TCP/IP Protocol Suite1Chapter 4Objectives Upon completion you will be able to:IP Addresses:Classful Addressing•Understand IPv4 addresses and classes•Identify the class of an IP address•Find the network address given an IP address•Understand masks and how to use them•Understand subnets and supernetsTCP/IP Protocol Suite24.1 INTRODUCTIONThe identifier used in the IP layer of the TCP/IP protocol suite to identify each device connected to the Internet is called the Internet address or IP address. An IP address is a 32-bit addressthat uniquely and universally defines the connection of a host or a router to the Internet. IP addresses are unique. They are unique in the sense that each address defines one, and only one, connection to the Internet. Two devices on the Internet can never have the same address. The topics discussed in this section include:Address SpaceNotationTCP/IP Protocol Suite3An IP address is a 32-bit address.Note:TCP/IP Protocol Suite4The IP addresses are unique.Note:TCP/IP Protocol Suite5The address space of IPv4 is232or 4,294,967,296.Note:TCP/IP Protocol Suite6Figure 4.1Dotted-decimal notationTCP/IP Protocol Suite7The binary, decimal, and hexadecimal number systems are reviewed in Appendix B.Note:TCP/IP Protocol Suite8ChangethefollowingIPaddressesfrombinarynotationtodotted-decimalnotation.a.10000001 00001011 00001011 11101111b. 11000001 10000011 00011011 11111111c.11100111 11011011 10001011 01101111d.11111001 10011011 11111011 00001111Example1SolutionWereplaceeachgroupof8bitswithitsequivalentdecimalnumber(seeAppendixB)andadddotsforseparation:a.129.11.11.239 b. 193.131.27.255c.231.219.139.111 d.249.155.251.15TCP/IP Protocol Suite9ChangethefollowingIPaddressesfromdotted-decimalnotationtobinarynotation.a.111.56.45.78b.221.34.7.82c.241.8.56.12d.75.45.34.78Example2SolutionWereplaceeachdecimalnumberwithitsbinaryequivalent:a.01101111 00111000 00101101 01001110b.11011101 00100010 00000111 01010010c.11110001 00001000 00111000 00001100d.01001011 00101101 00100010 01001110TCP/IP Protocol Suite10Findtheerror,ifany,inthefollowingIPaddresses:a.111.56.045.78b.221.34.7.8.20c.75.45.301.14d.11100010.23.14.67Example3Solutiona.There are no leading zeroes in dotted-decimal notation (045).b.We may not have more than four numbers in an IP address.c.In dotted-decimal notation, each number is less than or equalto 255; 301 is outside this range.d.A mixture of binary notation and dotted-decimal notation is notallowed.TCP/IP Protocol Suite11ChangethefollowingIPaddressesfrombinarynotationtohexadecimalnotation.a.10000001000010110000101111101111b.11000001100000110001101111111111Example4SolutionWereplaceeachgroupof4bitswithitshexadecimalequivalent(seeAppendixB).Notethathexadecimalnotationnormallyhasnoaddedspacesordots;however,0X(or0x)isaddedatthebeginningorthesubscript16attheendtoshowthatthenumberisinhexadecimal.a.0X810B0BEF or 810B0BEF16b.0XC1831BFF or C1831BFF16TCP/IP Protocol Suite124.2 CLASSFUL ADDRESSINGIP addresses, when started a few decades ago, used the concept of classes. This architecture is called classful addressing. In the mid-1990s, a new architecture, called classless addressing, was introduced and will eventually supersede the original architecture. However, part of the Internet is still using classful addressing, but the migration is very fast. The topics discussed in this section include:Recognizing ClassesNetid and HostidClasses and BlocksNetwork AddressesSufficient InformationMaskCIDR NotationAddress DepletionTCP/IP Protocol Suite13Figure 4.2Occupation of the address spaceTCP/IP Protocol Suite14Table 4.1Addresses per classTCP/IP Protocol Suite15Figure 4.3Finding the class in binary notationTCP/IP Protocol Suite16Figure 4.4Finding the address classTCP/IP Protocol Suite17Howcanweprovethatwehave2,147,483,648addressesinclassA?Example5SolutionInclassA,only1bitdefinestheclass.Theremaining31bitsareavailablefortheaddress.With31bits,wecanhave231or2,147,483,648addresses.TCP/IP