Enterasys Networks 2H253 Filtering Database, Identifier FDB ID, Tagged Frame, Untagged Frame

	VLAN Terms
Table 12-1 VLAN Terms and Definitions (Continued)
VLAN Term	Definition
Filtering Database	Addressing information that the device learns about a VLAN is
Identifier (FDB ID)	stored in the filtering database assigned to that VLAN. Several
	VLANs can be assigned to the same FDB ID to allow those
	VLANs to share addressing information. This enables the devices
	in the different VLANs to communicate with each other when the
	individual ports have been configured to allow communication to
	occur.
	The configuration is accomplished using the Local Management
	VLAN Forwarding Configuration screen. By default a VLAN is
	assigned to the FDB ID 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.
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
	switch makes a forwarding decision on a frame.

VLAN Operation and Network Applications 12-5