ĐỒ Án ipv6_dung

8/2/2019 N IPV6_DUNG

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Chng 1: ii thiu hung v h

SVTH: V Th Thy Dung_Lp 08B3 1

LI NI U

S pht trin ca khoa hc k thut trn th gii t c nhng thnh

tu to ln trn nhiu lnh vc khc nhau. Trong phi k n l s pht trin

nhanh chng ca cng ngh ch to in t v vi in t to ra c nhng

thit b mng, my tnh vi kh nng x l ngy cng cao. i lin vi n l s

pht trin rt nhanh ca mng Internet ton cu. Mng Internet to ra mt

mi trng hot ng ton cu cho tt c mi ngi tham gia, gn nh xa i

bin gii gia cc quc gia, thu ngn li khong cch a l.

Mt trong nhng vn quan trng m k thut mng trn th gii ang phi

nghin cu gii quyt l i mt vi s pht trin vi tc qu nhanh ca

mng li Internet ton cu. S pht trin ny cng vi s tch hp dch v,

trin khai nhng dch v mi, kt ni nhiu mng vi nhau, nh mng di ng

vi mng Internet t ra vn thiu ti nguyn dng chung. Vic s dng

h thng a ch hin ti cho mng Internet l IPv4 s khng th p ng ni spht trin ca mng li Internet ton cu trong thi gian sp ti v kho a ch

IPv4 chnh thc cn kit sau 30 nm s dng v chng ta ang phi tn

dng nhng di IP cui cng cn st li. Nhm gii quyt vn ny, IPv6

c ra i vi mc ch thay th hon ton v khc phc cc nhc im ca

IPv4.

Do em la chn ti Nghin cu v trin khai IPv6 cho doanh nghipva v nh cho ti n tt nghip ca mnh

V hiu r hn v cng ngh IPv6 em xin p dng kt qu tm kim,

hc hi ca mnh trin khai h thng IPv6 cho cng ty TNHH Vnh Phan

Ni dung n cp n mt s vn cn nghin cu: chng giao

thc TCP/IP, a ch IPv4/IPv6, cu trc, phng php nh a ch, cch thc

s dng trn Internet v cc vn trin khai IPv6 - IPv4.

B cc bn bo co n c chia ra lm 2 phn ln:


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Phn 1: Nghin cu v IPv6

Chng 1: Gii thiu v IPv6

Chng 2: Cu trc a ch IPv6

Chng 3: Trin khai mng IPv6

Phn 2: Trin khai IPv6 cho cng ty TNHH Vnh Phan

Chng 1:

Chng 2:

Chng 3:

hn : NHN CU V V6

CHNG 1 : GII THIU CHUNG VA CH IP

1.1 Khi qut v TC/1.1.1 Khi nim chung v TCP/IP

TCP/IP l vit tt ca Transmission Control Protocol (Giao thc iu khin

truyn thng)/ Internet Protocol (Giao thc Internet).

Giao thc TCP/IP c pht trin t mng ARPANET v Internet v c

dng nh giao thc mng v vn chuyn trn mng Internet. TCP

(Transmission Control Protocol) l giao thc thuc tng vn chuyn v IP

(Internet Protocol) l giao thc thuc tng mng ca m hnh OSI. H giao

thc TCP/IP hin nay l giao thc c s dng rng ri nht lin kt cc

my tnh v cc mng.

Hin nay cc my tnh ca hu ht cc mng c th s dng giao thc

TCP/IP lin kt vi nhau thng qua nhiu h thng mng vi k thut khc

nhau. Giao thc TCP/IP thc cht l mt h giao thc cho php cc h thng

mng cng lm vic vi nhau thng qua vic cung cp phng tin truyn

thng lin mng.

TCP/IP khng ch gm 2 giao thc m thc t n l tp hp ca nhiu giao

thc. Chng ta gi l 1 h giao thc hay b giao thc (Suite Of Protocols).

TCP/IP l mt b giao thc c thit k t hai mc tiu chnh:


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- Cho php truyn thng qua cc ung dy ca mng rng (WideArea NetworkWAN).

- Cho php truyn thng gia cc mi trng a dng.Do hiu c ci gc ca cc giao thc gip ta hiu cs quan trng

ca chng trong cc mng ngy nay.

Mth thng mng l tp hp ca nhiu my tnh hoc cc thit b tng

t, chng c th lin lc vi nhau thng qua mt trung gian truyn ti

Trong phm vi mt h thng mng, cc yu cu v d liu t mt my tnh

c chuyn qua b phn trung gian (c th l dy cp mng hoc ng in

thoi) ti mt my tnh khc.

Mt my tnh tng tc vi th gii thng qua mt hoc nhiu ng dng.

Nhng ng dng ny thc hin cc nhim v c th v qun l d liu ra v

vo. Nu my tnh l mt phn ca h thng mng, th mt trong s cc ng

dng trn s c th giao tip vi cc ng dng trn cc my tnh khc thuc

cng h thng mng. B giao thc mng l mt h thng cc quy nh chung

gip xc nh qu trnh truyn d liu phc tp. D liu i t ng dng trnmy ny, qua phn cng v mng ca my, ti b phn trung gian v n ni

nhn, thng qua phn cng ca my tnh ch ri ti ng dng.

Ccgiao thc TCP/IP c vai tr xc nh qu trnh lin lc trong mng v

quan trng hn c l nh ngha hnh dng ca mt n v d liu v nhng

thng tin cha trong n my tnh ch c th dch thng tin mt cch chnh

xc. TCP/IP v cc giao thc lin quan to ra mt h thng hon chnh qun lqu trnh d liu c x l, chuyn v nhn trn mt mng s dng TCP/IP.

1.1.2 Cu trc b giao thc TCP/IPTrc khi xem xt cc thnh phn ca TCP/IP, chng ta nn bt u bng

cch tm hiu qua nhim v ca mt h thng giao thc. Mt h thng giao

thc nh TCP/IP phi m bo kh nng thc hin nhng cng vic sau:

- Ct thng tin thnh nhng gi d liu c th d dng i quab phn truynti trung gian.
http://npower.vn/1647/chuyen-gia-he-thong-mang-va-bao-mat-quoc-te-hdsmhttp://npower.vn/1647/chuyen-gia-he-thong-mang-va-bao-mat-quoc-te-hdsmhttp://npower.vn/1647/chuyen-gia-he-thong-mang-va-bao-mat-quoc-te-hdsmhttp://npower.vn/1647/chuyen-gia-he-thong-mang-va-bao-mat-quoc-te-hdsmhttp://npower.vn/tag/giao-thuc-tcp/http://npower.vn/tag/giao-thuc-tcp/http://npower.vn/tag/giao-thuc-tcp/http://npower.vn/1647/chuyen-gia-he-thong-mang-va-bao-mat-quoc-te-hdsm


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- Tng tc vi phn cng ca adapter mng.- Xc nh a ch ngun v ch: My tnh gi thng tin i phi

c th xc nh c ni gi n. My tnh ch phi nhn ra

u l thng tin gi cho mnh.- nh tuyn: H thng phi c kh nng hng d liu ti cc

tiu mng, cho d tiu mng ngun v ch khc nhau v mt vt

l.

Kim tra li, kim sot truyn thngv xc nhn: i vi mt phng tin

truyn thng tin cy, my tnh gi v nhn phi xc nh v c th sa cha li

trong qu trnh vn chuyn d liu.Chp nhn d liu t ng dng v truyn n ti mng ch.

c th thc hin cc cng vic trn, TCP/IP c chia thnh nhiu lp

ring bit, theo l thuyt, hot ng c lp vi nhau. Mi lp c chc nng v

nhim v ring trong h thng mng.

Network Access: Cung cp giao din tng tc vi mng vt l. Formatd liu cho b phn truyn ti trung gian v to a ch d liu cho cctiu mng da trn a ch phn cng vt l. Cung cp vic kim tra li

trong qu trnh truyn d liu.

Lp nternet: Cung cp a ch logic, c lp vi phn cng, d liuc th lt qua cc tiu mng c cu trc vt l khc nhau. Cung cp

chc nng nh tuyn giao lu lng giao thng v h tr vic vn

chuyn lin mng. Thut ng lin mng c dng cp n cc

mng rng ln hn, kt ni t nhiu LAN. To s gn kt gia a ch

vt l v a ch logic.


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Hnh 1.1: M hnh TCP/ IP

Lp Transport: Gip kim sot lung d liu, kim tra li v xc nhncc dch v cho lin mng. ng vai tr giao din cho cc ng dng

mng.

LpApplication: Cung cp cc ng dng gii quyt s c mng, vnchuyn file, iu khin t xa, v cc hot ng Internet. ng thi h

tr Giao din Lp trnh ng dng (API) mng, cho php cc chng

trnh c thit k cho mt h iu hnh no c th truy cp mng.


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1.1.3 So snh TCP/IP v OSI

Hnh 1.2: So snh m hnh OSI v TCP/IP

So vi TCP/IP th OSI chia nhim v ca lp ng dng (Application) thnh

3 phn lp: Application, Presentation v Sesion. Lp Network Access cng

c tch thnh 2 lp Data Link v Physical. Vic chia nh chc nng lm

tng thm s phc tp, nhng ng thi cng to ra s linh hot cho cc nh

pht trin.

By lp ca m hnh OSI nh sau:

Lp Physical: Chuyn i d liu sang cc dng xung in, i qua bphn truyn ti trung gian v gim st qu trnh truyn d liu.

Lp Data Link: Cung cp giao din cho b iu hp mng, duy tr kt

ni logic cho tiu mng.

Lp Network: H tr a ch logic v nh tuyn. Lp Transport: Kim tra li v kim sot vic lu chuyn lin mng. Lp Sesion:Thit lp cc khu vc cho cc ng dng tng tc gia cc

my tnh.

Lp Presentation: Dch d liu sang mt dng tiu chun, qun l vicm ho v nn d liu.


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LpApplication: Cung cp giao din cho cc ng dng; h tr ng dnggi file, truyn thng

1.2 Cu tr h 1.2.1 Thnh phn v khun dng ca a ch IP

a ch IP ang c s dng hin ti ( IPv4) c 32 bit chia thnh 4 Octet

( mi Octet c 8 bit tng ng 1 byte), cch m u t tri qua phi t

bit 1 cho n bit 32. Cc Octet cch bit nhau bng mt du chm (.).

* a ch biu hin dng bit nh phn:

xyxyxyxy. xyxyxyxy. xyxyxyxy. xyxyxyxy

x, y = 0 hoc 1.

Hnh 1.3: Khun dng tiu h v4

* a ch biu hin dng thp phn: xxx.xxx.xxx.xxx

V d:

146.123.110.224

Dng vit y ca a ch IP l 3 con s trong tng Octet.

a ch IP thng thy trn thc t c th l 53.143.10.2 nhng dng y

l: 053.143.010.002

Bao gm c 3 thnh phn chnh.- Bit nhn dng lp (Class bit), phn bit a ch lp no.


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- a ch ca mng ( Net ID).- a ch ca my ch ( Host ID).

Class bit Net ID Host ID

Bit 1...32

Tn l a ch my ch nhng thc t khng ch c my ch m tt c cc trm

lm vic, cc cng truy nhp, v..v.. u cn c a ch nhn dng.

1.2.2 nh a ch IP.Mt b nh tuyn s dng a ch IP chuyn tip gi tin t mng ngun

ti mng ch. Gi tin phi ch ra c a ch mng ngun v mng ch. Khi

mt gi c nhn ti b nh tuyn, n s xc nh a ch mng ch v xc

nh ng i ca gi tin v chuyn tip gi tin qua cng tng ng. Mi a

ch IP cng gm c 2 phn: nhn dng a ch mng- ch ra mng, v nhn

dng a ch host - ch ra host. Mi octet u c th chia thnh nhng nhm a

ch mng khc nhau, qu trnh chia a ch c th c thc hin theo m hnhphn cp.

Cc a ch c thc hin theo m hnh phn cp bi n cha nhiu mc

khc nhau. Mt a ch IP thc hin 2 ch s v a ch mng v a ch host


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trong cng mt a ch. a ch ny phi l duy nht, bi khi thc hin mt a

ch trng lp s dn n nhng vn v nh tuyn. Phn u l a ch mng

(hay a ch ca h thng), phn th 2 l a ch host trong mng.

