Mode of the port. Set Normal to have the switch ignore frames received (or transmitted) on this port with VLAN stacking tags. Anything you configure in SPVID and Priority are ignored. Set Access mode to have the switch add the SP TPID tag to all incoming frames received on this port. Set Access mode for ingress ports at the edge of the service provider's network. Set Tunnel mode (available for Gigabit ports only) for egress ports at the edge of the service provider's network. In order to support VLAN stacking on a port, the port must be able to allow frames of 1526 Bytes (1522 Bytes + 4 Bytes for the second tag) to pass through it. normal (1), Access (2), tunnel (3)