Enterasys Networks 2H252, 2E253, 2H253, 2H258 manual Blue Industries Redco

Example 2, VLANs Across Multiple Switches

Figure 12-14 Transmitting to Switch 4

Redco					Blue Industries
			2
User A	Bridge 1	1	4		Bridge 2
				3
	Red VLAN				Blue VLAN
				4
Floor 4
Floor 3
Blue Industries					Redco
			2		Bridge 4	File Server
	Bridge 3	1	2 3
	Blue VLAN				Red VLAN
Floor 2
						30691_71

3.When Switch 2 receives the tagged frame on its Port 2, it checks the frame’s VLAN Tag Header and determines that the frame is classified as belonging to the Red VLAN, and that the frame is a broadcast frame. Switch 2 forwards the frame to all ports in the Red VLAN Forwarding List excluding Port 2, which received the frame. In this example, the only eligible port is Port 3, which connects to Bridge 4. Switch 2 checks its Forwarding List, which specifies that the VLAN frame type for that port is untagged. Switch 2 then updates its Source Address Table in FDB ID 2 for MAC address “Y” if necessary. The untagged frame is then transmitted out Port 3 to Bridge 4. Bridge 4 forwards the frame out all its ports because it is a broadcast frame, and the server receives it as shown in Figure 12-15.

12-30VLAN Operation and Network Applications