Hnh 1.4: M hnh phn p h


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a ch lp S mng S my trn tng mng

A 126* 16,777,216

B 16,384 65,535

C 2,097,152 254

D (Multicast) N/A N/A

a ch lp Bit nhndng

Di a ch S Bt dng phn cho mng

Class A 0 0127* 8

Class B 10 128191 16

Class C 110 192223 24

Class D 1110 224239 28


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Hnh 1.5: Cu tr lp h

a ch IP c chia thnh cc lp, A, B, C, D, E. Hin ti dng ht lp

A, B v gn ht lp C, cn lp D vE. T chc Internet ang dnh cho mc

ch khc khng phn, nn chng ta ch nghin cu 3 lp u.Qua cu trc cc lp a ch IP chng ta c nhn xt sau:

- Bit nhn dng l nhng bit u tin: ca lp A l 0, ca lp B l10, ca lp C l 110.

- Lp D c 4 bit u tin nhn dng l 1110, cn lp E c 5 bitu tin nhn dng l 11110.

- a ch lp A: a ch mng t v a ch my ch trn tngmng nhiu.

- a ch lp B: a ch mng va phi v a ch my ch trntng mng va phi.

- a ch lp C: a ch mng nhiu v a ch my ch trn tngmng t.

thc hin nhng mng vi quy m khc nhau, trc ht ta phi hiu c

c ch phn lp trong mng, a ch IP c chia thnh nhng nhm c gi

l nhng lp. Cc nhm ban u c gi l a ch phn lp y . Mi a

ch IP bao gm 32 bit c chia thnh 4 phn, mi phn 8 bit v s th t ca

cc bit s dng cho vic xc nh a ch mng v a ch host ty theo lp m

n thuc v.

Lp Athc hin trong nhng mng ln c kh nng h tr trn 16 triu

my. Ch bao gm octet u tin c s dng ch ra a ch mng, 3 octet

cn li s dng xc nh a ch ca host trong mng.


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Hnh 1.6: Cu tr lp A

Bit u tin ca lp A lun bng 0. s thp nht ca octet u tin c th th

hin l 0, v gi tr ln nht l 127. Tuy nhin gi tr 0 v 127 ca octet u

tin khng c s dng trong vic nh a ch mng, do tt c cc a ch

mng ca lp A s thc hin gi tr t 1 ti 126 ca octet u tin.

h lp Bc thit k h tr nhng nhu cu cho nhng mng ln.a ch lp B s dng 2 trong s 4 octet u tin lm a ch mng, 2 octet cn

li c s dng ch ra a ch host.

Hnh 1.7: Cu tr lp B

Hai bit u tin ca octet u tin ca mt a ch thuc v lp B lun l 10,

6 bit cn li ca octet u tin c th thay i l 0 hoc 1. Do gi tr nh

nht ca octet u tin ca mt a ch lp B s l 10000000 = 128, gi tr ln


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nht s l 10111111 = 191. Bt c a ch no c gi tr ca octet u tin nm

trong khong t 128 191 u l nhng a ch mng ca lp B.

h lp Ccng c quy lut tng t c thc hin, gi tr 3 bit u tin

ca mt a ch lp C lun l 110.Do gi tr nh nht ca octet u tin camt a ch lp C c th l 11000000 = 192, gi tr ln nht l 11011111 =

223. Nu mt a ch mng c gi tr ca octet u tin ri vo trong khong

191223 th l mt a ch IP thuclp C. Lp C thc hin 3 octet l a

ch mng cn 1 octet cn li c s dng lm a ch host. N c kh nng h

tr 254 a ch host cho mi mng thuc v lp C.

Hnh 1.8: Cu tr lp C

h lp Dc to ra to kh nng v a ch multicast. Mt a ch

IP multicast l mt a ch c kh nng thc hin vic truyn thng tin ti mt

nhm cc my trm vi a ch IP unicast. Do , mt my trm khi s dng

a ch multicast c kh nng truyn ng thi mt gi tin ti nhiu ngi

nhn.

Bn bit u tin ca mt a ch IP ca lp D lun l 1110. Do octet u

tin ca mt a ch mng thuc v lp C c gi tr nh nht l: 11100000 =

224 v gi tr ln nht s l 11101111 = 239.

h lp E thc hin trong phng th nghim phc v mc ch nghin

cu. Bn bit u tin ca mt a ch ca lp E l 1111. Do khong gi tr

ca octet u tin ca mt a ch lp E s l: 240 255.


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1.3 Khun dng gi tin Version IP-V4: Khi gi tin ti b nh tuyn, b nh tuyn s phn tch

nu thy phin bn c hn th b nh tuyn s hy b gi tin v thng

bo cho trm ngun bit.

Header length: di ca gi tin tnh theo n v 32 bit. Type of service:

Kiu dch v c s dng trong tiu gi tin IP ch ra quan h u

tin cho vic chuyn cc gi tin, thng thng cc gi tin IP c x l theo

nguyn tc FIFO, cc bit 0,1,1 trong trng kiu dch v ch ra cc thng tin v

tr, thng lng v tin cy. Total length: di ton b ca gi tin Max 216=64 KB, thng thng

ngn hn.

ID:s nh danh ca gi tin. Nu 1 gi tin phi phn thnh nhiu mnh truyn i th tt c cc mnh phi c cng nh danh.

Hnh 1.9: Khun dng gi tin v4

Flag:1 bit d tr Offset:Cho bit v tr ca mnh tin trong gi tin, n v tnh l 8 byte


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Time to live (TTL):Thi gian sng ca gi tin. Trng ny c 8 bit banu tnh n v l giy, vy thi gian gi tin c php tn ti trn mng

l:

2

8

=256 giy > 4 pht

Trong thc t trng ny cha s bc nhy chnh l s b nh tuyn m

gi tin c php i qua. C mi ln gi tin qua mt b nh tuyn th TTL s

tr i 1 v khi bng 0 th gi tin s b hy v thng bo cho trm ngun. y l

gii php iu khin tc nghn.

Protocol:Cho bit giao thc c s dng tng trn.-Nu tng giao vn l TCP th c m l 6.

-Nu tng giao vn l UDP th c m l 17.

-Nu l ICMP th c m l 1.

Heder checksum:Kim tra li cho u gi tin. Soure Address:a ch ngun. Destination Address:a ch ch.Cc a ch ny c dng nh ng trn mng Internet nn cn gi l

IP address. a ch di 32 bit c chia thnh 4 byte, mi byte c th hin

bng mt s thp phn v cch nhau bi du chm.

Option and padding: La chn.- Record Route: ghi li a ch ca tt c cc b nh tuyn m gi

tin i qua. di ca trng la chn ny do trm ngun quynh. Nu s b nh tuyn m gi tin i qua qu nhiu th a

ch ca cc b nh tuyn sau s khng c ghi vo gi tin.

- Time Stamp (nhn thi gian): ghi li thi gian m gi tin i quab nh tuyn. C 3 cch ghi:

Khi gi tin i qua b nh tuyn, ghi li danh sch thi giangi tin qua b nh tuyn.

Ghi a ch IP v thi gian tng ng khi gi tin i qua.


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Trm ngun s ghi sn mt s a ch cn o thi gian vgi tin ti b nh tuyn c a ch tng ng th s c

ghi thi gian vo.

1.4 ii php nh tuyn theo h 1.4.1 Cc phn t c bn ca mt h thng nh tuyn.

B nh tuyn l mt thit b lp 3 trong m hnh OSI 7 lp. N c hai chc

nng c bn l nh tuyn v chuyn mch gi tin IP t u vo n u ra.

Qu trnh nh tuyn l qu trnh tp hp cc thng tin v cu trc topo mng

nhm to ra mt bng nh tuyn. Qu trnh chuyn mch gi tin l sao chp

mt gi t mt giao din u vo ti mt giao din u ra thch hp da trnthng tin cha trong bng chuyn tip gi. Bt k h thng nh tuyn no u

cn 4 phn t c bn thc hin qu trnh nh tuyn v chuyn mch gi tin

l:

- Cc phn mm nh tuyn.- B phn x l gi.- Mt ma trn chuyn mch.- Card ng truyn.

Bn phn t c bn ny cu thnh mt b nh tuyn theo cu trc nh hnh

v.

B x l chnh thi hnh phn mm nh tuyn, phn mm nh tuyn ny

thc hin cc chc nng nh tuyn v duy tr cc thng tin v cu trc mng

Internet thng qua cc giao thc nh tuyn. Ma trn chuyn mch thc hin

hot ng chuyn mch gi tin bng cch s dng b x l gi, b x l ny

thng l mt ASIC ( Application Specific Intergrated Circuit-Mch tch hp

c trng cho ng dng) c ti u thc hin nhim v c th vi tc

cao. im ny th n ph hp vi b nh tuyn trn ng trc hin nay.

Ngoi ra b nh tuyn thng xuyn duy tr mt bng khc gi lbng

chuyn gi, bng ny c trong cc b my chuyn tip gi ( FE-Forwarding

Engine). FE thc hin vic c a ch ch t tiu gi n, thc hin vic


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tm kim tuyn, tm tin t ph hp di nht ( Longest Prefix Matching) v

chuyn gi n giao din u ra c xc nh.

Hnh 1.10: Cu tr b nh tuyn thng thng

V c bn th bng chuyn gi bt ngun t bng nh tuyn nhng n t

c cp nht hn. Bng nh tuyn c duy tr bi phn mm nh tuyn,

phn mm ny thc hin qu trnhx l tng i chm trong khi cp nht

bng v khi bng c cp nht, bn sao ca n s c chuyn n b my

chuyn gi. Bn sao ny c th l mt tp hp con ca ton b bng nh tuyn

v c th c bin i ph hp vi phin bn nh hn. Ma trn chuyn

mch l thnh phn ct yu ca mt b my chuyn gi. V bn cht, mt b

nh tuyn bao gm phng tin nh tuyn c thc hin trong phn mm v

s dng CPU chnh ca b nh tuyn tin hnh hot ng phc tp hn

nh thc hin cc giao thc nh tuyn, cc c im k thut lu lng, m

bo QoS, bin i tiu gi trc khi truyn i v cc c im da trn cc

phn mm khc ca b nh tuyn. Ngoi ra, FE cn tin hnh cc nhim v

n gin hn ti tc cao.


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1.4.2 X l gi tin b nh tuyn.Cc gi tin b nh tuyn cn c vo b m ca b nh tuyn v cc

thng s phn tiu ca gi IP a ra cc quyt nh ph hp vi gi

tin.

Kim tr gi tin - Header checksum nu c li th b nh tuyn hy gi tin.- Kim tra 1 s thng s : Version, Header length, Total length,

Protocol nu sai hy b gi tin.

- Kim tra xem nu TTL=0 th hy gi tin.- Nu b m ca b nh tuyn y khng cha c gi tin th

hy gi tin.

Chun b truyn :- Phn tch trng (Type of service) tm rang i tng ng.- Xc nh gi tin c phn mnh khng?

Nu phn mnh th thc hin chia gi tin. Nu khng c phn mnh nhng b nh tuyn li khng

c kh nng truyn c gi tin th s hi cc b nh tuyn

lng ging v nh b nh tuyn lng ging chuyn gi tin.

Nu khng c b nh tuyn lng ging no chuyn c

gi tin th b nh tuyn s hy gi tin v thng bo cho

trm ngun.

Tnh ton li mt s thng s gi tin:- TTL - 1 (khi qua 1 b nh tuyn).- in cc thng s cho trng hp phnmnh .- in cc thng s cho trng la chn (Option).- Tnh li Header checksum.

1.4.3 X l gi tin khi ti ch. Kim tr gi tin .


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- Header checksum: Nu c li th my ch hy gi tin.- Kim tra 1 s thng s: Version, Header length, Total length,

Protocol nu sai hy b gi tin.

- Kim tra xem nu TTL=0 th hy gi tin.- Nu b m ca b nh tuyn y khng cha c gi tin th

hy gi tin.

Chun b- Khng kim tra Type of service v y l trm ch nn khng

cn chuyn n trm khc.

- Kim tra xem gi tin c phn mnh?Khi nhn c mnh tinu tin ca gi tin phn mnh, trm ch s khi ng mt ng

h thi gian, nu ht thi gian quy nh m mnh tin cui cng

cha n th trm ch s hy b tt c cc mnh tin nhn.

Nu cc mnh tin n ng gi th trm ch s ghp cc mnh

tin thnh gi tin gc.

Chuyn gi tin ln tng trn x l tip.1.4.4 nh tuyn trn mng Internet (IP Routing).

Bng 1.1: Bng tm ng

a ch

ch

a ch tip

theo ca

Router

Giao din

(Cng ca

Router)

Mt n

mng

con

Khong

cch t

ngun ti

ch

Thi gian

cp nhp

bng tm

ng

--- --- --- --- --- --

io th tm ng ( rotool).Chc nng ca giao thc tm ng

- Thit lp bng tm ng.- Cp nht bng tm ng.


