Nghien Cuu IPv4 & IPv6

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Li cm nChng em xin chn th nh cm n thy gio thc

s H Mnh o trc tip hng dn chng em xydng v ho n th nh n.

Chng em xin chn th nh cm n cc thy ctrong trung tm cng ngh cao Bch Khoa HTC to

mi iu kin gip chng em ho n th nh n n y.

H Ni, thng 06 nm 2005

Hc vinNguyn Quc Tun

T Ho ng AnhNguyn Th Thu

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Chng 1 Nhng hn ch ca IPv4 v c im ca IPv6

1.1 Nhng hn ch ca IPv4:- Giao thc tng mng trong b giao thc TCP/IP hin ti ang l

IPv4 (Internet- working protocol verision 4). IPv4 cung cp truyn thnhost-to-host gia nhng h thng trn Internet. Mc d IPv4 c thit kkh tt, s thng i thng tin tin trin t lc khi u IPv4 v o nhnm 1970, nhng IPv4 c nhng s thiu ht khin cho n khng ng bcho s pht trin nhanh ca Internet, gm nhng th sau:

+ IPv4 c 2 level cu trc a ch (netid v hostid) phn nhm v olp (A, B, C, D v E). S s dng nhng a ch l khng hiu qu. Vnh khi cos mt t chc c cp cho 1 a ch lp A, 16 triu a cha ch c phn phi duy nht cho t chc s dng. Nu 1 t chc cp cho 1 a ch lp C, mt khc ch c 256 a ch c phn phchc, y khng phi l mt s . Cng vy, nhiu triu a ch b ltrong nhm D v E. Phng thc phn a ch n y dng ht nhng ch ca IPv4, v mau chng s khng cn a ch n o cn cp cho bmt h thng mi n o mun kt ni v o Internet. Mc d sch lc subnetv supernet gim bt nhng vn v a ch, nhng subnet v sup l m cho ng truyn tr ln kh khn hn.

+ Internet phi thch nghi c vi s chuyn giao audio v videothi gian thc. Loi chuyn giao n y yu cu nhng sch lc tr ho n tnht v s t trc ca t i nguyn khng c cung cp trong thit k.

+ Internet phi thch nghi c vi s m ho v s chng nhn cad liu cho mt s ng dng. Khng mt s m ho v s chng nhn n oc cung cp trong IPv4.- khc phc thiu st trn IPv6 c bit n nh l IPng (Interworking Protocol, next generation), c xng v nay l mt chun.

1.2 c im ca IPv6:- Trong IPv6 giao thc Internet c ci tin mt cch rng ln thnghi c s pht trin khng bit trc c ca Internet. nh dng v d i ca nhng a ch IP cng c thay i vi nhng gi nh dNhng giao thc lin quan, nh ICMP cng c ci tin. Nhng giao thkhc trong tng mng nh ARP, RARP, IGMP hoc b xo hoc trong giao thc ICMPv6. Nhng giao thc tm ng nh RIP, OSPF cnc ci tin kh nng thch nghi vi nhng thay i n y. Nhng chuygia truyn thng d on l IPv6 v nhng giao thc lin quan vi n snhanh chng thay th phin bn IP hin thi.Th h mi ca IP hay IPv6 c nhng u im nh sau:

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1.2.1 Khng gian a ch ln IPv6 c a ch ngun v ch d i 128 bt. Mc d 128 bt c th

hn 3,4*1038 t hp, khng gian a ch ca IPv6 c thit k d phngln cho php phn b a ch v mng con t trc xng sng internet tng mng con trong mt t chc. Cc a ch hin ang phn b

dng ch chim mt lng nh v vn cn tha rt nhiu a ch sncho s dng trong tng lai. Vi khng gian a ch ln n y, cc k thubo tn a ch nh NAT s khng cn cn thit na.

