Table of Contents
Advertisement
Chapter 4: Examples
Redco
User A
Floor 4
2. Switch 4 receives the frame from Bridge 1 and immediately classifies
it as belonging to the Red VLAN. After the frame is classified,
Switch 4 checks the Destination Address and, upon discovering that it
is a Broadcast Destination Address, forwards the frame out all ports in
the Red VLAN Forwarding List excluding Port 1, which received the
frame. In this example, it is only Port 4.
Switch 4 updates its Source Address Table in FID 2 if it didn't already
have a dynamic entry for MAC address "Y" in FID 2. Because
Switch 4 received the frame on Port 1, it does not forward the frame
out that port, but does forward the frame to Port 4.
The frame is transmitted to Switch 2 with a VLAN Tag Header
inserted in the frame. The VLAN Tag Header indicates that the frame
is classified as belonging to the Red VLAN. Figure 4-5 shows the path
taken to this point to reach Switch 2.
The VLAN Tag Header is inserted because Switch 4, Port 4 is
designated as an 802.1Q Trunk port. In this case, the Port Mode setting
for Port 4 is 802.1Q Trunk and the VLAN Frame format for that
VLAN is tagged.
4-8
Bridge 1
1
Red VLAN
Figure 4-4 Bridge 1 Broadcasts Frames
Blue Industries
2
Bridge 2
3
4
Blue VLAN
4
802.1Q VLAN User's Guide
2263_14
Advertisement
Table of Contents
