SteelHead supports the IEEE 802.1Q networking standard for Ethernet frame VLAN tagging. The standard adds a 32-bit field between the source MAC address and the EtherType fields of the original frame. VLAN tags, added to frames when they enter a VLAN-aware portion of the network to represent their VLAN membership, help keep traffic from different networks separated when traversing shared links and devices.

Several settings throughout the Management Console provide the option to specify VLAN tag IDs. A VLAN ID is a number from 1 to 4094. Unless otherwise noted in an item’s description, you can enter “all” to apply the setting to all VLANs, or “untagged” to apply it to untagged connections. A zero (0) value specifies untagged, or native VLAN, and is the correct setting if there are no VLANs present.

By default, rules apply to all VLAN values unless you specify a particular VLAN ID. Pass-through traffic maintains any preexisting VLAN tagging between the LAN and WAN interfaces.

If an appliance can’t determine which VLAN the traffic belongs, it doesn’t use the VLAN tag (assuming that there’s no router between the appliance and the client or server systems).