3Com 2928 User Guide - Page 228

Table 1-11 Protection types Protection type Edged Port Description Set the port as an edge port. Some ports of access layer devices are directly connected to PCs or file servers, which cannot generate BPDUs. You can set these ports as edge ports to achieve fast transition for these ports. You are recommended to enable the BPDU guard function in conjunction with the edged port function to avoid network topology changes when the edge ports receive configuration BPDUs. Root Protection Enable the root guard function. Configuration errors or attacks may result in configuration BPDUs with their priorities higher than that of a root bridge, which causes a new root bridge to be elected and network topology change to occur. The root guard function is used to address such a problem. Loop Protection Enable the loop guard function. By keeping receiving BPDUs from the upstream device, a device can maintain the state of the root port and other blocked ports. These BPDUs may get lost because of network congestion or unidirectional link failures. In this case, the device will re-elect a root port, and blocked ports may transit to the forwarding state, causing loops in the network. The loop guard function is used to address such a problem. Return to MSTP configuration task list. Displaying MSTP Information of a Port Select Network > MSTP from the navigation tree, and then click Port Summary to enter the page shown in Figure 1-10. Figure 1-10 The Port Summary tab 1-21