1.2.2 a ch phn cp, h tng nh tuyn hiu qu Cc a ch to n cc ca Ipv6 c thit k to ra mt h t

nh tuyn hiu qa, phn cp v c th tng qut ho da trn s phnthng thy ca cc nh cung cp dch v Internet (ISP) trn thc t. Trmng Internet da trn IPv6, cc router mng xng sng (backbone) c s mc trong bng nh tuyn nh hn rt nhiu.

1.2.3 Khun dng header n gin ho - Header ca IPv6 c thit k gim chi ph n mc ti thiun y t c bng cch chuyn cc trng khng quan trng v cc trngla chn sang cc header m rng c t pha sau ca IPv6 headKhun dng header mi ca IPv6 to ra s x l hiu qu hn ti ccrouter.

1.2.4 T cu hnh a ch n gin cho vic cu hnh cc trm, IPv6 h tr c vic t c

hnh a ch stateful nh kh nng cu hnh server DHCP v t cu hn

ch stateless (khng c server DHCP). Vi t cu hnh a ch dstateless, cc trm trong lin kt t ng cu hnh chng vi a ch IPca lin kt (a ch cc b lin kt) v vi a ch rt ra t tin t qung b bi router cc b. Thm tr nu khng c router, cc trm trncng mt lin kt c th t cu hnh chng vi cc a ch cc b lin kgiao tip vi nhau m khng phi thit lp cu hnh th cng.

1.2.5 Kh nng xc thc v bo mt an ninh Tch hp sn trong thit k IPv6 gip trin khai d d ng m b

tng tc ln nhau gia cc nt mng.

1.2.6 H tr tt hn v cht lng dch v QoS Lu thng trn mng c phn th nh cc lung cho php s l mc

u tin khc nhau ti cc router.

1.2.7 H tr tt hn tnh nng di ng

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Kh nng di ng MobileIP tn dng c cc u im ca IPv6 svi IPv4.

1.2.8 Kh nng m rng Thit k ca IPv6 c d phng cho s pht trin trong tng lai

thi d d ng m rng khi c nhu cu.1.3 Cu trc a ch IPv61.3.1 a ch IPv6

Mt a ch gm c 16 byte, l 128 bt d i. Kiu k hiu dchm trong h m 16 ( Hexadecimal Colon Notation):

l m cho nhng a ch tr nn c th c c nhiu hn, IPtrnh by r trong kiu k hiu du 2 chm trong h m 16. Trong kihiu n y, 128 bt c chia th ng 8 phn, mi phn rng 2 byte. 2 byttrong kiu k hi h m 16 yu cu 4 ch s trong h m 16 n y. Vcho nn a ch gm c 32ch s trong h m 16 vi mi 4 ch s mtc mt du : chm(Hnh1)

128 bt= 16 bytes= 32ch s trong h m 16

FDEC : : 7654 3210 ADBF 2922 FFFF

111111101111101100..111111111111

Hnh 1: a ch IP phin bn 6 ( IPv6 Address)

*Su rt gn:+ Mc d l a ch IP ngay c khi trong nh dnh h s m 16, vd i, nhiu ch s 0 trong mt a ch.

Th d: 1080:0000:0000:0000:0008:0800:200C:417A

Do c ch nn a ch c dng biu din d d ng hn cc lch dng n y. Ta khng cn vit cc s 0 u cc nhm, nhng nhng s0 bn trong th khng th xo.

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Cha rt gn

1080:0000:0000:0000:0008:0800:200C:417A rt gn

1080: 0: 0: 0: 8: 800:200C:417A

Hnh 2 : S rt gn a ch (Abbreviated Address)

Hn na ta c th s dng k hiu :: ch mt chui cc s 0. Tnhin k hiu trn ch c s dng mt ln trong mt a ch. a chc d i c nh, ta c th tnh c s cc bit 0 m k hiu biu d

Ta c th p dng u hay cui a ch. Cch vit n y c bit c lbiu din cc a ch multicast, loopback hay cc i ch cha ch

