Cabletron Systems DLE52-MA User Manual page 17

VLAN Terms
Configuration screen. By default a VLAN is assigned to the FID that
matches its VLAN ID.
Tag Header (VLAN Tag)
Four bytes of data inserted in a frame that identifies the VLAN/frame
classification. The Tag Header is inserted into the frame directly after the
Source MAC address field. Twelve bits of the Tag Header represent the
VLAN ID. The remaining bits are other control information.
Tagged Frame
A data frame that contains a Tag Header. A VLAN aware device can add
the Tag Header to any frame it transmits.
Untagged Frame
A data frame that does not have a Tag Header.
Port VLAN ID (PVID)
Identifies the VLAN into which untagged frames are classified according
to a specific port. For example, an untagged frame received by a port that
is a member of VLAN A would be classified as belonging to VLAN A.
Default VLAN
The VLAN to which all ports are assigned upon initialization. The
Default VLAN has a VLAN ID of 1 and cannot be deleted or renamed.
Forwarding List
A list of the ports on a particular device that are eligible to transmit
frames for a selected VLAN.
Port VLAN List
A per port list of all eligible VLANs whose frames can be forwarded out
one specific port and the frame format (tagged or untagged) of
transmissions for that port. The Port VLAN List specifies what VLANs
are associated with a single port for frame transmission purposes.
Filtering Database
A database structure within the switch that keeps track of the associations
between MAC addresses, VLANs, and interface (port) numbers. The
Filtering Database is referred to when a VLAN aware switch makes a
forwarding decision on a frame.
1Q Trunk
A connection between 802.1Q switches that passes only traffic with a
VLAN Tag Header inserted in the frame. By default, a port designated as
802.1Q VLAN User's Guide 1-5