Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 660

The range is from 0 to 240, in increments of 16. The default is 128. The values for interface PVST+ parameters are given in the output of the show spanning-tree pvst command, as previously shown. 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 you only implement bpduguard, 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. EdgePort can cause loops if you enable it on an interface connected to a network. To enable EdgePort on an interface, use the following command. • Enable EdgePort on an interface. INTERFACE mode spanning-tree pvst edge-port [bpduguard | shutdown-on-violation] The EdgePort status of each interface is given in the output of the show spanning-tree pvst command, as previously shown. Dell Networking OS Behavior: Regarding the bpduguard shutdown-on-violation command 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 an Error Disable state, the new member port is also disabled in the hardware. • When you remove a physical port from a port channel in an 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 a 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). - Disable spanning tree on the interface (the no spanning-tree command in INTERFACE mode). - Disabling global spanning tree (the no spanning-tree command in CONFIGURATION mode). PVST+ in Multi-Vendor Networks Some non-Dell Networking systems which have hybrid ports participating in PVST+ transmit two kinds of BPDUs: an 802.1D BPDU and an untagged PVST+ BPDU. Dell Networking systems do not expect PVST+ BPDU (tagged or untagged) on an untagged port. If this situation occurs, the system places the port in an Error-Disable state. This behavior might result in the network not converging. To prevent the system from executing this action, use the no spanning-tree pvst err-disable cause invalid-pvst-bpdu command. After you configure this command, if the port receives a PVST+ BPDU, the BPDU is dropped and the port remains operational. Per-VLAN Spanning Tree Plus (PVST+) 660