Transitioning to Ipv6

introduction

Transitioning to IPv6

Quick Learning Module

Welcome to the “T r a n s i ti on i n g to I P v 6 ” Q u i ck L ea r n i n g M od u le. Q u i ck L ea r n i n g M od u les a r e b y te-s i z ed chu n k s of lea r n i n g tha t ex p la i n the p u r p os e, op er a ti on , a n d con f i g u r a ti on of C i s co techn olog y f ea tu r es . T hi s con ten t i s d es i g n ed to s u p p lemen t y ou r lea r n i n g ex p er i en ce a n d ex a m p r ep a r a ti on . I t i s n ot mea n t to r ep la ce a n y i n -cla s s r oom tr a i n i n g or on li n e lea r n i n g mod u les . We hop e tha t y ou en j oy thi s tr a i n i n g .

1 Objectives Upon completing this module, you should be able to ex plain the f or mat of I P v er sion 6 ( I P v 6 ) addr esses and the components that ar e r eq uir ed to r un I P v 6 , ex plain the impact of I P v 6 on netw or k r outing, and conf igur e basic I P v 6 par ameter s. T hese abilities include being able to meet these obj ectiv es: Explain the need for IPv6 D es c rib e the form at of the IPv6 addres s Explain the m ethods that are u s ed to as s ig n an IPv6 addres s Explain how IPv6 affec ts c om m on rou ting protoc ols and the nec es s ary m odific ations that y ou need to m ak e to thes e protoc ols Explain trans ition s trateg ies for im plem enting IPv6 C onfig u re IPv6 w ith R ou ting Inform ation Protoc ol next g eneration (R IPng ) throu g h an IP vers ion 4 (IPv4 ) netw ork

U p on comp leti n g thi s mod u le, y ou s hou ld b e a b le to ex p la i n the f or ma t of I P v 6 a d d r es s es a n d the comp on en ts tha t a r e r eq u i r ed to r u n I P v 6 , ex p la i n the i mp a ct of I P v 6 on n etw or k r ou ti n g , a n d con f i g u r e b a s i c I P v 6 p a r a meter s . T hes e a b i li ti es i n clu d e b ei n g a b le to meet thes e ob j ecti v es : •E x p la i n the n eed f or I P v 6 •D es cr i b e the f or ma t of the I P v 6 a d d r es s •E x p la i n the method s tha t a r e u s ed to a s s i g n a n I P v 6 a d d r es s •E x p la i n how I P v 6 a f f ects common r ou ti n g p r otocols a n d the n eces s a r y mod i f i ca ti on s y ou n eed to ma k e to thes e p r otocols •E x p la i n tr a n s i ti on s tr a teg i es f or i mp lemen ti n g I P v 6 •C on f i g u r e I P v 6 w i th R ou ti n g I n f or ma ti on P r otocol n ex t g en er a ti on (R I P n g ) thr ou g h a n I P v er s i on 4 (I P v 4 ) n etw or k

2 IPv4 and IPv6

Currently, there are approximately 1.3 billion usable IPv4 addresses available.

T he I P v 4 a d d r es s s p a ce p r ov i d es a p p r ox i ma tely 4 .3 b i lli on a d d r es s es . O f tha t a d d r es s s p a ce, a p p r ox i ma tely 3 .7 b i lli on a d d r es s es a r e a ctu a lly a s s i g n a b le; the other a d d r es s es a r e r es er v ed f or s p eci a l p u r p os es s u ch a s mu lti ca s ti n g , p r i v a te a d d r es s s p a ce, loop b a ck tes ti n g , a n d r es ea r ch. B a s ed on f i g u r es a s of J a n u a r y 1 , 2 0 0 7 , a b ou t 2 .4 b i lli on of thes e a v a i la b le a d d r es s es a r e cu r r en tly a s s i g n ed to ei ther en d u s er s or I n ter n et s er v i ce p r ov i d er s (I S P s ). T ha t lea v es r ou g hly 1 .3 b i lli on a d d r es s es s ti ll a v a i la b le f r om the I P v 4 a d d r es s s p a ce.

A n I P v 6 a d d r es s i s a 1 2 8 -b i t b i n a r y v a lu e, w hi ch ca n b e d i s p la y ed a s 3 2 hex a d eci ma l d i g i ts , a s s how n i n the f i g u r e. I t p r ov i d es 3 .4 ti mes 1 0 to the 3 8 th I P a d d r es s es . T hi s v er s i on of I P a d d r es s i n g s hou ld p r ov i d e s u f f i ci en t a d d r es s es f or f u tu r e I n ter n et g r ow th n eed s .

I n a d d i ti on to i ts techn i ca l a n d b u s i n es s p oten ti a l, I P v 6 of f er s a v i r tu a lly u n li mi ted s u p p ly of I P a d d r es s es . B eca u s e of i ts g en er ou s 1 2 8 -b i t a d d r es s s p a ce, I P v 6 g en er a tes a v i r tu a lly u n li mi ted s tock of a d d r es s es —en ou g h to a lloca te mor e tha n the en ti r e I P v 4 I n ter n et a d d r es s s p a ce to ev er y on e on the p la n et.

3 I P v6 A d va n ced F ea tu r es

L arg er addres s s pac e S im pler header Global reachability and flexibility R ou ting efficiency A g g reg ation P erform ance and forw arding rate M u ltihom ing s calability A u toconfig u ration N o broadcas ts P lu g -and-p lay N o check s u m s E nd-to-end w ithou t N A T E xtens ion headers R enu m bering F low labels M ob ility and s ec u rity T rans ition ric hnes s M obile I P R F C -com p liant D u al-s tack m ethod I P s ec m andatory ( or nativ e) 6 to4 and m anu al tu nnels for I P v 6 T rans lation

