Chng 1

Cng ngh Mobile IP. SV:Quan Ch Linh 4 5K2.

MC LC.1MC LC.

5CC HNH S DNG TRONG N.

7LI NI U.

8TM TT N

10CHNG 1: S BNG N THNG TIN DI NG

101.1 Khi qut mng in thoi di ng:

121.2 Tm hiu mng di ng GSM:

121.2.1.Tiu chun GSM:

121.2.2 Hot ng ca GSM:

141.2.3 Cc c tnh k thut ca h thng GSM:

14a. S dng giao din v tuyn:

14b. S dng phng php a truy nhp:

161.2.4 Cc tiu chun ang c pht trin:

181.3 DCH V TRUYN S LIU GI:

201.3.1 Kin trc h thng GPRS:

21a.Thit b u cui s liu TE:

21b. u cui di ng:

21c. Trm di ng MS:

22d. H thng trm gc BSS:

23e. B ng k nh v thng tr HLR:

23g. Nt h tr dch v chuyn mch gi di ng SGSN:

24h. Nt h tr dch v chuyn mch gi di ng cng GGSN:

251.3.2 Hot ng ca GPRS:

281.3.3 Cc la chn cu hnh trin khai:

29a.Kt ni trc tip:

30b.Kt ni gin tip:

32CHNG 2: TNG QUAN CNG NGH IP

322.1 Gii thiu:

322.2 B giao thc TCP/IP:

332.2.1 u im ca b giao thc TCP/IP:

342.2.2 M hnh tham chiu TCP/IP:

382.2.3 Tng mng:

392.2.4 Tng Internet:

39a.Gi tin IP:

42b.Gi tin ICMP:

43c.Gi tin ARP:

432.2.5 Tng giao vn:

44a.Giao thc khng kt ni UDP:

46b. Giao thc iu khin truyn tin TCP:

492.2.6 Tng ng dng:

49a.Dch v tn min DNS:

49b. ng nhp t xa Telnet:

49c.Th in t Email:

50d.Giao thc truyn tp FTP:

502.2.7 C ch a ch Internet:

51a. a ch lp A:

51b.a ch lp B:

51c. a ch lp C:

522.2.8 Subnet v Subnet Mask:

532.3 Vn nh tuyn trong mng IP:

532.3.1 nh tuyn trc tip:

542.3.2 nh tuyn gin tip:

56CHNG 3: TNG QUAN V MOBILE IP

563.1 Gii thiu v cng ngh Mobile IP:

573.2 Cc khi nim v thut ng c bn dng trong giao thc:

593.3 Cc yu cu v mc tiu ca Mobile IP:

593.2.1 Cc yu cu m Mobile IP phi p ng:

603.2.2 Cc mc tiu ca Mobile IP:

603.4 Tng quan v Mobile IP:

613.4.1 Cc thnh phn chnh ca mng Mobile IP:

623.4.2 Cc c tnh ca Mobile IP:

64CHNG 4: HOT NG CA MOBILE IPv4

644.1 Tng quan v giao thc Mobile IP:

644.1.1 Khi nim a ch care of:

654.1.2 Nguyn l hot ng ca Mobile IPv4:

674.1.3 Cu trc chung ca cc bn tin s dng trong giao thc.

684.2 Phng php pht hin i l.

684.2.1 Qung co i l.

70a.M rng qung co i l di ng.

72b. M rng di tin t:

73c. Byte m m rng:

734.2.2 Tm kim i l.

744.2.3 Hot ng ca i l di ng.

754.2.4 Hot ng ca trm di ng.

75a. ng k khi c yu cu:

76b. Tr v mng gc:

764.2.5 Thng tin lin lc vi i l ngoi:

774.3 ng k vi i l gc:

774.3.1 Th tc ng k vi i l gc:

794.3.2 Cu trc bn tin ng k.

79a.Cc trng IP:

79b. Cc trng UDP:

80c. Cc trng Mobile IP:

814.4 Qu trnh truyn v nhn gi tin.

824.4.1 Vn i qua hai ln.

834.4.2 Ti u ho ng i:

85CHNG 5: GIAO THC MOBILE IPv6

855.1 Gii thiu v IPv6:

875.2 Tng quan v Mobile IPv6.

875.2.1 Cc c tnh ca Mobile IPv6:

895.2.2 Cc bn tin iu khin.

905.2.3 Cu trc d liu:

915.3 Hot ng ca Mobile IPv6:

915.3.1 Pht hin s di chuyn:

915.3.2 ng k vi i l gc:

925.3.3 nh tuyn tam gic:

935.3.4 Ti u ho ng i:

945.3.5 Qun l lin kt:

955.3.6 C ch pht hin i l gc:

975.4 So snh Mobile IPv4 v Mobile IPv6:

100CHNG 6:NG DNG CA MOBILE IP VO VIC TRUYN S LIU TRONG MNG THNG TIN DI NG

1006.1 Trin khai Mobile IP trong mng CDMA 2000:

1026.2 Trin khai Mobile IP trn mng GPRS:

1036.2.1 Bc 1 - H tr dch v Mobile IP:

1066.2.2 Bc 2 - Ti u ho ng i.

1076.3 Kt lun:

109KT LUN

110BNG CC T VIT TT V THUT NG

112TI LIU THAM KHO

CC HNH S DNG TRONG N.11Hnh 1. 1: M hnh lp t bo in hnh

13Hnh 1. 2: Cu trc ca mt mng GSM.

16Hnh 1. 3: Tn s sng mang GSM v cc khung TDMA.

20Hnh 1. 4: Cc phn t v giao din chnh ca mt mng GPRS

29Hnh 1. 5: Quyn s hu ton trnh v cc kh nng kt ni

TOC \h \z \c "Hnh 2."

34Hnh 2. 1: Tng ng gia cc lp ca OSI v TCP/IP.

36Hnh 2. 2: Cc tng trong b giao thc TCP/IP.

37Hnh 2. 3: Qu trnh truyn d liu qua cc lp.

38Hnh 2. 4: Qu trnh ng gi gi tin qua cc lp m hnh TCP/IP.

40Hnh 2. 5: Cu trc gi tin IP.

41Hnh 2. 6: Gi tin i qua Gateway.

42Hnh 2. 7: Cu trc gi tin ICMP.

43Hnh 2. 8: Gi tin ARP.

44Hnh 2. 9: Cu trc gi tin UDP.

45Hnh 2. 10: Qu trnh phn knh.

48Hnh 2. 11 : Cu trc gi tin TCP.

51Hnh 2. 12: Cc lp a ch IP.

54Hnh 2. 13: Qu trnh chuyn giao a ch ng.

TOC \h \z \c "Hnh 3."

57Hnh 3. 1: Mt trm di chuyn v khng thay i a ch IP.

61Hnh 3. 2: Thit b di ng sang mng khc v c cp a ch tm.

61Hnh 3. 3: Cc thnh phn ca Mobile IP v mi quan h ca chng.

62Hnh 3. 4: Tnh trong sut ca Mobile IP.

66Hnh 4. 1: M hnh nh tuyn gi tin trong IPv4.

67Hnh 4. 2: Cu trc ca m rng TLV.

69Hnh 4. 3: Cu trc bn tin qung co i l.

71Hnh 4. 4: M rng qung co i l di ng.

73Hnh 4. 5:M rng di tin t.

74Hnh 4. 6: Cu trc bn tin tm kim i l.

78Hnh 4. 7: ng k thng qua i l ngoi.

79Hnh 4. 8: Cu trc ca bn tin ng k.

81Hnh 4. 9: Cu trc bn tin yu cu ng k.

82Hnh 4. 10: Qu trnh chuyn v nhn gi tin IP.

83Hnh 4. 11: Vn i qua hai ln.

84Hnh 4. 12: Ti u ho ng i.

TOC \h \z \c "Hnh 5."

92Hnh 5. 1: ng k vi i l gc trong Mobile IPv6.

93Hnh 5. 2: nh tuyn tam gic.

95Hnh 5. 3: Pht hin a ch ca i l gc ng.

Error! Bookmark not defined.Hnh 5. 4: Hot ng ca Mobile IPv6.

101Hnh 6. 1: M hnh mng CDMA 2000 1x vi Mobile IP.

104Hnh 6. 2: Kin trc mng GPRS h tr Mobile IP.

106Hnh 6. 3: Th thc ng k Mobile IP trong GPRS.

108Hnh 6. 4: Cc trng hp chuyn vng trong GPRS.

LI NI U

Trong x hi pht trin nh hin nay, vi ngnh cng ngh in t thay i theo tng ngy, nhu cu trao i v nm bt thng tin l v cng quan trng. Cc hnh thc trao i thng tin cng ngy cng a dng, phong ph v i hi cht lng cao hn. Mt t nc mun pht trin th vic pht trin c s h tng ca vic thng tin lin lc ca quc gia l ti quan trng. V vi nc ta cng khng ngoi l, Internet v thng tin di ng l hai yu t pht trin mang tnh cht ton cu. Cng vi cc thng tin quan trng, cc dch v v cng ngh in t mi hin nay thng c trin khai nhanh chng trn mng Internet. Do vi cc thit b thng tin di ng th vic kt ni Internet l rt cn thit.

Trong khun kh bo co ny th em tp trung nghin cu cng ngh Mobile IP v ng dng ca Mobile IP vo vic truyn s liu trong mng thng tin di ng. Mc ch ca quyn n ny l a ra ci nhn tng quan v cng ngh Mobile IP v ng dng ca n trong mng di ng.

