Copyleft © 2005, Binnur Kurt
Transcript of 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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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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►WAN►Physical topology►Logical topology
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WWW Request-Responserk
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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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Network
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Data Link
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Why a Layered Network Model?
►Reduces complexityApplication
Presentation
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Presentation
Session
Transport
Network
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►Simplifies teaching and learningData Link
Physical
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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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Data Link
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The Seven Layers of the OSI Model
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
f li ti l
Session
Transport
Network
Data Link
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for application layerPhysical
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The Seven Layers of the OSI Model
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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The Seven Layers of the OSI Model
Network Process to Applications
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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Transport
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Data Link
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►Establishes, maintains and terminates virtual circuits
►Provides reliability through fault detection and recovery information flow control
Physical
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The Seven Layers of the OSI Model
Network Process to Applications
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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The Seven Layers of the OSI Model
Network Process to Applications
Data Representation
Application
Presentation
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Access to Media
End-to-End Connections
Data Delivery
Interhost CommunicationSession
Transport
Network
Data Link
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Access to Media►Defines how data is formatted for
transmission and how access to the network is controlled
Physical1
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The Seven Layers of the OSI Model
Network Process to Applications
Data Representation
Application
Presentation
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End-to-End Connections
Data Delivery
Access to Media
Interhost CommunicationSession
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Network
Data Link
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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
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HDR = header
Bits
User DataUser Data
User DataUser DataL2
HDRL3
HDRL4
HDRL5
HDRL6
HDRL7
HDR FCS
L7HDR
L6HDR
L5HDR
L4HDR
L3HDRNetwork
Data Link
Physical
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Data De-EncapsulationReceiver
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Presentation
Session
Transport
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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
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HDR = header
Bits
User DataUser Data
User DataUser DataL2
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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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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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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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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Fund
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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
PresentationPresentation
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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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PresentationPresentation
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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Fund
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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
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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.