VLAN Switch Operation
VLAN Operation and Network Applications 12-9
Figure 12-2 depicts the inside of a switch with six ports, numbered one through six. The switch has
been configured to associate VLAN A and B with Filtering Database Identifier (FDB ID) 2,
VLAN C and D with FDB ID 3, and VLAN E with FDB ID 4. Port 6 has been classified to serve
as a VLAN trunk connection (will only transmit and receive tagged frames). This classification
establishes that all VLANs are members of the Port VLAN List for Port 6 and the frames
transmitted for all VLANs will contain a tag header. Also the PVID for Port 6 is set to the default
VLAN with its corresponding relationship to FDB ID 1. Although untagged frames are not usually
present on a VLAN trunk connection, any untagged frames received would need to be classified if
the port has not been configured to drop all untagged frames.
Figure 12-2 View from Inside the Switch
NOTE: The example in Figure 12-2 shows ports sharing the same FDB ID, which is
supported by the switch. However, this feature cannot be configured using Local
Management at this time, but it can be configured using an SNMP management
application.
Port 4
D
FID 3
30691_59
Port 3
C
FID 3
Port 6
Port 2
B
FID 2
Port 1
A
FID 2
Default
FID 1
Port 5
E
FID 4