Do s hn ch v thi gian cng nh s hiu bit cha c y , quyn n kh trnh khi nhng thiu st. Em rt mong c thy c v bn b ng gp kin.

Trong qu trnh thc hin n ny em nhn c s gip ca rt nhiu tp th v c nhn. Trc ht em xin chn thnh cm n TS.Phm Vn Bnh, ging vin khoa in T Vin Thng trng i Hc Bch Khoa H Ni gip em thc hin n ny. Thy cng dnh nhiu thi gian qu bu ca mnh c v gp cho n c hon thin hn. Em cng xin cm n gia nh v bn b ng vin gip trong qu trnh lm n. Vinh thng 5 nm 2009.

Sinh Vin:

Quan Ch LinhTM TT N

Trong khun kh n ny, em tp trung nghin cu cng ngh Mobile IP v ng dng ca Mobile IP vo vic truyn s liu trong mng thng tin di ng. Ni dung ca n gm 6 chng:

Chng 1: Chng ny gii thiu tng qut v cu trc v thnh phn mng GSM; v s phn vng a l v cc c tnh k thut ca h thng GSM. Gii thiu v dch v truyn s liu gi, kin trc cng nh cc thnh phn chnh ca mng GPRS.

Chng 2: Tng quan v cng ngh IP, v giao thc TCP/IP, cc vn v nh tuyn trong mng IP.

Chng 3: Khi qut chung v giao thc Mobile IP.

Chng 4: Tp trung vo giao thc Mobile IPv4 vi cc ni dung nh: cu trc bn tin dng trong giao thc, cc th tc tm kim, ng k v nh tuyn gi tin.

Chng 5: Gii thiu v hot ng ca cc trm s dng giao thc IPv6 c h tr kh nng di ng (hay Mobile IPv6), vi mc ch tm hiu v nguyn l hot ng v cc c trng c bn ca giao thc so snh vi giao thc Mobile IPv4.

Chng 6: ng dng ca Mobile IP vo vic truyn s liu trong mng thng tin di ng.

THE SUMMARISATION OF PROJECT

In the framework of this project, I focus on studying Mobile IP technology and Mobile IP applications in data transmission in a mobile information system. The content includes six chapters in total.

Chapter 1: General introduction of structure and elements of a GSM network; geographical placement anh technical characteristics of a GSM system. Introduction of services data packet transmission; structure and elements of a GPRS network.

Chapter 2: Overview of IP technology, TCP/IP protocol, and routing in a IP network.

Chapter 3: General introduction of Mobile IP Protocol.

Chapter 4: Focusing on Mobile IPv4 with content: Structure of message, searching procedures, information packet registration and routing.

Chapter 5: Introduction of operation of station using IPv6 protocol with mobile ability, or Mobile IPv6, in order to study operation principles and its basic characterisations compared to Mobile IPv4 protocol.

Chapter 6: Mobile IP applications in data transmission in a mobile information system.CHNG 1: S BNG N THNG TIN DI NG

1.1 Khi qut mng in thoi di ng:

Tc pht trin mng in thoi di ng l ng ghi nhn. Trong vng hn 20 nm n tr thnh i th cnh tranh vi mng c nh pht trin 100 nm t ti trng thi hin nay.V con ngi ngy cng phi di chuyn nhiu hn, xa hn nn thit b di ng ngy cng tr thnh mt phng tin khng th thiu c trong cng vic cng nh trong cuc sng. Ngi ta d bo s c khong 1 t my in thoi di ng c s dng vo nm 2003.S pht trin nhanh nh mng in thoi di ng - vi tc pht trin in hnh l 40% nm - chc chn cc dch v mi s pht trin cho cng ng rt nhiu ngi s dng. Chnh iu l ng lc pht trin dch v dch v d liu vo kh nng thoi hin c. hiu iu ny s xy ra nh th no, ta hy xem bc tranh v mng hin ti v cho thy mng s pht trin nh th no h tr dch v d liu di ng.Hai yu t hn ch ca bt k h thng no da trn truyn dn v tuyn l: Ngun ti nguyn ph tn s l hu hn cng ngh hin c khai thc ngun ti nguyn ph tn s ny. Gii hn u tin c khc phc phn no khi vin nghin cu Bell (Bell labs) pht minh ra k thut s dng li tn s vo nhng nm 1950. Nhng phi n u nhng nm 1980 vi s ra i ca b vi s l pht minh ny mi c trin khai trong cc mng v thit b thc t.Cng ngh t bo cho php s dng c hiu qu ph tn s bng cch chia vng ph sng a l thnh cc vng nh ( hoc t bo), mi vng c trm gc ring. Cc t bo c ghp nhm vo thnh cc cm (cluster) v cc knh v tuyn c phn b cho mi cm tng ng vi mt quy lut khng i, lp i lp li trong vng ph sng.S lng cc t bo trong cm cng nh th s knh v tuyn trong mt cm cng ln v do kh nng truyn ti lu lng ca cc t bo cng ln. Song c mt nhc im l trong khong cch gia cc cm cng gn th nhiu gia cc cm cng ln. T s gia khong cch lp trn bn knh t bo v ca cng tn hiu nhiu i vi mi cu hnh c trnh by hnh di v bng 1.1.

Hnh 1. 1: M hnh lp t bo in hnhBng 1.1: Hng dn lp quy hoch cho cc m hnh lp t bo.S lng cc t bo4712

Khong cch lp/bn knh t bo3,54,66,0

Tn hiu nhiu (dB)13,719,424,5

Do khng c im kt ni c nh ti mt mng di ng v h tr chuyn vng gia cc t bo, tt c cc mng di ng cn trin khai mt s hnh thc qun l v tr. Cc mng t bo c chia thnh cc min qun l gi l cc vng nh v nhn dng ( tng i ) khu vc m ngi gi ang ng. Min qun l s gi cc bn ghi thu bao ca mt khch hng trong mt c s d liu thng tr ( home database ) v c s d liu ny c s dng cho c vic kt ni cuc gi v thanh ton. Bt c s chuyn giao no cn thit gia cc t bo trong mt cuc gi c gii quyt bng vic x l cuc gi trong phm vi mng.Mt s cng ngh h thng v tuyn hin ang c s dng. Cc h thng tng t c bao gm h thng truyn thng truy nhp ton b ( TACS Total Access Communication System ) v h thng in thoi di ng tin tin ( APMS Advanced Mobile Phone System ). Cc h thng s c a ra gn y bao gm h thng truyn thng di ng ton cu ( GSM Global System for Mobile Communication ) v DSC 1800 ( hin nay gi l GSM 1800 ). GSM cng xut hin trn bng tn 1900MHz ( GSM 1900 ) Bc M, Chil, gn y c quy nh cho bng tn 450MHz mt s ni. GSM chu s cnh tranh ca cc h thng IS-136 v IS-95. Tiu chun IS-136 trin khai k thut v tuyn ging GSM, cn IS-95 khai thc k thut v tuyn tri ph. y chng ta s dng GSM v c rt nhiu nhu cu v dch v d liu di ng da trn cng ngh GSM, cho ti nay y l cng ngh di ng t bo s quan trng nht.Cng nh mng in thoi di ng th mng Internet hin nay cng pht trin vi mt tc chng mt. Ngi ta tnh rng, c mi nm th s lng thu bao internet li tng gp i so vi nm trc . Cng vi , giao thc TCP/IP tr thnh giao thc s dng trao i d liu ph bin nht trn th gii. V do s pht trin k trn t ra mt nhu cu tt yu l kt hp hai hng pht trin ny nhm p ng nhu cu ngy cng tng v a dng ca khch hng.

1.2 Tm hiu mng di ng GSM:

1.2.1.Tiu chun GSM:GSM s dng rng bng tn 200KHz cho mi knh c lp v trong phm vi mi knh cho tc bt l 270kbit/s. Lung bit c chia thnh chui cc khung vi mt mu lp vi tc 270 ln/s. Mi khung c khe thi gian. Mi khe thi gian c di 0.577 m/s v tng ng vi 156.25 bit.Cc bit cha trong mi khe thi gian c b xung mt s bit mo u (overhead bits ), mt vi mu c nh v theo chu k cc bit c phn b cho bn thn tn hiu. Cc mu c nh cho php cc b iu chnh trong phm vi ton h thng thch ng cc c tnh ca tn hiu v tuyn cn cc bit mo u cho php kim sot cuc gi t my cm tay ti trm gc.GSM m ho tn hiu ting ni ti tc 13kbit/s v tn hiu ny bo v chng li bng cch cho thm mt s bit b xung vo lung tn hiu truyn dn. kt qu tc d liu ton b l 22,8 kbit/s.Tn s phn b cho ton b h thng GSM l t 900 n 960 MHz cho cc trm gc v 890 n 915 MHz cho cc my cm tay. Cc bng tn 1800 n 1880 MHz cho cc trm gc v 1710 n 1785 MHz cho cc my cm tay ginh cho vic trin khai GSM 1800.1.2.2 Hot ng ca GSM:Mt thit b GSM hot ng ging nh h thng tng t c thit lp (hnh trn). Th nht, my cm tay lin lc vi trm gc gn nht v sau l b iu khin trm gc. B iu khin trm gc ny xc nh v tr hin ti ca my cm tay ny u. B iu khin trm gc c kt ni vi mt trung tm chuyn mch di ng c th lin lc vi cc trung tm chuyn mch khc cng nh mng c nh. Trong mt tin trnh gi, lin lc n my cm tay c duy tr thng qua mt trm gc ph hp. Tnh lin tc ca cuc gi c th hin thng qua thanh ghi nh v tm tr, m bo tt c cc cuc gi ang m thoi c theo di v kt ni ti cc trm gc ph hp. Bn thn cc trm gc c trin khai trong mt t chc t bo theo a l sao cho my cm tay c th c lin lc lin tc.