IPv6 is a powerful enhancement to IPv4. Several features in IPv6 offer functional improvements, includ ing the following : •Larger address space, including: •Improved g lob al reachab ility and flex ib ility •T he ag g reg ation of prefix es that are announced in routing tab les •M ultihoming to several ISPs •A utoconfig uration that can includ e d ata link lay er ad d resses in the ad d ress space •Plug -and -play options •Pub lic-to-private read d ressing end -to-end without N etwork A d d ress T ranslation ( N A T ) •Simplified mechanisms for ad d ress renumb ering and mod ification •A sim pler h eader, including: •B etter routing efficiency for performance and forward ing -rate scalab ility •N o b road casts and thus no potential threat of b road cast storms •N o req uirement for processing check sums •Simpler and more efficient ex tension head er mechanisms •F low lab els for per-flow processing with no need to open a transport inner pack et to id entify the various traffic flows •M o b ilit y and securit y , to help comply with mob ile IP and IP Security ( IPsec) stand ard s functionality . M ob ility enab les people with mob ile network d evices—many with wireless connectivity —to move around within network s. •M ob ile IP is an Internet E ng ineering T ask F orce ( IE T F ) stand ard that is availab le for b oth IPv4 and IPv6. T he stand ard enab les mob ile d evices to move without b reak s in estab lished network connections. B ecause IPv4 d oes not automatically provid e this k ind of mob ility , y ou must ad d it with ad d itional config urations. •In IPv6, mob ility is b uilt in, which means that any IPv6 nod e can use mob ility when necessary . T he routing head ers of IPv6 mak e mob ile IPv6 much more efficient for end nod es than mob ile IPv4. •IPsec is the IE T F stand ard for IP network security , availab le for b oth IPv4 and IPv6. A lthoug h the functionalities are essentially id entical in b oth environments, IPsec is mand atory in IPv6. IPsec is enab led on every IPv6 nod e and is availab le for use, mak ing the IPv6 Internet more secure. IPsec also req uires k ey s for each party , which implies a g lob al k ey d eploy ment and d istrib ution. •F inally , t ransit io n rich ness: T here are several way s to incorporate ex isting IPv4 capab ilities with the ad d ed features of IPv6. •O ne approach is to implement a d ual-stack method , with b oth IPv4 and IPv6 config ured on the interface of a network d evice. •T unneling is another techniq ue that should b ecome more prominent as the ad option of IPv6 g rows. T here is a variety of IPv6-over-IPv4 tunneling method s. Some method s req uire manual config uration, while others are d y namic. •C isco IO S R elease 1 2 .3 ( 2 ) T and later also includ e N etwork A d d ress T ranslation-Protocol T ranslation ( N A T -PT ) b etween IPv6 and IPv4. T his translation allows d irect communication b etween hosts that use d ifferent versions of the IP protocol.

4 I P v6 A d d r ess R ep r esen ta tio n

Format: x: x: x: x: x: x: x: x, w here x is a 1 6 -bit hexadecim al field. – C as e-ins ens itiv e for hexadecim al A , B , C , D , E , and F L eading z eros in a field are op tional. S u cces s iv e fields of z eros can be rep res ented as : : only once p er addres s . E x amp l e s : 2 0 3 1 : 0 0 0 0 : 1 3 0 F : 0 0 0 0 : 0 0 0 0 : 0 9 C 0 : 8 7 6 A : 1 3 0 B – C an be rep res ented as 2 0 3 1 : 0 : 1 3 0 f: : 9 c0 : 8 7 6 a: 1 3 0 b – C annot be rep res ented as 2 0 3 1 : : 1 3 0 f: : 9 c0 : 8 7 6 a: 1 3 0 b F F 0 1 : 0 : 0 : 0 : 0 : 0 : 0 : 1 F F 0 1 : : 1 0 : 0 : 0 : 0 : 0 : 0 : 0 : 1 : : 1 0 : 0 : 0 : 0 : 0 : 0 : 0 : 0 : : F F 0 1 : 0 : 0 : 0 : 0 : 0 : 0 : 1

C olon s s ep a r a te en tr i es i n a s er i es of 1 6 -b i t hex a d eci ma l f i eld s tha t r ep r es en t I P v 6 a d d r es s es . T he hex a d eci ma l d i g i ts A , B , C , D , E , a n d F tha t a r e r ep r es en ted i n I P v 6 a d d r es s es a r e n ot ca s e-s en s i ti v e.

I P v 6 d oes n ot r eq u i r e ex p li ci t a d d r es s s tr i n g n ota ti on . U s e the f ollow i n g g u i d eli n es f or I P v 6 a d d r es s s tr i n g n ota ti on s : •T he lea d i n g z er os i n a f i eld a r e op ti on a l, s o tha t 0 9 C 0 eq u a ls 9 C 0 a n d 0 0 0 0 eq u a ls 0 . •S u cces s i v e f i eld s of z er os ca n b e r ep r es en ted a s “: : ” on ly on ce i n a n a d d r es s . •A n u n s p eci f i ed a d d r es s i s w r i tten a s “: : ” b eca u s e i t con ta i n s on ly z er os . •U s i n g the “: : ” n ota ti on g r ea tly r ed u ces the s i z e of mos t a d d r es s es . F or ex a mp le, F F 0 1 : 0 : 0 : 0 : 0 : 0 : 0 : 1 b ecomes F F 0 1 : : 1 . •A n a d d r es s p a r s er i d en ti f i es the n u mb er of mi s s i n g z er os b y s ep a r a ti n g the tw o p a r ts a n d en ter i n g 0 u n ti l the 1 2 8 b i ts a r e comp lete. I f tw o “: : ” n ota ti on s a r e p la ced i n the a d d r es s , ther e i s n o w a y to i d en ti f y the s i z e of ea ch b lock of z er os .

5 I P v6 A d d r ess T y p es

Unicast – A d d r e ss is f o r a sing l e inte r f ace . – I P v 6 h as se v e r al ty p e s ( f o r e x am p l e , g l o b al , r e se r v e d , and l ink -l o cal ) . M u l ticast – O ne -to -m any . – E nab l e s m o r e e f f icie nt u se o f th e ne tw o r k . – Use s a l ar g e r ad d r e ss r ang e . A ny cast – O ne -to -ne ar e st ( al l o cate d f r o m u nicast ad d r e ss sp ace ) . – M u l tip l e d e v ice s sh ar e th e sam e ad d r e ss. – A l l any cast no d e s sh o u l d p r o v id e u nif o r m se r v ice . – S o u r ce d e v ice s se nd p ack e ts to any cast ad d r e ss. – R o u te r s d e cid e o n cl o se st d e v ice to r e ach th at d e stinatio n. – S u itab l e f o r l o ad b al ancing and co nte nt d e l iv e r y se r v ice s.

Broadcasting in IPv4 results in a number of problems. Broadcasting generates interrupts in every computer on th e netw ork and, in some cases, triggers malfunctions th at can completely h alt an entire netw ork . T h is disastrous netw ork event is k now n as a “broadcast storm.”

