Cabletron Systems 802.1Q manual 9 Switch 2 Forwards to 1Q Trunk, 10 Switch 1 Forwards to 1D Trunk

Models: 802.1Q

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Figure 4-9 Switch 2 Forwards to 1Q Trunk

Example 3, 1D Trunk Connection to 802.1Q VLAN Network

Floor 3

Bridge 3

 

2 3

Blue VLAN

1

 

 

4

Floor 2

Bridge 4

Red VLAN

File Server

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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.

Floor 2

Green, Inc.

 

 

2

Mail Server

Green VLAN

1

1 3

 

 

 

4

 

Floor 1

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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).

802.1Q VLAN User’s Guide

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Page 81
Image 81
Cabletron Systems 802.1Q manual 9 Switch 2 Forwards to 1Q Trunk, 10 Switch 1 Forwards to 1D Trunk