Cisco Systems 6500, EA6500 Learning State

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Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
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Chapter 15 Configuring STP and IEEE 802.1s MST
Understanding How STP Works
Learning State
A Layer 2 LAN port in the learning state prepares to participate in frame forwarding. The Layer 2 LAN
port enters the learning state from the listening state. Figure 15-5 shows a Layer 2 LAN port in the
learning state.
Figure 15-5 Interface 2 in Learning State
A Layer 2 LAN port in the learning state performs as follows:
• Discards frames received from the attached segment.
• Discards frames switched from another port for forwarding.
• Incorporates end station location into its address database.
• Receives BPDUs and directs them to the system module.
• Receives, processes, and transmits BPDUs received from the system module.
• Receives and responds to network management messages.
Filtering
database
Frame
forwarding
System
module
Port 1
BPDUs
All segment
frames
BPDU and network
management frames
All segment
frames Forwarding
Learning
BPDUs
Station
addresses
Network
management
and data frames
Port 2
S5694
Network
management
frames
Station
addresses
Data
frames