In IPv6 , broadcasting does not ex ist. IPv6 replaces broadcasts w ith multicasts and any casts. M ulticast enables efficient netw ork operation by using a number of functionally specific multicast groups to send req uests to a limited number of computers on a netw ork . T h e multicast groups prevent most of th e problems th at are related to broadcast storms in IPv4.

T h e range of multicast addresses in IPv6 is larger th an in IPv4. F or th e near future, allocation of multicast groups is not being limited.

IPv6 also defines a new ty pe of address k now n as an any cast address. A n any cast address identifies a list of devices or nodes; th erefore, an any cast address identifies multiple interfaces. A ny cast addresses are lik e a cross betw een unicast and multicast addresses. U nicast sends pack ets to one specific device w ith one specific address, and multicast sends a pack et to every member of a group. A ny cast addresses send a pack et to any one member of th e group of devices w ith th e any cast address assigned.

F or efficiency , a pack et th at is sent to an any cast address is delivered to th e closest interface—as defined by th e routing protocols in use—th at is identified by th e any cast address, so any cast can also be th ough t of as a “one-to-nearest” ty pe of address. A ny cast addresses are sy ntactically indistinguish able from global unicast addresses because any cast addresses are allocated from th e global unicast address space.

N ote th at th ere is little ex perience w ith w idespread, arbitrary use of Internet any cast addresses, and th ere are some k now n complications and h az ards w h en using th em in th eir full generality . U ntil more ex perience h as been gained and solutions h ave been agreed upon for th ose problems, th e follow ing restrictions are imposed on IPv6 any cast addresses: A n any cast address M U S T N O T be used as th e source address of an IPv6 pack et. A nd an any cast address M U S T N O T be assigned to an IPv6 h ost, th at is, it may be assigned to an IPv6 router only .

6 I P v6 U n ica st A d d r essin g

T hes e are ty pes of IPv6 u nic as t addres s es . – G lob al: S tarts w ith 2 0 0 0 : : / 3 and as s ig ned b y IA N A – R es erved: U s ed b y the IET F – Private: L ink loc al (s tarts w ith F E8 0 : : / 1 0 ) – L oopb ac k (: : 1 ) – U ns pec ified (: : ) A s ing le interfac e m ay b e as s ig ned m u ltiple IPv6 addres s es of any ty pe: u nic as t, any c as t, or m u ltic as t. IPv6 addres s ing ru les are c overed b y m u ltiple R F C s . – A rc hitec tu re defined b y R F C 4 2 9 1

T here are several b asic ty pes of IPv6 unicast ad d resses: g lob al, reserved , private ( includ ing link -local) , loopb ack , and unspecified .

T he IPv6 g lob al unicast ad d ress is eq uivalent to the IPv4 g lob al unicast ad d ress. A g lob al unicast ad d ress is an IPv6 ad d ress from the g lob al unicast prefix . T he structure of g lob al unicast ad d resses enab les the ag g reg ation of routing prefix es, which limits the numb er of routing tab le entries in the g lob al routing tab le. G lob al unicast ad d resses used on link s are ag g reg ated upward throug h org aniz ations and eventually to the ISPs.

T he IE T F reserves a portion of the IPv6 ad d ress space for various uses, b oth present and future. R eserved ad d resses represent 1 / 2 5 6th of the total IPv6 ad d ress space. Some of the other ty pes of IPv6 ad d resses come from this b lock .

A b lock of IPv6 ad d resses is set asid e for private ad d resses, j ust as is in IPv4. T hese private ad d resses are local only to a particular link or site and are never routed outsid e of a particular company network . Private ad d resses have a first octet value of “F E ” in hex ad ecimal notation, with the nex t hex ad ecimal d ig it b eing a value from 8 to F . T hese ad d resses are further d ivid ed into ty pes b ased on their scope. •T he concept of link -local ad d resses is new to IPv6. T hese ad d resses have a smaller scope than site-local ad d resses; they refer only to a particular phy sical link ( such as a phy sical network ) . R outers d o not forward d atag rams using link -local ad d resses, not even within an org aniz ation; they are only for local communication on a particular phy sical network seg ment. •T hese ad d resses are used for link communications such as automatic ad d ress config uration, neig hb or d iscovery , and router d iscovery . M any IPv6 routing protocols also use link -local ad d resses.

J ust as in IPv4, a provision is mad e for a special loopb ack IPv6 ad d ress for testing ; d atag rams sent to this ad d ress “loop b ack ” to the send ing d evice. H owever, in IPv6 there is j ust one ad d ress, not a whole b lock , for this function. T he loopb ack ad d ress is 0 : 0 : 0 : 0 : 0 : 0 : 0 : 1 , which is normally ex pressed using z ero compression as “: : 1 ”.

In IPv4, an IP ad d ress of all z eros has a special meaning ; it refers to the host itself, and is used when a d evice d oes not k now its own ad d ress. In IPv6, this concept is formaliz ed , and the all-z eros ad d ress ( 0 : 0 : 0 : 0 : 0 : 0 : 0 : 0 ) is named the “unspecified ” ad d ress. It is ty pically used in the source field of a d atag ram that is sent b y a d evice that seek s to have its IP ad d ress config ured . Y ou can apply ad d ress compression to this ad d ress; b ecause the ad d ress is all z eros, the ad d ress b ecomes j ust “: : ”.

7 I P v6 G l o ba l U n ica st ( a n d A n y ca st) A d d r esses

I P v 6 h as th e s ame ad d re s s f ormat f or g l ob al u n i c as t an d f or an y c as t ad d re s s e s . U s es a g lobal rou ting p refix—a s tru ctu re that enables ag g reg ation u p w ard, ev entu ally to the I S P . A s ing le interface m ay be as s ig ned m u ltip le addres s es of any typ e ( u nicas t, anycas t, and m u lticas t) . E v ery I P v 6 -enabled interface contains at leas t one loop back ( : : 1 / 1 2 8 ) and one link -local addres s . O p tionally, ev ery interface can hav e m u ltip le u niq u e local and g lobal addres s es .

