Configuring a Dot1q Termination Sub-interface to Implement Inter-VLAN Communication

Context

When a Layer 3 switch connects to users located in different VLANs through a Layer 3 Ethernet interface, configure Dot1q termination sub-interfaces on this Layer 3 Ethernet interface to implement inter-VLAN communication. This allows the users to communicate with each other.

To implement inter-VLAN communication, hosts in each VLAN must use the IP address of the corresponding sub-interface as the default gateway address.
When VLAN IDs terminated by a sub-interface are used for Layer 3 forwarding, only the first VLAN takes effect even if multiple inner VLAN IDs are specified.

Procedure

Run system-view
The system view is displayed.
Run interface interface-type interface-number
The interface view is displayed.
Run port link-type { hybrid | trunk }
The link type of the interface is set.
Run quit
Exit from the interface view.
Run interface interface-type interface-number.subinterface-number
The sub-interface view is displayed.
Run ip address ip-address { mask | mask-length } [ sub ]
An IP address is assigned to the sub-interface.
Run dot1q termination vid low-pe-vid [ to high-pe-vid ]
Dot1q termination is configured on the sub-interface.

Sub-interfaces of different main interfaces can be associated with the same VLAN, whereas sub-interfaces of the same main interface cannot be associated with the same VLAN.
Run arp broadcast enable
ARP broadcast is enabled on the sub-interface.

When you enable or disable ARP broadcast on a sub-interface, the routing status of the sub-interface alternates between Down and Up. This may result in route flapping on the entire network, affecting normal operation of services.