A method and system for performing VLAN provisioning using packet discovery and learning allows a network transport device to support existing VLAN configurations in a new network environment. When Ethernet frames having a VLAN tag are received from a client-side device, an association of the VLAN tag with the client port is recorded at the network transport device. Then, when an Ethernet frame including the VLAN tag is received from a network-side device, the Ethernet frame is directed to the client port associated with the VLAN tag. Additional security measures may restrict a learning period for recording VLAN tag associations. The network transport device may also flood client-side devices and/or network-side devices to associate respective client ports and/or network ports with a VLAN tag.