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Catalyst 2960 and 2960-S Switch Software Configuration Guide
OL-8603-09
Chapter 16 Configuring STP
Understanding Spanning-Tree Features
Does not learn addresses
Receives BPDUs
Listening State
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 forwar ding
Does not learn addresses
Receives BPDUs
Learning State
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 forwar ding
Learns addresses
Receives BPDUs
Forwarding State
A Layer 2 interface in the forwarding state forwards frames. The interface enters the forwa rding 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
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 these functions:
Discards frames received on the interface
Discards frames switched from another interface for forwar ding
Does not learn addresses
Does not receive BPDUs