Communicating over the
Network
Network Fundamentals – Chapter 2
Version 4.0
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What will we Learn from chapter 2?

Describe the structure of a network

Explain the function of protocols.

Explain the advantages of using a layered model .

Describe the role of each layer In the:
TCP/IP model
OSI model.

Describe the importance of addressing and naming
schemes.
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Network Structure
 Elements of communication
• Message source
• The channel
• Message destination
– Networks carrying different types of messages:
– Data, voice, video, images
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Network Structure
 How messages are transmitted
– Messages are sent across a network in small “chunks” called
segments, packets, frames, cells…
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Network Structure
Components of a network
• Hardware
• Software
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Network Structure
 End Devices
– Interface with humans or other devices
– Role of end devices:
•
•
•
•
Client
Server
Printers, routers…
Any terminating
networking
device
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Network Structure
Intermediary devices in contrasted to the role of end
devices
• Provides connectivity and ensures data flows
through the and across network
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Network Structure
 What is network media?
 The path or channel over which a message travels
 What are the criteria for making media choice?
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Network Types
Local Area Network (LAN)
– A network serving a home, building or campus may be
considered a Local Area Network (LAN)
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Network Types
Wide Area Networks (WANs)
– Specialize networks connecting LANs, MANs, PANs…
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Network Types
 What is the Internet
– A global mesh of interconnected networks (WANs, MANs,
LANs, PANs…
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Network Types
 Symbols used to represent network devices and media
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Function of Protocol in Network Communication
 Protocol
– A set of rules
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Function of Protocol in Network Communication
Network protocols are used to govern communicate between
devices
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Function of Protocol in Network Communication
Industry standards
– A process or protocols that has been endorsed by the
networking industry and ratified by a standards organization
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Function of Protocol in Network Communication
 Technology independent Protocols
– Diverse types of devices can interact using standard sets of
protocols
– Network protocols specify network functionality, not the
underlying device technology
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Layers within the OSI and TCP/IP Reference
Models
 The benefits of a layered model
•
•
•
•
Aids in protocol design
Provides for corporate competition
Changes in one layer do not affect other layers
Provides for standard interfaces between devices
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Layers with TCP/IP and OSI Model
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Layers with TCP/IP and OSI Model
The Communication Process
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Layers with TCP/IP and OSI Model
Protocol Data Units (PDU) and encapsulation
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Layers with TCP/IP and OSI Model
Process of sending and receiving messages
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Layers with TCP/IP and OSI Model
– A protocol model provides a model that closely matches
the structure of a particular protocol suite
– A reference model provides a common reference for
maintaining consistency within all types of network
protocols and services
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Layers with TCP/IP and OSI Model
OSI Reference Model
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Layers with TCP/IP and OSI Model
OSI and TCP/IP model
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Addressing and Naming Schemes
How labels in encapsulation headers are used to manage
communication in data networks
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Addressing and Naming Schemes
 Ethernet MAC Addresses, IP Addresses, and TCP/UDP
Port numbers
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Addressing and Naming Schemes
How labels in encapsulation headers are used to manage
communication
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Addressing and Naming Schemes
How information in the encapsulated header is used to
identify the source and destination processes for
communication
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What did I Learn from Chapter 2

Describe the structure of a network

Explain the function of protocols.

Explain the advantages of using a layered model .

Describe the role of each layer In the:
TCP/IP model
OSI model.

Describe the importance of addressing and naming
schemes.
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
29
Communicating over the Network
Next
Application Layer Functionality and Protocols
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