Scaling the Spanning Tree Protocol

Scaling the Spanning Tree Protocol
The STP prevents loops in layer 2 switched networks and is basically plug-and-play. It might be
advantageous nonetheless, to change some of the default timers and settings to attempt to create
a more stable environment.
In this section, we’ll discuss how to scale the STP protocol on a large, switched internetwork.
It is important to understand how to provide proper placement of the root bridge to create an
optimal topology. If the root bridge is automatically chosen through an election, which is the
default, the actual path that the frames can take might not be the most efficient. As the administrator,
you can then change the root placement to create a more optimal path. However, it’s
possible that your changes could cause more damage instead, so you want to think through your
network design before making any changes.
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Chapter 16 
Using Spanning Tree with VLANs
To change the root placement, you need to do the following:

Determine the root device.

Configure the device.

Set the port cost.

Set the port priorities.

Change the STP timers.