Inter-vlan routing using router on stick
Asalam o alikum Brothers/sisters. you maybe familiar with VLAN(s) and there uses in layer 2 network. In case you don’t know what a VLAN is and why do we create it ? Also how do we create it in cisco switches? To get answer to all these questions please visit this page:
Once you are clear about vlans, the question arises that what if we want 2 different vlans to communicate with each other? The answer is simple we need a layer 3 device such as Router or layer 3 switch to enable communication between devices in different vlans.
there are 2 methods to achieve this goal
- Router on a stick
- layer 3 switch
In this tutorial we will learn about Router on a stick.
Let’s look at an example below to better understand
if you have 2 differnet subnets both in different vlans , you need a Router to enable communication between both Vlans. Please note here that Router has unique subnet on each of it’s Interfaces. So we would require 2 cable on different ports/interfaces of Router . what if we decide to create another Vlan and assign different subnet to it? .
in that case we would require another cable and for each subnet the number of cables increases. But we have limited number of ports on a Router. so instead of having seperate cable plugged into seperate port. we would only have a single cable plugged in one port of Router to a switch. And we would virtually chop down single interface into multiple sub-interfaces .
The router connects to a core switch with a single interface and acts as the relay point between networks. If a device on one VLAN wants to talk to a device on another VLAN, that traffic must leave the switch and pass through the router which “routes” the traffic back to the switch, over the same interface, to the other VLAN.
