CCNA 3 v3.0 Module 7
Spanning Tree Protocol
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Purpose of This PowerPoint
• This PowerPoint primarily consists of the Target
Indicators (TIs) of this module in CCNA version
3.0.
• It was created to give instructors a PowerPoint to
take and modify as their own.
• This PowerPoint is:
NOT a study guide for the module final assessment.
NOT a study guide for the CCNA certification exam.
• Please report any mistakes you find in this
PowerPoint by using the Academy Connection
Help link.
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Objectives
• Redundant topologies
• Spanning Tree Protocol
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Redundancy
Redundant networking topologies are
designed to ensure that networks continue
to function in the presence of single points
of failure.
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Redundant Topologies
• A goal of redundant topologies is to
eliminate network outages caused by a
single point of failure.
• All networks need redundancy for
enhanced reliability.
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Simple Redundant Switched Topology
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Broadcast Storm
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Multiple Frame Transmissions
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Media Access Control Database Instability
In a redundant switched network, it is
possible for switches to learn the wrong
information. A switch can learn that a MAC
address is on a port when it is not.
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Using Bridging Loops for Redundancy
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Spanning-Tree Protocol
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Spanning Tree Link Costs
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A Spanning Tree
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Spanning-Tree Operation
• One root bridge per
network.
• One root port per
nonroot bridge.
• One designated
port per segment.
• Nondesignated
ports are unused.
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Bridge Protocol Data Unit
Bridge protocol data unit
(BPDU)
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Bridge IDs
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Spanning-Tree Port States
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Spanning-Tree Recalculation
A switched internetwork has converged when
all the switch and bridge ports are in either the
forwarding or blocked state.
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Rapid Spanning-Tree Protocol
• The standard and protocol introduce the
following:
Clarification of port states and roles
Definition of a set of link types that can go
to forwarding state rapidly
Allowing switches, in a converged network,
to generate their own BPDUs rather than
relaying root bridge BPDUs
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Rapid Spanning-Tree Port Designations
The Rapid Spanning Tree Protocol, IEEE
802.1w, will eventually replace the Spanning
Tree Protocol, IEEE 802.1D.
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