Spanning Tree Protocol (STP) convergence (Layer 2 convergence) happens when bridges and switches have transitioned to either the forwarding or blocking state. When layer 2 is converged, Root Switch is elected and Root, Designated and Non-Designated ports in all switches are selected. At Converged condition, the Root and Designated are in forwarding state, and all other ports are in blocking state.
The time it usually takes to change from blocking to forwarding state is 50 seconds (Blocking to listening is 20 seconds; Listening to learning is 15 seconds; Learning to forwarding is 15 seconds), when Spanning Tree Protocol (STP) timers are in their default values. Until the port reaches forwarding state, no user traffic is forwarded through the port and the end user may feel that there is no network connectivity.