Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.100.0 - Page 722

To view the current values for interface parameters, use the show spanning-tree rstp command from EXEC privilege mode. Enabling SNMP Traps for Root Elections and Topology Changes To enable SNMP traps collectively, use this command. Enable SNMP traps for RSTP, MSTP, and PVST+ collectively. snmp-server enable traps xstp Influencing RSTP Root Selection RSTP determines the root bridge, but you can assign one bridge a lower priority to increase the likelihood that it is selected as the root bridge. To change the bridge priority, use the following command. • Assign a number as the bridge priority or designate it as the primary or secondary root. PROTOCOL SPANNING TREE RSTP mode bridge-priority priority-value • priority-value The range is from 0 to 65535. The lower the number assigned, the more likely this bridge becomes the root bridge. The default is 32768. Entries must be multiples of 4096. Example of the bridge-priority Command A console message appears when a new root bridge has been assigned. The following example example shows the console message after the bridge-priority command is used to make R2 the root bridge (shown in bold). Dell(conf-rstp)#bridge-priority 4096 04:27:59: %RPM0-P:RP2 %SPANMGR-5-STP_ROOT_CHANGE: RSTP root changed. My Bridge ID: 4096:0001.e80b.88bd Old Root: 32768:0001.e801.cbb4 New Root: 4096:0001.e80b.88bd Configuring an EdgePort The EdgePort feature enables interfaces to begin forwarding traffic approximately 30 seconds sooner. In this mode an interface forwards frames by default until it receives a BPDU that indicates that it should behave otherwise; it does not go through the Learning and Listening states. The bpduguard shutdown-on-violation option causes the interface hardware to be shut down when it receives a BPDU. When only bpduguard is implemented, although the interface is placed in an Error Disabled state when receiving the BPDU, the physical interface remains up and spanning-tree drops packets in the hardware after a BPDU violation. BPDUs are dropped in the software after receiving the BPDU violation. This feature is the same as PortFast mode in Spanning Tree. CAUTION: Configure EdgePort only on links connecting to an end station. If you enable EdgePort on an interface connected to a network, it can cause loops. Dell Networking OS Behavior: Regarding bpduguard shutdown-on-violation behavior: • If the interface to be shut down is a port channel, all the member ports are disabled in the hardware. • When you add a physical port to a port channel already in the Error Disable state, the new member port is also disabled in the hardware. • When you remove a physical port from a port channel in the Error Disable state, the error disabled state is cleared on this physical port (the physical port is enabled in the hardware). • You can clear the Error Disabled state with any of the following methods: • Perform an shutdown command on the interface. • Disable the shutdown-on-violation command on the interface (the no spanning-tree stp-id portfast [bpduguard | [shutdown-on-violation]] command). 722 Rapid Spanning Tree Protocol (RSTP)