Cabletron Systems 802.1Q Manual De Usuario

Chapter 4: Examples

The File Server responds with a unicast frame to User A. All switches 
between the File Server and User A have an entry in their respective 
Source Address Tables identifying which port to use for forwarding 
the frame to User A, MAC address “Y” in FID 3. All switches update 
their Source Address Tables for the File Server’s MAC address “Z” as 
the frame is forwarded through the switch fabric to User A. The 
802.1D switches update their Source Address Tables based on the 
source MAC address and receive port and the 802.1Q switches update 
their databases based on the source MAC address, VLAN, and receive 
port.

The frame from the File Server is received on Switch 2, and forwarded 
to Switch 1 as a tagged frame classified as belonging to the Red 
VLAN. Switch 1 removes the tag and forwards the frame to Bridge 1, 
which in turn forwards the frame out of the port attached to User A. 
All subsequent frames between User A and the File Server are 
forwarded through the switch fabric in the same manner.

This example illustrates the use of a 1D Trunk to connect a device to a 
network of 802.1Q VLAN switches.

In this example, a merger has taken place between the companies in the 
previous example, Redco and Blue Industries. The two companies have 
become divisions within a single corporation, Green Incorporated.

Floor 2

2263_16

Floor 3

1

3

2

Bridge 3

Bridge 4

2