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Chapter 4
Layer 2 Switching and the Spanning Tree Protocol (STP)
Bridge ID Priority The priority set; the bridge output above is using the
default of 32768.
Bridge Timers The timers used by this bridge.
Ports in the Spanning Tree Not all available ports are displayed in the
output above. However, this field does show all ports participating in this
spanning tree. It also shows whether they are forwarding or not.
Summary
T
his chapter covered layer 2 switching. You learned how redundant
links can be used to provide redundancy in a network but also how they can
cause problems.
The Spanning Tree Protocol was discussed at length, including how it can
be used to stop network loops, broadcast storms, and multiple frame copies.
We discussed STP configuration and showed you some examples. How-
ever, we showed you only how to turn spanning tree off and on. In Chapter 5,
we'll show you how to use STP to create complex configurations on the
switch.
Key Terms
Before you take the exam, be sure you're familiar with the following terms:
Application-Specific Integrated
Circuits (ASICs)
layer 2 switching
bridge ID
loop avoidance
Bridge Protocol Data Units (BPDUs)
Media Access Control (MAC)
address
broadcasts
nondesignated ports
cut-through
root bridge
designated ports
Spanning Tree Protocol (STP)
FragmentFree
store-and-forward
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