Web OS 10.0 Application Guide52 n Chapter 2: VLANs 212777-A, February 2002Example of a Four-Switch Topology with a Single Spanning TreeIn the four-switch topology example shown in Figure 2-4 on page 52, and assuming Webswitch A has a higher priority, you can have at least three loops on the network: Data flowing from Web switches A to B to C and back to Web switch A. Data flowing from Web switches A to C to D and back to Web switch A Data flowing from Web switches A to B to C to D and back to Web switch A.With a single Spanning Tree environment, as shown in Figure 2-4, you will have two linksblocked to prevent loops on the network. It is possible that the blocks may be between Webswitches C and D and between Web switches B and C, depending on the bridge priority, portpriority, and port cost. The two blocks would prevent looping on the network, but the blockedlink between Web switches B and C will inadvertently isolate VLAN 3 altogether.N OTE – For more information on bridge priority, port priority, and port cost see the Web OS10.0 Command Reference.Figure 2-4 VLAN 3 Isolated in a Single Spanning Tree GroupSTG 1VLAN 1VLAN 1VLAN 2VLAN 3Web Switch BWeb Switch CWeb Switch DWeb Switch AVLAN 1Blocked Port
