25.1.2 Prerequisites for using VLAN tunneling

The use of the VLAN tunneling functionality requires a network configured to meet all of the following conditions:

• A port VLAN is used.

• On the VLAN implementing the VLAN tunneling functionality, the tunneling port is on the access line, and the trunk port is on the backbone line.

• Because VLAN tags are stacked on the backbone line within the VLAN-tunneled network, frames that are 4 bytes larger than usual need to be handled.

• Access ports and tunneling ports cannot both exist within a switch. When at least one tunneling port is set, ports set as access ports also run as tunneling ports.