Using a Dot1q Termination Sub-interface to Implement Inter-VLAN Communication
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.
Context
When a Layer 3 switch connects to users on different network segments across different VLANs, configure Dot1q termination and IP addresses for the sub-interfaces to implement Layer 3 connectivity.
NOTE: 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-viewThe 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:
quitExit 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, but sub-interfaces of the same main interface cannot be associated with the same VLAN.
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NOTE: When VLAN IDs terminated by a sub-interface are used for Layer 3 forwarding, it is recommended that 128 VLANs be in all VLAN ranges.
- Run:
arp broadcast enableARP broadcast is enabled on the sub-interface.
When you enable or disable ARP broadcast on a sub-interface, the routing status on the sub-interface alternates between Down and Up. This may result in route flapping on the entire network, and affects normal operation of services.
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