Field descriptions for RPVST+ debug command output

Field

Shows the number of —

Invalid BPDUs

Received BPDUs that failed standard RPVST+ (802.1Q-REV/D5.0 14.4) validation checks and were dropped. This counter is maintained on a per-port per-VLAN basis.

Errant BPDUs

Received BPDUs that were dropped on a port that is configured to not expect BPDU packets. This counter is maintained on a per-port basis and is incremented each time a BPDU is received on a port configured with the BPDU filter to ignore incoming BPDU packets (spanning-tree bpdu-filter command) or the BPDU protection feature to disable the port when BPDU packets are received (spanning-tree bpdu-protection command).

Looped-back BPDUs

Times that a port has received self-sent BPDU packets as the result of an external loop condition in which the BPDUs were looped back to the originating transmission port. The received BPDU is still processed by RPVST+ and the port changes to a blocked state. This counter is maintained on a per-port per-VLAN basis.

Starved BPDUs

Times that no BPDUs are received within the scheduled interval (three times the Hello Time value configured with the spanning-tree vlan hello-time command) from a VLAN-designated peer port on the VLAN root, alternate, or backup port. As a result, the “starved” port triggers a spanning tree topology regeneration. This counter is maintained on a per-port per-VLAN basis.

Exceeded Max Age BPDUs

Times that a BPDU packet is received from a bridge with a Message Age value greater than the configured value of the Max Age parameter (spanning-tree maximum age command). This may occur if the receiving bridge is located too far from the root bridge (beyond the configured size of the spanning tree domain on the root bridge) or if a BPDU packet with invalid root information is continuously circulating between bridges in a spanning tree domain and needs to be aged out.

Topology Changes Detected

Times that a Topology Change event is detected by the port on a given VLAN and the port triggers a topology change propagation throughout the network. A Topology Change event occurs when a non-edge port enters forwarding state. This counter is maintained on a per-VLAN per-port basis.

Topology Changes Tx

Times that Topology Change information is propagated (sent out) through the port to the rest of the network. For a VLAN port running PVST (non-rapid), the counter is the number of times that a CFG or RST BPDU with the TC flag set is transmitted out of the port. This counter is maintained on a per-VLAN per-port basis.

Topology Changes Rx

Times that Topology Change information is received from the peer port. For a VLAN port running PVST (non-rapid), the counter is the number of times that a CFG or RST BPDU with the TC flag set is received. This counter is maintained on a per-port per-VLAN basis.

Topology Change ACKs Tx

Times that the Topology Change acknowledgement is transmitted through the port (number of CFG or RST BPDUs transmitted with the Topology Change Acknowledge flag set). This counter is maintained on a per-port per-VLAN basis.

Topology Change ACKs Rx

Times that the Topology Change acknowledgement is received on the port (number of CFG or RST BPDUs received with the Topology Change Acknowledge flag set). This counter is maintained on a per-VLAN basis.

TCN BPDUs Tx

Topology Change Notification BPDUs that are transmitted through the port. This counter is maintained on a per-port basis.

TCN BPDUs Rx

Topology Change Notification BPDUs that are received on the port. This counter is maintained on a per-port per-VLAN basis.

CFG BPDUs Tx

802.1D configuration BPDUs that are transmitted through the port. This counter is maintained on a per-port per-VLAN basis.

CFG BPDUs Rx

802.1D configuration BPDUs that are received on the port. This counter maintained on a per-port per-VLAN basis.

RST BPDUs Tx

802.1w RST BPDUs that are transmitted through the port. This counter is maintained on a per-port per-VLAN basis.

RST BPDUs Rx

802.1w RST BPDUs that are received on the port. This counter is maintained on a per-port per-VLAN basis.