G lob a l u n i ca s t a d d r es s es a r e d ef i n ed b y a g lob a l r ou ti n g p r ef i x , a s u b n et I D , a n d a n i n ter f a ce I D . T he I P v 6 u n i ca s t a d d r es s s p a ce en comp a s s es the en ti r e I P v 6 a d d r es s r a n g e, w i th the ex cep ti on of F F 0 0 : : / 8 (1 1 1 1 1 1 1 1 ), w hi ch i s u s ed f or mu lti ca s t a d d r es s es . T he cu r r en t g lob a l u n i ca s t a d d r es s a s s i g n men t b y the I n ter n et A s s i g n ed N u mb er s A u thor i ty (I A N A ) u s es the r a n g e of a d d r es s es tha t s ta r t w i th b i n a r y v a lu e 0 0 1 (2 0 0 0 : : / 3 ), w hi ch i s 1 / 8 of the tota l I P v 6 a d d r es s s p a ce a n d i s the la r g es t b lock of a s s i g n ed b lock a d d r es s es .

A d d r es s es w i th a p r ef i x of 2 0 0 0 : : / 3 (0 0 1 ) thr ou g h E 0 0 0 : : / 3 (1 1 1 ) a r e r eq u i r ed to ha v e 6 4 -b i t i n ter f a ce i d en ti f i er s i n the ex ten d ed u n i v er s a l i d en ti f i er (E U I )-6 4 f or ma t.

T he I A N A i s a lloca ti n g the I P v 6 a d d r es s s p a ce i n the r a n g es of 2 0 0 1 : : / 1 6 to the r eg i s tr i es .

T he g lob a l u n i ca s t a d d r es s ty p i ca lly con s i s ts of a 4 8 -b i t g lob a l r ou ti n g p r ef i x a n d a 1 6 -b i t s u b n et I D . I n d i v i d u a l or g a n i z a ti on s ca n u s e a 1 6 -b i t s u b n et f i eld k n ow n a s a “S u b n et I D ” to cr ea te thei r ow n loca l a d d r es s i n g hi er a r chy a n d to i d en ti f y s u b n ets . T hi s f i eld a llow s a n or g a n i z a ti on to u s e u p to 6 5 , 5 3 5 i n d i v i d u a l s u b n ets . F or mor e i n f or ma ti on , r ef er to R F C 3 5 8 7 , IPv6 Global Unicast Address Format, w hi ch r ep la ces R F C 2 3 7 4 .

8 L in k -L o ca l A d d r esses

L ink -local addres s es hav e a s cop e lim ited to the link and are dynam ically created on all I P v 6 interfaces by u s ing a s p ecific link -local p refix F E 8 0 : : / 1 0 and a 6 4 -bit interface identifier. L ink -local addres s es are u s ed for au tom atic addres s config u ration, neig hbor dis cov ery, and rou ter dis cov ery. L ink -local addres s es are als o u s ed by m any rou ting p rotocols . L ink -local addres s es can s erv e as a w ay to connect dev ices on the s am e local netw ork w ithou t needing g lobal addres s es . W hen com m u nicating w ith a link -local addres s , you m u s t s p ecify the ou tg oing interface becau s e ev ery interface is connected to F E 8 0 : : / 1 0 .

IPv6 is defined on most of th e current data link lay er protocols, including th e follow ing: •E th ernet* •PPP •H igh -L evel D ata L ink C ontrol ( H D L C ) •F D D I •T ok en R ing •A ttach ed R esource C omputer netw ork ( A R C net) •N onbroadcast multiaccess ( N BM A ) •A T M •F rame R elay •A nd IE E E 13 9 4

A n R F C describes th e beh avior of IPv6 in each of th ese specific data link lay ers, but C isco IO S softw are does not necessarily support all of th em. T h e data link lay er defines h ow IPv6 interface identifiers are created and h ow neigh bor discovery deals w ith data link lay er address resolution.

9 L a r g er A d d r ess S p a ce E n a bl es A d d r ess A g g r eg a tio n

2001:0410:0001::/48

2001:0410:0002::/48

A d d re s s ag g re g ati on p rov i d e s th e f ol l ow i n g b e n e f i ts : A g g reg ation of p refixes annou nced in the g lobal rou ting table E fficient and s calable rou ting I m p rov ed bandw idth and fu nctionality for u s er traffic

I P v 6 a lloca tes la r g e n u mb er s of a d d r es s es to I S P s a n d or g a n i z a ti on s . A n I S P a g g r eg a tes a ll of the p r ef i x es of i ts cu s tomer s i n to a s i n g le p r ef i x a n d a n n ou n ces the s i n g le p r ef i x to the I P v 6 I n ter n et. T he i n cr ea s ed a d d r es s s p a ce i s s u f f i ci en t to a llow or g a n i z a ti on s to d ef i n e a s i n g le p r ef i x f or thei r en ti r e n etw or k .

A g g r eg a ti on of cu s tomer p r ef i x es r es u lts i n a n ef f i ci en t a n d s ca la b le r ou ti n g ta b le. S ca la b le r ou ti n g i s n eces s a r y to ex p a n d b r oa d er a d op ti on of n etw or k f u n cti on s . S ca la b le r ou ti n g a ls o i mp r ov es n etw or k b a n d w i d th a n d f u n cti on a li ty f or u s er tr a f f i c tha t con n ects the v a r i ou s d ev i ces a n d a p p li ca ti on s .

I n ter n et u s a g e—b oth n ow a n d i n the f u tu r e—ca n i n clu d e the f ollow i n g elemen ts : •A la r g e i n cr ea s e i n the n u mb er of b r oa d b a n d con s u mer s w i th hi g h-s p eed con n ecti on s tha t a r e a lw a y s on •U s er s w ho s p en d mor e ti me on li n e a n d a r e g en er a lly w i lli n g to s p en d mor e mon ey on commu n i ca ti on s s er v i ces a n d hi g h-v a lu e s ea r cha b le of f er i n g s •H ome n etw or k s w i th ex p a n d ed n etw or k a p p li ca ti on s s u ch a s w i r eles s V oI P , home s u r v ei lla n ce, a n d a d v a n ced s er v i ces s u ch a s r ea l-ti me v i d eo on d ema n d (V oD ) •A n d ma s s i v e s ca la b le g a mes w i th g lob a l p a r ti ci p a n ts a n d med i a -r i ch e-lea r n i n g , p r ov i d i n g lea r n er s w i th on -d ema n d r emote la b s or la b s i mu la ti on s

10 A ssig n in g I P v6 G l o ba l U n ica st A d d r esses

S tatic as s ig nm ent – M anu al interfac e ID as s ig nm ent – EU I-64 interfac e ID as s ig nm ent D y nam ic as s ig nm ent S tateles s au toc onfig u ration D H C Pv6 (s tatefu l)

RouterX(config-if) ipv6 address 2001:DB8:2222:7272::72/64

RouterX(config) # in t erf ac e et h ern et 0 RouterX(config-if) # ipv6 address 2001:0DB8:0:1::/64 eu i-64

Interface id entifiers in IPv6 ad d resses are used to id entify interfaces on a link . T hey can also b e thoug ht of as the “host portion” of an IPv6 ad d ress. Interface id entifiers are req uired to b e uniq ue on a specific link . Interface id entifiers are alway s 64 b its and can b e d y namically d erived from a L ay er 2 med ia and encapsulation.