Cha rt gn

1080: 0: 0: 0: 8: 800:200C:417A rt gn

1080::8:800:200C:417A

Hnh 3: S rt gn a ch c s 0 lin tip(Abbreviated Address with consecutive zeros)

Vic khi phc li s rt gn a ch l rt n gin: thm s 0 vcho n khi nhn c a ch nguyn bn (4 ch s trong 1 phn , 32s trong mt a ch)

IPv6 cho php gim ln a ch v c biu din theo k phCIDR.V d: Biu din mng con c d i tin t 80 bt:

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1080:0:0:0:8::/80

Hnh 4 : a ch CIDR ( CIDR Address)

1.3.2 Khng gian a chKhng gian a ch c d i ln hn IPv4( 128 bt so vi 32 bt)

cung cp khng gian a ch ln hn rt nhiu. Trong khi khng gianch 32 bt ca IPv4 cho php khong 4 t a ch, khng gian a chth c khong 6.5*10

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a ch trn mi mt vung b mt tri t. a IPv6 128 bt c chia th nh cc min phn cp theo trt t trn InternN to ra nhiu mc phn cp v linh hot trong a ch ho v nh tuhin khng c trong IPv4.

Khng gian a ch c nhiu mc ch khc nhau. Ngi ta thia ch IP chia khng gian a ch th nh 2 phn, vi phn u ckiu tin t. Phn gi tr tin t n y cho bt mc ch ca a ch. m s c thit k sao cho khng c m s n o ging phn u ca bt km s n o khc. Do khng c s nhp nhng khi mt a ch c trkiu tin t c th d d ng xc nh c. Hnh 5 cho chng ta thy dca a ch IPv6:

128 bt

Bin Bin

Kiu tin t Phn cn li ca a ch

Hnh 5 : Cu trc a ch ( Address Structure)

Khng gian IPv6 c chia trn c s cc bt u trong a chTrng c d i thay i bao gm cc bt u tin trong a ch gi l t nh dng ( Format Prefix) FP. C ch phn b a ch nh sau:

Phn b Tin t nh dng T l trong khng gian

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a chD phng 0000 0000 1/256D phng 0000 0001 1/256D phng cho a ch NSAP 0000 001 1/128D phng cho a ch IPX 0000 010 1/128

Cha cp pht 0000 011 1/128Cha cp pht 0000 1 1/32Cha cp pht 0001 1/16a ch da trn v tr a l (Hin loi b)

001 1/8

Cha cp pht 101 1/8Cha cp pht 110 1/8Cha cp pht 1110 1/16Cha cp pht 1111 0 1/32Cha cp pht 1111 10 1/64

Cha cp pht 1111 110 1/128Cha cp pht 1111 1110 0 1/512a ch lin kt cc b 1111 1110 10 1/1024a ch site cc b 1111 1110 11 1/1024a ch multicast 1111 1111 1/256

Hnh 6 : C ch phn b a ch

1.3.3 Cp pht a ch IPv61.3.3.1 a ch unicast trn c s ngi cung cp

a ch trn c s ngi cung cp c s dng chung bi 1 hosbnh thng nh 1 a ch unicast. nh dng a ch c din t nh

128 bits

8 bits

3 bits 5 bits

ProviderIndentifler

SubscriberIndentifler

SubnetIndentifler

NodeIndentifler

010 Registry

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Hnh 7: a ch trn c s ngi cung cp (Provider-based Address)

Nhng trng cho a ch ngi dng trn c s cung cp nh sau :+ Chng thc kiu (Type indentifier): Trng 3 bt n y nh ngha

nhng a ch nh l 1 a ch trn c s ngi cung cp.+ Chng thc ng k (Registry indentifier) : Trng 5 bt n y

trnh b y chi nhnh ng k a ch. Hin thi th c 3 trung tm c nh ngha:

RIPE- NCC (m 01000): Ti Chu u.INTERNIC (m 11000): Ti Bc M.APNIC (m 101