Hnh 1. 2: Cu trc ca mt mng GSM.

Ngoi cc kha cnh gim st ca h thng, mt s cc hnh thc kim sot khc cng c trin khai. Mt thanh ghi nhn dng thit b c duy tr sao cho h thng bit ci g c th hoc khng th c kt ni ti mng. Mt b thanh ghi nhn thc cha ng chi tit cc m-un nhn dng thu bao c th chp nhn c ( c cc th c a vo cc my cm tay ). Mt b ng k v tr thng tr cha cc thng tin v lp dch m mt khch hng c th c php s dng.1.2.3 Cc c tnh k thut ca h thng GSM:

a. S dng giao din v tuyn:

Trong mi , trm BTS lin lc vi nhiu trm di ng. Qua giao din v tuyn trm di ng c th thit lp v thc hin cuc gi vi bt k thu bao no khc, bao gm cc thu bao di ng cng nh cc thu bao ca mng c nh PSTN, ISDN,.Vic phn chia cc knh lin lc cho mi trm di ng c gi l k thut a truy nhp.

u im ca vic s dng giao din v tuyn l c th xy dng c mt h thng a truy nhp. iu c ngha l, trong vng ph sng bt k thu bao no bt k v tr no u c th truy nhp vo mng.

Hn ch ca vic s dng giao din v tuyn chnh l s gii hn v bng tn. Vi h thng GSM, tc truyn s liu b hn ch mc 9,6kbit/s; GPRS cho php thay i tc linh hot hn, t 9,6 n 179kbit/s (trng hp s dng ng thi c 8 khe thi gian). Tuy nhin khng th tng tc ln qu ln v s nh hng n lu lng ca cc thu bao khc. Tc 9,6 nh hn rt nhiu so vi mng dial up 56kbit/s dnh cho cc my PC truy cp Internet qua ng in thoi. Tc 56kbit/s vn c xem l chm so vi s pht trin nhanh chng v a dng ca cc loi hnh dch v trn Internet v tm thi c chp nhn truyn ti d liu n thun nh cc trang Web, hnh nh, m thanh,.

T l li bit trn ng truyn v tuyn cao hn nhiu so vi cc phng tin truyn hu tuyn hin c. iu dn ti cht lng ng truyn v tuyn thp. Trong cc knh v tuyn, tp m ln, trc tip l tp m KTB, tip n l tp m do giao thoa gia cc knh. Tn hiu trn ng truyn v tuyn chu tc ng nhiu bi iu kin mi trng nh ma, che chn a hnh, nh ca,Ngoi ra, do vic s dng li tn s, cng sut ca my pht cng b hn ch trnh nh hng n cc vng khc cng nh nh hng n cc tn s ln cn.

b. S dng phng php a truy nhp:

Trong GSM, giao din v tuyn s dng kt hp hai phng thc a truy nhp l FDMA v TDMA. Nh hnh 1.3, trong h thng GSM 900MHz, hai di tn s ca tuyn ln v tuyn xung cch nhau 45MHz.Di tn s 890 915 MHz c s dng cho cc knh kt ni trm di ng vi h thng trm gc - tuyn ln; Cn di tn s 935 960MHz c s dng truyn dn t trm gc ti trm di ng - tuyn xung. Nh vy rng ca mi bng tn cho tuyn ln v tuyn xung l 25MHz.Mi bng tn k trn c chia thnh 124 sng mang tng ng vi 124 knh tn s (FCH Frequency Channel) khc nhau. Mi knh tn s c rng l 200KHz. Mi trong h thng GSM s c phn b mt s lng nht nh cc knh k trn.

Mi knh tn s FCH c chia thnh 8 khe thi gian (TS Time Slot) hay 8 knh vt l khc nhau. Thng tin c pht i trong mt khe thi gian c gi l mt cm (burst). Nh vy s knh vt l trong h thng GSM l 124 x 8 = 992 knh. Phng php phn chia knh nh vy c gi l phng php a truy cp phn chia theo thi gian TDMA.

Tm khe thi gian ny to thnh mt khung TDMA. Mi khe thi gian trong khung TDMA c rng l 156,25 ln chiu di bit (tng ng vi 577s). Do vy, mt khung TDMA s c chiu di l 4,615 ms. H thng GSM s dng cng mt khe thi gian truyn cc knh ca tuyn ln v tuyn xung. Trong khe thi gian ca tuyn ln tr hn so vi khe thi gian tuyn xung vi rng bng 3 ln rng ca mt khe thi gian, thun tin cho vic chuyn i t thu sang pht v ngc li.Mt knh v tuyn trong h thng GSM s dng 2 tn s ring bit, mt dng cho tuyn ln v mt dng cho tuyn xung. Cc knh ny c gi l knh song cng (FDD Frequency Division Duplex). Khong cch gia 2 tn s ni trn l khng i v bng 25MHz. Do m bo c mch lc my thu khng thu tn hiu ca my pht ca cng mt trm.

Hnh 1. 3: Tn s sng mang GSM v cc khung TDMA.

Vng mng trong h thng GSM c chia thnh nhiu v tuyn, mi v tuyn c iu khin bi mt trm thu pht BTS. s dng trit bng tn, h thng GSM c ra phng php s dng li tn s mt cch hiu qu, qua mt nhm tn s c th c s dng li mt khu vc khc vi khong cch thch hp trnh nhiu ng knh. K thut ny c gi l phn chia theo khng gian.1.2.4 Cc tiu chun ang c pht trin:

Nu d bo bc tranh tng lai cc cng ngh ca h thng v tuyn th c th nhn thy s hi t gia cc mng di ng v c nh hin ang c khai thc thng qua sng kin vi cc tn gi khc nhau l Truyn thng di ng quc t (IMT 2000), Dch v vin thng di ng ton cu (UMTS Universal Mobile Telecommunication Services) hoc di ng th h th ba (3G Third Generation Mobile). Cc giy php khai thc h thng thng tin di ng th h th ba c cp mt s nc nhng cc dch v vn cha c cung cp nn cc kin tho lun v trin vng tng lai vn cn tip tc. Cho n nay, chng ta s dng tiu chun GSM c thit lp nh mt chun. Tnh trng ca mt s cng ngh v tiu chun ca cc ng c vin khc cho mng di ng trong bng 1.2 sau:Cng nghThi imCh thch

Tc d liu nng cao cho pht trin GSM (ton cu) (EDGE Enhanced Data rate for GSM Evulation).UMTSa truy nhp phn chia theo thi gian (TDMA-Time Division Multiple Access).

a truy nhp phn chia theo mu (CDMA Code Division Multiple Access) (IS 95 B).

D liu chuyn mch knh tc cao (HSCSD-High Speed Circuit-Switched Data).Giao thc truy nhp v tuyn (WAP-Wireless Access Protocol).20012003

Hin nay

Hin nay

Hin nayHin nayMt bin th km cht ch hn ca GSM cung cp d liu tc cao hn nhng i hi thit b v tuyn mi v cc thit b c nng cp.Mt tiu chun ton cu thc th c th c li th rt ln so vi GPRS.

c thit lp M khng th thay th n khi UMTS ra i.TDMA ang hi t vi GSM trong cc cng ngh dch v v tuynchuyn mch gi chung v EDGE.

Phin bn CDMA ca chun m rng GPRS ca GSM.

H thng chuyn mch knh ch i hi nng cp phn mm ca GSM nhng li yu cu i mi cc thit b ngi tiu dng.B xung tnh nng trnh duyt Web v th in t v cc my di ng WAP.

Bng 1.2: Mt s cng ngh ng c vin cho dch v d liu di ng.Ngoi ra cn c rt nhiu mng in thoi di ng tr gi nhiu t USD khc. Thm ch cn c nhiu cng ngh cho mng cc b v tuyn (LAN) v mng truy cp c nhn (PAN personal Access Network). Do vy, chng ti s gii thiu cc phn t c bn cn thit lin kt cho my di ng ti cc my tnh cung cp dch v ca n. 1.3 DCH V TRUYN S LIU GI:

S pht trin ca Internet thc y s pht trin ca mt s cng ngh truy nhp d liu nhanh cho in thoi di ng. V gn y d liu c truyn qua mng GSM ging nh cch m mt my tnh gi n s kt ni ca mt nh cung cp dch v Internet (ISP). Kt ni l mt kt ni dnh ring m ngi s dng c gn vo mng trong thi gian cuc gi. Tc kt ni thng thng b gii hn 14,4 kbit/s. GSM th h th hai a ra chun Dch v v tuyn chuyn mch gi chung GPRS cho php thit b di ng gi v nhn cc gi tin m khng cn mt kt ni dnh ring.Khc vi k thut truyn s liu theo phng thc knh, trong phng thc truyn s liu gi, mng ch truyn thng tin ti thu bao khi c nhu cu. Do cng mt knh v tuyn c th c s dng ng thi cho nhiu trm di ng khc nhau. Khng nhng th mt trm di ng c th s dng ng thi 8 khe thi gian v tuyn. Khi trm di ng cn truyn mt gi tin, mng s chuyn gi tin ny ln khe thi gian u tin cn trng, v cc tin tip theo trn khe thi gian khc nu c th. Do bn cht ca thng tin s liu thng tn ti di dng cm nn vic cp khe thi gian ng nh trn gip cho vic s dng cc knh v tuyn tr nn hiu qu hn.Cng ngh d liu chuyn mch gi li rt quan trng bi v cc gi cung cp mt kt ni tc thi v thng sut t mt my di ng ti Internet hoc ti mng Intranet cng ty. iu ny cho php tt c cc ng dng Internet hin c nh th in t, trnh duyt web c khai thc thun li m khng phi quay s vo mt ISP. Cc dch v nh BT Gennie l v d cho kh nng ny.T quan im ca nh cung cp mng, u im ca cch tip cn chuyn mch gi nh GPRS l n ch s dng phng tin dng chung m trong trng hp ny l mt ph tn s qu him, trong thi gian d liu thc s c truyn hoc c nhn. iu ny c ngha l nhiu ngi s dng chung mt knh v tuyn v v ha hn vic s dng hiu qu ph tn s v tuyn. Ngc li, cc kt ni chuyn mch knh hin ti cho php ngi s dng gi v nhn cc gi tin ca h qua cc kt ni dnh ring trong ton b thi gian gi, bt k h c dang gi hay nhn d liu hay khng. Do nhiu ng dng c thi gian trng trong mt phin lin lc nn lng ph l kh c th trnh khi i vi cc kt ni chuyn mch knh, c bit khi cc ng dng tr nn phi i xng. Vi d liu chuyn mch gi, ngi s dng s chi tr tin cho lng d liu h thc t lin lc v khng tr tin cho thi gian trng. Thi gian b lng ph trong cc kt ni ginh ring c th cho ngi dng khc s dng chung di tn s . Trong thc t, vi GPRS, ngi dng c th c kt ni o nhiu gi ti mt thi im, nhng ch tr cc kt ni mt cch khim tn.Nu bn tin cn truyn c dung lng qu ln , bn tin ny c th c chia nh thnh nhiu gi tin. Khi cc gi tin ny ti ni nhn, bn nhn tin c nhim v sp xp v ni ghp cc gi tin li thnh bn tin ban u. Vic nh tuyn cc gi tin ti ch da vo cc thng tin a ch c gi km trong mi gi tin.Mt kha cnh th v ca GPRS l n t c tc cao nh th no khi m d liu chuyn mch knh ngy nay b gii hn mc 9.6 hoc 14.4 kbit/s. GPRS s dng chung mt knh v tuyn nh mt cuc gi thoi, mt knh rng 200kHz. Knh v tuyn ny truyn ti mt lung tn hiu v tuyn s gc 271 kbit/s. i vi cc cuc gi thoi, lung d liu ny c chia thnh 8 lung d liu ring r, mi lung tc 34 kbit/s. Ngoi phn tiu ca giao thc v sa li, khong 14 kbit/s nn kt qu l mt nhm ngi s dng c th t tc cao nht ln ti 100 kbit/s.Nhng khng phi tt c cc knh thoi c s dng. Trong thc t, vic trin khai kinh t nht s l gii hn bng thng cung cp cho mi ngi s dng, ginh mt phn dung lng d phng cho cc mc ch khc. Tiu chun GPRS nh ngha mt c ch m mt my di ng c th yu cu lng bng thng cn thit ti thi im n thit lp mt phin lin lc d liu.1.3.1 Kin trc h thng GPRS:

GPRS c xem nh l mt dch v ca mng GSM. GPRS c thit k bi ETSI trin khai trn c s h tng mng c sn ca GSM m khng nh hng n cc dch v hin ti. Mc ch l cho php trin khai nhanh cc dch v s liu gi trn mng GSM vi chi ph u vo thp. Cc phn t hin hu ca mng GSM ch cn nng cp v phn mm, ngoi tr khi BSC phi nng cp v phn cng. Mt s tuyn truyn dn c s dng chung cho c dch v chuyn mch knh v dch v chuyn mch gi, v d nh tuyn gia BTS v BSC. Hai nt mi c b xung l: nt h tr dch v chuyn mch gi di ng (SGSN) v nt h tr dch v chuyn mch gi di ng cng.

Cc giao din ca GSM cng c s dng li v b xung thm chc nng h tr cc nt GPRS. Trm BTS ca GSM c b xung thm cc giao thc mi truyn ti d liu di dng gi. Ngoi ra mt s cc chc nng nh phn b ti nguyn khe thi gian v phn b knh s liu gi cng c thc thi ti y.Do cc knh s liu gi (PDCH) ca GPRS c trn ln vi cc knh lu lng (TCH) ca chuyn mch knh. Trong khi mt s knh lu lng c phn b cho ch mt ngi dng th mt knh s liu gi c th c chia s ng thi bi nhiu thu bao GPRS khc nhau.

Di y l kin trc chnh ca mt h thng GPRS v chc nng c th ca tng khi.Hnh 1. 4: Cc phn t v giao din chnh ca mt mng GPRSa.Thit b u cui s liu TE:

Thit b u cui s liu (TE) v bn cht l mt my tnh, thng l mt my tnh xch tay, m thng qua n ngi s dng c th truy cp v ly cc thng tin t mng. Thit b u cui c nhim v trao i cc gi tin vi mng. H thng GPRS s cung cp kt ni IP gia thit b u cui s liu vi mt nh cung cp dch v (ISP) hay mt mng LAN cng tc.b. u cui di ng:

Nu nhn t gc ngi s dng, u cui di ng (MT) c th c xem nh mt modem lm nhim v kt ni thit b u cui vi h thng GPRS. u cui di ng c nhim v kt ni thit b u cui s liu vi h thng GPRS thng qua giao din v tuyn. Xt v bn cht, u cui di ng l mt my in thoi GSM thng thng, tuy nhin n c trang b thm mt s chc nng cung cp dch v chuyn mch gi di ng.

u cui di ng gn lin vi mt thu bao GSM thng thng. Khi thit b u cui cn trao i s liu th u cui di ng s thit lp mt lin kt vi nt SGSN. Nhim v ca u cui di ng l phi lm sao cho thit b u cui s liu kt ni c vi mng thng qua giao thc IP m khng nhn bit c s di ng ca n. Ngha l TE khng nhn bit c rng n ang di chuyn v a ch IP ca n cn c gn chng no MT cn lin kt vi h thng GPRS.

c. Trm di ng MS:

h tr dch v s liu gi, trm di ng (MS) s bao gm mt thit b u cui di ng (MT) v mt thit b u cui s liu (TE). u cui di ng v thit b u cui s liu c th c t trn hai phn t vt l ring bit. Tuy nhin trm di ng cng c th l mt thit b duy nht thc hin c hai chc nng MT v TE.

Cc h thng GPRS v GSM phi c kh nng tng tc vi nhau v chia s ti nguyn ng gia nhng ngi s dng. Chnh l do ny, ba kiu thit b u cui (ng vi ba ch lm vic khc nhau ca trm di ng) c nh ngha , l: Nhm A: Mt trm di ng thuc nhm A c th ng thi s dng cc kt ni chuyn mch knh v chuyn mch gi (khi trm di ng ang trong ch truyn gi), cho pp thu bao thc hin cuc gi m khng phi ngt qu trnh truyn s liu. Kiu thit b ny c th khng c a ra th trng khi mng GPRS mi c trin khai do s phc tp v gi thnh cao.

Nhm B: Mt trm di ng thuc nhm B c th gim st tt c cc dch v chuyn mch knh v chuyn mch gi nhng ti mt thi im ch c th h tr mt loi dch v. Trng hp trm di ng ang trong ch truyn gi v ang trao i d liu m c mt cuc gi ca chuyn mch knh n, nhn cuc gi, trm di ng phi tm dng trao i d liu. Khi cuc gi kt thc, qu trnh trao i d liu tip tc c thc hin. Nhm C: Trm di ng ch c th s dng mt trong hai loi dch v ti mt thi im. Ch hot ng ny thng c p dng vi cc trm di ng ch h tr dch v GPRS m khng h tr cc dch v ca chuyn mch knh.

Tu theo yu cu c im ca trm di ng v kh nng ca mng m trm di ng c th la chn ch s dng cc dch v chuyn mch gi hoc kt hp cc dch v chuyn mch gi v cc dch v chuyn mch knh.

d. H thng trm gc BSS:

H thng GPRS s dng chung cc ti nguyn vi GSM trn giao din v tuyn. Ngha l c th trn ln cc knh GPRS vi cc knh ca chuyn mch knh trong cng mt . GPRS c th phn ti nguyn ng, xen gia cc khong h trong cc phin lm vic ca chuyn mch knh, do di ph c s dng hiu qu hn. Vi GPRS nhiu ngi s dng c th cng chia s mt knh vt l. Ngoi ra cc knh vt l GPRS ch c phn b khi cn truyn hoc nhn d liu.

H thng GPRS tn dng hiu qu c s h tng sn c ca mng GSM. GPRS s dng BTS v BSC ca GSM. c th truyn d liu di dng gi th c BTS v BSC, cng vi mt s b phn khc ca h thng GSM c nh MSC, VLR, HLR, u phi nng cp v phn mm; ch ring BSC phi b xung thm c phn cng, l khi iu khin gi (PCU).

