Cisco WS-C2950SX-48-SI Configuration Manual page 106

Understanding How STPs Work
Figure 7-6
addresses
database
addresses
A port in the forwarding state performs as follows:
• Forwards frames received from the attached segment
• Forwards frames switched from another port for forwarding
Incorporates station location information into its address database
•
Receives BPDUs and directs them to the system module
•
Processes BPDUs received from the system module
•
Receives and responds to network management messages
•
Use spanning tree PortFast mode only on ports directly connected to individual workstations to allow
Caution
these ports to come up and go directly to the forwarding state, instead of having to go through the entire
spanning tree initialization process. To prevent illegal topologies, enable spanning tree on ports
connected to switches or other devices that forward messages. For more information on PortFast, see
Chapter 8, "Configuring Spanning Tree PortFast, BPDU Guard, BPDU Filter, UplinkFast,
BackboneFast, and Loop Guard."
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide
7-10
Port 2 in Forwarding State
All segment
Forwarding
frames
Port 1
Station
BPDUs
Filtering System
module
BPDUs
Station
Port 2
Forwarding
Network
management
& data frames
Frame
forwarding
Network
management
& data frames
All segment
frames
Chapter 7 Configuring Spanning Tree
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Release 8.1
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