Configuring Inter-VLAN Communication

Configuring inter-VLAN communication allows users in different VLANs to communicate with each other. The inter-VLAN communication configuration involves the configurations of VLAN sub-interfaces or VLANIF interfaces.

Applicable Environment

Currently, schemes listed in Table 1 are provided for inter-VLAN communication. You can choose one of them based on the real world situation.

**Table 1** Schemes for inter-VLAN communication
Inter-VLAN Communication Scheme	Advantage	Disadvantage	Usage Scenario
Sub-interface	After sub-interfaces are configured, users in different VLANs and network segments can communicate with each other as long as routes are reachable.	Both Layer 2 and Layer 3 devices are required, which increases expenditure. If multiple users on a network belong to different VLANs, each VLAN requires a sub-interface on a Layer 3 device. Each sub-interface needs to be assigned an IP address. This increases configuration workload and uses up a large number of IP addresses.	This scheme is applicable to small-scale networks on which users belong to different network segments. If Layer 3 forwarding of packets is mainly required, use sub-interfaces.
VLANIF interface	After sub-interfaces are configured, users in different VLANs and network segments can communicate with each other as long as routes are reachable. Inter-VLAN communication can also be implemented by Layer 3 switches if routes are reachable. This scheme boasts of low operating costs.	If multiple users on a network belong to different VLANs, each VLAN requires a VLANIF interface. Each VLANIF interface needs to be assigned an IP address. This increases configuration workload and uses a lot of IP addresses.	This scheme is applicable to small-scale networks on which users belong to different network segments and IP addresses of these users are seldom changed. If a large number of VLANs are configured and both Layer 2 and Layer 3 forwarding of packets are required, use VLANIF interfaces.
VLAN mapping	This scheme is easily configured and does not rely on routes.	IP addresses of users in different VLANs must belong to the same network segment.	This scheme is applicable to large-scale networks on which multiple users belong to one network segment.

Pre-configuration Tasks

Before configuring communication between VLANs, complete the following task:

Creating VLANs

Configuring Sub-interfaces for Inter-VLAN Communication: If users belong to different VLANs and reside on different network segments, sub-interfaces can be created on an Layer 3 device and assigned IP addresses to allow these users to communicate with each other at the network layer.

Configuring VLANIF Interfaces for Inter-VLAN Communication: Configuring VLANIF interfaces for inter-VLAN communication saves expenditure and helps implement fast forwarding.

Configuring VLAN Mapping for Inter-VLAN Communication: The configuration of VLAN mapping is simple and independent of Layer 3 routing.

Verifying the Inter-VLAN Communication Configuration: After inter-VLAN communication is configured, you can check whether users in different VLANs can communicate with each other and check information about VLANs to which users belong.