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| 3.7 |  | Tuning, Verifying, and Troubleshooting Spanning-Tree Protocol |
| 3.7.3 |  | Configuring BackboneFast |

Accepting inferior BPDUs – this concept is what makes up the core of the BackboneFast engine. The IEEE 802.1w committee decided to incorporate a similar mechanism into RSTP. When a bridge receives inferior information from its designated or Root Bridge, it immediately accepts it and replaces the one previously stored.

BackboneFast can be enabled to detect indirect link failures and to start the spanning tree reconfiguration sooner. To use BackboneFast, it must be enabled it on all switches in the network. BackboneFast is not supported on Token Ring VLANs. This feature is supported for use with third-party switches.

The BackboneFast feature is supported only when the switch is running PVST. Beginning in privileged EXEC mode, follow the steps outlined in Figure to enable BackboneFast.

To disable the BackboneFast feature, use the no spanning-tree backbonefast global configuration command.