Chapter 3 IPv6 Addressing At the end of this chapter,you should be able to do the following: ■Describe the IPv6 address space,and state why the address length of128 bits was chosen. ■Describe IPve6 address syntax,including zero suppression and compression and prefixes. ■Enumerate and describe the function of the different types of unicast IPve6 addresses. ■Describe the format of multicast IPv6 addresses. ■Describe the function of anycast IPve6 addresses. ■Describe how IPve6 interface identifiers are determined. Describe how to perform bit-level subnetting on the subnet identifier portion of a unicast IPv6 address prefix. List and compare the different addressing concepts between IPv4 addresses and IPv6 addresses. The IPv6 Address Space The most obvious distinguishing feature of Internet Protocol version 6 (IPv6)is its use of much larger addresses.The size of an address in IPv6 is 128 bits,a bit-string that is four times longer than the 32-bit IPv4 address.A 32-bit address space allows for 232,or 4,294,967,296, possible addresses.A 128-bit address space allows for 2128,or 340,282,366,920,938,463,463. 374,607,431,768,211,456(3.4×1038or340 undecillion),possible addresses. In the late 1970s,when the IPv4 address space was designed,it was unimaginable that it could ever be exhausted.However,the administrative procedures that defined address alloca- tion did not anticipate the recent explosion of hosts on the Internet.The IPv4 address space was thus consumed to the point that,by 1992,it was clear a replacement would be necessary. With IPv6,it is even more difficult to conceive that the IPv6 address space will ever be con- sumed.To help put this number in perspective,a128-bit address space provides6.65×1023 addresses for each square meter of the Earth's surface. It is important to remember that the decision to make the IPv6 address 128 bits in length was not so that every square meter of the Earth could have6.65×1023 addresses.Rather,the relatively large size of the IPv6 address is designed to be divided into hierarchical unicast routing domains that reflect the topology of the modern-day Internet.The use of 128 bits allows for multiple levels of hierarchy and flexibility in designing hierarchical unicast addressing and routing that is currently lacking on the IPv4-based Internet. 49￾           ! "#$%& '( !() * #*)    ))+ ,- . /0123450 670 89:; <==3011 1><20? <@= 16<60 A7B 670 <==3011 C0@D67 EF GHI 5461 A<1 27E10@J . /0123450 89:; <==3011 1B@6<K? 4@2CL=4@D M03E 1L>>30114E@ <@= 2EN>30114E@ <@= >30F4K01O . P@LN03<60 <@= =0123450 670 FL@264E@ EF 670 =4FF030@6 6B>01 EF L@42<16 89:; <==301101O . /0123450 670 FE3N<6 EF NLC642<16 89:; <==301101J . /0123450 670 FL@264E@ EF <@B2<16 89:; <==301101J . /0123450 7EA 89:; 4@603F<20 4=0@64F4031 <30 =0603N4@0=O . /0123450 7EA 6E >03FE3N 546QC0:0C 1L5@0664@D E@ 670 1L5@06 4=0@64F403 >E364E@ EF < L@42<1689:; <==3011 >30F4KO . R416 <@= 2EN><30 670 =4FF030@6 <==30114@D 2E@20>61 506A00@ 89:S <==301101 <@= 89:; <==301101O TU    VWXY Z[\ ]^_` ^abc^d_ ec_`cfgdc_[cfg h\i`dj\ ^h kf`\jf\` lj^`^m^n b\j_c^f o pklboq c_ c`_ d_\ ^h ]dm[ nijg\j ieej\__\_J Z[\ _cr\ ^h if ieej\__ cf klbo c_ stu ac`_v i ac`w_`jcfg `[i` c_ h^dj `c]\_ n^fg\j `[if `[\ xtwac` klby ieej\__J z xtwac` ieej\__ _{im\ inn^|_ h^j txtv ^j yvt}yv}o~vt}ov {^__can\ ieej\__\_J z stuwac` ieej\__ _{im\ inn^|_ h^j tstuv ^j xyvtutvxoov}tv}xuvyoxvyoxv x~yvo~vyxsv~ouvtssvy€o pxJy  sxu ^j xy dfe\mcnnc^fqv {^__can\ ieej\__\_J kf `[\ ni`\ s}~_v |[\f `[\ klby ieej\__ _{im\ |i_ e\_cgf\ev c` |i_ dfc]igcfian\ `[i` c` m^dne \b\j a\ \‚[id_`\eJ ƒ^|\b\jv `[\ ie]cfc_`ji`cb\ {j^m\edj\_ `[i` e\hcf\e ieej\__ inn^miw `c^f ece f^` if`cmc{i`\ `[\ j\m\f` \‚{n^_c^f ^h [^_`_ ^f `[\ kf`\jf\`J Z[\ klby ieej\__ _{im\ |i_ `[d_ m^f_d]\e `^ `[\ {^cf` `[i`v a„ s}}tv c` |i_ mn\ij i j\{nim\]\f` |^dne a\ f\m\__ij„J …c`[ klbov c` c_ \b\f ]^j\ echhcmdn` `^ m^fm\cb\ `[i` `[\ klbo ieej\__ _{im\ |cnn \b\j a\ m^fw _d]\eJ Z^ [\n{ {d` `[c_ fd]a\j cf {\j_{\m`cb\v i stuwac` ieej\__ _{im\ {j^bce\_ oJo€  stx ieej\__\_ h^j \im[ _†dij\ ]\`\j ^h `[\ ‡ij`[ˆ_ _djhim\J k` c_ c]{^j`if` `^ j\]\]a\j `[i` `[\ e\mc_c^f `^ ]i‰\ `[\ klbo ieej\__ stuac`_ cf n\fg`[ |i_ f^` _^ `[i` \b\j„ _†dij\ ]\`\j ^h `[\ ‡ij`[ m^dne [ib\ oJo€  stx ieej\__\_J Ši`[\jv `[\ j\ni`cb\n„nijg\ _cr\ ^h `[\ klbo ieej\__ c_ e\_cgf\e `^ a\ ecbce\e cf`^ [c\jijm[cmin dfcmi_` j^d`cfg e^]icf_ `[i` j\hn\m` `[\ `^{^n^g„ ^h `[\ ]^e\jfwei„ kf`\jf\`J Z[\ d_\ ^h stu ac`_ inn^|_ h^j ]dn`c{n\ n\b\n_ ^h [c\jijm[„ ife hn\‚cacnc`„ cf e\_cgfcfg [c\jijm[cmin dfcmi_` ieej\__cfg ife j^d`cfg `[i` c_ mdjj\f`n„ nim‰cfg ^f `[\ klbywai_\e kf`\jf\`J