H ere are several way s to assig n an IPv6 ad d ress to a d evice: •Static assig nment using a manual interface ID •Static assig nment using an E U I-64 interface ID •Stateless autoconfig uration •D H C P for IPv6 ( D H C Pv6)

O ne way to statically assig n an IPv6 ad d ress to a d evice is to manually assig n b oth the prefix ( or network ) and interface ID ( or host) portion of the IPv6 ad d ress. T o config ure an IPv6 ad d ress on a C isco router interface and enab le IPv6 processing on that interface, use the ipv 6 address command in interface config uration mod e.

T he ex ample shows how to enab le IPv6 processing on the interface and config ure an ad d ress b ased on the d irectly specified b its.

A nother way to statically assig n an IPv6 ad d ress is to config ure the prefix portion of the IPv6 ad d ress and d erive the interface ID from the L ay er 2 M A C ad d ress of the d evice, k nown as the E U I-64 interface ID .

T o config ure an IPv6 ad d ress for an interface and enab le IPv6 processing on the interface using an E U I-64 interface ID in the low-ord er 64 b its of the ad d ress ( or host) , use the ipv 6 address eui-6 4 command in interface config uration mod e.

T he ex ample assig ns an IPv6 ad d ress to E thernet interface 0 and uses an E U I-64 interface ID in the low ord er 64 b its of the ad d ress.

A utoconfig uration, as the name implies, is a mechanism that automatically config ures the IPv6 ad d ress of a nod e. In IPv6, it is assumed that b oth PC s and non-PC d evices are connected to a network . T he autoconfig uration mechanism was introd uced to enab le plug -and -play network ing of these d evices and to help red uce ad ministrative overhead .

D H C P for IPv6 enab les D H C P servers to pass config uration parameters such as IPv6 network ad d resses to IPv6 nod es. It automatically allocates reusab le network ad d resses and ad d itional config uration with flex ib ility . T his protocol is a stateful counterpart to IPv6 stateless ad d ress autoconfig uration ( und er R F C 2 462 ) , and can b e used separately or concurrently with IPv6 stateless ad d ress autoconfig uration to ob tain config uration parameters.

11 IPv6 E U I-64 Int e r f ac e Ide nt i f i e r

Cisco can use the EUI-6 4 f or m at f or inter f ace id entif ier s. T his f or m at ex p and s the 4 8 -b it M A C ad d r ess to 6 4 b its b y inser ting “F F F E” into the m id d l e 1 6 b its. T o ind icate that the chosen ad d r ess is f r om a uniq ue Ether net M A C ad d r ess, the U/ L b it is set to 1 f or g l ob al scop e ( 0 f or l ocal scop e) .

T h e 6 4-bit interface identifier in an IPv6 address identifies a uniq ue interface on a link . A link is a netw ork medium over w h ich netw ork nodes communicate using th e data link lay er. T h e interface identifier can also be uniq ue over a broader scope. In many cases, an interface identifier is th e same as, or is based on, th e data link lay er ( or M A C ) address of an interface. A s in IPv4, a subnet prefix in IPv6 is associated w ith one link .

Interface identifiers in global unicast and oth er IPv6 address ty pes must be 6 4 bits long and can be constructed in th e 6 4-bit E U I-6 4 format. T h e E U I-6 4 format interface ID is derived from th e 48 -bit data link lay er ( M A C ) address by inserting th e h ex adecimal number F F F E betw een th e upper th ree by tes ( or th e O rganiz ational U niq ue Identifier [ O U I] field) and th e low er th ree by tes ( or serial number) of th e data link lay er address. T o indicate th at th e ch osen address is from a uniq ue E th ernet M A C address, th e seventh bit in th e h igh -order by te is set to 1 ( eq uivalent to th e IE E E G/ L bit) to indicate th e uniq ueness of th e 48 -bit address.

T h e interface identifier for stateless autoconfiguration in an E th ernet environment uses th e modified E U I-6 4 format. T h is format ex pands th e 48 -bit E th ernet M A C address format to a 6 4-bit version by inserting " F F F E " in th e middle of th e 48 bits. T h is creates a 6 4-bit version.

T h e seventh bit ( starting w ith th e leftmost bit as “1”) in an IPv6 interface identifier is referred to as th e U niversal/ L ocal bit, or U / L bit. T h is bit identifies w h eth er th is interface identifier is locally uniq ue on th e link or th at it is universally uniq ue. In th e case w h ere th e interface identifier is created from an E th ernet M A C address, it is assumed th at th e M A C address is universally uniq ue and, th erefore, th e interface identifier is universally uniq ue.

T h e rationale of th e U / L bit is for future use of th e upper-lay er protocols to uniq uely identify a connection, even in th e contex t of a ch ange in th e leftmost part of th e address. H ow ever, th is is not y et used.

T h e eigh th bit ( starting w ith leftmost bit as “1”) , also k now n as th e “G” bit, is a group/ individual bit for managing groups.

12 IPv6 Routing Protocols

IPv6 routing types – S ta tic – R IPng ( R F C 2 0 8 0 ) – O S PF v3 ( R F C 2 7 4 0 ) – IS -IS f or IPv6 – M P-B G P4 ( R F C 2 5 4 5 / 2 8 5 8 ) – E IG R P f or IPv6 T h e ipv6 unicast-r o uting c om m a nd is req uired to ena b l e IPv6 b ef ore a ny routing protoc ol is c onf igured .

