Cisco 7604 User Manual

20-10
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 20 Configuring STP and Prestandard 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 20-5 shows a Layer 2 LAN port in the
learning state.
Figure 20-5 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

Cisco 7604 Specifications

General

Brand	Cisco
Model	7604
Category	Network Router
Language	English