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- Tnh ton qung ng i ngn nht chn ach ca b nhtuyn tip theo nhm chuyn gi tin i nhanh nht.

Giao thc tm ng n gin l giao thc da vo topo mng lp bng tm

ng bng tay v cp nht bng tay nhm tm ng ngn nht. Giao thcny ch s dng cho mng n gin.

Giao thc tm ng trn Internet, s dng trong mng phc tp.

- Cp nht t ng.- T ng tnh ton tm ra b nh tuyn tip theo da trn hin

trng ca mng.

Tiu chun nh gi giao thc tm ng:

Thch nghi rt nhanh vi thay i ca mng. Tnh ccon ng ti u. D dng nng cp khi mng pht trin. Tit kim ti nguyn ca my. Bng thng tit kim nht.

S o s dng trong nternet.S o c tnh nh sau:

- S bc nhy m gi tin i qua.- S bc nhy m gi tin i qua nhng c trng s.- Tng hp t nhiu thng s nh bng thng, tr, ti hin ti,

gi thnh....

- Thut ton da trn s o tnh ng i ngn nht gi lDVA (Distance Vector Algorithm). Giao thc RIP s dng thut

ton DVA.

- Thut ton trng thi lin kt gi l LSA ( Link StateAlgorithm). Giao thc OSPF s dng thut ton LSA.


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1.5 Kt lunhngTrong chng ny cp ti cu trc a ch IPv4. a ch IPv4 c hai

chc nng c bn: a ch cc giao din mng ( cung cp mt a ch duy nht

cho nhng giao din khi tham gia vo mng Internet), h tr cho nh tuyn (

truyn ti thng tin t mng ny sang mng khc).

Giao thc tng mng trong b giao thc TCP/IP hin ti ang l IPv4. IPv4

cung cp truyn thng host- to- host gia nhng h thngtrn Internet. Mc d

IPv4 c thit k kh tt, nhng IPv4 c nhng thiu ht khin cho n khng

ng b cho s pht trin nhanh ca Internet nh sau:

- IPv4 c 2 level cu trc a ch (netid v hostid) phn nhm vo5 lp ( A, B, C, D v E). S s dng cc a ch khng hiu

qu. V d nh khi c mt t chc c cp cho 1 a ch lp A,

16 triu a ch t a ch c phn phi duy nht cho t chc

s dng. Do s dn dn khng cn a ch cp cho bt k

mt h thng mi no mun kt ni vo Internet.

- Internet phi thch nghi c vi s chuyn giao audio v videothi gian thc. Loi chuyn giao ny yu cu nhng sch lc

tr hon t nht v s t trc ca ti nguyn khng c cung

cp trong thit k.

- Internet phi thch nghi c vi s m ha v s chng nhnca d liu cho mt s ng dng. Khng mt s m ha v s

chng nhn no c cung cp trong IPv4

Chng tip theo s trnh by v a ch Internet phin bn 6 - IPv6, y l

phin bn c thit k nhm khc phc nhng hn ch ca giao thc Internet

IPv4.


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Chng II: Cu trc chIPv6


CHNG 2 : CU TRC A CH IPv6

2.1 im v6Ti sao th gii cn nhanh chng chuyn sang chun IPv6 t chun IPv4

qu c k? chnh l vic cung cp s lng a ch IP qu t, khng th p

ng nhu cu s dngInternet hin nay ca cc qun tr vin cng nh ngi

dng c bn.

Hin nay kho a ch IPv4 chnh thc cn kit sau 30 nm s dng v

chng ta ang phi tn dng nhng di IP cui cng cn st li. Nhm gii

quyt vn ny, IPv6 c ra i vi mcch thay th hon ton v khcphc cc nhc im ca IPv4

IPv6 c pht trin theo cp s nhn m rng bng thng c sn cho

a ch IP, trong khi cng cung cp mt s li ch khc.

Sau y l nhng li th ca IPv6:

Thm s lng ln h: ach IPv6 s dng cng ngh 128-bit thay v

32-bit a ch hin ti, cho php tng theo hm s m ca cc a ch IP c sn.Mng li s lng a ch IP ca IPv4 c tn ti t nhng nm 1980, iu

m lc th gii cha ngh rng Internet c th pht trin v tn ti nhanh

n mc nh hin nay, c bit l khi Web tr nn ph bin.

Vi 32-bit, IPv4 ch cho php cung cp khong 4,3 t a ch IP. V mi

thit b c kt ni Web nh: my ch, my tnh bn, xch tay, in thoi

thng minh, Tablet PC v nhiu hn na cn phi c a ch IP. V k t khiWeb bng n cc nc nh Trung Quc v n , th gii ang nhanh

chng tip cn n nhng a ch c sn cui cng ca IPv4.

Trong khi , vi 128-bit m IPv6 mang li, n c kh nng cung cp mt

s lng rt ln a ch IP vt xa nhu cu s dng Internet hin nay cng

nh cc thit b kt ni web. Thay v 4,3 t a ch gii hn ca IPv4, a ch

IPv6 c cung cp hng t t a ch IP cho ngi dng trn khp hnhtinh ny.


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Kh nng tng thh ng:IPv6 c th tng thch ngc vi IPv4 cc

mng khc nhau hoc cc nh sn xut phn cng c th chn nng cp vo

cc thi im khc nhau m khng lm gin on s pht trin hin ti ca d

liu trn internet. Do s ph thuc ca th gii trn mng Internet v web tin tc,

thng mi, an ton cng cng, an ninh quc gia, y chnh l mt tnh nng

quan trng ca IPv6.

Cui cng, tt c cc thit b IPv4 s dn dn c thay th v IPv6 s l a

ch giao thc ch c s dng duy nht trn Internet trong tng lai. Tuy nhin,

n c th mt n hng thp k, do , tnh tng thch ngc s rt quan trng

cho tng lai.

Hnh 2.1: M hnh mt s thit b kt ni Web m n h

Kh nng bo mt tt hn: IPv6 c thit k vi cng ngh m ho v xc

thc mt cch an ton. Trong khi IPsec l mt thnh phn bo mt ty chn ca

IPv4 th i vi IPv6 n l thnh phn bt buc. Vi Ipsec, mi gi d liu c

nhn c m ha v xc thc, khin cho nhiu thnh phn hot ng cc v tn

cng m c hi gy rc ri ca Internet ngy nay khng th - hoc t nht l

thc hin kh khn hn.


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Hiu sut hot ng tt hn: Thay i c thc hin v c hnh

thnh cho cc gi tp tin IP, vi cch thc m IPv6 thc hin trong qu trnh

nh tuyn cc gi tin ci thin hiu sut s gip vic mt d liu b t xy ra

hn, tin cy cao hn cng nh hiu qu kt ni tt hn. Vi nhiu ngi

cng nh cc thit b chia s Internet hn, nhu cu s dng cho VoIP (thoi

qua IP) v video, hiu sut s cng quan trng hn bao gi ht.

N c tn ti ti hn hai thp k, nhng cuc khng hong a ch

IPv4 ang l rt thc t. Vic ch i s thay th ca IPv6 s din ra trong thi

gian gn nht.

Sau y chng ta snghin cu c th chi tit v nhc im ca IPv4 vu im vt tri ca IPv6:

* Giao thc Internet phin bn 4 ( IPv4) tuy ang c s dng rng ri

hin nay nhng c mt s nhc im :

- a ch IP c 32 bit, cho ti nay gn cn kit, cn phi cm rng.

- Phn u ( phn tiu ) ca khun dng gi tin IPv4 c nhngthng tin d tha.

- An ninh thng tin cha tht m bo, cn thiu.- Cha h tr tt cho vic truyn thng a phng tin (

multimedia).

* S ra i ca IPv6 s khc phc nhng nhc im trn l:

- nh dng Tiu mi.- Khng gian a ch rng.- C s h tng nh tuyn v nh a ch phn cp v hiu qu. - Cu hnh a ch Stateful v Stateless.- Bo mt.-

H tr tt hn cho QoS.- Giao thc mi cho s tng tc node lng ging.


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- C kh nng m rng.

Kiu nh dng tiu mi.Tiu ca IPv6 c mt kiu nh dng mi c thit k gi cho tiu

bn trn mc ti thiu. iu ny t c bng cch chuyn c cc trng

hp khng cn thit v cc trng la chn sang phn tiu m rng, phn

m rng ny i theo sau phn tiu ca IPv6. Tiu IPv6 c t chc tt,

x l hiu qu hn ti cc b nh tuyn trung gian.

Cc tiu IPv4 v IPv6 l khng gn lin. IPv6 khng phi l siu tp ca

chc nng m tng thch ngc vi IPv4. Mt host hoc mt b nh tuynphi dng mt s b sung ca IPv4 v IPv6 nhn ra v x l c 2 kiu nh

dng tiu . Tiu IPv6 mi ch rng gp 2 ln IPv4 mc d a ch IPv6

rng gp 4 ln IPv4.

Khng gin h m rng.IPv6 c a ch IP di 128 bit. Mc d 128 bit c th biu din hn

3.4x1038 t hp, khng gian a ch rng ca IPv6 c thit k cho php

nhiu mc subneting v chia vng i ch t a ch gc Internet n cc mng

ring trong cng 1 t chc.

Mc d ch mt s lng nh a ch hin ti c chia phn cho host, vn

cn nhiu a ch cho tng lai. Vi mt s lng a ch ln nh vy th cc

k thut tit kim a ch nh NAT l khng cn thit na.

C s h tng nh tuyn v nh h phn p v hiu qu.Cc a ch IPv6 ton cu c dng trong phn IPv6 ca Internet c

thit k to mt c s h tng nh tuyn c th tm tt, phn cp v hiu

qu. C s h tng ny c da trn s trin khai chung nhiu cp ca cc

nh cung cp dch v ISP.


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Cu hnh h Stteful v Stteless n gin ha cu hnh host, IPv6 h tr c hai kiu cu hnh l stateful,

nh l cu hnh a ch trong s c mt ca mt DHCP server v stateless ( cu

hnh a ch trong khng c mt ca mt DHCP). Vi kiu cu hnh a chstateless th cc host trn mt lin kt s t ng cu hnh vi a ch IPv6 cho

lin kt ( c gi l a ch lin kt ni b) v vi cc a ch c phn pht

t Prefixes qung co bi cc b nh tuyn ni b. Ngay c khi khng c cc

bnh tuyn th cc host trn cng mt lin kt vn c th t ng cu hnh

vi cc i ch lin kt ni b v lin lc vi nhau m khng cn cu hnh nhn

cng.

Bo mt.Trong hot ng Internet, bo mt ti tng IP c thc hin ph bin bng

cng ngh IPSec. IPSec thc hin chc nng xc nh ni gi v m ha

ng kt ni, do vy m bo c kt ni bo mt. Cng ngh IPSec h tr c

a ch IPv4 v IPv6. Tuy nhin trong IPv6, IPSec c nh ngha nh l mtc tnh bt buc ca a ch IPv6 khi cc th tc bo mt ca IPSec c a

vo thnh hai c tnh l hai tiu m rng ca a ch IPv6. l tiu

Xc thc, v tiu M ha.

H tr tt hn ho QoS.Cc trng mi trong tiu ca IPv6 nh ngha cch thc m lu lng

qun l v nhn dng. S nhn dng lu lng dng mt trng nhn lu

lng trong tiu IPv6 cho php cc b nh tuyn nhn dng v cung cp

vic qun l c bit cho cc gi thuc cng mt lung, mt seri cc gi gia

ngun v ch. Bi v lu lng c nhn dng trong tiu IPv6, vic h tr

QoS c th t c ngay c khi trng ti ca gi c m ha thng qua

IPSec.


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io th mi ho s tng t Node lng ging.Giao thc tm kim lng ging cho IPv6 l mt seri ca ICMP cho cc bn

tin ca IPv6, chng qun l vic tng tc gia cc node lng ging. Tm kim

lng ging thay th cho cc bn tin giao thc ARP da vo vic broadcast, ccbn tin ICMPv4 b nh tuyn tm kim v multicast hiu qu.

C kh nng m rng.IPv6 c th d dng c m rng cho cc tnh nng mi bng cch thm

vo cc tiu m rng vo sau tiu ca IPv6. Khng ging nh cc la

chn ca tiu IPv4 ch c th h tr 40 byte option, kch thc ca tiu m rng ca IPv6 khng ch bi kch thc ca gi IPv6.