I P v 6 u s es lon g es t-p r ef i x ma tch r ou ti n g j u s t li k e I P v 4 cla s s les s i n ter d oma i n r ou ti n g (C I D R ). M a n y of the common r ou ti n g p r otocols ha v e b een mod i f i ed to ha n d le lon g er I P v 6 a d d r es s es a n d d i f f er en t hea d er s tr u ctu r es . T he u p d a ted r ou ti n g p r otocols s how n i n the f i g u r e a r e cu r r en tly a v a i la b le.

Y ou ca n u s e a n d con f i g u r e I P v 6 s ta ti c r ou ti n g i n the s a me w a y tha t y ou w ou ld w i th I P v 4 . T her e i s a n I P v 6 -s p eci f i c r eq u i r emen t p er R F C 2 4 6 1 tha t a r ou ter mu s t b e a b le to d eter mi n e the li n k -loca l a d d r es s of ea ch of i ts n ei g hb or i n g r ou ter s to en s u r e tha t the ta r g et a d d r es s of a r ed i r ect mes s a g e i d en ti f i es the n ei g hb or r ou ter b y i ts li n k -loca l a d d r es s . T hi s r eq u i r emen t mea n s tha t u s i n g a g lob a l u n i ca s t a d d r es s a s a n ex t-hop a d d r es s w i th I P v 6 r ou ti n g i s n ot r ecommen d ed .

T he C i s co I O S g lob a l comma n d to en a b le I P v 6 i s ipv6 unicast-r o uting . Y ou mu s t en a b le I P v 6 u n i ca s t r ou ti n g b ef or e a n I P v 6 -ca p a b le r ou ti n g p r otocol, or a n I P v 6 s ta ti c r ou te, w i ll w or k .

13 R IPng ( R F C 2 0 8 0 )

S im il a r IPv4 f ea tures D istance v ector , r ad ius of 1 5 hop s, sp l it hor iz on, and p oison r ev er se B ased on R IP v 2 U pd a ted f ea tures f or IPv6 IP v 6 p r ef ix , nex t-hop IP v 6 ad d r ess Uses the m ul ticast g r oup F F 0 2 : : 9 , the al l -r ip -r outer s m ul ticast g r oup , as the d estination ad d r ess f or R IP up d ates Uses IP v 6 f or tr ansp or t N am ed R IP ng

R ou ti n g I n f or ma ti on P r otocol n ex t g en er a ti on (R I P n g ) i s a d i s ta n ce v ector r ou ti n g p r otocol w i th a li mi t of 1 5 hop s tha t u s es s p li t hor i z on a n d p oi s on r ev er s e to p r ev en t r ou ti n g loop s . R I P n g i n clu d es the f ollow i n g f ea tu r es : •I s b a s ed on a n d i s s i mi la r to I P v 4 R I P v er s i on 2 •U s es I P v 6 f or tr a n s p or t •I n clu d es the I P v 6 p r ef i x a n d n ex t-hop I P v 6 a d d r es s •U s es the mu lti ca s t g r ou p F F 0 2 : : 9 , the a ll-R I P -r ou ter s mu lti ca s t g r ou p , a s the d es ti n a ti on a d d r es s f or R I P u p d a tes •S en d s u p d a tes on U s er D a ta g r a m P r otocol (U D P ) p or t 5 2 1 •I s s u p p or ted b y C i s co I O S R elea s e 1 2 .2 (2 )T a n d la ter

14 IPv4 -to-IPv6 T ra nsition

IPv6 IPv4 IPv6 IPv6

Transition richness means: No fixed day to convert; no need to convert all at once D ifferent trans ition m ech anis m s are availab le – D u al s tack – M anu al tu nnel – 6 to4 tu nnel – I S A T A P tu nnel – T eredo tu nnel D ifferent com p atib ility m ech anis m s – P roxying and trans lation ( NA T -P T )

T h e transition from IPv4 does not req uire upgrades on all nodes at th e same time. M any transition mech anisms enable smooth integration of IPv4 and IPv6 . O th er mech anisms th at allow IPv4 nodes to communicate w ith IPv6 nodes are available. A ll of th ese mech anisms are applied to different situations.

T h e th ree most common tech niq ues to transition from IPv4 to IPv6 are as follow s: • D ual stack is an integration meth od w h ere th e node h as connectivity to both an IPv4 and IPv6 netw ork . A s a result, th e node and its corresponding routers h ave tw o protocol stack s. • T h ere are several tunneling tech niq ues available: • M anual IPv6 -over-IPv4 tunneling is an integration meth od w h ere an IPv6 pack et is encapsulated w ith in IPv4. T h is req uires dual-stack routers. • D y namic 6 to4 tunneling is a meth od th at automatically connects IPv6 islands th rough an IPv4 netw ork , ty pically th e Internet. T h e 6 to4 tunneling meth od dy namically applies a valid, uniq ue IPv6 prefix to each IPv6 island, enabling fast deploy ment of IPv6 in a corporate netw ork w ith out address retrieval from IS Ps or registries. • Intra-S ite A utomatic T unnel A ddressing Protocol ( IS A T A P) tunneling is an automatic overlay tunneling mech anism th at uses th e underly ing IPv4 netw ork as a link lay er for IPv6 . IS A T A P tunnels allow individual IPv4 or IPv6 dual-stack h osts w ith in a site to communicate w ith oth er such h osts on a virtual link , creating an IPv6 netw ork using th e IPv4 infrastructure. • T eredo tunneling is an IPv6 transition tech nology th at provides h ost-to-h ost automatic tunneling instead of gatew ay tunneling. It passes unicast IPv6 traffic w h en dual-stack ed h osts ( th at is, h osts th at are running both IPv6 and IPv4) are located beh ind one or multiple IPv4 N etw ork A ddress T ranslators. • Prox y ing and translation is a translation mech anism th at sits betw een an IPv6 netw ork and an IPv4 netw ork . T h e j ob of th e translator is to translate IPv6 pack ets into IPv4 pack ets and vice versa.

15 Cisco IOS Dual Stack IPv4

IPv6

D u al s tac k is an integ ration m ethod in w hic h a node has im plem entation and c onnec tivity to b oth an IPv4 and IPv6 netw ork .

