© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-1

Exploring the Functions of Networking

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What Is a Network?

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Common Physical Components of a Network

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Physical Topology Categories

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Full-Mesh Topology

Highly fault-tolerant Expensive to implement

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-6

Partial-Mesh Topology

Trade-off between fault tolerance and cost

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-7

Understanding Host-to-Host Communications

Older model– Proprietary– Application and combinations software controlled by one vendor

Standards-based model– Multivendor software– Layered approach

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-8

Why a Layered Network Model?

Reduces complexity Standardizes interfaces Facilitates modular engineering

Ensures interoperable technology

Accelerates evolution Simplifies teaching and learning

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The Seven Layers of the OSI Model

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The Seven Layers of the OSI Model (Cont.)

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-11

The Seven Layers of the OSI Model (Cont.)

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-12

The Seven Layers of the OSI Model (Cont.)

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-13

The Seven Layers of the OSI Model (Cont.)

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-14

The Seven Layers of the OSI Model (Cont.)

© 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-15

The Seven Layers of the OSI Model (Cont.)

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Data Encapsulation

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Data De-Encapsulation

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Peer-to-Peer Communication

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Defines four layers Uses different names for Layers 1 through 3

Combines Layers 5 through 7 into single application layer

TCP/IP Stack

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TCP/IP Stack vs. the OSI Model

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