PCU bao gm c phn cng v phn mm, c nhim v iu khin cc knh s liu gi v chia s cc knh v tuyn gia GPRS v GSM. D liu chuyn mch knh c gi qua giao din A ti MSC trong khi d liu gi qua giao din Gb ti SGSN v mng ng trc GPRS.

e. B ng k nh v thng tr HLR:

HLR l c s d liu cha cc thng tin v thu bao thuc phm vi qun l ca n, bao gm thng tin ca tt c cc dch v chuyn mch knh v dch v chuyn mch gi. Cc thng tin trong HLR gm c: Cc dch v m thu bao ng k, b ba tham s nhn thc, thu bao c s dng dch v chuyn mch gi hay khng, tn ca im truy cp (APN) hay nh cung cp dch v Internet (ISP), a ch IP tnh (nu c) c phn b cho trm di ng, v tr hin thi ca thu bao,Cc thng tin ny c thit lp bi nh khai thc mng. Trong GPRS cc thng tin v thu bao s c trao i gia HLR v SGSN.

g. Nt h tr dch v chuyn mch gi di ng SGSN:

SGSN l b phn khng th thiu trong cc mng di ng GSM c h tr dch v chuyn mch gi. Nhim v chnh ca SGSN l chuyn cc gi tin IP i v n tt c cc trm di ng trong vng phc v ca n.

SGSN gim st mi thu bao nm trong vng phc v ca n. Mt SGSN thc thi hu ht cc chc nng trong GPRS, ging nh MSC trong h thng GSM. Ngha l n phi iu khin vic lin kt, hu lin kt, cp nht v tr cho trm di ng,...

Cc thu bao GPRS c th c phc v bi bt k SGSN no tu theo v tr hin ti ca chng. SGSN thc hin cc chc nng ch yu sau:

Qun l di ng: SGSN qun l s di ng ca thu bao ti giao din v tuyn. Cc th tc qun l di ng bao gm: lin kt GPRS, cp nht vng nh tuyn (RA) v cc th tc cp nht RA v LA kt hp.

Qun l phin lm vic: Th tc qun l phin lm vic bao gm: kch hot, gii kch hot, v hiu chnh giao thc s liu gi (PDP). Vic kch hot giao thc s liu gi s thit lp mt knh d liu o gia thit b u cui s liu vi mt GGSN thch hp. Truyn v nh tuyn gi tin i v n cc trm di ng trong vng phc v ca mnh. Gi tin t SGSN s c nh tuyn ti BSC, qua BTS ti trm di ng.

Bo mt ng truyn v tuyn bng cc th tc nhn thc v m ho.

La chon GGSN thch hp cho trm di ng da trn cc thng tin nh: kiu giao thc s liu gi, tn im truy nhn (APN) v cc tham s cu hnh.

Kt ni ti cc nt GSM nh: MSC, HLR, BSC, SMS SC,

a ra cc thng tin v cc: SGSN ghi nhn cc thng tin v cc s dng ti nguyn v tuyn ca trm di ng. C SGSN v GGSN u ghi cc thng tin v cc s dng ti nguyn mng ca tng trm di ng.

Thc hin cc chc nng ca b ng k nh v tm tr (VLR): SGSN thc hin tt c cc chc nng ging nh chc nng ca VLR (trong GSM) cho cc dch v chuyn mch gi di ng. Ngha l SGSN cha cc thng tin hin thi ca thu bao cng nh cc thng tin v thu bao tm tr. Khi trm di ng chuyn ti vng phc v ca SGSN mi, SGSN ny (ng vai tr nh mt VLR) gi yu cu n b ng k nh v thng tr (HLR) ca trm di ng v yu cu HLR gi cc thng tin v trm di ng. Cc thng tin ny c SGSN lu tr trong sut qu trnh thu bao lu chuyn trong vng phc v ca n. Khi trm di ng cn truyn s liu th SGSN c th cung cp ngay cc thng tin cn thit.h. Nt h tr dch v chuyn mch gi di ng cng GGSN:

GGSN c chc nng ch yu l giao tip vi cc mng s liu gi bn ngoi, in hnh l mng da tren giao thc IP. Do n phi c cc chc nng truy cp mng. C th GGSN lin kt vi cc phn t mng ngoi nh: cc b nh tuyn, cc my ch RADIUS (dng cho mc ch nhn thc), cc my ch phc v, Nu nhn t mng ngoi GGSN hot ng nh mt b nh tuyn cho ton b a ch IP ca tt c cc thu bao c phc v bi mng GPRS. GGSN phi thc hin nh tuyn gi tin n ng SGSN hin thi ang phc v trm di ng v chuyn i giao thc gia mng GPRS vi mng ngoi. GGSN thc hin cc chc nng c bn sau: Kt ni vi mng IP bn ngoi.

Qun l phin lm vic: GGSN h tr cc th tc qun l phin lm vic, bao gm: kch hot, gii kch hot v hiu jchnh giao thc s liu gi.

a ra cc thng tin v cc: GGSN c nhim v ghi nhn cc thng tin v cc lin quan ti vic s dng ti nguyn ca mng bn ngoi i vi tng thu bao. C GGSN v SGSN u ghi nhn cc thng tin v cc lin quan ti vic s dng ti nguyn ca bn thn mng di ng.

Bo mt IP (IPSec): c trng bo mt IP ( l cc bin php bo mt c thc hin ti lp IP) cho php truyn dn mt cch an ton gia GGSN v SGSN (giao din Gn) v gia GGSN vi cc my trm v cc b nh tuyn mng ngoi (Giao din Gi). iu ny l cn thit khi m cc thu bao GPRS mun kt ni vi cc mng cng tc ca h hay cc mng ring o (VPN). N cng tng cng tnh bo mt trong vic qun l di ng gia nt h tr dch v chuyn mch gi di ng (GSN) v h thng qun l. IPSec cho php m ho ton b d liu truyn ti trn mng, chng li nhng truy cp tri php, m bo tin cy, tnh ton vn v nhn thc c ngun gc d liu. Chc nng bc tng la (firewall): Khi GGSN kt ni vi mng ngoi, nhiu la chn gi c thc thi chng li s tn cng v xm nhp tri php. Cc thng tin c s dng lc gi bao gm: a ch ngun, a ch ch, giao thc, s hiu cng,..

Chc nng cng bin (BG): Hot ng nh mt im truy cp mng trong trng hp kt ni cc mng GPRS khc nhau. Chc nng BG thng c tch hp trong GGSN v n s dng cng mt b nh tuyn vi GGSN. Do vy cc giao din vt l cng c dng chung truyn s liu. Trong thc t, tng kh nng x l, BG v GGSN c th c t trn hai phn t vt l ring bit.1.3.2 Hot ng ca GPRS:

Khi hot ng mt thit b GPRS lm vic ging nh mt in thoi di ng chun - c hai lin lc vi mt trm gc v c s h tng gn km cung cp tnh nng xc thc, kt ni v dch v. C mt s khc bit ln, tuy nhin khc bit chnh l GPRS cho php ngi s dng c kt ni lin tc ti mng.

Thay v gi d liu ti mt ch c nh, kt ni quay s, GPRS cho php cc gi d liu c chn vo mt lung kt ni thng trc. Cc gi tin t nhng ngi s dng khc nhau trong mt t bo c an xen sao cho dung lng truyn dn lun c c chia s m khng c khe thi gian nh trc thng trc c phn b cho mt c nhn. Do , dung lng c th c phn b khi cn thit v gii phng khi khng cn.

Tc d liu GSM l 14.4 thng qua mt kt ni c nh c thay th trong GPRS bng cch truy nhp ln ti 8 khe thi gian vi dung lng kt ni vo khong 14.4 kbit/s cho mi khe. Tc d liu chnh xc ph thuc vo cc iu kin v tuyn. Dung lng ny c c n mc no th c th bin i khc nhau. Cc phin bn GPRS khc nhau c cc c tnh khc nhau. V d, GPRS lp 8 khe (class 8 GPRS) c th x l ti nm khe thi gian k tip nhau, 4 khe cho nhn v mt khe cho pht tn hiu, cho tc d liu v ln ti 50 kbit/s. Lp 12 (class 12) cho php bt k t hp no ca 5 khe thi gian gia thu v pht.

Tt c cc gi tin c truyn dn trn cc khe thi gian c gi t trm gc (BTS) bng nt mng h tr dch v GPRS (SGSN). Mt SGSNc th h tr nhiu trm gc. Nh cp trn, SGSN truy tm tt c cc my di ng trong phm vi vng phc v ca n. Khi mt thit b di ng gi ti gi dch v, chng i qua SGSN n GGSN, ti y cc gi c bin i truyn qua mng, mng c th l Internet, X25 hoc mt mng ring. Cc gi tin nhn t Internet ( ngha l gi IP) gi n my di ng c nhn bi GGSN, chuyn tip n SGSN ph hp v sau gi ti ngi s dng di ng.

chuyn tip cc gi tin cho nhau, SGSN c GGSN bc gi chng bng mt giao thc chuyn dng c gi l giao thc chuyn dng GPRS (GTP GPRS Tunnel Protocol) hot ng trn nn giao thc TCP/IP chun. Chi tit cu SGSN v GGSN u khng nhn thy v khng lin quan n ngi s dng l nhng ngi ch n gin cm thy mt kt ni IP thng sut n mi ch xy ra di phng thc v tuyn.

Cc giao thc v th tc c thit lp qun l cch thc m mt thit b di ng truy nhp v lm vic vi mt mng GPRS. Chng kh phc tp cc tiu chun lin quan (c bit l ETSI, EN 301 204 m t dch v GPRS) cho chng ta mt nn tng dc bit. By gi chng ta cn nhn mnh c th vo s tng tc gia thit b di ng vi mng bi v chng lin quan trc tip n cc ni dung tip theo.

