Copyleft © 2005, Binnur Kurt

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N ki F d lN ki F d l1 Networking FundamentalsNetworking Fundamentals1

Copyleft © 2005, Binnur Kurt

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Objectives

►Define basic networking terms►Describe some commonly used network applications►Describe the main purposes and functions of computer

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►Describe the history and purposes of the OSI reference model

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BTE550 – Internet and Intranet Applications

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Objectives (Cont.)

►Discuss the functions of each of the seven layers of the OSI reference model and provide examples of each

►Describe the basic process of communication between the

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►Describe the functions of the TCP/protocol stack and provide examples of each layer’s function

►Compare the TCP/IP protocol stack to the OSI reference model

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Basic Networking Terminology►NIC►Media►Protocol

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l ►Protocol►NOS►Connectivity devices►LAN►MAN►WAN

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►WAN►Physical topology►Logical topology

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WWW Request-Responserk

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BTE550 – Internet and Intranet ApplicationsWeb Browser Web Server

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Sending E-Mail

E-mailServer

E-mailServer

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Client A Client B

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Defining Components of the NetworkHome Office Mobile Users

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Internet

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Branch Office Main Office

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Computer Networks

BranchOffice

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Floor 2

ServerFarm

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HomeOffice

ISDN

Remote Campus

Floor 1

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The OSI Reference Model

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Session

Transport

Network

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Data Link

Physical

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Why a Layered Network Model?

►Reduces complexityApplication

Presentation

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Presentation

Session

Transport

Network

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5

4

3

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►Simplifies teaching and learningData Link

Physical

2

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The Seven Layers of the OSI Model

Network Processes to Applications►Provides network services to

application processes (such as

Application

Presentation

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l pp c o p ocesses (suc selectronic mail, file transfer, and terminal emulation)Session

Transport

Network

Data Link

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4

3

2

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Data Link

Physical

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Data Representation

Network Process to ApplicationsApplication

Presentation

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►Ensures data is readable byreceiving system

►Formats data►Structures data►Negotiates data transfer syntax

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Session

Transport

Network

Data Link

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3

2

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for application layerPhysical

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Network Process to Applications

Data Representation

Application

Presentation

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Interhost Communication►Establishes, manages, and

terminates sessions between applications

Session

Transport

Network

Data Link

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4

3

2

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Physical

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Data Representation

Application

Presentation

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End-to-End Connections►Handles transportation issues between hosts►Ensures data transport reliability►Establishes maintains and terminates virtual

Interhost Communication

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Session

Transport

Network

Data Link

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►Establishes, maintains and terminates virtual circuits

►Provides reliability through fault detection and recovery information flow control

Physical

2

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Data Representation

Application

Presentation

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Data Delivery►Provides connectivity and path

selection between two host

End-to-End Connections

Interhost CommunicationSession

Transport

Network

Data Link

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selection between two host systems

►Routes data packets►Selects best path to deliver data

Physical

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Data Representation

Application

Presentation

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Access to Media


Data Delivery


Transport

Network

Data Link

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4

3

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Access to Media►Defines how data is formatted for

transmission and how access to the network is controlled

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Data Representation

Application

Presentation

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Data Delivery

Access to Media


Transport

Network

Data Link

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3

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Binary Transmission►Defines the electrical, mechanical,

procedural, and functional specifications for activating, maintaining, anddeactivating the physical link.

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Data EncapsulationSender

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User DataUser Data

User DataUser Data

User DataUser Data

User DataUser Data

User DataUser DataL7

L7HDR

L7HDR

L7HDR

L7HDR

L6

L6HDR

L6HDR

L6HDR

L5

L5HDR

L5HDR

L4

L4HDR

L3

Application

Presentation

Session

Transport

N t k

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6

5

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HDR = header

Bits

User DataUser Data


HDRL3

HDRL4

HDRL5

HDRL6

HDRL7

HDR FCS

L7HDR

L6HDR

L5HDR

L4HDR

L3HDRNetwork

Data Link

Physical

3

2

1

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Data De-EncapsulationReceiver

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Application

Presentation

Session

Transport

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6

5

4

User DataUser Data

User DataUser Data

User DataUser Data

User DataUser Data

User DataUser DataL7HDR

L7HDR

L7HDR

L7HDR

L6HDR

L6HDR

L6HDR

L5HDR

L5HDR

L4HDR

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Network

Data Link

Physical

3

2

1

HDR = header

Bits

User DataUser Data


HDRL3

HDRL4

HDRL5

HDRL6

HDRL7

HDR FCS

L7HDR

L6HDR

L5HDR

L4HDR

L3HDR

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Peer-to-Peer Communication

ReceiverSender

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Frames

Packets

Segments

Application

Presentation

Session

Transport

Network

Application

Presentation

Session

Transport

Network

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NetworkBits

FramesData Link

Physical

Data Link

Physical

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ApplicationApplication

TCP/IP Modelrk

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Fund

amen

tal ApplicationApplication

PresentationPresentation

InternetInternet

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Network AccessNetwork Access

