The propose of Inter VLAN routing is to connect one virtual local area network to another virtual local area network. Only one network can communicate over the VLAN, but inter VLAN can connect to one network over another. When we learned regarding VLANs, we tend to aforesaid that every VLAN is sometimes on its own subnet, switches chiefly operate at layer two of the OSI model and so they are doing not examine the logical addresses.

Therefore, user nodes placed on totally different VLANs cannot communicate by default. In several cases, we tend to may have property between users placed on totally different VLANs. The method this could be accomplished is through inter-VLAN routing. In this course, we’ll inspect one variety of inter-VLAN routing, which is through the employment of a router.

Only computers in the same VLAN can communicate among themselves on a common VLAN-based network. But for a variety of reasons a production network may need to communicate with one VLAN computer to another VLAN computer. And the mechanism used to properly communicate between these VLAN computers is inter-VLAN routing. Inter-VLAN routing is a method by which traffic from one VLAN is forwarded to another VLAN. For inter-VLAN routing, an additional layer 3 devices such as the Cisco router, Mikro Tik router, Linux based server is used.

Inter VLAN
Figure: Inter VLAN

For Example

An example of Inter virtual local area network Routing is given in the figure. Here two VLANs 10 and 30 were created using a switch S2. These VLAN 10 and VLAN 30 are two separate logical sub-networks that usually cannot communicate with each other. An additional router R1 is used here to do this. This router is connected to the switch via two separate links (VLAN 10 and VLAN 30) (since there are two VLAN numbers).

There are two separate sub-networks, PC1 and PC3, so if PC1 wants to communicate with PC3, then PC1 will send its data packet directly to the router’s F0/0 interface. The router’s F0/0 interface here is PC1’s default gateway. When the router receives the packet, it will see that the destination network /24 of the packet is its own directly connected network that is connected to the F0/1 interface. The router will then send the packet directly to PC3 with its F0/1 interface. When PC3  receives the packet, it will send acknowledge to PC1 for the same procedure. Thus, inter VLAN routing is used to exchange data between multiple VLANs using a router.

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