2.2 Nhng hn h v4Giao thc tng mng trong b giao thc TCP/IP hin ti ang l IPv4

(Internet- working protocol verision 4). IPv4 cung cp truyn thng host-to-

host gia nhng h thng trn Internet. Mc d IPv4 c thit k kh tt, s

thng i thng tin tin trin t lc khi u IPv4 vo nhng nm 1970,

nhng IPv4 c nhng s thiu ht khin cho n khng ng b cho s pht

trin nhanh ca Internet, gm nhng th sau:

IPv4 c 2 level cu trc a ch (netid v hostid) phn nhm vo 5lp (A, B, C, D v E). S s dng nhng a ch l khng hiu

qu. V d nh khi cos mt t chc c cp cho 1 a ch lp A,

16 triu a ch t a ch c phn phi duy nht cho t chc

s dng. Nu 1 t chc c cp cho 1 a ch lp C, mt khc ch

c 256 a ch c phn phi cho t chc, y khng phi l mt

s . Cng vy, nhiu triu a ch b lng ph trong nhm D v

Phng thc phn a ch ny dng ht nhng a ch ca

IPv4, v mau chng s khng cn a ch no cn cp cho bt

k mt h thng mi no mun kt ni vo Internet. Mc d schlc subnet v supernet gim bt nhng vn v a ch,


28/72



nhng subnet v suprnet lm 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 ny yu cu nhng sch lc trhon t nht v s t trc ca ti 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 no c cung cp trong IPv4.

khc phc thiu st trn IPv6 c bit n nh l IPng(Internet working Protocol, next generation), c xng v

nay l mt chun.

2.3 S kh bit gi v4 v v6Bng 2.1: S kh bit gi v4 v v6.

IPv4 IPv6

Dng a ch 32 bit Dng a ch 128 bit

IPSec l ty chn IPSec l bt buc

Khng c xc nhn lung gi cho vic

qun l QoS bi cc b nh tuyn

trong phn tiu

Vic xc nhn lung gi cho qun l

QoS bi cc b nh tuyn c dng

trong trng nhn lung.

Phn mnh c thc hin bi host v

b nh tuyn

Phn mnh ch thc hin bi host gi

Tiu bao gm c phn checksum Tiu khng bao gm phn

checksum


29/72



Tiu c phn ty chn Tt c d liu ty chn c chuyn

sang phn tiu m rng.

ARP dng broadcast ARP Request

frames chuyn mt a ch IPv4sang a ch MAC

ARP Request frames thay th bng cc

bn tin Neighbor Solicitation multicast

IGMP c dng qun l cc local

subnet group membership.

IGMP c thay th bi cc bn tin

Multicast Listener Discovery (MLD).

ICMP b nh tuyn tm kim c

dng xc nh ia ch IPv4 default

gateway tt nht v y l mt ty

chn

ICMP b nh tuyn tm kim c

thay bng cc bn tin ICMPv6b nh

tuyn Solicitation v b nh tuyn

qung co v y l 1 yu cu.

Phi c cu hnh nhn cng hoc

thng qua DHCP

Khng yu cu cu hnh nhn cng

hoc thng qua DHCP

Dng cc bng ghi ti nguyn trong

min DNS nh x a ch IPv4 sangtn host

Dng cc bng ghi ti nguyn con tr

trong min DNS nh x a ch IPv6sang tn host

Phi h tr mt kch thc gi l 576

byte ( c th c phn mnh)

Phi h tr mt kch thc gi l 128

byte ( khng phn mnh)

Dng cc bng ghi ti nguyn a ch

host trong DNS nh x tn host sang

IPv4

Dng cc bng ghi ti nguyn a ch

host trong DNS nh x tn host sang

IPv6

a ch broadcast c dng gi

thng tin ti tt c cc node trn cng

mt subnet

Khng c a ch broadcast. Thay vo

l a ch link-local scope all-node

multicast


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2.4 h v62.4.1 Khng gian a ch IPv6

Kch thc a ch IPv6 l 128 bit, rng gp 4 ln a ch ca IPv4. Khng

gian a ch 32 bit cho php 232 hay 4.294.967.296 a ch. Khng gian a ch

128 bit chophp 2128 a ch hay

340.282.366.920.938.463.463.374.607.431.768.211.456 (3.4x1038) a ch.

Vo nhng nm cui thp nin 70 ca th k trc khi m khng gian a ch

IPv4 c thit k th ngi ta cha tng tng c rng n s cn kit trong

tng lai. Tuy nhin do c nhiu s thay i trong k thut v thc t phn vng

khng thy trc c s bng n ca cc host trn Internet v khng gian a

ch IPv4 c phn pht ht vo nm 1992, do cn 1 khng gian a ch

mi thay th..

Vi IPv6 tht kh c th tng tng c rng n s c phn pht ht

bi v theo c tnh khng gian a ch IPv6 s cung cp cho mi m2 b mt

tri t l 655.570.793.348.866.943.898.599 ( 6.5x1023) a ch. Kch thc

tng i ln ca a ch IPv6 c thit k chia nh thnh cc min nh

tuyn phn cp phn nh topo ca Internet hin nay. Vic s dng 128 bit cho

php nhiu mc phn cp v tnh linh ng trong vic thit k nh tuyn v

nh a ch phn cp.

Khng gian a ch c nhiu mc ch khc nhau. Ngi ta thit k a ch

IP chia khng gian a ch thnh 2 phn, vi phn u c gi l kiu tin

t. Phn gi tr tin t ny cho bt mc ch ca a ch. Nhng m s c

thit k sao cho khng c m s no ging phn u ca bt k m s no

khc. Do khng c s nhp nhng khi mt a ch c trao kiu tin t c

th d dng xc nh c. Hnh sau cho chng ta thy dng ca a ch IPv6:


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Hnh 2.2 : Cu tr h v6

2.4.2 Cu trca ch IPv6.Mt a ch gm c 16 byte, l 128 bt di. Kiu k hiu du 2 chm

trong h m 16 ( Hexadecimal Colon Notation)

lm cho nhng a ch tr nn c th c c nhiu hn, IPv6 trnh by

r trong kiu k hiu du 2 chm trong h m 16. Trong kiu k hiu ny,

128 bt c chia thnh 8 phn, mi phn rng 2 byte. 2 byte trong kiu k

hiu h m 16 yu cu 4 ch s trong hm 16 ny. V th cho nn a ch

gm c 32ch s trong h m 16 vi mi 4 ch s mt li c mt du : chm

Hnh 2.3 : h phin bn 6 ( v6 Address)

*S rt gn:

+ Mc d l a ch IP ngay c khi trong nh dnh h s m 16, vn rt di,

nhiu ch s 0 trong mt a ch.

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


32/72



Do c ch nn a ch c dng biu din d dng hn cc loi a

ch dng ny. Ta khng cn vit cc s 0 u cc nhm, nhng nhng s 0

bn trong th khng th xo.

Hnh 2.4 : S rt gn h (Abbrevited Address)

Hn na ta c th s dngk hiu :: ch mt chui cc s 0. Tuy nhin

k hiu trn ch c s dng mt ln trong mt a ch. a ch IP c di

c nh, ta c th tnh c s cc bit 0 m k hiu biu din. Ta c th p

dng u hay cui a ch. Cch vit ny c bit c li khi biu din cc

a ch multicast, loopback hay cc i ch cha ch nh.

Hnh 2.5: S rt gn h s 0 lin tip

(Abbreviated Address with consecutive zeros)

xc nh c bao nhiu con s 0 ng gia :: th ta c cng thc

sau:

N= ( 8-n)*16


33/72



trong n l s khi bit 16 bit a ch cn li c biu din dng s

hexa.

Vic nn 0 ch c dng 1 ln i vi 1 a ch cho trc, nu khng th ta

s khng th xc nh c con s khng c gin lc.

2.4.3 Prefix ca IPv6.Prefix l mt phn ca a ch IPv6, n ch ra cc bit c gi tr c nh hoc

l cc bit ng vai tr l ID ca mng. Cc prefix cho nh danh mng con ca

IPv6, cc tuyn, cc vng a ch c biu din nh trong k hiu CIDR (

classless Inter-Domain Routing) cho IPv4. V d 21DA::/48 cho mt a ch

Prefix tuyn v 21DA:D3:0:2F3B::/64 cho 1 prefix mng con. Trong IPv6ch dng prefix ch khng dng mt n mng con nh IPv4.

2.4.4 Cc dng a ch IPv6.Cc dng a ch IPv6 gm:

- a ch unicast- a ch multicast- a ch anycast.

h unist.a ch unicast xc nh mt giao din duy nht trong phm vi tng ng.

Trong m hnh nh tuyn, cc gi tin c a ch ch l a ch unicast ch c

gi ti mt giao din duy nht (Hnh 2.6). a ch unicast c s dng trong

giao tip mt mt.

Hnh 2.6: i tin gi ti h Unist

Vi mt topology nh tuyn unicast thch hp, cc gi c nh a ch

unicast c chuyn n mt giao din n.

a ch unicast IPv6 bao gm cc loi sau: a ch unicast ton cu, a chlink-local, a ch site-local v a ch c bit.


34/72



- h Unist ton u

a ch Unicast ton cu tng ng vi a ch public ca IPv4. N c th

nh tuyn ton cu trong Internet. Khng ging nh Internet da trn IPv4 c

s nh tuyn trn c dng phng v phn phn cp Internet IPv6 c thit kt nn mng ca n l h tr cho vic nh tuyn v nh a ch phn cp v

hiu qu.

Cc trng ca a ch Unicast ton cu c m t nh sau:

- Phn c nh c gn cho gi tr l 001.- Prefix nh tuyn ton cu: ch prefix nh tuyn ton cu cho

mt site ca mt t chc c th. Ba bit c nh cng vi 45 bitprefix nh tuyn ton cu to thnh mt prefic site 48 bit, prefix

ny c cp cho mt site c nhn ca mt t chc. Mt khi

c cp cc b nh tuyn trn Internet IPv6 s chuyn lu

lng IPv6 ph hp vi prefix 48 bit n cc b nh tuyn

thuc site ca t chc.

- Subnet ID: Subnet ID c dng cho site ca t chc xcnh cc mng con. Kch thc ca trng ny l 16 bit. Site ca

t chc c th dng 16 bit ny vi site ca n to 65.536

mng con hoc nhiu mc ca s phn cp nh a ch v

mt c s h tng nh tuyn hiu qu.

- Giao din ID: ch giao din trn mt subnet c th ca mt site.Kch thc ca trng ny l 16 bit. Cc trng vi a chunicast ton cu to ra cu trc 3 cp nh hnh v:

Hnh 2.7: h Unist ton u


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Topology cng cng l tp hp ca cc ISP ln hn v nh hn m cung

cp truy nhp vo Internet IPv6. Topo ca site l tp hp ca cc mng con

trong cng site ca t chc. Ch th giao din ch mt giao din c th trn mt

mng con trong cng site ca mt t chc.

- h Unist dng ni b.

C 2 loi: a ch link-local v a ch site-loca

+a ch Link-Local.

y l loi a ch dng cho cc host khi chng mun giao tip vi cc host

khc trong cng mng. Tt c IPv6 ca cc interface u c a ch link local

Cc a ch link-local c dngbi cc node khi truyn thng vi ccnode lng ging trn cng 1 lin kt. V d nh trn mng IPv6 lin kt n

khng c b nh tuyn, cc a ch link-local c dng truyn thng gia

cc host trn link.

Mt a ch link-local cn thit cho cc qu trnh x l tm kim lng ging

v lun lun c t ng c cu hnh ngay c khi khng c tt c cc a

ch unicast khc.

Hnh 2.8: M t u tr h link-local

Cc a ch link-local lun lun bt u vi FE80. Vi 64 bit xc nh giaodin. Prefix cho a ch link-local lun lun l FE80::/64. Mt b nh tuyn

IPv6 chuyn lu lng link-local vt ngoi gii hn lin kt.

Lu : Mt router khng th chuyn bt k gi tin no c a ch ngun

hoc a ch ch l LinkLocal Address

+a ch Site khu vc (Site-Local).

Cc a ch site-local tng ng vi khng gian a ch IPv4 ring (

10.0.0.0, 172.16.0.0/24 v 192.168.0.0/16). V d cc mng ni b ring m


36/72



khng c mt hng, nh tuyn kt ni n Internet IPv6 c th dng cc a

ch site-local m khng xung t vi cc a ch Unicast ton cu. Cc a ch

site-local khng n c t cc site khc v cc b nh tuyn phi khng

c chuyn lu lng site-local ra ngoi site. Cc a ch site-local c th

c dng thm vo cc a ch unicast ton cu. Mt site l mt mng t

chc hoc 1 phn ca mng t chc m c nh ngha v mt a l, nh 1

c quan hay 1 t hp c quan, mt trng hc. Khng ging nh cc a ch

link-local, cc a ch site-local khng c t ng cu hnh v c cp pht

bi cc qu trnh cu hnh a ch stateful hay stateless. Cu trc ca a ch

site-locak nh sau:

Hnh 2.9: M t u tr h Site-Local

10 bit u tin lun lun c nh cho cc a ch site-local ( FEC0::/10). Sau10 bit c nh l trng ID Subnet cung cp 54 bit m ta c th to ra mt c

s h tng nh tuyn c th tm tt v phn cp trong cng 1 site. Sau trng

ID mng con l 64 bit trng ID giao din m ch th mt giao din c th trn

mt subnet.

