13. Rapid Spanning Tree Protocol (RSTP)MN700004 Rev 01 134rapid-spanning-tree detect-protocolsThe rapid-spanning-tree detect-protocols command, in Interface Configuration mode,forces the port to work by the Rapid Spanning Tree Protocol (RSTP) and not by the SpanningTree Protocol (STP).A switch running RSTP supports a built-in protocol migration mechanism that enables RSTPto interoperate with legacy 802.1D STP.When an RSTP switch receives a legacy 802.1D configuration BPDU (BPDU with protocolversion 0) it start transmitting legacy 802.1D BPDU (configuration messages and TCNmessages), however, when the switch stops receiving BPDU it cannot automatically revert tothe RSTP mode because the switch cannot determine whether the legacy switch has beenremoved from that link unless the legacy switch is a designated switchThe RSTP supports a mechanism that forces the port to restart protocol migration process(force the renegotiation with neighboring switches) by mean of:1. CLI command rapid-spanning-tree detect-protocols.2. A link up event.Command Syntaxdevice-name(config-if 1/1/1)#rapid-spanning-tree detect-protocolsDisplaying Port Rapid-Spanning-Tree TopologySettingsTable 13-6 RSTP Display Commands in View / Privileged ModeC o m m a n d D e s c r i p t i o nshow rapid-spanning-tree Displays the current RSTP parameter settings, and Rapid-Spanning-Tree topology of all ports.show rapid-spanning-tree interface Displays the Rapid-Spanning-Tree topology for the specifiedport.show rapid-spanning-treeThe show rapid-spanning-tree command, in Privileged (Enable) mode, displays the currentRSTP parameter settings and Rapid-Spanning-Tree topology for all ports.Command Syntaxdevice-name#show rapid-spanning-tree