D u a l s ta ck i s a n i n teg r a ti on method w her e a n od e ha s con n ecti v i ty to b oth a n I P v 4 a n d I P v 6 n etw or k , thu s the n od e ha s tw o s ta ck s . Y ou ca n con f i g u r e thi s on the s a me i n ter f a ce or on mu lti p le i n ter f a ces . F ea tu r es of the d u a l-s ta ck method a r e a s f ollow s : •A d u a l-s ta ck n od e choos es w hi ch s ta ck to u s e b a s ed on the d es ti n a ti on a d d r es s . A d u a l-s ta ck n od e s hou ld p r ef er I P v 6 w hen i t i s a v a i la b le. T he d u a l-s ta ck a p p r oa ch to I P v 6 i n teg r a ti on , i n w hi ch n od es ha v e b oth I P v 4 a n d I P v 6 s ta ck s , i s on e of the mos t common ly u s ed i n teg r a ti on method s . O ld I P v 4 -on ly a p p li ca ti on s con ti n u e to w or k a s b ef or e. N ew a n d mod i f i ed a p p li ca ti on s ta k e a d v a n ta g e of b oth I P la y er s . •A n ew a p p li ca ti on p r og r a mmi n g i n ter f a ce (A P I ) s u p p or ts b oth I P v 4 a n d I P v 6 a d d r es s es a n d D N S r eq u es ts . T hi s n ew A P I r ep la ces the “g et hos t b y n a me” a n d “g et hos t b y a d d r es s ” ca lls . A con v er ted a p p li ca ti on ca n ma k e u s e of b oth I P v 4 a n d I P v 6 . A n a p p li ca ti on ca n b e con v er ted to the n ew A P I w hi le s ti ll u s i n g on ly I P v 4 . •E x p er i en ce i n p or ti n g I P v 4 a p p li ca ti on s to I P v 6 s u g g es ts tha t, f or mos t a p p li ca ti on s , ther e i s a mi n i ma l cha n g e i n s ome loca li z ed p la ces i n s i d e the s ou r ce cod e. T hi s techn i q u e i s w ell k n ow n a n d ha s b een a p p li ed i n the p a s t f or other p r otocol tr a n s i ti on s . I t en a b les g r a d u a l a p p li ca ti on u p g r a d es , on e b y on e, to I P v 6 .

16 C isco IO S D ua l S ta ck ( C ont. )

IPv4: 192.168.99.1 IPv6: 3 f f e :b 0 0 :c 18:1::3

W h en b oth IPv4 a nd IPv6 a re c onf igured on a n interf a c e, th e interf a c e is c onsid ered d ua l -sta c k ed .

C i s co I O S S of tw a r e R elea s e 1 2 .2 (2 )T a n d la ter a r e I P v 6 -r ea d y . A s s oon a s y ou con f i g u r e b a s i c I P v 4 a n d I P v 6 on a n i n ter f a ce, i t i s d u a l-s ta ck ed a n d f or w a r d s I P v 4 a n d I P v 6 tr a f f i c. U s i n g I P v 6 on a C i s co I O S r ou ter r eq u i r es tha t y ou u s e the g lob a l con f i g u r a ti on comma n d ipv6 unicast-r o uting . T hi s comma n d en a b les f or w a r d i n g of I P v 6 d a ta g r a ms .

N ote tha t y ou mu s t con f i g u r e a ll i n ter f a ces tha t f or w a r d I P v 6 tr a f f i c w i th a n I P v 6 a d d r es s u s i n g the i n ter f a ce comma n d ipv6 ad d r e ss.

17 IP v 6 T un n e lin g

IPv6 IPv4 IPv6 IPv6

Tunneling is an integration method in which an IPv6 packet is encapsulated within another protocol, such as IPv4 . This method of encapsulation is IPv4 . Includes a 20-b y t e IP v 4 h eader w i t h no o p t i o ns and an IP v 6 h eader and p ay lo ad R eq ui r es dual-st ack r o ut er s

T u n n eli n g i s a n i n teg r a ti on method w her e a n I P v 6 p a ck et i s en ca p s u la ted w i thi n a n other p r otocol, s u ch a s I P v 4 . When I P v 4 en ca p s u la tes the I P v 6 p a ck et, a p r otocol ty p e of 4 1 i s s p eci f i ed i n the I P v 4 hea d er , a n d the p a ck et ha s the f ollow i n g cha r a cter i s ti cs : •I t i n clu d es a 2 0 -b y te I P v 4 hea d er w i th n o op ti on s a n d a n I P v 6 hea d er a n d p a y loa d . •I t r eq u i r es d u a l-s ta ck r ou ter s . T hi s p r oces s con n ects I P v 6 i s la n d s w i thou t n eed i n g to a ls o con v er t a n i n ter med i a r y n etw or k to I P v 6 . T u n n eli n g p r es en ts thes e tw o i s s u es : •T he ma x i mu m tr a n s mi s s i on u n i t (M T U ) i s ef f ecti v ely d ecr ea s ed b y 2 0 octets i f the I P v 4 hea d er d oes n ot con ta i n a n y op ti on a l f i eld . •A tu n n eled n etw or k i s of ten d i f f i cu lt to tr ou b les hoot. T u n n eli n g i s a n i n ter med i a te i n teg r a ti on a n d tr a n s i ti on techn i q u e tha t s hou ld n ot b e con s i d er ed a f i n a l s olu ti on . A n a ti v e I P v 6 a r chi tectu r e s hou ld b e the u lti ma te g oa l.

18 E nab l i ng IPv6 o n C i s c o R o u t e r s

RouterX(config)# ipv6 unicast-r o uting Enab l es IP v 6 tr af f ic f or w ar d ing

RouterX(config-if)# ipv6 ad d r e ss ipv6prefix/prefix-l en g t h e ui-64 Conf ig ur es the inter f ace IP v 6 ad d r esses

T her e a r e tw o b a s i c s tep s to a cti v a te I P v 6 on a r ou ter . F i r s t, I P v 6 tr a f f i c f or w a r d i n g mu s t b e a cti v a ted , then ea ch i n ter f a ce w her e I P v 6 i s r eq u i r ed mu s t b e con f i g u r ed .

B y d ef a u lt, I P v 6 tr a f f i c f or w a r d i n g i s d i s a b led on a C i s co r ou ter . T o a cti v a te I P v 6 tr a f f i c f or w a r d i n g b etw een i n ter f a ces , the g lob a l comma n d ipv6 unicast- r o uting mu s t b e con f i g u r ed . T hi s en a b les the f or w a r d i n g of u n i ca s t I P v 6 tr a f f i c.

