So, when you now issue the show vlan brief command. We will then assign ports fa0/1-2 to VLAN 10 and ports fa0/4-5 to VLAN 20. This will create VLANs 10 and 20 with their corresponding names, descriptions and ip address. Switch(config-if)#description ***Marketing-dept*** Switch(config-if)#description ***Payroll-dept*** You will then issue the commands: Switch#conf t In our case, there are no pre-configured vlans. Let’s get inside the switch to create the VLANs 10 and 20 and assign machines into it.įirst, issue the show vlan brief to command to check for any existing vlans. We will then configure 802.1Q trunking on the router and switch. Our network topology will consist of a router and a switch with VLANs 10 and 20, having two computers each. The router then treats the frames tagged with VLAN 10 as if they came in or out of G0/0.10, and the frames tagged with VLAN 20 as if they came in or out G0/0.20. Looking at the figure above, two subinterfaces, named G0/0.10 and G0/0.20 are created for the router to be able to route to VLANs 10 and 20. The router creates multiple virtual router interfaces that is associated with each VLAN on the trunk, and then it treats all frames tagged with that VLAN ID as if they came in and out of that subinterface. You will use a router to be able to route between the VLANs for your servers and client data instead of using a layer 3 switch. It simply means routing within your network between VLANs. ROAS is usually used in small to medium sized organizations that wants to implement inter-VLAN routing. It uses a router VLAN trunking configuration to give the router a logical interface connected to each VLAN. Router-on-a-stick (ROAS) is a feature that allows us to route packets to subnets associated with VLANs connected to a router 802.1Q trunk. And on the right side of the figure, each router has a VLAN trunk to connect and route for both VLANs. Two of the switches act as Layer 3 switches, combining the functions of a router and a switch, routing between all 12 subnets/VLANs. The figure shows a central site campus LAN on the left with 10 VLANs. The example network below shows what the second and third option looks like. Use a router with a VLAN trunk connected to a LAN switch.Use a router, with one router LAN interface and cable connected to the switch for each and every VLAN (typically not used).There are three options available for connecting a router to each subnet on a VLAN: The hosts inside each subnet can then use the router IP addresses as their default gateways, respectively. Each VLAN is a separate subnet and in order to route IP packets in and out of those VLANs – or more accurately, the subnets that sit on each of those VLANs – some router needs to have an IP address in each subnet and have a connected route for each of those subnets. Router on a stick is a network configuration used to allow the routing of traffic between different VLANs.Īlmost all enterprise networks use VLANs which stands for Virtual Local Area Network.