Cisco WS-C6506 User Manual

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Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 7 Configuring Spanning Tree
Understanding How Spanning Tree Protocols Work
Forwarding State
A port in the forwarding state forwards frames, as shown in Figure 7-6. The port enters the forwarding
state from the learning state.
Figure 7-6 Port 2 in Forwarding State
A port in the forwarding state performs as follows:
• Forwards frames that are received from the attached segment.
• Forwards frames that are 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 that are received from the system module.
• Receives and responds to network management messages.
Caution Use spanning-tree PortFast mode only on ports that are 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
that are connected to switches or other devices that forward messages. For more information about
PortFast, see Chapter 9, “Configuring Spanning-Tree PortFast, UplinkFast, BackboneFast, and Loop
Guard.”
Filtering
database
Frame
forwarding
System
module
Port 1
BPDUs
All segment
frames
All segment
frames
Forwarding
Forwarding
BPDUs
Station
addresses
Network
management
and data frames
Port 2
S5695
Network
management
and data frames
Station
addresses

Cisco WS-C6506 Specifications

General

Brand	Cisco
Model	WS-C6506
Category	Switch
Language	English