Transcript CCNA 3 Module 3 Single-Area OSPF

CCNA 3 Chapter 8
Spanning Tree Protocol
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Your Name
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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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Redundant Switched Topologies
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Broadcast Storms
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Multiple Frames Transmission
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MAC 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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Spanning Tree Protocol
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Bridging Loops for Redundancy
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Spanning Tree
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Spanning-Tree Costs
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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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Selecting the Root Bridge
Bridge protocol data unit
(BPDU)
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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
• 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
The Rapid Spanning Tree Protocol,
relaying root bridge
IEEE 802.1w, will eventually replace
BPDUs
the Spanning Tree Protocol, IEEE
802.1D.
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