Phm vi s dng Site-Local Addresses l trong cng Site.

- h v6 bit.

+ a ch khng ch r.

a ch 0:0:0:0:0:0:0:0hay :: ch c dng ch s khng c mt ca

mt a ch. N tng thch vi a ch khng r trong IPv4 l 0.0.0.0. a ch

khng ch r thng c dng nh l mt a ch ngun cho cc gi c gng

xc nhn s c mt duy nht ca mt a ch khngch r. a ch khng

ch r khng c cp cho 1 giao din hoc l dng nh 1 a ch ch n.

+ a ch loopback.


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a ch loopback 0:0:0:0:0:0:0:1 hoc ::1 c dng xc nh 1 giao

din loopback cho php 1 node c th gi cc gi gi ngc v ch nh n. N

tng ng vi a ch loopback 127.0.0.1 trong IPv4. Cc gi c nh a

ch cho a ch loopback phi khng c gi trn ng lin kt hoc c

chuyn tip bi 1 b nh tuyn IPv6.

h multist.

Hnh 2.10: Gi tingi ti h Multist

Mt a ch multicast xc nh nhiu giao din.Vi topo nh tuyn thch

hp th cc gi c nh a ch multicast s c chuyn ti tt c cc giao

din m c xc nh bi a ch ny. Mt a ch multicast c dng trong

truyn thng mt-nhiu, c chuyn n nhiu giao din.

Trong IPv6 lu lng multicast hot ng ging nh IPv4. Cc node IPv6

c nh v ty c th lng nghe lu lng multicast trn 1 a ch multicastty . Cc node IPv6 c nh v ty c th lng nghe nhiu a ch

multicast ti cng 1 thi im. Cc node c th tham gia hoc ri khi nhm

multicast bt c lc no.

a ch multicast IPv6 c 8 bit u tin l 1111 1111. Mt a ch IPv6

multicast c th d dng nhn ra v n lun bt u bng FF. Cc a ch

multicast khng th c dng nh l cc a ch ngun hoc l cc ch trung


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gian trong 1 tiu nh tuyn. Pha sau 8 bit u tin a ch multicast bao

gm cu trc thm vo xc nh cc c, phm vi v nhm multicast.

Hnh 2.11:M t u tr h Multist

Cc trng trong a ch multicast l:

- C: ch cc c c thit lp trong a ch multicast. Kch thcca trng ny l 4 bit. Nh RFC 3513 c ch c nh ngha

l c T (Transient: tm thi). C T dng bit bc thp ca trng

c. Khi c set v 0 c T ch ra rng a ch multicast l mt

a ch multicast c cp thng trc, c cp pht bi IANA

(Internet Assigned Number Authority). Khi c set ln 1, c T

ch ra a ch multicast ny l a ch multicast tmthi.

- Phm vi: ch phm vi ca lin mng IPv6 cho lu lng multicastc d nh. Kch thc ca trng ny l 4 bit. Thm vo

thng tin cung cp bi cc giao thc nh tuyn multicast , cc b

nh tuyn dng phm vi multicast xc nh ni m lu lng

multicast s c chuyn i. Cc gi tr thng thng nht cho

trng phm vi l 1 (phm vi giao din cc b), 2 (phm vi lin kt

ni b) v 5 (phm vi site ni b). V d lu lng vi a ch

multicast l FF02::2 c 1 phm vi lin kt ni b th 1 b nh tuyn

IPv6 s khng chuyn lu lng ny ra lin kt ni b.

- ID nhm: ch nhm multicast v l duy nht i vi mi phmvi. Kch thc ca trng ny l 112 bit. Cc ID nhm c gn

thng trc khng ph thuc vo phm vi. Cc ID nhm tm

thich lin quan n 1 phm vi c th.


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Hnh 2.12: h multist v6 nh x sng h MAC multist

Vi 112 bit cho ID nhm th c th c 2112 ID nhm a ch. Tuy nhin

theo cch m cc i ch multicast IPv6 nh x sang cc a ch MAC

multicast ca Ethernet nn RFC 3513 khuyn co cp pht ID nhm t 32 bit

bc thp ca a ch multicast IPv6 v xt cc bit ID nhm cn li l 0. Bng

cch ch s dng 32 bit bc thp mi ID nhm nh x 1 a ch MAC multicast

duy nht.

h nyst.Mt a ch Anycast xc nh nhiu giao din. Vi topology nh tuyn

thch hp th cc gi c nh a ch anycast c chuyn n mt giao din

n gn nhtc xc nh bi a ch anycast ny. Khi nim giao din gnnht c xc nh gn nht trong gii hn khong cch nh tuyn. a ch

anycast c dng trong truyn thng 1-1 trong nhiu.

Hnh 2.13 i tin gi ti h Anyst

Anycast Address l a ch c bit c th gn cho nhiu interface, gi tin

chuyn n Anycast Address s c vn chuyn bi h thng Routing n


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Interface gn nht. Hin nay, a ch Anycast c s dng rt hn ch, rt t

ti liu ni v cch s dng loi a ch ny. Hu nh Anycast addresss ch

c dng t cho Router, khng t cho Host, l do l bi v hin nay a

ch ny ch c s dng vo mc ch cn bng ti.

V d : khi mt nh cung cp dch v mng c rt nhiu khch hng mun

truy cp dch v t nhiu ni khc nhau, nh cung cp mun tit kim nn ch

mt Server trung tm phc v tt c, h xy dng nhiu Router kt ni

khch hng vi Server trung tm, khi mi khch hng c th c nhiu con

ng truy cp dch v. Nh cung cp dch v t a ch Anycast cho cc

Interfaces l cc Router kt ni n Server trung tm, by gi mi khch hng

ch vic ghi nh v truy cp vo mt a ch Anycast thi, t ng h s c

kt ni ti Server thng qua Router gn nht. y tht s l mt cch x l

n gin v hiu qu.

Khi tm hiu v a ch Anycast, s d nhm ln. Bi v nu nh gn a ch

ny cho mt Interface th n y nh l a ch Unicast, nhng khi gn cho nhiu

Interfaces th n li c v nh l a ch Multicast. Nhng tm hiu v

Multicasr, s thy s khc bit gia Multicast v Anycast

2.4.5 S tng thch a ch.Nhm chuyn i t IPv4 sang IPv6 v s tn ti ca c 2 loi host, cc a

ch sau c nh ngha:

h tng thhIPv4.a ch IPv6, a ch 0:0:0:0:0:0:w.x.y.z hoc ::w.x.y.z c dng bi cc

node IPv6/IPv4 m truyn thng dng IPv6. Cc node IPv6/IPv4 l cc node

dng c 2 giao thc IPv4 v IPv6. Khi a ch tng thch IPv4 c dng nh

1 ch n IPv6 th lu lng IPv6 s t ng ng gi vi 1 tiu ca IPv4

v gi n ch dng c s h tng IPv4.

h nh x sng v4a ch c nh x sang IPv4 0:0:0:0:0:FFFF:w.x.y.z hoc ::FFFF:w.x.y.z

c dng din t 1 node ch dng IPv4 sang 1 node IPv6. N ch c


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dng cho din t ni b. a ch c nh x sang IPv4 khng c dng nh

l mt a ch ngun hoc ch ca 1 gi IPv6.

h 6 sng 4.a ch 6 sang 4 c dng cho truyn thng gia 2 node chy c IPv4 v

IPv6 trn 1 c s h tng nhtuyn IPv6. a ch 6 sang 4 c hnh thnh

bng cch kt hp prefix 2002::/16 vi 32 bit ca 1 a ch IPv4 public ca

node v hnh thnh nn 1 prefix 48 bit.

h v6 ho 1 Host.Mt host IPv4 vi mt b thch ng mng n thng c mt a ch IP n

c cp cho b thch ng . Tuy nhin, 1 host IPv6 thng c nhiu a chIPv6, ngay c vi giao din n. Mt host IPv6 c cp cho cc a ch

unicast sau y:

- Mt a ch lin kt ni b cho mi giao din.- a ch unicast cho mi giao din ( c th l 1 a ch site ni b

v 1 hoc nhiu a ch unicast ton cu )

- a ch loopback ( ::1) cho giao din loopback.Cc host IPv6 thng thng l logically multihomed bi v chng c t nht

2 a ch m chng c th nhn cc gi, 1 a ch lin kt ni b cho lu lng

lin kt ni b v 1 a ch ton cu hoc site ni b c th nh tuyn c.

Thm vo , mi host lng nghe lu lngtrn cc a ch multicast sau:

- a ch multicast tt c cc node phm vi giao din ni b (FF01::1)

- a ch multicast tt c cc node phm vi lin kt ni b (FF02::1)

- a ch soliticated cho mi a ch unicast trn mi giao din.- Cc a ch multicast ca cc nhm c tham gia trn mi giao

din. h v6 ho 1 B nh tuyn.


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Mt b nh tuyn IPv6 c cp cc a ch unicast sau y:

- Mt a ch lin kt ni b cho mi giao din.- Cc a ch unicast cho mi giao din (c th l 1 a ch site ni

b v 1 hoc nhiu a ch unicast ton cu)- 1 a ch anycast subnet b nh tuyn.- Cc a ch anycast thm vo (option).- a ch loopback (::1) cho giao din loopback.

2.4.6 a ch IPv4 v s tng ng IPv6Bng 2.2: h v4 v s tng ng v6

IPv4 Address IPv6 Address

Cc lp a ch Internet Khng tng xng trong IPv6

a ch multicast IPv4 (224.0.0.0/4) a ch multicast IPv6 (FF00::/8)

Cc a ch broadcast Khng tng xng trong IPv6

a ch khng r rng 0.0.0.0 a ch khng r rng ::

a ch loopback 127.0.0.1 a ch loopback ::1

Public IP address Global unicast address

a ch IP ring (10.0.0.0/8,

172.16.0.0/12 and 192.168.0.0/16)

a ch site cc b ( FEC0::/10)

a ch t ng c cu hnh

(169.254.0.0/16)

a ch lin kt cc b ( FF80::/64)

Cch th hin: k hiu du chm thp

phn phn cch

Cch th hin: dng du hai chm c

gin lc cc s 0 v nn cc s 0 lin

tip

Th hin cc bit mng: dng Mt n

mng con hoc chiu di prefix

Th hin cc bit mng: ch dng chiu

di prefix


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Chuyn i tn DSN: bng ghi ti

nguyn a ch host IPv4

Chuyn i tn DSN: bng ghi ti

nguyn a ch host IPv6

Chuyn ingc DNS Chuyn i ngc DNS

2.5 Khun dng gi tin v62.5.1 Khun dng gi tin IPv6

hin bn : 6. Lp vn huyn:tng t cc kiu dch v (Type of service) trong

IPv4.

Nhn lung:dng nh du tt c cc gi tin cng thuc mt lung dliu.

VD: cng ting ni, cng video.

Trm ngun mun cc B nh tuyn trung gian x l cc thng tin cng

lung ging nhau.

- Cc gi tin cng lung phi c a ch ngun , a ch ch v snhn lung ging nhau.

- S nhn lung c pht sinh ngu nhin nhng khng cdng li khi thi gian sng ca lung vn cn tn ti trn mng.

- Nhn lung phc v cho truyn thng a phng tin.


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Hnh 2.14 : Khun dng gi tin v6

Payload length_ di ti: Cha thng tin hu ch trong gi tin. Next header_Tiu tip theo:

- Tiu thm vo ph thuc ty chn b sung. N c t giatiu ca IPv6 vi tiu ca tng trn.

- Tiu ny ch c a vo khi cn thit, trnh vic truynnhng thng tin d tha.

- Mt s la chn : Routing: yu cu gi tin phi i qua ng no. Flagment: Trong trng hp cn phn mnh. Yu cu c x l trn ng truyn: hop by hop. Yu cu x l gi tin khi n ch. Thng tin xc thc trm thu nhn bit thng tin ch

thc ca my ngun khng b gi danh, khng b thay i.

