Creating an Eth-Trunk Layer 3 Sub-interface
Context
Layer 3 Sub-interfaces can be configured on a Layer 3 Eth-Trunk. When Layer 3 devices connect to Layer 2 devices in different VLANs through the Layer 3 Eth-Trunk, Layer 3 sub-interfaces must be configured on the Eth-Trunk to identify packets from different VLANs and to enable users in these VLANs to communicate with each other.
Procedure
- Run system-view
The system view is displayed.
- Run interface eth-trunk trunk-id
An Eth-Trunk is created and the Eth-Trunk interface view is displayed.
- Run undo portswitch
A Layer 3 Eth-Trunk is configured.
- Run quit
Exit the Eth-Trunk interface view.
- Run interface eth-trunk trunk-id.subnumber
An Eth-Trunk Layer 3 sub-interface is created, and the Layer 3 sub-interface view is displayed.
subnumber specifies the number of the Layer 3 sub-interface. The value is in the range 1 to 99999999.
By default, the LinkDown alarm (Trap OID: 1.3.6.1.6.1.1.5.3) is generated when the status of a Layer 2 or Layer 3 sub-interface changes. If a large number of Layer 2 or Layer 3 sub-interfaces exist on a device, the LinkDown alarm is reported on the sub-interfaces at the interval of several minutes. In this case, an NMS has to process a large number of interface status change alarms, which overloads the NMS. To resolve this problem, run the subinterface trap updown disable command in the system view to disable LinkDown alarm generation on the Layer 2 or Layer 3 sub-interfaces as needed. After this command is run, the LinkDown alarm is no longer generated on any of the device's Layer 2 or Layer 3 sub-interfaces in case of a status change. Therefore, exercise caution when running this command.
- Run ip address ip-address { mask | mask-length } [ sub ]
An IP address is configured for the Layer 3 sub-interface.
When configuring multiple IP addresses for an Eth-Trunk Layer 3 sub-interface, use the sub keyword to indicate the second and subsequent IP addresses.
- Run dot1q termination vid vid
The Eth-trunk Layer 3 sub-interface is configured to terminate single-tagged packets.
- Run commit
The configuration is committed.
