VLAN Terms
Virtual Local Area Networks
1-5
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.
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 a 1Q Trunk port has all VLANs in its Port VLAN
List and is configured to transmit all frames as tagged frames. A 1Q Trunk drops all incoming
frames that do not have a VLAN tag.
1D Trunk
A connection from a switch that passes only untagged traffic. By default, a port designated as a 1D
Trunk port has all VLANs on its Port VLAN List and is configured to transmit all frames as
untagged frames.
Generic Attribute Registration Protocol (GARP)
GARP is a protocol used to propagate state information throughout a switched network.
GARP VLAN Registration Protocol (GVRP)
A GARP application used to dynamically create VLANs across a switched network.
GARP Multicast Registration Protocol (GMRP)
A GARP application that functions in a similar fashion as GVRP, except that GMRP registers
multicast addresses on ports to control the flooding of multicast frames.