Th nht l cch thc m thit b di ng nhn bit v n. Tc nghip ny gi l mt gn kt (attach) s thit lp mt lin kt logic gia thit b vi SGSN. Tc nghip gn kt cng tn ti trong cc mng di ng chuyn mch knh truyn thng trong n c s dng lm cho mng bit v tr v vic nhn thc ca my in thoi di ng. Kt ni ch c thit lp khi my di ng cn chuyn lu lng qua giao din v tuyn, cng ging nh khi nhn thc v xc nh v tr ca thit b, th tc gn kt thit lp a ch ca thit b di ng. Mt gii php cho vn ny l phn b mt a ch IP tnh; c gi l nh a ch PDP tnh trong cc thng s k thut ca GPRS. a ch PDP tnh thng c gi ti HLR ( Mc d c th gi n trong mo-un nhn dng thu bao hay SIM card ca my di ng ). Gii php thay th l a ch IP tm thi c th c phn b. a ch ny c gi l a ch ng c th c lin kt vi thit b di ng trong khong thi gian xc nh bi mt vi s kin. V d, khi kt thc mt phin lin lc hoc thi im ngi s dng i khi im c nh ca anh ta c th kch hot s cp pht mt a ch ng khc.

C mt s gii php khc nhau cho a ch ng. N c phn b bng mng di ng khch hoc mng thng tr ca ngi s dng. N c th c cu trc theo bt c khun dng a ch IP no.

Th hai l nt GGSN ca GPRS s phi kt ni ti mt vi thit b trn mng khc ( v d: mt b nh tuyn ranh gii thng qua giao din Gi kt ni ti Internet ). Bn cnh kt ni vt l, giao thc c s dng ti giao din mng ny cn c xem xt nh mt phn ca mt thit k mng tng th. Mt s la chn v cn i khc nhau trong lnh vc ny cng cn c xem xt k.

Khi vn nh a ch v kt ni c xem xt dng nhu GPRS cho php vn chuyn thng sut cc gi tin, ngha l thng mi in t tiu chun vi kh nng chuyn vng b xung. Tuy nhin, mt s vn c hi thc t cng cn c xem xt mc ny.1.3.3 Cc la chn cu hnh trin khai:

Vi nhiu im linh hot nh vy, cc nh khai thc di ng, cc nh cung cp dch v v cc mng cng ty c th ng vai tr khc nhau trong vic h tr ngi s dng chuyn vng ph hp vi cu hnh mng. Cho n nay, chng ta cha cp xem ai cung cp bit hoc cc bit mng. Trong thc t, iu ny c tc ng ln n cch thc dch v c cung cp.

Thc t ta xem xt trin vng cho mt nh khai thc di ng hin ti cung cp giao din v tuyn cho cc nh khai thc v tr thnh nh khai thc mng o di ng (MVNO Mobile Virtual Network Operator ) cho mt nh cung cp dch v. iu ny tht hp dn v nh khai thc di ng khng pah xy dng mng d liu ring h - h ch n gin bm vo mt mng c nh mng con c mc ch c bit.

Trong trng hp ny, mt s tnh hung c th xy ra. Nu chng ta ng ti giao din Gi ( l im linh hot gia mng di ng ca chng ta v mng IP ) v xem xt quyn s hu v kt ni th c bn tnh hung c bn nh trnh by trong hnh nh sau:

La chn 1: Truy nhp mng IP c bn cho cc khch hng ca ring nh khai thc di ng ca mnh.

La chn 2: Truy nhp mng IP c bn cho cc khch hng ca nh khai thc di ng khc, nhng n v s dng mng di ng ( ngha l h tr cho cc khch hng chuyn vng ).La chn 3: Nh trong la chn 1 nhng ti mt mng Intranet hoc mt ISP m khng trc tip c kt ni ti mng di ng.

La chn 4: Nh trong la chn 2 nhng ti mt mng Intranet hoc mt ISP m khng trc tip c kt ni mng ti mng di ng.

Hnh 1. 5: Quyn s hu ton trnh v cc kh nng kt niHai la chn u tin trong danh sch c ngha l nh khai thc di ng c s kim sot no i vi phin lin lc ton trnh ( kt ni trc tip). Hai la chn tip theo nh khai thc di ng cch bit hn, ph thuc vo mt bn th 3 hon thnh dch v ( Kt ni khng trc tip). Ta c th nh gi u im, nhc im ca c hai trng hp tng qut ny.a. Kt ni trc tip:

Ti im ny, cn lm r s khc bit khi ngi s dng ang mng thng tr hay tm tr. Mt khi nt GPRS chp nhn ngi s dng, ngi gn kt v mt logic ti cng mt GGSN ( c th c s khc bit trong cc h s ngi s dng l thu bao ca cc mng khc nhau).

Khi khch hng ring ca mng di ng mun truy nhp ti mt mng IP c kt ni trc tip, a ch c phn b cho cc thit b di ng ca h c th c x l hoc bi nt GPRS hoc bi ISP c kt ni trc tip. iu ny ph thuc vo v tr chc nng DHCP c t u. Mt ngi s dng vng lai s c mt a ch do mng thng tr ca anh ta phn b.i vi c ngi s dng vng lai hoc thng tr, nt GPRS s phi nhn trch nhim xc thc thit b di ng trc khi n kt ni ti mt mng IP bn ngoi. V c th mng ny t chi kt ni i vi mt s ngi s dng nht nh (v d nhng ngi c a ch IP khng hp l ) hoc c th ngt kt ni ( v d chng gi mt lung d liu nhiu hn so vi tho thun).Nh khai thc di ng v/hoc nh cung cp dch v IP xa c th cn tri khai bc tng la bo v cc mng tng ng ca h. Cc c tnh ca bc tng la cn c thng nht ( v d: c c php truyn FTP hay khng). Trong trng hp ny, y l mt vn chnh sch khi c hai pha c chung s hu.b. Kt ni gin tip:

Trong hai trng hp cui c lit k, cn mt con ng hn gia nt GPRS v ISP hoc Internet c kt ni gin tip. Cc c tnh ca ng hm cn c thng nht gia nh khai thc di ng vi ISP. Thc t, y c th n gin l mt tuyn chuyn tip khung hoc knh thu. Thc s, la chn ( trong hnh v trn) thng l gii php a chung bi v nt GPRS c th phc v nh mt tuyn truy nhp thay th n mt mng dng ring.Trong c hai trng hp, khi s lng ngi s dng tng ln, c th cn a mt kt ni phc tp hn vo mng IP. V d: c th s dng mt h thng phn cp cc b nh tuyn kt ni cung cp mt s ng hm. Do s lng ng hm ln, ngi thit k cn m bo cht lng ng hm. Bn cnh , nh khai thc di ng c th m bo s cng bng gia nhng ngi s dng ( Nhng ngi c th c cc c tnh dch v c thng nht khc nhau c bit l tc kt ni).Trong la chn 4 hnh trn c th khng c ng hm trc tip ti mng intranet hoc ISP ( ngha l khi cc gi tin c chuyn ng hm t GGSN), thit b di ng c cho mt a ch thuc v ISP/Intranet. Trong trng hp ny, GGSN cn mt lin kt ti my ch phn b a ch ( v d my ch DHCP hoc my ch khu vc ) thuc v ISP hoc Intranet cho vic xc thc v cu hnh giao thc.Hu ht cc tho lun nu trn lin quan n phn phi dch v. Cc vn nu ra cn c gii quyt bi mt tho thun gia nh khai thc di ng vi nh cung cp mng IP hoc bng thit k ca nt GPRS v mng IP. Ngay c khi nh khai thc di ng mun kt ni ti mt vi mng IP, vic lp cu hnh cc kt ni cn thit l tng i d dng.Trong thc t, la chn n gin nht l kt ni trc tip ca ngi s dng ca nh khai thc di ng ( bt k h l thng tr hay chuyn vng t nh cung cp dch v khc) ti mng IP. CHNG 2: TNG QUAN CNG NGH IP

2.1 Gii thiu:

Mng my tnh ngy nay tr thnh mt thnh phn quan trng trong ngnh truyn thng. Trn th gii, ban u ch c vi mng my tnh c a vo s dng cc vin nghin cu v phc v quc phng. Cng vi thi gian, khoa hc cng ngh pht trin, mng my tnh c mt khp mi ni: t trng hc, cc cng ty cho ti cc hc vin.Mc ch chnh ca s ra i mng my tnh l chia s cc ti nguyn h thng, trao i thng tin. Ta bit rng, trong thi i thng tin hin nay, khi lng thng tin ngy cng phong ph, a dng th vn sp xp khi thng tin khng l mt cch khoa hc, d truy tm, d trao i, s dng mt cch nhanh chng l vn cp bch. Mng Internet ra i v gp phn gii quyt cc vn nu trn.Internet khng phi l mt mng my tnh n l m l mt mng truyn thng ton cu kt ni hng trm ngn mng my tnh khc nhau. Cc mng my tnh c kt ni ny l nhng mng ln din rng (WAN) nh l cc mng ca cc cng ty xuyn quc gia nh IBM, AT&T, DEC.. cho n nhng mng cc b (LAN) nh ca bt k s hu no nm khp ni trn th gii. Mi mng my tnh li c th c nhiu my ch cung cp dch v v hng trm ngn cc my tnh n l kt ni s dng cc dch v. c th hiu r khi nim v internet ta hy hnh dung rng, t my tnh ang s dng, ngi dng c th tm kim bt k thng tin no, c th lin lc vi bt k ai trn th gii, c th thit lp mt hi ngh t xa, khai thc cc ti nguyn thng tin phong ph, d tm cc th vin tt nht v thm nhng bo tng s nht th gii. Ngi dng c th xem phim, nghe nhc, c tp ch a phng tin c bit, thc hin mua sm mi th. Tt c cc iu trn u c th thc hin c bng cch khai thc t mng internet.2.2 B giao thc TCP/IP:

Vo cui nhng nm 1960 v u nm 1970, trung tm nghin cu cp cao (ARPA Advanced Research Projects Agency) thuc b quc phng M (DoD Department of Defence) c giao trch nhim pht trin mng ARPANET ( tin thn ca mng Internet). Mng ARPANET bao gm mng cu nhng t chc qun i, cc trng i hc v cc t chc nghin cu c dng h tr cho nhng d n nghin cu khoa hc v qun i. Ngy nay ARPA c gi l DARPA. Nm 1984, DoD chia ARPANET ra thnh 2 phn ARPANET s dng cho nghin cu khoa hc v MILNET s dng cho qun i. u nhng nm 1980, mt b giao thc mi c a ra lm giao thc chun cho mng ARPANET v cc mng ca DoD mang tn DARPA Internet protocol suit, thng c gi l b giao thc TCP/IP hay cn gi tt l TCP/IP. B giao thc TCP/IP ny c t tn theo hai giao thc chnh ca n l TCP (giao thc iu khin giao vn) v IP (giao thc lin mng).Nh nhiu b giao thc khc, b giao thc TCP/IP c th c xem l tp hp cc tng, mi tng gii quyt mt tp cc vn c lin quan n vic truyn d liu v cung cp cho cc tng lp trn mt dch v c nh ngha r rng da trn vic s dng cc dch v ca cc tng thp hn. V mt logic, cc tng trn gn vi ngi s dng hn v lm vic vi d liu tru tng hn, chng da vo cc giao thc tng cp di bin i d liu thnh cc dng m cui cng c th c truyn i mt cch vt l.2.2.1 u im ca b giao thc TCP/IP:

Giao thc chun m sn sng pht trin c lp vi phn cng v h iu hnh. TCP/IP l giao thc l tng cho vic hp nht phn cng v phn mm khc nhau, ngay c khi truyn thng trn internet. S c lp rnh mch vi phn cng vt l ca mng cho php TCP/IP hp nht cc mng khc nhau. TCP/IP c th chy trn mng Ethernet, mng Token Ring, mng quay s ( Dial up line ), mng X-25, mng o v mi loi mi trng vt l truyn thng.Mt s a ch dng chung cho php mi thit b TCP/IP c duy nht mt a ch trn mng ngay c khi l mng ton cu Internet.Tiu chun ho mc cao ca giao thc ph hp vi ch li ca dch v ngi dng. c tch hp vo h iu hnh UNIX, h tr m hnh client server, m hnh mng bnh ng, h tr k thut dn ng ng.2.2.2 M hnh tham chiu TCP/IP:

B giao thc TCP/IP c chia lm 4 tng:

Tng mng (Network layer). Tng Internet ( Internet layer). Tng giao vn (Transport layer).

Tng ng dng (Application layer).

Hnh 2. 1: Tng ng gia cc lp ca OSI v TCP/IP.

Vic phn tng ny m bo mt s nguyn tc sau:

Mt lp c to ra khi cn n mc tru tng ho tng ng. Mi lp cn thc hin cc chc nng c nh ngha r rng.

Vic chn chc nng cho mi lp cng ch ti vic nh ngha cc quy tc chun ho quc t.

Ranh gii cc mc cn chn sao cho thng tin i qua l t nht ( tham s cho chng trnh con l t. S mc phi ln cc chc nng tch bit khng nm trong cng mt lp v nh m hnh khng qu phc tp. Mt mc c th c phn thnh cc lp nh nu cn thit.

Cc mc con c th li b loi b. Hai h thng khc nhau c th truyn thng vi nhau nu chng m bo nhng quy tc chung ( ci t cng mt giao thc truyn thng ).

Cc chc nng c t chc thnh mt tp cc tng ng mc cung cp chc nng nh nhau. Cc tng ng mc phi s dng mt giao thc chung.Mt tng khng nh ngha mt giao thc n, n nh ngha mt chc nng truyn thng c th c thi hnh bi mt s giao thc. Do vy, mi tng c th cha nhiu giao thc, mi giao thc cung cp mt dch v ph hp cho chc nng ca tng. V d c giao thc truyn file (file Transfer Protocol FTP) v giao thc th in t (Electronic Mail Protocol) u cung cp dch v cho ngi dng v c hai u thuc tng ng dng. Mi mc phi c chun ho giao tip vi mc tng ng vi n. Trn l thuyt, giao thc ch lin quan ti lp ca n m khng quan tm ti mc trn hoc mc di ca n. Tuy nhin phi c s ng lm sao chuyn d liu gia cc tng trn mt my tnh, bi mi tng, mng li lin quan ti vic gi d liu t ng dng ti mt ng dng tng ng trn mt my khc. Tng cao hn da vo tng thp hn chuyn d liu qua mng pha di. D liu chuyn xung ngn xp t tng ny xung tng thp hn cho ti khi c chuyn qua mng nh giao thc ca tng vt l. Ti ni nhn, d liu i ln ngn xp ti ng dng nhn. Nhng tng ring l khng cn bit cc tng trn v di n x l ra sao, n ch cn bit cch chuyn thng tin ti cc tng . S c lp cc hm truyn thng trn cc tng khc nhau gim thiu s tch hp cng ngh ca u vo mi b giao thc. Cc ng dng mi c th thm vo m khng cn thay i tng vt l ca mng, phn cng c th c b xung m khng cn vit li cc phn mm ng dng.

Hnh 2. 2: Cc tng trong b giao thc TCP/IP. FTP (File Transfer Protocol): Giao thc truyn tp cho php ngi dng ly hoc gi ti mt my khc. Telnet: Chng trnh m phng thit b u cui cho php ngi dng login vo mt my ch t mt my tnh no trn mng. SMTP (Simple Mail Transfer Protocol): Cc giao thc th tn in t.

DNS (Domain Name Server): Dch v tn min cho php nhn ra my tnh t mt tn min thay cho chui a ch internet kho nh. SNMP (Simple Network Management Protocol): Giao thc qun tr mng cung cp nhng cng c qun tr mng. RIP (Routing Internet Protocol): Giao thc dn ng ng.

ICMP ( Internet Control Message Protocol): Giao thc bn tin iu khin Internet. UDP (User Datagram Protocol): Giao thc truyn thng khng kt ni, cung cp dch v truyn thng khng tin cy nhng tit kim chi ph truyn. TCP (Tranmission Control Protocol ): Giao thc hng kt ni, cung cp dch v truyn thng tin tng. IP (Internet Protocol): Giao thc Internet chuyn giao cc gi tin qua cc my tnh n ch. ARP ( Address Resolution Protocol): C ch chuyn a ch TCP/IP thnh a ch vt l ca thit b mng.

Hnh 2. 3: Qu trnh truyn d liu qua cc lp.Ging nh trong m hnh tham chiu OSI, d liu gi t tng Application i xung ngn xp, mi tng c nhng nh ngha ring v d liu m n s dng. Ti ni gi mi tng coi gi tin ca tng trn chuyn xung l d liu ca n v thm vo gi tin cc thng tin iu khin ca mnh sau chuyn tip xung tng di. Ti ni nhn, qu trnh din ra ngc li, mi tng li tch thng tin iu khin ca mnh ra v chuyn d liu ln tng trn.

Hnh 2. 4: Qu trnh ng gi gi tin qua cc lp m hnh TCP/IP.2.2.3 Tng mng:

Tng mng l tng thp nht ca kin trc giao thc TCP/IP, cc giao thc trong tng ny cung cp bin php cho h thng chuyn giao d liu gia cc thit b c kt ni trc tip. N m t cch s dng mng truyn mt gi thng tin IP.Khng ging nhng giao thc ca tng cao hn l s dng dch v ca tng di n v cung cp dch v cho tng trn, giao thc ca tng mng cn phi bit chi tit ca mng vt l pha di (cu trc ca gi, a ch, .) nh dng ng thng tin s c truyn tun theo nhng quy nh rng buc ca mng. Tng mng ca TCP/IP cha cc chc nng ca tt c hai tng thp nht ca m hnh tham chiu OSI (tng lin kt d liu, tng vt l). Tng mng thng khng c ngi dng ti v thit k ca TCP/IP che du nhng chc nng ca tng thp nht ny v nhng iu cn bit cho ngi s dng cng nh ngi lp trnh ch l nhng giao thc ca tng cao hn ( IP, TCP, UDP, .). Mi khi c cng ngh phn cng xut hin, nhng giao thc tng mng phi c pht trin TCP/IP c th s dng phn cng mi (thng thng chnh l cc trnh iu khin ca chnh nh cung cp phn cng ). Cc chc nng trnh din trong phn ny bao gm ng gi thng tin IP thnh cc Frame c truyn dn trn mng v chuyn a ch vt l s dng bi mng my tnh. Mt trong s cc im mnh ca TCP/IP l a ch ca n c phi hp sao cho trn mng Internet khng c mt thit b no cng tn. a ch ny phi c chuyn i thch hp vi mng vt l ni m d liu c truyn i.2.2.4 Tng Internet:

Tng IP cung cp mt h thng chuyn giao khng kt ni v i khi ngi ta cn gi l khng tin cy. Khng kt ni bi mi gi tin c truyn i trn mng mt cch c lp, s kt hp d liu ca cc gi tin c cung cp bi cc dch v lp trn. Mi gi tin IP cha a ch ni gi, a ch ni nhn v da vo n c th c truyn trn mng ti ch. Nhng chnh vic d liu c th i ti ch trn nhiu ng khc nhau to nn s mm do cho Internet khi mt ng dy b t hay mt nt no b qu ti, cc gi tin c th c truyn i theo nhng con ng khc, nu mt gi tin no c li th ch phi truyn li gi tin thay vo vic phi truyn li ton b thng bo. Khng tin cy bi v IP khng c c ch kim tra tin ng n ca d liu c truyn nhn, dch v tin tng phi c cung cp bi cc giao thc lp trn.a.Gi tin IP:

Cu trc gi tin IP c th hin nh hnh di y: 0 7 8 15 16 31VersHlenType of ServiceTotal length

IndentificationFlagFragment offset

Time to liveProtocolHeader checksum

Source IP Address

Destination IP Address

IP OptionsPadding

IP Datagram Data (Max 65535 bytes)

Destination AddressSource IP AddressType FeildIP DataCRC

Hnh 2. 5: Cu trc gi tin IP.

