8-8
Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
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Chapter 8 Configuring Spanning Tree
Understanding How Spanning Tree Protocols Work
Figure 8-4
Port 2 in Listening State
A port in the listening state performs as follows:
•
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.
Learning State
A port in the learning state prepares to participate in frame forwarding. The port enters the learning state
from the listening state.
Figure 8-5
shows a port in the learning state.
A port in the learning state performs as follows:
•
Discards frames received from the attached segment.
•
Discards frames switched from another port for forwarding.
•
Incorporates station location into its address database.
•
Receives BPDUs and directs them to the system module.
Filtering
database
Frame
forwarding
System
module
Port 1
BPDUs
All segment
frames
BPDU and network
management frames
All segment
frames
Forwarding
Listening
Station
addresses
Network
management
and data frames
Port 2
S5693
Network
management
frames
Data
frames
BPDUs
