communicating over the network

© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 1Version 4.0

Communicating over the Network

Network Fundamentals – Chapter 2

2© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

Objectives Describe the structure of a network, including the

devices and media that are necessary for successful communications.

Explain the function of protocols in network communications.

Explain the advantages of using a layered model to describe network functionality.

Describe the role of each layer in two recognized network models: The TCP/IP model and the OSI model.

Describe the importance of addressing and naming schemes in network communications.


Network Structure Define the elements of communication

– 3 common elements of communication• Message source• The channel• Message destination

Define a network– Data or information networks capable of carrying many different

types of communications


Network Structure Describe how messages are communicated

– Data is sent across a network in small “chunks” called segments


Network Structure Define the components of a network

– Network components• Hardware• Software


Network Structure End Devices and their Role in the Network

– End devices form interface with human network & communications network

– Role of end devices:• Client• Server• Both client and server


Network Structure Identify the role of an intermediary device in a data

network and be able to contrast that role with the role of an end device

– Role of an intermediary device• Provides connectivity and ensures data flows

across network


Network Structure Define network media and criteria for making a network

media choice– Network media – this is the channel over which a message

travels


Network Types Define Local Area Networks (LANs)

– A network serving a home, building or campus is considered a Local Area Network (LAN)


Network Types Define Wide Area Networks (WANs)

– LANs separated by geographic distance are connected by a network known as a Wide Area Network (WAN)


Network Types Define the Internet

– The internet is defined as a global mesh of interconnected networks


Network Types Describe network representations


Function of Protocol in Network Communication The importance of protocols and how they are used to

facilitate communication over data networks– A protocol is a set of predetermined rules


Function of Protocol in Network Communication Explain network protocols

– Network protocols are used to allow devices to communicate successfully


Function of Protocol in Network Communication Describe Protocol suites and industry standards

– A standard is a process or protocol that has been endorsed by the networking industry and ratified by a standards organization


Function of Protocol in Network Communication Define different protocols and how they interact


Function of Protocol in Network Communication Technology independent Protocols

– Many diverse types of devices can communicate using the same sets of protocols

– This is because protocols specify network functionality, not the underlying technology to support this functionality


Layers with TCP/IP and OSI Model Explain the benefits of using a layered model

– Benefits include• Assists in protocol design• Fosters competition• Changes in one layer do not affect other layers• Provides a common language


Layers with TCP/IP and OSI Model Describe TCP/IP Mode


Layers with TCP/IP and OSI Model Describe the Communication Process


Layers with TCP/IP and OSI Model Explain protocol data units (PDU) and encapsulation


Layers with TCP/IP and OSI Model Describe the process of sending and receiving

messages


Layers with TCP/IP and OSI Model Explain protocol and reference models

– 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


Layers with TCP/IP and OSI Model Define OSI


Layers with TCP/IP and OSI Model Compare OSI and TCP/IP model


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The OSI Reference Model

The OSI reference model is the primary model for network communications.

Allows you to view the network functions that occur at each layer.

It is a framework that you can use to understand how information travels throughout a network

7 layers -- each of which illustrates a particular network function.


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OSI – The Application Layer

Provides network services to the user's applications.

It does not provide services to any other OSI layer

***Think of any network application you use daily


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OSI – The Presentation Layer

It ensures that the information that the application layer of one system sends out is readable by the application layer of another system.

*** Think of any common file formats (JPEG, txt etc)


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OSI – The Session Layer

*** After you prepare your data, you need to establish the communication channels to send data

This layer establishes, manages, and terminates sessions between two communicating hosts.

It also synchronizes dialogue between the two hosts' presentation layers and manages their data exchange.


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OSI – The Transport Layer

Data will be segmented and send to destination device. Transport layer of destination device will reassemble them.

This layer handles details of reliable transfer. (ensures that the data arrive completely )


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OSI – The Network Layer

Many paths to the same destination. So, which path to follow?

Segmented data needs address to reach the destination (network address)

This layer handle 2 above stated issues.


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OSI – The Data Link Layer

It provides means for exchanging data frames over a common media

To detect and possibly correct errors that may occur in the Physical layer

Physical Addressing, topologies and flow control


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OSI – The Physical Layer

It defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link between end systems.

Voltage levels, timing of voltage changes, physical data rates, maximum transmission distances, physical connectors, and other, similar, attributes defined by physical layer specifications.


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TCP/IP Model

Network Access: Detailing the components that make up the psysical link and how to access it


35

Comparison --Both have application layers, though they include

very different services

--Both have comparable transport and network

(Internet) layers

--TCP/IP combines the presentation and session

layer issues into its application layer

--TCP/IP combines the OSI data link and physical layers

into one layer

--TCP/IP appears simpler because it has fewer layers


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Data Encapsulation Build the data

Package the data for end to end support (Segments)

The data is put into a packet or datagram that contains a network header with source and destination logical addresses

PDU: Transport layer: Segment, Network: Packet, Data Link: Frame


Data Encapsulation Each network

device must put the packet into a frame.

The frame must be converted into a pattern of 1s and 0s (bits)

***Data Segments Packet Frames Bits

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Network header: IP address (host), Frame header: MAC address (physical

address)


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Addressing in the Network There are various types of addresses that must be

included to successfully deliver the data from a source application running on one host to the correct destination application running on another

Transport Layer (#4): to identify the processes or services that are communicating within the end

devices


Addressing and Naming Schemes Explain how labels in encapsulation headers are used

to manage communication in data networks


Addressing and Naming Schemes Describe examples of Ethernet MAC Addresses, IP

Addresses, and TCP/UDP Port numbers


Addressing and Naming Schemes Explain how labels in encapsulation headers are used

to manage communication in data networks


Addressing and Naming Schemes Describe how information in the encapsulation header

is used to identify the source and destination processes for data communication


Summary

communicating over the network

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