Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 895

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: %SYSTEM-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 shutdownon-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). • The reset linecard command does not clear the Error Disabled state of the port or the hardware disabled state. The interface continues to be disables in the hardware. • You can clear the Error Disabled state with any of the following methods: - Perform an shutdown command on the interface. Rapid Spanning Tree Protocol (RSTP) 895