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TCP/IP Protocol Stack vs. OSI Model

Application

TCP/IP Protocol StackTCP/IP Protocol Stack OSI ModelOSI Model

Application

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Presentation

Session

Transport

Network

Application

Transport

Internet

Protocols

Data Flow

ApplicationLayers

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Data Link

Physical

NetworkAccess

NetworksLayers

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Summary

►There are a number of basic computer network terms, including NIC, media, protocol, physical topology, and logical topology, that are fundamental to an understanding

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►Network applications are software programs that run between computers that are connected together on a network.

►Some common network applications include HTTP, POP3 FTP Telnet and SNMP

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POP3, FTP, Telnet, and SNMP.

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Summary (Cont.)

►There are many different ways in which a computer network can be constructed to meet the requirements of an organization, but user components are generally grouped

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l g , p g y g pinto the categories of main office, remote locations, and mobile users.

►The ISO created and released the OSI reference model in 1984 to provide vendors with a set of standards to ensure greater compatibility and interoperability between various types of network technologies

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types of network technologies.

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Summary (Cont.)

►The OSI reference model reduces complexity, standardizes interfaces, facilitates modular engineering, ensures interoperable technology, accelerates evolution,

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l and simplifies teaching and learning.►Each layer of the OSI model has a set of unique

functions. The seven layers of the OSI model are the application, presentation, session, transport, network, data-link, and physical layers.

►Encapsulation is the process in which data is wrapped in

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►Encapsulation is the process in which data is wrapped in a particular protocol header before network transit.

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Summary (Cont.)

►The TCP/IP protocol stack has four layers: the application layer, transport layer, internet layer, and network access layer.

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TCP/IP protocol stack and the OSI reference model.

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Repeaterrk

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Hub (Multiport Repeater)

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Network Interface Cardrk

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Bridge

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S t 2S t 1

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Segment 2Segment 1CorporateInternet

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Switchrk

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FirewallsCalifornia

MassachusettsNo Access

to HQ

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Allow Access to HQ

AAAServer

• Permit access from MA• Permit packets from NH

CorporateHeadquarters

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Vermont

NewHampshire

• Permit packets from VT• Deny all other packets

Allow Access to HQ

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Summary

►Networking devices are products used to connect networks.

►Hubs, switches, and routers interconnect devices within

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l ►Hubs, switches, and routers interconnect devices within LANs, MANs, and WANs.

►Networking devices function at different layers of the OSI model, primarily Layers 1, 2, and 3.

►Repeaters reshape, amplify, and retime signals before sending them along the network.

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Summary (Cont.)

►The term "hub" (also called a multiport repeater) is used instead of “repeater" when referring to the device that serves as a connection point in a network. Hubs work

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l Layer 1 only and make no filtering decisions. ►Layer 2 LAN switches work at Layer 2, and they make

limited MAC hardware address decisions. ►Routers can make decisions as to the best path for

delivery of data on the network.

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Summary (Cont.)►Working at Layers 2, 3, and 4, multilayer switches enable

implementation of Layer 3 QoS and security functionality and perform many of the same functions as routers do, but

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types of network connectivity devices.►Firewalls and AAA servers provide security to the

network.

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Physical Topologies

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Bus Topology Ring Topology Star Topology

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Mesh TopologyExtended Star Topology

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Logical Topologies

Main

Main Server

Internet2

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Repeater

WorkgroupSwitch

Switch

D

EF

H

E0

E2

E11

A CB

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Bridge

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Bus Topology

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Star Topologyrk

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Extended-Star Topology

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Ring Topologyrk

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Dual-Ring Topology

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Two links connected to thesame networking device

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Full-Mesh Topologyrk

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Partial-Mesh Topology

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Summary►A physical topology describes the plan for wiring the

physical devices, while a logical topology describes how information flows through a network.

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►In a physical bus topology, a single cable connects all the devices.

►The most commonly used architecture in Ethernet LANs is the physical star topology, with each host in the network connected to the central device with its own cable.

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Summary (Cont.)

►When a star network is expanded to include additional networking devices that are connected to the main networking device, it is called an extended-star topology.

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►In a ring topology, all the hosts are connected in the form of a ring or circle.

►A full-mesh topology connects all devices to each other, while in a partial-mesh topology, at least one device has multiple connections to others.

