Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 789

• 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. Enabling PVST+ Extend System ID In the following example, ports P1 and P2 are untagged members of different VLANs. These ports are untagged because the hub is VLAN unaware. There is no data loop in this scenario; however, you can employ PVST+ to avoid potential misconfigurations. If you enable PVST+ on the Dell Networking switch in this network, P1 and P2 receive BPDUs from each other. Ordinarily, the Bridge ID in the frame matches the Root ID, a loop is detected, and the rules of convergence require that P2 move to blocking state because it has the lowest port ID. Per-VLAN Spanning Tree Plus (PVST+) 789