M ha ni dung ca gi tin. Hop limit_ii hn b nhy:s B nh tuyn m gi tin c php

i qua.


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Soure Add_ h ngun: 128bit Destintion Add_ h h: 128bit

2.5.2 So snh khun dng IPv4 v IPv6.IPv4 IPv6

Ver4IH

L

Type of

ServiceTotal Length Ver 6

Traffic

ClassFlow Label

Identification FlagsFrag

OffsetPlayload Length

Next

Hdr

Hop

Limit

Time to

LiveProtocol

Header

Checksum

Source AddressSource Address

Destination Address

IP Options

Destination AddressIPv4 Header = 20 Bytes + Options

IPv6 Header = 40 Bytes

Hnh 2.15: Khun dng gi tin v4/ v6

Bng 2.3: So Snh khun dng gi tin v4/ v6

IPv4 IPv6

Version Cng trng nhng vi cc s phin bn

khc nhau.

Tiu Length c loi b trong IPv6. IPv6 khng cha

trng Tiu Length bi v tiu ca

IPv6 lun lun c nh l 40 byte. Mi

tiu m rng c kch thc c nh


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hoc c a ch ca ring n.

Type of Service c thay th bng trng Traffic Class

Total Length c thay th bng trng Payload

Length ch kch thc ca trng ti.

Identification, Fragmentation,

Fragment Offset

c loi b trong IPv6. Thng tin phn

mnh khng c trong tiu ca IPv6. N

c cha trong tiu m rng phn

mnh.

Time to live c thay th bng trng Hop Limit.

Protocol c thay th bng trng Next Header.

Tiu Checksum c loi b trong IPv6. Trong IPv6 vic

pht hin li cp bit cho c gi IPv6

c thc hin bi lp lin kt.

Source Address Trng ny ging nhau ch khc l a ch

IPv6 c 128 bit.

Destination Address Trng ny ging nhau ch khc l a ch

IPv6 c 128 bit.

Options c loi b trong IPv6. IPv4 options

c thay th bi IPv6 extension header.

2.5.3 Cc tiu m rng ca IPv6.Tiu ca IPv4 bao gm tt c cc option. V th, mi b nh tuyn trung

gian phi kim tra s tn ca chng v x l chng khi chng hin din. iu

ny lm gim hiu sut vn chuyn trong vic vn chuyn cc gi IPv4. Vi


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IPv6, cc option phn pht v c chuyn sang cc tiu m rng. Tiu

m rng duy nht phi c x l ti mi b nh tuyn trung gian l tiu

m rng Hop-by-Hop Option. iu ny s tng tc x l tiu v tng

kh nng x l chuyn tip.

RFC 2460 nh ngha cc tiu m rng IPv6 sau y phi c h tr bi

tt c cc node IPv6:

- Hop-by-Hop Option tiu .- Destination Options tiu .- Routing tiu .- Fragment tiu .- Authentication tiu .- Encapsulation Security Trng ti tiu .

Trong 1 gi IPv6 thng thng th khng c mt tiu m rng no. Nu

vic iu khin c bit c yu cu bi cc b nh tuyn trung gian hoc

ch th 1 hoc nhiu tiu m rng c thm vo bi host gi. Mi tiu

m rng c phm vi 64 bit. Cc tiu m rng c kch thc thay i cha 1

trng tiu Extension Length v phi dng m khi cn chc chn rng

kch thc ca chng l 1 bi s ca 8.

2.6 KtlunhngTrong chng 2 gii thiu cc dng a ch, cu trc nh a ch IPv6, qua

thy c s khc bit v thay i trong a ch IPv6. y l phin bn

c thit k nhm khc phc nhng hn ch ca IPv4 v b sung nhng tnh

nng mi cn thit trong hot ng v dch v mng th h sau. Chng tip

theo s cp n vic trin khai mng IPv6 trn nn mng s dng IPv4.


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Chng III: Trin khai mngIPv6


CHNG 3: TRIN KHAI MNG IPv6

3.1 Trin khi mng v6 trn nn v43.1.1 t vn

Giao thc IPv6 c nhiu u im vt tri so vi

IPv4, p ng c nhu cu pht trin ca mng

Internet hin ti v trong tng lai. Do , giao

thc IPv6 s thay th IPv4.

Tuy nhin, khng th chuyn i ton b cc nt mng

IPv4 hin nay sang IPv6 trong mt thi gian ngn.

Hn na, nhiu ng dng mng hin ticha h tr

IPv6.

Theo d bo ca t chc ISOC, IPv6 s thay th

IPv4 vo khong 2020- 2030. V vy, cn c mt qu

trnh chuyn i gia hai giao thc trnh hin

tng tng t nh s c Y2K.

Cc c ch chuyn i (Transition mechanism) phim bo kh nng tng tc gia cc trm, cc ng

dng IPv4 hin c vi cc trm v ng dng IPv6.

Ngoi ra, cc c ch cng cho php chuyn tip cc

lung thng tin IPv6 trn h tng nh tuyn hin

c.

Trong giai on chuyn i, iu quan trng l

phi m bo s hot ng bnh thng ca mng IPv4

hin ti.

Yu cu i vi cc c ch chuyn i:

Vic th nhim IPv6 khng nh hng n ccmng IPv4 hin ang hot ng.

Kt ni v cc dch v IPv4 tip tc hoat ngbnh thng.


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Hiu nng hot ng ca mng IPv4 khng b nhhng. Giao thc IPv6 ch tc ng n cc mng

th nghim.

Qu trnh chuyn i din ra tng bc. Khngnht thit phi chuyn i ton b cc nt mng

sang giao thc mi.

- Cc c ch chuyn i c phn thnh 2 nhm vi

hai chc nng khc nhau:

Kt ni cc mng v cc nt mng IPv6 qua htng nh tuyn IPv4 hin c. Cc c ch ny bao

gm: ng hm (tunnel), 6to4, 6over4.

Kt ni cc nt mng IPv4 vi cc nt mngIPv6. Cc c ch ny bao gm: SIIT, NAT- PT,

ALG, DSTM, BIS, BIA, SOCK64.

Mi c ch u c u, nhc im v phm vi p

dng khc nhau. Ty tng thi im trong giai on

chuyn i, mc s dng ca cc c ch chuyn i

s khc nhau.

Giai on u: Giao thc IPv4 chim u th. Ccmng IPv6 kt ni vi nhau trn nn h tng IPv4

hin c thng qua cc ng hm IPv6 qua IPv4.

Giai on gia: Giao thc IPv4 v IPv6 ctrin khai v phm vi ngang nhau trn mng. Cc

mng IPv6 kt ni vi nhau qua h tng nh

tuyn IPv6. Cc mng IPv4 kt ni vi cc mng

IPv6 s dng cc phng php chuyn i a ch

giao thc nh NAT- PT, ALG

Giai on cui: Giao thc IPv6 chim u th. Ccmng IPv4 cn li kt ni vi nhau trn h tng


50/72



nh tuyn IPv6 thng qua cc ng hm IPv4 qua

IPv6 khi chuyn hon ton sang IPv6.

3.2 C h huyn iHin nay s lng cc mng IPv4 l rt ln; hu ht cc dch v v cc giao

dch trn mng u da trn h tng mng IPv4; do vy xut hin nhiu c ch

chuyn i cho php kt ni cc host IPv6 qua mng IPv4.

Vic xy dng li giao thc ca tng Internet trong m hnh TCP/IP dn

n nhiu thay i. Trong vn thay i ln nht ca IPv6 vi IPv4 l

vic thay i cu trc a ch. S thay i ny nh hng n cc vn sau:

- nh hng ti hot ng ca cc giao thc tng trn ( Tnggiao vn v tng ng dng)

- nh hng ti cc phng thc nh tuyn.Mt khc , mt yu cu quan trng trong vic trin khai IPv6 l phi thc

hin c mc tiu ban u ra khi thit k giao thc IPv6 l : IPv6 phi

lm vic c trong mi trng s dng giao thc IPv4. S c hin tng ch

c nhng host dng duy nht IPv6 v ng thi cng tn ti nhng host ch

duy nht IPv4. ng thi nhng host thun IPv6 phi giao tip c vi

nhng host IPv4 trong khi vn m bo a ch IPv4 l c tnh thng nht

ton cu. Do vy, m bo thc hin cc s tng thch gia IPv4 v IPv6,

cc nh thit k IPv6 xy dng mt s c ch chuyn i khc nhau.

Cc c ch chuyn i ny c nhng c im chung nh sau:

- m bo cc host/b nh tuyn ci t IPv6 c th lm vicc vi nhau trn nn IPv4.

- H tr cc kh nng trin khai cc host v b nh tuyn hotng trn nn IPv6 vi mc tiu thay th dn cc host ang hot

ng IPv4.

- C mt phng thc chuyn i d dng, thc hinc cccp khc nhau t pha ngi dng cui ti ngi qun tr h

thng, cc nh qun l mng v cung cp dch v.


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Cc c ch ny l mt tp cc giao thc thc hini vi cc host v cc b

nh tuyn, km theo l cc phng thc nh gn a ch v trin khai, thit k

lm qu trnh chuyn i Internet sang IPv6 lm vic vi t ri ro nht c

th c.

Hin nay cc nh thit k IPv6 a ra 3 c ch chuyn i chnh cho

php kt ni IPv6 trn nn IPv4 nh sau:

Dual Ip layer: c ch ny m bo mt host/b nh tuyn c ci tc IPv4 v IPv6 tng Internet Layer trong kin trc TCP/IP ca n.

IPv6 tunnel qua IPv4: C ch ny thc hin ng gi mt gi tin IPv6theo chun giao thc IPv4 c th mang gi tin trn nn kin trcIPv4. C 2 loi tunneling l ci t sn ( Configured) v t ng

(Automantic).

6to4:C ch ny hot ng da trn cc host IPv4 sn c cc a chIPv4 t xy dng mt a ch IPv6 c cu trc c bit; cc host s

dng c ch ny khng cn phi thng qua mt ISP c h tr IPv6.

3.2.1 Lp IP song song ( Dual IP layer).C ch ny m bo mt host/b nh tuyn c ci t c 2 giao thc IPv4 v

IPv6.

Vi c ch song song ny, hot ng ca cc host/b nh tuyn hon ton

tng thch vi IPv4 v IPv6. Theo c ch ny, IPv6 s cng tn ti vi IPv4 v

n s dng c s h tng ca IPv4. S la chn s dng ngn xp ( la chn

giao thc no trong lp TCP/IP) s da vo thng tin c cung cp bi dch v

qua DNS server.

Application

TCP/UDP


52/72



IPv4 IPv6

Network layer

Hnh 3.1: Minh h h Dul lyer

y l c ch n gin nht cho php nt mng ng thi h tr c hai giao

thc IPv6 v IPv4. C c kh nng trn do mt trm Dual Stack ci t c

hai giao thc, IPv4 v IPv6. Trm Dual Stack s giao tip bng giao thc IPv4

vi cc trm IPv4 v bng giao thc IPv6 vi cc trm IPv6.

Do hot ng vi c hai giao thc, nt mng kiu ny cn t nhtmt a chIPv4 v mt i ch IPv6. a ch IPv4 c th c cu hnh trc tip hoc

thng qua c ch DHCP. a ch IPv6 c cu hnh trc tip hoc thng qua

kh nng t cu hnh a ch.

Nt mng h tr cc ng dng vi c hai giao thc. Chng trnh tra cu tn

min c th tra cu ng thi c cc truy vn kiu A ln kiu AAAA (A6).

Nu kt qu v l bn ghi kiu A, ng dng s s dng giao thc IPv4. Nu ktqu tr v l bn ghi AAAA (A6), ng dng s s dng giao thc IPv6. Nu c

hai kt qu tr v, chng trnh s la chn tr v cho ng dng mt trong hai

kiu a ch hoc c hai.

u im:

- y l c ch c bn nht nt mng c th hot ng ngthi vi c hai giao th do , n c h tr trn nhiu nntng khc nhau nh: FreeBSD, Linux, Windows v Solaris.

- Cho php duy tr cc kt ni bng c hai giao thc IPv4 v IPv6.Nhc im:

- Kh nng m rng km v phi s dng a ch IPv4.


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3.2.2 ng hm IPv6 qua IPv4.y l cch nhanh vd nht trin khai IPv6 qua nhng v tr b gii hn.

