Exploration Network Chapter2

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

Communicating over the Network

Network Fundamentals – Chapter 2

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

Network Structure The main elements of communication

–3 common elements of communication

• message source

• the channel

• message destination

The data or information network can carry many different types of communicatons


Network Structure How messages are communicated

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


segmentation is division of the data stream into smaller pieces segmentation.

Segmenting messages has two primary benefits.

First, by sending smaller individual pieces from source to destination, many different conversations can be interleaved on the network. The process used to interleave the pieces of separate conversations together on the network is called multiplexing.

Second, segmentation can increase the reliability of network communications

If part of the message fails to make it to the destination, only the missing parts need to be

retransmitted.


Network Structure The components of a network

–Network components

Hardware Devices and media are the physical elements or hardware of the network

software Services and processes are the communication programs, called software, that run on the networked devices.


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


end devices are:

Computers (work stations, laptops, file servers, web servers)

Network printers

VoIP phones

Security cameras

Mobile handheld devices (such as wireless barcode scanners, PDAs)

)


intermediary network devices are:

Network Access Devices (Hubs, switches, and wireless access points)

Internetworking Devices (routers)

Communication Servers and Modems

Security Devices (firewalls


Communication across a network is carried on a medium. The medium provides the channel over which the message travels from source to destination.

Modern networks primarily use three types of media to interconnect devices and to provide the pathway over which data can be transmitted. These media are:

Metallic wires within cables

Glass or plastic fibers (fiber optic cable)

Wireless transmission


Network StructureNetwork media:- is the channel over which a message travels.

Criteria for choosing a network media are:

The distance the media can successfully carry a signal.

The environment in which the media is to be installed.

The amount of data and the speed at which it must be transmitted.

The cost of the media and installation


Network Types Local Area Networks (LANs)

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

Criteria for choosing a network media are:

•The distance the media can successfully carry a signal.•The environment in which the media is to be installed.•The amount of data and the

speed at which it must be transmitted.

•The cost of the media and installation


Network Types Wide Area Networks (WANs)

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

LANs and WANs are very useful to individual organizations. They connect the users within the organization. They allow many forms of communication including exchange e-mails,

corporate training, and other resource sharing.


Network Structure–Role of an intermediary device

• provides connectivity and ensures data flows across network


Network Types the Internet:- is defined as a

global mesh of interconnected networks

Intranet

The term intranet is often used to refer to a private connection of LANs and WANs that belongs to an

organization, and is designed to be accessible only by the

organization's members, employees, or others with

authorization.


Network Types In addition to these representations, specialized terminology is used when discussing how each of these devices and media connect to each other. Important terms to remember are:

Network Interface Card - A NIC, or LAN adapter, provides the physical connection to the network at the PC or other host device. The media connecting the PC to the networking device plugs directly into the NIC.


Physical Port - A connector or outlet on a networking device where the media is connected to a host or other networking device.

Interface - Specialized ports on an internetworking device that connect to individual networks. Because routers are used to interconnect networks, the ports on a router are referred to network interfaces.


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

facilitate communication over data networksA protocol is a set of predetermined rules


Function of Protocol in Network Communication Network protocol are used to

allow devices to communicate

successfully


Function of Protocol in Network Communication

Protocol suites and industry standards

A standard is

a process or protocol that has been authorized by the networking industry and ratified by a standards organization


Function of Protocol in Network Communication There are different protocols that acts together to

manage successful communication


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 The benefits of using a layered model

•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 TCP/IP ModeL


A complete communication process includes these steps:

1. Creation of data at the application layer of the originating source end device

2. Segmentation and encapsulation of data as it passes down the protocol stack in the source end device

3. Generation of the data onto the media at the network access layer of the stack

4. Transportation of the data through the internetwork, which consists of media and any intermediary devices

5. Reception of the data at the network access layer of the destination end

6. Decapsulation and reassembly of the data as it passes up the stack in the destination device

7. Passing this data to the destination application at the Application layer of the destination end device


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


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

messages in this course, the PDUs are

named according to the protocols of the TCP/IP suite.

Data - The general term for the PDU used at the Application

layerSegment - Transport Layer

PDUPacket - Internetwork Layer

PDU Frame - Network Access Layer

PDUBits - A PDU used when

physically transmitting data over the medium


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.


Layers with TCP/IP and OSI Model Define OSI


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


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

to manage communication in data networks


Addressing and Naming Schemes Examples of Ethernet MAC Addresses, IP Addresses,

and TCP/UDP Port numbers


Addressing and Naming Schemes 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

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