VLAN Switch Operation
2.3.3Customizing the VLAN Forwarding List
Each port on a VLAN aware switch has a VLAN forwarding list that contains, as a minimum, the PVID of the VLAN configured. Additionally, the Port VLAN Forwarding List of each port can be configured to allow any number of VLANs to be added to its list. In the case of GMRP (dynamic VLANs), the list can have VLANs added and deleted by the switch as directed by the protocol.
2.4VLAN SWITCH OPERATION
IEEE 802.1Q VLAN switches act on the classification of frames into VLANs. Sometimes, VLAN classification is based on tags in the headers of data frames. These VLAN tags are added to data frames by the switch as the frames are transmitted out certain ports, and are later used to make forwarding decisions by the switch and other VLAN aware switches. In the absence of a VLAN tag header, the classification of a frame into a particular VLAN depends upon the configuration of the switch port that received the frame.
The operation of an 802.1Q VLAN switch is best understood from a point of view of the switch itself. To illustrate this concept, the examples that follow view the switch operations from inside the switch.
802.1Q VLAN User’s Guide |