As configuring of VLANs helps in controlling the size of broadcast domains. There are some key components of inter-VLAN routing such as
- VLAN capable switch
- Router
- Router to VLAN connection
These are the main components for processing routing between VLANs. The router to be used in the system can perform two roles i.e. either it can an external standalone or can be integrated with a switch for performing inter-VLAN routing between long geographical locations.
Both external and internal routers can be used with sub-interfaces for performing inter-VLAN routing between long geographical locations. For this inter-VLAN routing a solution is Router-switch bridging. Kevin Dooley (2002) cites that "Every additional VLAN in a Distribution Area requires additional CPU and memory resources in the Distribution (and possibly also the Core) Level of the network."
The inter-VLAN routing should be configured in following ways:
- By enabling 802.1Q Encapsulation: For performing inter-VLAN routing, 802.1Q encapsulation must be enabled which generated and adds a 32-bit header. This 32-bit header is added for VLAN tagging which fits in the frame to be shared between source and client field. This tag is sent by fitting it in between the Ethernet Frame which is sent between source address field and media access control (MAC) client type field.
- Creating a Sub-Interface: After enabling 802.1Q encapsulation, a sub-interface should be created for performing inter-VLAN routing. A sub-interface can be created in step by step procedure such as:
1 Entering Ethernet configuration mode
2 Creating sub-interface for VLAN usage
3 Adding comment line to identify any new interface
- Assigning an IP address and a VLAN ID: After enabling 802.1Q encapsulation and creating a sub-interface, a VLAN ID is assigned to the sub-interface which is used to tag the data going and coming from VLAN. After it a final step is to assign a IP address to the sub-interface which is unique for each sub-interface. An IP address provides a default gateway for the VLAN.