Dell PowerConnect 7048P User Manual - Page 655

Of the four switches in Figure 22-15, the administrator decides that Switch A is the most centrally located in the network and is the least likely to be moved or redeployed. For these reasons, the administrator selects it as the root bridge for the spanning tree. The administrator configures Switch A with the highest priority and uses the default priority values for Switch B, Switch C, and Switch D. For all switches, the administrator also configures ports 4-17 in Port Fast mode because these ports are connected to hosts and can transition directly to the Forwarding state to speed up the connection time between the hosts and the network. The administrator also configures Port Fast BPDU filtering and Loop Guard to extend STP's capability to prevent network loops. For all other STP settings, the administrator uses the default STP values. To configure the switch: 1 Connect to Switch A and configure the priority to be higher (a lower value) than the other switches, which use the default value of 32768. console#config console(config)#spanning-tree priority 8192 2 Configure ports 4-20 to be in Port Fast mode. console(config)#interface range gi1/0/4-20 console(config-if)#spanning-tree portfast console(config-if)#exit 3 Enable Loop Guard on ports 1-3 to help prevent network loops that might be caused if a port quits receiving BPDUs. console(config)#interface range gi1/0/1-3 console(config-if)#spanning-tree guard loop console(config-if)#exit 4 Enable Port Fast BPDU Filter. This feature is configured globally, but it affects only Port Fast-enabled access ports. console(config)#spanning-tree portfast bpdufilter default 5 Repeat step 2 through step 4 on Switch B, Switch C, and Switch D to complete the configuration. Configuring the Spanning Tree Protocol 655