Configuring a Virtual-Template Interface
When a PPP link needs to transmit data of other link layer protocols, configure a Virtual-Template (VT) interface.
Context
A VT interface is used in VPN, ATM and MP applications. The system creates and deletes VT interfaces and the process is transparent to users.
The link layer of VT interfaces only supports the PPP protocol, and the network layer only supports IP.
The newly configured or modified parameters of a VT interface take effect only after the shutdown and the undo shutdown command are run.
After configuring or modifying services such as MTU, MPLS, or IS-IS, modify VT configuration on the interfaces with the services configured.
Pre-configuration Tasks
Before configuring a VT interface, complete the following tasks:
- Powering on the device and performing self-check
- Configuring a VT interface
Procedure
- Run system-view
The system view is displayed.
- Run interface virtual-template vt-number
A VT interface is created, and the VT interface view is displayed.
After a VT interface is deleted, all of its derived VA interfaces are deleted automatically.
- Run ip address ip-address { mask| mask-length } [ sub ]
The IP address of the VT interface is configured.
- Run broadcast-limit link number
The maximum number of links supported by the VT interface for sending multicast or broadcast packets is configured.
Multicast or broadcast packets sent out from each link may affect system performance if there are too many links in the VT interface.
Using the broadcast-limit link command, you can restrict the packets since the packets are dropped when the link number exceeds the maximum number.
Do not configure multiple services such as MP, L2TP and, PPPoE on a VT interface.
By default, the maximum link number is 30 for the VT interface.
Verifying the Configuration
Run the display interface virtual-template [ vt-number ] command to check the status of a VT interface.
Run the display virtual-access [ vt vt-number | dialer dialer-interface-number | user user-name | peer peer-address | va-number ]* command to check the status of a VA interface.