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Communications Protocol

Host Host

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TCP

Host Host

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TCP/IP Protocol Stack

FTP,TelnetFTP,

Telnet

DNS, SNMPDNS, SNMP7

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ApplicationApplication


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TCPTCP

ICMPICMP

Telnet,SMTPTelnet,SMTP

IPIP OSPFOSPF IGRPIGRP RIPRIP INT, IS-ISINT, IS-IS

NetBIOSNetBIOS

ARP, RARP, SNAPARP, RARP, SNAPLLCLLC

Many Physical ImplementationsMany Physical Implementations

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SessionSession

TransportTransport

NetworkNetwork

Data-linkData-link

PhysicalPhysical

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TCP/IP Protocol StackOSI Reference Model

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TCP Characteristics

Connection-Oriented Protocol

Full-Duplex Operation

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Error Checking

Sequencing

Acknowledgments

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Flow Control

Packet Recovery

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UDP Characteristics

Minimal ServiceMinimal Service

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UnreliableUnreliable

Not-GuaranteedNot-Guaranteed

Direct Access to DatagramsDirect Access to Datagrams

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• File Transfer– TFTP *– FTP *– NFS

Application Layer Overviewrk

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Application

Transport

Net ork

NFS• E-Mail

– SMTP• Remote Login

– Telnet *– rlogin *

• Network Management– SNMP *

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*Used by the router

Network

Data Link

Physical

• Name Management– DNS*

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Summary

►Protocols define a standard set of rules for communicating between devices.

►TCP/IP is a suite of protocols arranged as a stack.

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control and reliable data delivery services.►UDP provides minimal, non-guaranteed, transport

services. ►The transport layer supports multiple application

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protocols.

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Network and Host Addresses

Network HostNetwork Host

1 12

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3.1

2.11.2

1.1

2 13 1

3

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Dotted-Decimal Notation

►An IP address is a 32-bit binary number:10101100000100001000000000010001

►The 32-bit binary number can be divided into four octets:

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►Each octet (or byte) can be represented in decimal:172 16 128 17

►The address can be written in dotted-decimal notation: 172.16.128.17

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IP Address ClassesNo. of bits 1 7 24

No. of bits 1 1 14 16

Class A: 0 Network no. Host no.

Cl B 1 0 N t k H t

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No. of bits 1 1 1 21 8

No. of bits 1 1 1 1 28

No. of bits 1 1 1 1 28

Class B: 1 0 Network no. Host no.

Class C: 1 1 0 Network no. Host no.

Class D:* 1 1 1 0 Address

Class E:** 1 1 1 1 Address

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►*Class D addresses are used for multicast groups. There is no need to allocate octets or bits to separate network and host addresses.

►**Class E addresses are reserved for research use only.

Class E: 1 1 1 1 Address

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IP Address Class Components

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Class A:

Class B:

Class C: NN

HH

1 Byte8 Bits

1 Byte8 Bits

1 Byte8 Bits

1 Byte8 Bits

HH HH

HH HH

HHNN NN

NN NN

NN

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– N = Network number assigned by ARIN– H = Host number assigned by administrator

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IP Address Range

IP Address ClassIP Address Class IP Address Range(First octet decimal value)

IP Address Range(First octet decimal value)

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Class AClass A

Class BClass B

Class CClass C

Class DClass D

Class EClass E

1-126 (00000001-01111110) *1-126 (00000001-01111110) *

128-191 (10000000-10111111)128-191 (10000000-10111111)

192-223 (11000000-11011111)192-223 (11000000-11011111)

224-239 (11100000-11101111)224-239 (11100000-11101111)

240-255 (11110000-11111111)240-255 (11110000-11111111)

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*127 (011111111) is a Class A address reserved for loopback testing and cannot be assigned to a network.

Determine the class based on the decimal value of the first octet.

Determine the class based on the decimal value of the first octet.

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Network Addresses

32 Bit

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172 0016

8 Bits1 Byte

8 Bits1 Byte

8 Bits1 Byte

8 Bits1 Byte

32 Bits

NETWORK HOST

N HN H

• • •

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Network Address (host bits = all zeros)

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Broadcast Address

32 Bits

NETWORK HOST

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172 0016

Network Address (host bits = all zeros)

8 Bits1 Byte

8 Bits1 Byte

8 Bits1 Byte

8 Bits1 Byte

NETWORK HOST

N HN H

• • •

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Broadcast Address (host bits = all ones)

N HN H

255 255172 16• • •

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Private IP Addresses

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ClassClass RFC 1918 Internal Address RangeRFC 1918 Internal Address Range

AA

BB

CC

10.0.0.0 to 10.255.255.25510.0.0.0 to 10.255.255.255

172.16.0.0 to 172.31.255.255172.16.0.0 to 172.31.255.255

192.168.0.0 to 192.168.255.255192.168.0.0 to 192.168.255.255

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IPv4 Address Allocation

Class C12 5%

Other Classes

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Class B 25%

Class B 25%

Class A 50%

Class A 50%

12.5%

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– With Class A and B addresses virtually exhausted, Class C addresses (12.5 percent of the total space) are left to assign to new networks.

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Copyleft © 2005, Binnur Kurt