Protocol Suite18Findtheclassofeachaddress:a.00000001 00001011 00001011 11101111b.11000001 10000011 00011011 11111111c.10100111 11011011 10001011 01101111d.11110011 10011011 11111011 00001111Example6SolutionSee the procedure in Figure 4.4.a.The first bit is 0. This is a class A address.b.The first 2 bits are 1; the third bit is 0. This is a class C address.c.The first bit is 0; the second bit is 1. This is a class B address.d.The first 4 bits are 1s. This is a class E address..TCP/IP Protocol Suite19Figure 4.5Finding the class in decimal notationTCP/IP Protocol Suite20Findtheclassofeachaddress:a.227.12.14.87b.193.14.56.22c.14.23.120.8d.252.5.15.111e.134.11.78.56Example7Solutiona.Thefirstbyteis227(between224and239);theclassisD.b.Thefirstbyteis193(between192and223);theclassisC.c.Thefirstbyteis14(between0and127);theclassisA.d.Thefirstbyteis252(between240and255);theclassisE.e.Thefirstbyteis134(between128and191);theclassisB.TCP/IP Protocol Suite21InExample5weshowedthatclassAhas231(2,147,483,648)addresses.Howcanweprovethissamefactusingdotted-decimalnotation?Example8SolutionTheaddressesinclassArangefrom0.0.0.0to127.255.255.255.Weneedtoshowthatthedifferencebetweenthesetwonumbersis2,147,483,648.Thisisagoodexercisebecauseitshowsushowtodefinetherangeofaddressesbetweentwoaddresses.Wenoticethatwearedealingwithbase256numbershere.Eachbyteinthenotationhasaweight.Theweightsareasfollows(seeAppendixB):See Next SlideTCP/IP Protocol Suite222563,2562,2561,2560Example8 (continued)Last address: 127 ×2563+ 255 ×2562+ 255 ×2561 + 255 ×2560= 2,147,483,647First address: = 0Nowtofindtheintegervalueofeachnumber,wemultiplyeachbytebyitsweight:Ifwesubtractthefirstfromthelastandadd1totheresult(rememberwealwaysadd1togettherange),weget2,147,483,648or231.TCP/IP Protocol Suite23Figure 4.6Netid and hostidTCP/IP Protocol Suite24Millions of class A addresses are wasted.Note:TCP/IP Protocol Suite25Figure 4.7Blocks in class ATCP/IP Protocol Suite26Figure 4.8Blocks in class BTCP/IP Protocol Suite27Many class B addresses are wasted.Note:TCP/IP Protocol Suite28Figure 4.9Blocks in class CTCP/IP Protocol Suite29The number of addresses in class C is smaller than the needs of most organizations.Note:TCP/IP Protocol Suite30Class D addresses are used for multicasting; there is only one block in this class.Note:TCP/IP Protocol Suite31Class E addresses are reserved for future purposes; most of the block is wasted.Note:TCP/IP Protocol Suite32In classful addressing, the network address (the first address in the block) is the one that is assigned to the organization. The range of addresses can automatically be inferred from the network address.Note:TCP/IP Protocol Suite33Giventhenetworkaddress17.0.0.0,findtheclass,theblock,andtherangeoftheaddresses.Example9SolutionTheclassisAbecausethefirstbyteisbetween0and127.Theblockhasanetidof17.Theaddressesrangefrom17.0.0.0to17.255.255.255.TCP/IP Protocol Suite34Giventhenetworkaddress132.21.0.0,findtheclass,theblock,andtherangeoftheaddresses.Example10SolutionTheclassisBbecausethefirstbyteisbetween128and191.Theblockhasanetidof132.21.Theaddressesrangefrom132.21.0.0to132.21.255.255.TCP/IP Protocol Suite35Giventhenetworkaddress220.34.76.0,findtheclass,theblock,andtherangeoftheaddresses.Example11SolutionTheclassisCbecausethefirstbyteisbetween192and223.Theblockhasanetidof220.34.76.Theaddressesrangefrom220.34.76.0to220.34.76.255.TCP/IP Protocol Suite36Figure 4.10Masking conceptTCP/IP Protocol Suite37Figure 4.11AND operationTCP/IP Protocol Suite38Table 4.2 Default masksTCP/IP Protocol Suite39The network address is the beginning address of each block. It can be found by applying the default mask to any of the addresses in the block (including itself). It retains the netid of the block and sets the hostid to zero.Note:TCP/IP Protocol