.0
VLAN 3 – 192.168.3.0
VLAN 4 – 192.168.4.0
VLAN 100 – 192.168.100.0
VLAN 200 – 192.168.200.0
Now the configuration:
In my next post I’m going to write about how to join a VLAN.