User's Manual

6-5
Cisco 3200 Series Wireless MIC Software Configuration Guide
OL-7734-02
Chapter 6 Configuring Spanning Tree Protocol
Understanding Spanning Tree Protocol
Spanning-Tree Timers
Table 6-1 describes the timers that affect the entire spanning-tree performance.
Creating the Spanning-Tree Topology
In Figure 6-1, bridge 4 is elected as the spanning-tree root because the priority of all the bridges is set
to the default (32768) and bridge 4 has the lowest MAC address. However, because of traffic patterns,
number of forwarding interfaces, or link types, bridge 4 might not be the ideal spanning-tree root. By
increasing the priority (lowering the numerical value) of the ideal bridge so that it becomes the
spanning-tree root, you force a spanning-tree recalculation to form a new topology with the ideal bridge
as the spanning-tree root.
Figure 6-1 Spanning-Tree Topology
Table 6-1 Spanning-Tree Timers
Variable Description
Hello timer Determines how often the bridge broadcasts hello messages to other bridges.
Forward-delay timer Determines how long each of the listening and learning states last before the
interface begins forwarding.
Maximum-age timer Determines the amount of time the bridge stores protocol information
received on an interface.
LAN segment A
LAN segment B
Bridge 1
Bridge 3
Bridge 2
Bridge 4
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