Listening State - Cisco WS-C4003 - Catalyst 4000 Chassis Switch Software Configuration Manual

How Spanning Tree Protocols Work

Listening State

The listening state is the first transitional state a port enters after the blocking state. The port enters this
state when the spanning tree determines that the port should participate in frame forwarding. Learning
is disabled in the listening state.
Figure 7-4
A port in the listening state performs as follows:
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Software Configuration Guide—Catalyst 4000 Family, Catalyst 2948G, Catalyst 2980G, Releases 6.3 and 6.4
7-8
Port 2 in Listening State
All segment
frames
Port 1
Station
addresses
BPDUs
Filtering System
database module
BPDUs
Data
frames
Port 2
Listening
BPDU and network
management frames
Discards frames received from the attached segment.
Discards frames switched from another port for forwarding.
Does not incorporate station location into its address database. (There is no learning at this point, so
there is no address database update.)
Receives BPDUs and directs them to the system module.
Processes BPDUs received from the system module.
Receives and responds to network management messages.
Figure 7-4 shows a port in the listening state.
Forwarding
Network
management
and data frames
Frame
forwarding
Network
management
frames
All segment
frames
Chapter 7 Configuring Spanning Tree
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