Suite40Giventheaddress23.56.7.91,findthebeginningaddress(networkaddress).Example12SolutionThedefaultmaskis255.0.0.0,whichmeansthatonlythefirstbyteispreservedandtheother3bytesaresetto0s.Thenetworkaddressis23.0.0.0.TCP/IP Protocol Suite41Giventheaddress132.6.17.85,findthebeginningaddress(networkaddress).Example13SolutionThedefaultmaskis255.255.0.0,whichmeansthatthefirst2bytesarepreservedandtheother2bytesaresetto0s.Thenetworkaddressis132.6.0.0.TCP/IP Protocol Suite42Giventheaddress201.180.56.5,findthebeginningaddress(networkaddress).Example14SolutionThedefaultmaskis255.255.255.0,whichmeansthatthefirst3bytesarepreservedandthelastbyteissetto0.Thenetworkaddressis201.180.56.0.TCP/IP Protocol Suite43Note that we must not apply the default mask of one class to an address belonging to another class.Note:TCP/IP Protocol Suite444.3 OTHER ISSUESIn this section, we discuss some other issues that are related to addressing in general and classful addressing in particular. The topics discussed in this section include:Multihomed DevicesLocation, Not NamesSpecial AddressesPrivate AddressesUnicast, Multicast, and Broadcast AddressesTCP/IP Protocol Suite45Figure 4.12Multihomed devicesTCP/IP Protocol Suite46Table 4.3 Special addressesTCP/IP Protocol Suite47Figure 4.13Network addressTCP/IP Protocol Suite48Figure 4.14Example of direct broadcast addressTCP/IP Protocol Suite49Figure 4.15Example of limited broadcast addressTCP/IP Protocol Suite50Figure 4.16Examples of “this host on this network”TCP/IP Protocol Suite51Figure 4.17Example of “specific host on this network”TCP/IP Protocol Suite52Figure 4.18Example of loopback addressTCP/IP Protocol Suite53Table 4.5 Addresses for private networksTCP/IP Protocol Suite54Multicast delivery will be discussed in depth in Chapter 15.Note:TCP/IP Protocol Suite55Table 4.5 Category addressesTCP/IP Protocol Suite56Table 4.6 Addresses for conferencingTCP/IP Protocol Suite57Figure 4.19Sample internetTCP/IP Protocol Suite584.4 SUBNETTING AND SUPERNETTINGIn the previous sections we discussed the problems associated with classful addressing. Specifically, the network addresses available for assignment to organizations are close to depletion. This is coupled with the ever-increasing demand for addresses from organizations that want connection to the Internet. In this section we briefly discuss two solutions: subnetting and supernetting.The topics discussed in this section include:SubnettingSupernettingSupernet MaskObsolescenceTCP/IP Protocol Suite59IP addresses are designed with two levels of hierarchy.Note:TCP/IP Protocol Suite60Figure 4.20A network with two levels of hierarchy (not subnetted)TCP/IP Protocol Suite61Figure 4.21A network with three levels of hierarchy (subnetted)TCP/IP Protocol Suite62Figure 4.22Addresses in a network with and without subnettingTCP/IP Protocol Suite63Figure 4.23Hierarchy concept in a telephone numberTCP/IP Protocol Suite64Figure 4.24Default mask and subnet maskTCP/IP Protocol Suite65Whatisthesubnetworkaddressifthedestinationaddressis200.45.34.56andthesubnetmaskis255.255.240.0?Example15SolutionWe apply the AND operation on the address and the subnet mask.Address ➡11001000 00101101 00100010 00111000Subnet Mask ➡11111111 11111111 11110000 00000000Subnetwork Address ➡11001000 00101101 00100000 00000000.TCP/IP Protocol Suite66Figure 4.25Comparison of a default mask and a subnet maskTCP/IP Protocol Suite67Figure 4.26A supernetworkTCP/IP Protocol Suite68In subnetting, we need the first address of the subnet and the subnet mask to define the range of addresses.In supernetting, we need the first address of the supernet and the supernet mask to define the range of addresses.Note:TCP/IP Protocol Suite69Figure 4.27Comparison of subnet, default, and supernet masksTCP/IP Protocol Suite70The idea of subnetting and supernetting of classful addresses is almost obsolete.Note: