Cabletron Systems 802.1Q - Manual (Page 81)

Example 3, 1D Trunk Connection to 802.1Q VLAN Network
802.1Q VLAN User’s Guide 4-15
Figure 4-9 Switch 2 Forwards to 1Q Trunk
4. When Switch 1 receives the tagged broadcast frame, it also examines
the tag and classifies the frame as belonging to the Red VLAN. This
broadcast frame is then sent to all ports eligible to receive Red VLAN
frames. In this case only the 1D trunk, Port 3, is eligible, as it is
considered a member of all VLANs for forwarding purposes. The
VLAN Tag is stripped from the frame and the frame is transmitted out
Port 3 as shown in
Figure 4-10 . The Source Address Table, FID 1 for
Switch 1 is updated to contain User B.
Figure 4-10 Switch 1 Forwards to 1D Trunk
5. The Mail Server receives the broadcast frame and recognizes it. The
Mail Server responds with a unicast frame to User B. This frame
crosses the 1D Trunk and is received by Switch 1. Switch 1 classifies
the unicast frame as belonging to the Default VLAN (the only
membership for the 1D Trunk port).
4
Floor 2
Floor 3
Bridge 3 Bridge 4
Red VLAN Red VLAN Blue VLAN Blue VLAN
File Server
2 1
2
3
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Floor 1
Floor 2
1 1
2
3
4
Mail Server
Green VLAN Green VLAN
Green, Inc.
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