I P v 6 i s en a b led on a p er -i n ter f a ce b a s i s .

T he ipv6 ad d r e ss comma n d con f i g u r es a g lob a l I P v 6 a d d r es s . T he li n k -loca l a d d r es s i s a u toma ti ca lly con f i g u r ed w hen a n a d d r es s i s a s s i g n ed to a n i n ter f a ce. Y ou mu s t s p eci f y the en ti r e 1 2 8 -b i t I P v 6 a d d r es s or u s e the 6 4 -b i t p r ef i x b y u s i n g the e ui-64 op ti on .

19 IPv6 A ddr e s s C o nf i g u r at i o n E x am p l e

Mac Address: 0060.3e47.1530

Y ou ca n comp letely s p eci f y the I P v 6 a d d r es s or comp u te the hos t i d en ti f i er (w hi ch i s the r i g htmos t 6 4 b i ts ) f r om the E U I -6 4 i d en ti f i er of the i n ter f a ce. I n thi s ex a mp le, the I P v 6 a d d r es s of the i n ter f a ce i s con f i g u r ed u s i n g the E U I -6 4 f or ma t.

A lter n a ti v ely , y ou ca n comp letely s p eci f y the en ti r e I P v 6 a d d r es s to a s s i g n a r ou ter i n ter f a ce a n a d d r es s u s i n g the ipv6 ad d r e ss comma n d i n i n ter f a ce con f i g u r a ti on mod e.

N ote tha t con f i g u r i n g a n I P v 6 a d d r es s on a n i n ter f a ce a u toma ti ca lly con f i g u r es the li n k -loca l a d d r es s f or tha t i n ter f a ce.

20 C o nf i g u r i ng and V e r i f y i ng R IPng f o r IPv6

RouterX(config)# ip v 6 router rip tag C reat es an d en t ers R I P ro u t er co n f i g u rat i o n m o de

RouterX(config-if)# ip v 6 rip tag ena b l e C o n f i g u res R I P o n an i n t erf ace

s h ow ip v 6 rip D i sp l ay s t h e st at u s o f t h e v ari o u s R I P p ro cesses

s h ow ip v 6 route rip S h o w s R I P ro u t es i n t h e I P v 6 ro u t e t ab l e

T hi s f i g u r e s how s ex a mp les of comma n d s y n ta x u s ed to con f i g u r e R I P n g . T he s y n ta x i s s i mi la r , i f n ot i d en ti ca l, to thei r I P v 4 cou n ter p a r ts .

F or R I P n g , i n s tea d of u s i n g the ne tw o r k comma n d to i d en ti f y w hi ch i n ter f a ces s hou ld r u n R I P n g , u s e the comma n d ipv6 r ip tag e nab l e i n i n ter f a ce con f i g u r a ti on mod e to en a b le R I P n g on a n i n ter f a ce. T he tag p a r a meter tha t y ou u s e f or the ipv6 r ip e nab l e comma n d mu s t ma tch the tag p a r a meter i n the ipv6 r o ute r r ip comma n d .

N ote tha t en a b li n g R I P on a n i n ter f a ce d y n a mi ca lly cr ea tes a “r ou ter r i p ” p r oces s , i f n eces s a r y .

21 R IPng f o r IPv6 C o nf i g u r at i o n E x am p l e

T he ex a mp le s how s a n etw or k of tw o r ou ter s . R ou ter Y i s con n ected to the d ef a u lt n etw or k . O n b oth r ou ter X a n d r ou ter Y , “R T 0 ” i s a ta g tha t i d en ti f i es the R I P n g p r oces s . R I P n g i s en a b led on the f i r s t E ther n et i n ter f a ce of r ou ter Y u s i n g the ipv6 r ip R T 0 e nab l e comma n d . R ou ter X s how s tha t R I P n g i s en a b led on b oth E ther n et i n ter f a ces u s i n g the ipv6 r ip R T 0 e nab l e comma n d .

22 Sum m ar y

IPv6 offers many additional benefits to IPv4, including a larger address sp ace, easier address aggregation, and integrated security. A n IPv6 address is 1 2 8 bits long and is made up of a 48 -bit global p refix , a 1 6-bit subnet ID , and a 64-bit interface identifier. T h ere are several w ays to assign IPv6 addresses: statical, stateless autoconfiguration, and D H C Pv6. C isco sup p orts all of th e maj or IPv6 routing p rotocols: R IPng, O S PF v3 , and E IG R P. T ransitioning from IPv4 to IPv6 req uires dual stack s, tunneling, and p ossibly N A T -PT . U se th e ipv6 unicast-r o uting command to enable IPv6 and th e ipv6 ad d r e ss ipv6-a d d r e s s / pr e f ix -l e n g t h command to assign interface addresses and enable an IPv6 routing p rotocol.

I n s u mma r y , IPv6 offers many additional benefits to IPv4, including a larger address sp ace, easier address aggregation, and integrated security.

A n IPv6 address is 1 2 8 bits long and is made up of a 48 -bit global p refix , a 1 6-bit subnet ID , and a 64-bit interface identifier.

T h ere are several w ays to assign IPv6 addresses: statical, stateless autoconfiguration, and D H C Pv6.

C isco sup p orts all of th e maj or IPv6 routing p rotocols, including R IPng, O S PF v3 , and E IG R P.

T ransitioning from IPv4 to IPv6 req uires dual stack s, tunneling, and p ossibly N A T -PT .

U se th e ipv6 unicast-r o uting command to enable IPv6 and th e ipv6 ad d r e ss command to assign interface addresses and enable an IPv6 routing p rotocol.

23 Q uiz Q ue stion 1

Which address type from IPv4 was eliminated in IPv6?

a) u n i c as t b ) m u l t i c as t c ) e v e r y c as t d ) b r o ad c as t

The correct answer is d.

24 Q uiz Q ue stion 2

H ow can you condense consecu tive sets of z eros in an IPv6 address?

a) w i t h t h e “: : : ” s y m b o l b ) b y e l i m i n at i n g l e ad i n g z e r o s c ) b y r e p l ac i n g f o u r c o n s e c u t i v e z e r o s w i t h a s i n g l e z e r o d ) w i t h t h e “: : ” s y m b o l

The correct answer is d.

25 T ha n k y ou f or ta k i n g the T r a n s i ti on i n g to I P v 6 Q u i ck L ea r n i n g M od u le.