IPv6 ch xut hin cc access point c h tr cc IPv6 host. Interface h tr

IPv6 segment s c cu hnh cho c IPv4 v IPv6 hay ch l IPv6. IPv6

traffic sau s c ng gi vo cc IPv4 packet truyn qua mng. Ch

nhng router h tr cc tunnel interface u vo v c u ra mi yu cu l

dual-stack (chy c IPv6 v IPv4). Mi tunnel interface s x l cc IPv6

packet ging nh cch cc interface vt l x l. Cc IPv6 host s s dng a

ch ca tunnel lm default gateway v mt giao thc nh tuyn (nh RIPv6)

forward cc packet gia cc tunnel.

C s h tng mng Internet hot ng trn nn IPv4 hot ng kh n nh

v c quy m rng ln. Tn dng kh nng ny, cc nh thit kIPv6 a ra

gii php l thc hin c ch tunneling ( ng hm) trn nn IPv4.

Hnh 3.2: Cng ngh ng hm

Nguyn tc ca vic to ng hm trong cng ngh tunnel nh sau:

- Xc nh thit b kt ni ti cc im u v cui ng hm.Hai thit b ny phi c kh nng hot ng dual-stack.

- Xc nh a ch IPv4 v a ch IPv6 ngun v ch ca giaodin tunnel (hai u kt thc tunnel).


54/72



- Trn hai thit b kt ni ti u v cui tunnel, thit lp mt giaodin tunnel (giao din o, khng phi giao din vt l) dnh cho

nhng gi tin IPv6 s c bc trong gi tin IPv4 i qua.

-

Gn a ch IPv6 cho giao din tunnel.- To tuyn (route) cc gi tin IPv6 i qua giao din tunnel. Ti

, chng c bc trong gi tin IPv4 c gi tr trng Protocol

41 v chuyn i da trn c s h tng mng IPv4 v nh nh

tuyn IPv4.

Cng ngh ng hm l mt phng php s dng c s h tng sn c

ca mng IPv4 thc hin cc kt ni IPv6 bng cch s dng cc thit bmng c kh nng hot ng dual-stack ti hai im u v cui nht nh.

Cc thit b ny bc gi tin IPv6 trong gi tin IPv4 v truyn ti i trong

mng IPv4 ti im u v g b gi tin IPv4, nhn li gi tin IPv6 ban u ti

im ch cui ng truyn IPv4.

Ni chung, cng ngh ng hm gi gi tin IPv6 trong gi tin IPv4

truyn i c trn c s h tng mng IPv4. Tc thit lp mt ng ktni o (mt ng hm) ca IPv6 trn c s h tng mng IPv4.

C hai loi c ch Tunneling nh sau: l Automatic v Configured

Tunneling.

C hai c ch ny khc nhau c bn l vic quyt nh a ch cui ca qu

trnh ng hm, cn li v c bn hot ng ca hai c ch ny l ging

nhau.

C ch ng gi/ m gi thc hin ng hm:

- im khi to ng hm ( im ng gi tin) to mt tiu IPv4 ng gi v truyn gi tin c ng gi.


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- Node kt thc ca qu trnh ng hm ( im m gi) nhnc gi tin ng gi, xa bphn tiu IPv4, sa i mt s

trng ca tiu IPv6, v x l phn d liu ny nh mt gi

tin IPv6.

- Node ng gi cn duy tr cc thng tin v trng thi ca miqu trnh trong ng hm. V d cc tham s MTU x l cc

gi tin IPv6 bt u thc hin ng hm. V s lng cc tin

trnh trong ng hm c th tng ln mt s lng kh ln,

trong khi cc thng tin ny thng lp li v do c th s

dng k thut m v c loi b khi cn thit.

Hnh 3.3: C h ng gi th hin nghm


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Hnh 3.4: C h m gi khi th hin ng hm

Automatic Tunneling:Cc k thut to tunnel ng: l mt k thut m 32 bit cui ca a ch

IPv6 c thay th bi mt a ch IPv4 v 6 phn cn li bng 0. Do , s

to ra mt a ch IPv6 c dng: 0:0:0:0:0:0:A.B.C.D hay ::A.B.C.D. Mc d

cch ny cung cp mt cch ng xy dng cc tunnel, nhng s khng tn

dng c tm a ch ln ca IPv6 v mi host phi c mt a ch IPv4 k

thut ny s khng tn dng c IPv6 v khng ph hp cho nhng mi

trng ln. ISATAP l mt k thut m rng ca k thut ny.

Vi phng thc ny tunneling ny, a ch ch trong gi tin ng gi IPv4

c xc nh l a ch ch ca gi tin IPv6. Do vy, a ch ch ca gi tin

IPv6 c ng gi phi c dng a ch IPv4 tng thch vi IPv6 ( IPv4

compability IPv6). i vi nhng gi tin IPv6 m a ch ch l dng a ch

khng c dng IPv4-compabile th s khng th thc hin automatic tunneling.

C ch Automatic Tunneling thng c s dng khi cn thc hin nhngkt ni vi cc host hoc vi cc mng IPv6 trong mt thi gian ngn, hoc

trong nhng tnh hung ngu nhin.

c im ca ng hm t ng l a ch im cui ng hm c xc

nh mt cch t ng. ng hm c to ra mt cch t ng v cng t

ng mt i. M hnh u tin l dng a ch IPv6 c khun dng c bit: a

ch IPv6 tng thch IPv4 m ho thng tin v a ch IPv4 trong a chIPv6.

Hnh 3.5: h v6 tng thh h v4


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Ti im u ng hm, nt mng ng gi s tch phn a ch IPv4 lm

a ch im cui ng hm ng gi gi tin.

u im:

- ng hm t ng n gin, cho php hai nt mng IPv6 ddng kt ni vi nhau qua kt ni IPv4 hin c m khng cn

cc cu hnh c bit.

Nhc im:

- Hn ch v khng gian a ch do ph thuc vo khng gian ach IPv4.

- Nguy c b tn cng ph hoi bi cc tin tc: Do a ch cui cng ng hm c xc nh hon ton

t ng v gi tin ng hm s c gi n a ch IPv4

. Nu khng c c ch kim tra c bit, gi s c mt

gi tin c gi n router ca mng (203.162.7.0) vi a

ch IPv6 ch: 203.162.7.255. a ch IPv4: 203.162.7.255

l a ch broadcast ca mng do , cc gi tin ng hms c gi ti mi trm trong mng.

Do , cc ng hm t ng thng c hn ch sdng. Sau ny ngi ta xut mt s phng php ci tin

nh 6over, 6to4.

Cc thng s lin quan n Automatic Tunneling

- Kh nng ng dng: i vi cc host.- Yu cu giao thc IPv4: Yu cu c cc kt ni IPv4 gia cc

site.

- Yu cu a ch IPv4: ti thiu c mt a ch IPv4- Yu cu giao thc IPv6: khng cn thit.- Yu cu a ch IPv6: i ch dng IPv4 compabile.- Yu cu i vi host: ci t dual satck IPv4/IPv6.


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- Yu cu i vi route: none. Configured TunnelingVi phng thc ny tunneling ny, a ch m gi c quyt nh bi cc

thng tin c cu hnh node ng gi. i vi mi tunnel dng ny, ccnode ny phi lu a ch ca cc trm cui ( cc trm m gi end-point ). Khi

cc gi IPv6 c chuyn qua tunnel ny, a ch ca cc endpoint c cu

hnh sao cho ging vi a ch ch trong phn tiu ca gi tin IPv4 ng

gi.

c im ca ng hm c cu hnh l a ch im cui ng hm

khng c xc nh t ng m da trn nhng thng tin cu hnh trc tiim u ng hm.

Hnh 3.6. ng hm u hnh

Cc thng s yu cu i vi c ch Configured Tunneling nh sau:

- Kh nng ng dng :site.- Yu cu giao thc IPv4: kt ni gia cc site s dng IPv4.- a ch IPv4: ti thiu c mt a ch IPv4 trong mt site.


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- Yu cu giao thc IPv6: khng cn thit.- Yu cu v a ch IPv6: khng cn thit .- Yu cu host: IPv6 stack hoc IPv4/IPv6 stack.- Yu cu i vi b nh tuyn: IPv4/IPv6 b nh tuyn.

3.2.3 C ch 6to4.C ch 6to4 tunnel ng: vi k thut ny th mng IPv4 s c xem nh

mt lin kt unicast P2P. Mc ch ca vic s dng 6to4 tunnel l kt ni cc

IPv6 domain ch khng phi cc host, tuy nhin k thut ny kh m rng.

Mc d cc gi IPv6 c bao ng bn trong cc gi IPv4, nhng cc tunnel

li khng c nh ngha. V 13 bit TLA l: 0x0002 hay :2002::/16. 32 bit

tip theo (high level NLA) s l a ch IPv4 ton cc ca interface router. Khi

mt 6to4 router nhn c mt IPv6 packet khng phi thuc domain ca n

vi mt TLA l 2002, n s bao ng d liu trong gi IPv4 packet v thit lp

trng protocol thnh 41. Router sau s s dng high level NLA (32 bit

IPv4) nh l mt a ch ch v nh tuyn gi tin qua mng IPv4. Cn nu

TLA khc 2002 th packet s cbao ng v gi ra mt default route nmt 6to4 router khc forward.

a ch 6to4 c dng:

Hnh 3.7: C h 6 to4

Khun dng ca mt a ch 6to4 nh sau:


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Hnh 3.8: Khun dng h 6to4

C ch hot ng:

Khi c mt gi tin IPv6 vi a ch ch c dng 2002::/16 c gi n

mt router 6to4, router 6to4 tch a ch IPv4 (a ch IPv4 va tch c

chnh l a ch IPv4 ca 6to4 router ch), bc gi tin IPv6 trong gi tin IPv4

vi a ch ch l a ch IPv4 va tch c. Sau , cc gi tin s c

chuyn tip trn h tng IPv4. Khi router 6to4 ch nhn c gi tin, gi tin

IPv6 s c tch ra v chuyn n nt mng IPv6 ch.

Hnh 3.9: C h hot ng 6to4

u im:

- Cc nt mng khng bt buc phi dng a ch IPv6 kiu tngthch IPv4 nh ng hm t ng.

- Khi cn nhiu cu hnh c bit nh ng hm c cu hnh.- Khng b nh hng bi cc h thng tng la ca mng, ch

cn router ca mng c a ch IPv4 ton cc c th nh tuyn.


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Nhc im:

- Ch thc hin vi mt lp a ch mng c bit.- C nguy c b tn cng theo kiu ca ng hm t ng nu

phn a ch IPv4ADDR trong a ch ch ca gi tin 6to4 la ch broadcast hay multicast.

3.2.4 C ch 6over4C ch cho php cc trm IPv6 c lptrn cc lin kt vt l khng c cc

router IPv6 hot ng da trn cc gi tin multicast IPv4 nh mt lin kt cc

b o. C ch ny cn gi l mng Ethernet o.

h tr cc c ch Pht in lng ging v t cu hnh a ch stateless,

mt s cc a ch c phm vi qun tr c s dng. Cc nhm multicast

gi lp mt tng lin kt Ethernet. Do , c ch pht hin lng ging (ND)

gia cc trm IPv6 vi cc trm 6over 4 ging nh trong tng Ethernet thng

thng. Cch tip cn ny to ra lin kt IPv6 tht trn mt mng Lan o.

im khc bit l cc trm 6over4 vo cng mt min IPv4 multicast thay v

mt mng chia s ng truyn.Vic nh x a ch IPv6 sang a ch tng lin kt c thc hin ging

giao thc ND. Trong trng hp ny, tu chn a ch tng lin kt ngun/ch

s dng IPv4 lm tng lin kt. Do , ton b mng IPv4 c coi nh mt

tng lin kt chia s ng truyn thng qua vic s dng cc a ch multicast

sau y:

- a ch multicast tt c cc nt mng (239.X.0.1): a ch quntr ny c dng n mi nt mng trong min IPv4 h tr

c ch ny.

- a ch multicast tt c cc router (239.X.0.2): a ch qun trny c dng n mi router trong min IPv4 h tr c ch

ny.


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- a ch multicast solicited node (239.X.C.D): a ch qun trny c dng xc nh a ch nt lng ging (C v D l hai

byte thp trong a ch IPv4).

Trong tt c cc a ch ny, X ch nh danh cc blin kt (thng bng192).

S dng tng IPv4 lm tng lin kt loi b cc hn ch ca tng vt l i

vi k hoch chuyn i. Cc trm c th tri trn nhiu min v thm ch cch

nhiu bc so vi router IPv6.

Hnh 3.10: C h 6over4

Cc trm 6over4 nhn cu hnh ( a ch lin kt cc b v tin t, a chIPv4 ca router h tr IPv6) s dng giao thc ND trn cc a ch multicast

IPv4.

