D-Link DGS-3130 Emulator - Page 809

DGS-3130 Layer 3 Stackable Managed Switch CLI Reference Guide Command Default Level Level: 12. Usage Guideline This command is used to configure the hello time used in MSTP version for each port. This only takes effects in the MSTP mode. Example This example shows how to configure the hello time used in MSTP version for ethernet 1/0/1. Switch(config)#interface ethernet 1/0/1 Switch(config-if)#spanning-tree mst hello-time 1 Switch(config-if)# 78-17 spanning-tree loop-guard This command is used to enable the loop guard mode. Use the no form of this command to revert to the default setting. spanning-tree loop-guard no spanning-tree loop-guard Parameters None. Default By default, this option is disabled. Command Mode Interface Configuration Mode. Command Default Level Level: 12. Usage Guideline The command is available for port interface and port channel interface. The STP loop guard feature provides additional protection against Layer 2 forwarding loops (STP loops). An STP loop is created when an STP blocking port in a redundant topology erroneously transitions to the forwarding state. This usually happens because one of the ports of a physically redundant topology (not necessarily the STP blocking port) no longer receives STP BPDUs. In its operation, STP relies on continuous reception or transmission of BPDUs based on the port role. The designated port transmits BPDUs, and the non-designated port receives BPDUs. When one of the ports in a physically redundant topology no longer receives BPDUs, the STP conceives that the topology is loop free. Eventually, the blocking port from the alternate or backup port becomes designated and moves to a forwarding state. This situation creates a loop. Example This example shows how to enable the loop guard mode on interface ethernet 1/0/3. 805