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Configuring Out-of-Band ANCP Messages to Trigger Dynamic VLAN Instantiation

The instantiation of conventional autosensed dynamic VLANs is triggered by in-band PPPoE or DHCP control packets that the Packet Forwarding Engine exceptions to the Routing Engine. A VLAN is authorized based on information extracted from specific fields and created according to a dynamic profile assigned to the VLAN range or stacked VLAN range.

Another way to instantiate an autosensed dynamic VLAN is with the processing of packets from an out-of-band protocol, ANCP. The out-of-band protocol method is useful where the traffic received might not be PPPoE or DHCP, such as in a Layer 2 wholesale scenario, where the traffic for an entire outer VLAN is wholesaled to a retailer and the VLANs are based on access line identifiers.

For this method, you configure the dynamic profile to accept packets from the out-of-band protocol. The dynamic profile is on an access-facing physical interface and is associated with a VLAN range available for the autosensed VLANs.

This configuration assumes the following:

  • The dynamic profile is configured to instantiate a dynamic VLAN when notified by the ANCP agent that it has received an out-of-band ANCP Port Up message.

  • The RADIUS authentication server is properly configured to authorize the VLANs and apply services as needed.

  • The ANCP agent is configured to notify AAA when it receives ANCP Port Up and Port Down messages.

  • The ANCP agent is configured to initiate interim accounting updates (which also enables immediate interim accounting updates) in response to information received in Port Up messages.


Out-of-band triggering is supported only for single-tag VLANs; it is not supported for stacked VLANs.

To configure the instantiation of autosensed dynamic VLANs by out-of-band ANCP packets:

  • Specify that ANCP packets are accepted.