Sau cc gi d liu IPv6 c gi trong cc gi d liu IPv4 vi kiu

giao thc 41. Chnh cc trm s thc hin ng hm.

u im:

- Cc trm IPv6 khng i hi c a ch tng thch hay nghm cu hnh. Chnh cc trm s thc hin ng hm. Kin trc


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c s bao gm mt router vi kt ni IPv6 v h tr 6over4, mt

mng c kh nng multicast kt ni cc trm v router. Trong

mi trng , cc trm 6over4 c th kt ni vi cc trm IPv6

khc.

- C tnh m rng nh IPv6 trn hu ht cc phng tin truyn.Nhc im:

- Suy gim Mtu ca gi tin dn n gim thng lng.- Trong qu trnh chuyn i, cc router phi qung b t nht hai

tin t IPv6, mt cho lin kt LAN thc s v mt cho min

6over4. Ngoi ra, di tin t phi l 128 phn bit hai loitin t cng c kiu FE80::/64.

3.2.5 Mi gii ng hm (Tunnel Broker)Hin nay, mng IPv6 s dng rt nhiu ng hm trn h tng IPv4.

Tunnel Broker l hnh thc tunnel, trong mt t chc ng ra lm trung

gian, cung cp kt ni ti Internet IPV6 cho nhng thnh vin ng k s dng

dch v Tunnel Broker do t chc cung cp. Tunnel Broker c a ra gim nh chi ph cu hnh v duy tr cc ng hm ny.

C ch ny s dng mt tp cc server chuyn dng gi l Tunnel Broker

cu hnh v duy tr cc ng hm. Chng c th xem nh cc ISP IPv6 o

cho cc ngi dng kt ni vo Internet IPv4. C ch ny ph hp cho cc

trm (hoc site) IPv6 nh c lp mun kt ni d dng vo mng IPv6.

Cu trc ca Tunnel Broker bao gm:

- Mt server Tunnel Broker.- Mt DNS server.- Mt s cc server ng hm.

Sau y l m hnh cng ngh ng hm trong cc im kt thc ng

hm c thc hin bng mt thit b gi l Tunnel Broker.


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T chc cung cp dch v Tunnel Broker c vng a ch IPv6 c lp, ton

cu, xin cp t cc t chc qun l a ch IP quc t, mng IPv6 cat chc

c kt ni ti Internet IPv6 v nhng mng IPv6 khc. Thnh vin ng k v

c cp quyn s dng dch v Tunnel Broker s nhn c nhng thng tin

t t chc qun l Tunnel Broker thit lp ng hm tunnel t host hoc t

router gateway mng IPv6 ca t chc mnh ti mng ca t chc duy tr

Tunnel Broker, t kt ni ti c Internet IPv6 hay nhng mng IPv6 khc

m t chc duy tr Tunnel Broker c kt ni ti.

Ngi s dng s kt ni ti c IPv6 Internet v cc mng IPv6 khc khi

ng k v c php s dng dch v Tunnel Broker ca nh cung cp.

Ngi s dng s c cung cp thng tin thit lp ng hm t host hoc

mng ca mnh n mng ca t chc duy tr Tunnel Broker v dng mng ny

nh mt trung gian kt ni ti cc mng IPv6 khc. Ngi ng k s dng

dch v Tunnel Broker s c cp mt vng a ch thun IPv6, tu theo nhu

cu s dng t khng gian a ch IPv6 ca nh cung cp dch v tunnel broker

v c chuyn giao mt khng gian tn min cp di khng gian tn min

ca nh cung cp dch v Tunnel Broker. y l a ch v tn min hp l

ton cu, thnh vin ca Tunnel Broker c th s dng tn min ny thit

lp IPv6 Website cho php nhng mng IPV6 c kt ni ti mng ca nh

cung cp dch v Tunnel Broker truy cp ti.

Hnh 3.11: Kt ni v6 vi Tunnel Broker

Cch thc thc hin:


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- Cc khch hng ca dch v Tunnel Broker l cc nt mng IPv6stack kp (host hoc router) kt ni vo Internet IPv4. Trc

khi thit lp ng hm, cn c s trao i thng tin gia Tunnel

Broker vi khch hng nh xc thc, qun l v thng tin ti

khon.

- Khch hng kt ni ti Tunnel Broker ng k v kch hotcc ng hm. Tunnel Broker c th chia s ti cc im cui

ng hm trn cc server ng hm. N cng c th ng k

tn v a ch IPv4 ca u ng hm pha h, tn ng k

trong DNS v l mt trm hay mt router.

- Tunnel Broker chn mt server ng hm lm im cuing hm thc s. N chn tin t cp pht cho khch hng (t

0 n 128) v c nh thi gian tn ti ca ng hm.

- Tunnel Broker ng k a ch IPv6 cp cho cc im cuing hm trong DNS.

- Tunnel Broker cu hnh ng hm pha server v thng bo ccthng tin lin quan cho khch hng.

ng hm thit lp gia ngi s dng v mng ca nh cung cp dch v

Tunnel Broker c cu hnh trn nguyn l Tunnel bng tay.

Sau , khch hng c th kt ni vo mng IPv6 thng qua c ch ng

hm nh bnh thng.

- Cc n v kt ni vi VNIXv6 khng c ngn chn cc lulng thng tin trong nc i vo/ra mng ca mnh qua kt ni

VNIXv6.

- Cc ISP kt ni ti VNIXv6 c th qua kt ni trc tip (native)hoc qua kt ni c hm (Tunnel).

- Cc ISP kt ni ti VNIXv6 c ton quyn s dng cc dch vtrn nn IPv6 do VNNIC cung cp.


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M hnh ca mt Tunnel Broker:

Hnh 3.14: M hnh mt Tunnel Broker

Trong

Tunnel Broker: l nhng my ch dch v lm nhim v qun l thng tin

ng k, cho php s dng dch v, qun l vic to ng hm, thay i

thng tin ng hm cng nh xo ng hm. Trong h thng dch v

Tunnel Broker ca nh cung cp, my ch Tunnel Broker s lin lc vi

Tunnel Server (thc cht l cc dual-stack router) v my ch tn min ca nh

cung cp Tunnel Broker thit lp ng hm pha nh cung cp dch v

Tunnel Broker v to bn ghi tn min cho ngi ng k s dng dch v

Tunnel Broker.

Ngi s dng thng qua mng Internet IPV4 s truy cp my ch Tunnel

Broker v ng k ti khon s dng dch v Tunnel Broker thng qua mu

ng k di dng Web.

Tunnel Server: Thc cht l cc router dual-stack lm nhim v cung cp

kt ni ngi ng ks dng dch v kt ni ti truy cp vo mng

IPv6 ca t chc cung cp Tunnel Broker. Cc router ny l im kt thc

tunnel pha nh cung cp dch v Tunnel Broker. Tunnel Server nhn yu cu


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t my ch Tunnel Broker v to, hoc xo ng tunnel pha nh cung cp

Tunnel Broker.

u im:

- Qun l tp trung cc ng hm pha server, gim bt chi ph.- C th s dng cc ISP o trn IPv6.- Cc Tunnel Broker trn mng Internet

3.2.6 Dch a ch - Dch giao thc (SIIT v NAT PT)Dch a ch v dch giao thc c pht trin trn c s c ch NAT trong

IPv4 nhm cho php cc nt mng IPv4 v IPv6 kt ni vi nhau. C ch ny

hot ng trn c s chuyn i cc khc bit gia cc gi tin IPv4 v IPv6.

Khc bit v a ch: Dch a ch IPv4 IPv6.

Khcbit v phn m u header: Dch giao thc thay i header gi tin.

Thit b NAT PT c ci t ti bin gii gia mng IPv4 v IPv6. C

ch ny khng i hi cc cu hnh c bit ti cc my trm v cc s chuyn

i gi tin ti thit b NAT-PT hon ton trong sut vi ngi dng.

Mi thit b NAT PT duy tr mt tp cc a ch IPv4 dng nh x cc

yu cu vi a ch IPv6.

NATPT c th m rng thnh NAPT PT cho php s dng mt a ch

- IPv4 cho nhiu phin lm vic khc nhau.

NAT- PT cngnh NAT cng nh IPv4 khng c kh nng hot ng vicc gi tin c cha a ch trong phn ti tin. Do , NAT PT thng i km

vi c ch Ca khu tng ng dng ALG. C ch ny cho php x l cc gi

tin ng vi tng dch v nht nh nh DNS hay FTP,

u im:

- Qun tr tp trung ti thit b NAT PT.- C th trin khai nhiu thit b NAT- PT tng hiu nng hot

ng.


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Nhc im:

- To ln mt im gy li lon single poin of failure ti thit bNATPT.

Cc trin khai ca NAT- PT: NATPT cth nghim trn cch iu hnh mng nh:

- Linux, Free BSD, Microsoft Windows 2000.- Ngoi ra, n cng l mt phn ca h iu hnh Cisco IOSIPv6

bn beta vi hai phin bn da trn IOS v11.3 v IOS v12.0. Cc

trin khai ny c cho nhiu loi router khc nhau.

Cng ngh bin dch thc cht l mt dng cng ngh NAT, thc hin bindch a ch v dng thc ca mo u gi tin, cho php thit b ch h tr IPv6

c th ni chuyn vi thit b ch h tr IPv4. Cng ngh ph bin c s

dng l NAT-PT. Thit b cung cp dch v NAT-PT s bin dch li mo u

v a ch cho php mng IPv6 ni chuyn vi mng IPv4.

Hnh 3.15: Cng ngh bin dh NAT-PT

SIIT (Stateless IP/ ICMP Translation Algorithm) l mt chun ca IETF

(RFC2765) m t b dch IPv6/ IPv4 khng lu trng thi (Stateless).

Tng t c ch NAT PT ngoi tr n khng cp pht ng a ch IPv4

cho cc trm IPv6. Chc nng chuyn i thc hin gia header IPv6 v IPv4.

SIIT khng bao gm cc ty chn IPv4 v header m rng trong IPv6.

SIIT cng thc hin chuyn i cc thng ip iu khin ICMP gia hai

giao thc.

LAN IPV4

LAN IPV6

Cu hnh NAT-PT trnrouter Cisco 2 LAN ni

chuyn c vi nhau

LAN IPV4

LAN IPV6

Cu hnh NAT-PT trnrouter Cisco 2 LAN ni

chuyn c vi nhau


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i vi qu trnh chuyn i IPv4 sang IPv6, mt a ch IPv4 tm thi

c gn cho nt mng IPv6.

Cc gi tin n thit b SIIT s c chuyn i header v a ch t IPv4

sang cc a ch IPv4- dch (IPv4 translated) v IPv4 nh x (IPv4 mapped). Mt a ch IPv4 dch tng ng vi mt nt mng IPv6 cn a

ch IPv4- nh x tng ng mt nt mng IPv4. i vi chiu ngc li, cc

a ch ny s c chuyn i ngc lithnh a ch IPv4.

Do qu trnh chuyn i khng lu trng thi, c th tn ti nhiu b

chuyn i gia hai mng IPv4 v IPv6. Khng c s rng buc mi phin

truyn phi i qua mt thit b duy nht nh trong NAT-PT.hin.

3.3 KtlunhngTrong chng ny cp n cng ngh chuyn i IPv6-IPv4. Trong

thi gian u pht trin, kt ni IPv6 cn thc hin trn c s h tng mng

li IPv4. Mng Ipv6 v IPv4 s cng song song tn ti trong thi gian di,

thm ch l mi mi.

Phn 2: Xy dng v trin khai m hnh thnghim ti cng tyTNHH Vnh Phan

Chng 1: Phn tch v thit k h thng cho cng ty TNHHVnh Phan

1.1 Kho st th t1.1.1 S m hnh mng thc t ca cng ty

Cu trc ta nh gm 3 tng nh sau:


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A CHIPv6 Ti liu tham kho


Tng 1:

Tng 2:


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Tng 3:

1.1.2 Yu cu T chc phn quyn theo tng ngi dng Cho php nhn vin xa cng c th truy nhp vo h thng

mng ca cng ty Chia s file trong cng ty H thng Mail, Web ni b, forum trong cng ty t tng la, cp pht quyn cho ngi dng trong cng ty

1.1.3 Phn loi yu cui vi h thng bn trongi vi h thng bn ngoi

1.2 hn th v x l yu u1.2.1 S mng xut1.2.2 M t

M hnh xut s dng my ch Domaincontroller nhm bo vmng ni b mt cch an ton vi internet. Mt khc ta c th kim sotc vic truy cp Internet ca cc my tnh bn trong mng ni b1.2.3 S i dy mng1.2.4 Hng gii quyt

1.3 S phn r h nng mng


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