Cisco Systems 3560 Manual De Usuario

there is only one switch in the network, no exchange occurs, the forward-delay timer expires, and the 
interface moves to the listening state. An interface always enters the blocking state after switch 
initialization.

An interface in the blocking state performs these functions:

Discards frames received on the interface

Discards frames switched from another interface for forwarding

Does not learn addresses

Receives BPDUs

The listening state is the first state a Layer 2 interface enters after the blocking state. The interface enters 
this state when the spanning tree decides that the interface should participate in frame forwarding.

An interface in the listening state performs these functions:

Discards frames received on the interface

Discards frames switched from another interface for forwarding

Does not learn addresses

Receives BPDUs

A Layer 2 interface in the learning state prepares to participate in frame forwarding. The interface enters 
the learning state from the listening state.

An interface in the learning state performs these functions:

Discards frames received on the interface

Discards frames switched from another interface for forwarding

Learns addresses

Receives BPDUs

A Layer 2 interface in the forwarding state forwards frames. The interface enters the forwarding state 
from the learning state.

An interface in the forwarding state performs these functions:

Receives and forwards frames received on the interface

Forwards frames switched from another interface

Learns addresses

Receives BPDUs