Cisco Systems 2940 Listening State, Learning State, Forwarding State, Disabled State

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Catalyst 2940 Switch Software Configuration Guide
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Chapter11 Configuring STP
Understanding Spanning-Tree Features
Listening State
The listening state is the first state a Layer 2 i nterface enter s after the blo cking s tate. T he interf ace e nters
this state when the spanning tree determines that the interface should participate in frame forwarding.
An interface in the listening state performs as follows:
•Discards frames received on the port
•Discards frames switched from another interface for forwardi ng
•Does not learn addresses
•Receives BPDUs
Learning State
A Layer 2 interface in the learning state prepares to participate in f rame for warding . The inte rface enters
the learning state from the listening state.
An interface in the learning state performs as follows:
•Discards frames received on the port
•Discards frames switched from another interface for forwardi ng
•Learns addresses
•Receives BPDUs
Forwarding State
A Layer 2 interface in the forwarding state forwards frames. The interface enters the forwa rding sta te
from the learning state.
An interface in the forwarding state performs as follows:
•Receives and forwards frames received on the port
•Forwards frames switched from another port
•Learns addresses
•Receives BPDUs
Disabled State
A Layer 2 interface in the disabled state does not particip ate in frame forwarding or in the spanning tree.
An interface in the disabled state is nonoperational.
A disabled interface performs as follows:
•Discards frames received on the port
•Discards frames switched from another interface for forwardi ng
•Does not learn addresses
•Does not receive BPDUs