Forwarding State; Disabled State - Cisco WS-C4003 - Catalyst 4000 Chassis Switch Software Configuration Manual

How Spanning Tree Protocols Work

Forwarding State

A port in the forwarding state forwards frames, as shown in
state from the learning state.
Figure 7-6
A port in the forwarding state performs as follows:
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Caution Use spanning tree PortFast mode only on ports directly connected to individual workstations to allow
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 about PortFast, see
Chapter 8, "Configuring Spanning Tree PortFast, UplinkFast, and BackboneFast, and Loop Guard."

Disabled State

A port in the disabled state does not participate in frame forwarding or STP, as shown in
port in the disabled state is virtually nonoperational.
Software Configuration Guide—Catalyst 4000 Family, Catalyst 2948G, Catalyst 2980G, Releases 6.3 and 6.4
7-10
Port 2 in Forwarding State
All segment
frames
Port 1
Station
addresses
BPDUs
Filtering System
database module
BPDUs
Station
addresses
Port 2
Forwarding
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.
Forwarding
Network
management
and data frames
Frame
forwarding
Network
management
and data frames
All segment
frames
Chapter 7 Configuring Spanning Tree
Figure 7-6. The port enters the forwarding
Figure 7-7. A
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