Vers: Di 4 bit, m t chnh xc version ca IP. Hlen: Di 4 bit, m t di ca IP Header (tnh bng t di 32 bit). Type of Service: Di 8 bit, m t th t u tin ca d liu. Total length: Di 16 bit (2 byte), y l di ca datagram ( in byte c ngha l di vng datagram l 1518 bytes). Do vy khi size ca datagram vt qu kch thc cho php, n s b chia nh ra v cc trng hp ny s m bo rng cc datagram b phn chia ny l t mt datagram ban u. Time to live: Dng xc nh xem datagram ny c b truyn lp li hay khng ( thng thng n c gn l 1, nu b lp li n b gn l 0). Protocol: Trng ny n cho bit lp giao thc cao hn no s c s dng (UDP hay TCP). CRC: Trng ny c s dng kim tra s ton vn ca header. Nu IP Header li, gi tin IP b loi b v giao thc lp trn s truyn mt gi tin khc. IP option: Cha cc thng tin nh: d ng, bo mt, xc nhn, thi gian. Padding: Trng in thm cc s 0 m bo header kt thc ti mt a ch bi ca 32. Source IP address, destination IP address: Cha a ch ca trm gi v a ch ca mng ch.Tng IP lm cng vic dn ng cc gi tin qua mng Internet t my tnh ny ti my tnh khc, qua cc mng khc nhau cho ti khi n n c trm ch hoc b li. Vic truyn gi tin qua cc mng khc nhau, n c th b chia ra thnh nhiu gi tin nh hn. Thng tin truyn c th qu ln c th truyn trn mt gi tin trn mt mng khc. Vn ny ch gp phi khi gateway c ni gia cc mng vt l khc nhau. Mi kiu mng c mt di ti a gi tin c th truyn (MTU Maximum Transmission Unit) nu thng tin nhn c t mng ny di hn MTU ca mng kia, n cn phi c chia nh ra thnh nhiu mnh truyn.

Hnh 2. 6: Gi tin i qua Gateway.

Khi nhng gi tin n Gateway qu nhanh, chng c th b loi b v IP tr li mt thng bo li (ICMP). b.Gi tin ICMP:

ICMP s dng gi tin IP truyn thng bo ca n. ICMP gi cc thng bo lm cc cng vic: iu khin, thng bo cc li v chc nng thng tin cho TCP/IP Thng thng ICMP c gi khi mt gi tin khng th i ti ch, mt gateway khng cn ch nh nhn thm gi tin hay mt gateway hng dn my tnh s dng gateway khc truyn thng tin theo mt con ng ti u hn.

Mi thng bo ICMP c mt kiu nh dng ring ca n, song thng bo u c 3 trng u tin ging nhau: Type: nh ngha thng bo i sau. Code: Cung cp thng tin thm v thng bo.

Checksum: Cha checksum ca thng bo.

07 8 15 16

31TypeCodeChecksum

ICMP Data (Ph thuc vo loi bn tin)

.Hnh 2. 7: Cu trc gi tin ICMP.

Cc gi tr ca trng Type v cc bn tin tng ng theo sau:

TypeICMP Message TypeTypeICMP Message Type

03

4

5

8

9

10

11Echo ReplyDestination UnreachableSource Quench

Redirect

Echo

Router Advertisement

Router Solicitation

Time Exceeded1213

14

15

16

17

18Parameter ProblemTimestamp Request

Timestamp Reply

Information Request

Information Reply

Address Mask Request

Address Mask Reply

c.Gi tin ARP:

Mt gi tin ARP l mt Ethernet Frame c truyn trc tip t my ny ti my kia. V khng phi s dng IP, gi tin ny khng c a ch IP cng nh khng cn c nh tuyn, n phi c gi broadcast ti tt c cc my trn mng Ethernet (ti a ch l: FFFFFFFFFFFF). Gi tin ARP c m t nh sau: 0 15 1631

Hardware Address Space

Protocol Address Space

Hardware Address LengthProtocol Address Length

Operation Code

Source Hardware Address (Ethernet Address)

(Internet Address)

Source Protocol Address

Targe Hardware Address (Ethernet Address)

Destination AddressSource IP AddressType of LengthARP DataCRC

Hnh 2. 8: Gi tin ARP.

Khng ging phn ln cc giao thc khc, d liu trong ARP khng c mt nh dng chun cho header. ARP c th lm vic vi nhiu cng ngh khc nhau, ngi ta dng mt trng cha di ca nhng trng i sau n.2.2.5 Tng giao vn:

Tng giao thc ngay trn tng Internet l tng giao vn (Host to Host Transport Layer hay thng gi l Transport Layer). Hai giao thc quan trng nht ca tng ny l Tranmission Control Protocol (TCP) v User Datagram Protocol (UDP). TCP cung cp dch v chuyn giao thng tin c kt ni (connection oriented), n bao gm vic kim tra v sa li. UDP cung cp dch v km tin cy hn v khng thit lp lin kt trc (connectionless). C hai giao thc u chuyn giao thng tin gia tng ng dng v tng internet. Chng trnh ng dng c th la chn dch v np thch hp vi n.a.Giao thc khng kt ni UDP:

UDP cho php chng trnh ng dng truy cp trc tip n gi tin ca dch v chuyn giao ging nh dch v m giao thc IP cung cp. N cho php ng dng trao i thng tin qua mng vi t thng tin iu khin nht. UDP l giao thc khng kt ni, km tin cy v khng c c ch kim tra tnh ng n ca d liu truyn.a.1 Cu trc gi tin UDP:Source PortDestination Port

Message LengthChecksum

Data

Destination AddressSourse AddressType FieldIP HeaderUDP DataCRC

Hnh 2. 9: Cu trc gi tin UDP.

Mi gi thng tin UDP gi l mt datagram c phn chia lm 2 phn: Header v Data. Trong header cha thng tin v a ch cng ngun, a ch cng ch, di ca gi v checksum.

a.2. Phn knh, hp knh v Port:

Phn knh, hp knh chnh l vic la chn nhng tin trnh ng dng trong mt s ln cc tin trnh s dng giao thc UDP, v cn la chn ra cc ng dng tng ng vi gi thng tin chuyn n.

Hnh 2. 10: Qu trnh phn knh.

Vic ny c gii quyt bng c ch cng (Port Mechanism), c ch ny gn mi ng dng vi mt con s gi l s hiu cng ( Port number), v mi gi thng tin m ng dng gi i u mang mt trng SOURCE PORT.

Ti ni nhn, da vo thng tin trong trng DESTINATION PORT m gi tin c truyn ti cng tng ng vi ng dng. V d mt bn TCP/IP u c dch v FTP (File Transfer Protocol) gn vi cng 21 v TFTP (Trivial File Transfer Protocol) gn vi cng 69 ca UDP.Cc cch s dng cng:

Dng nhng cng dnh ring cho tng ng dng c ng k trc (Well Known Port Assignment). Mt Port Number s c sinh ra khi c mt ng dng i hi (Dynamic Binding).

Cch tip cn kt hp cc kiu trn (Hybird) va s dng Well Known Port Assignment cho mt s Port Number va c th nh ngha cc Port Number khc khi cn thit. Cc Port Number thng dng ca UDP thng c dnh ch t 1 ti 255. Mt s h iu hnh (nh 4.3 BSD UNIX) cn dnh ch ti Port Number 1023, cc Port Number c th s dng c l t s 1024 tr ln.Mt s l do s dng UDP nh mt dch v giao vn: Nu mt s lng ln cc gi tin nh c truyn, thng tin cho vic kt ni v sa li c th ln hn nhiu so vi thng tin cn truyn. Trong trng hp ny, UDP l gii php hiu qu nht. Nhng ng dng kiu Query Response cng rt ph hp vi UDP, cu tr li c th dng lm s xc nhn ca mt cu hi. Nu khng nhn c s tr li sau thi gian no , ng dng ch cn gi i mt cu hi khc. Mt s ng dng t n cung cp cng ngh ring chuyn giao thng tin tin cy, v khng i hi dch v ny ca Transport Layer.b. Giao thc iu khin truyn tin TCP:

Mt s ng dng i hi giao thc giao vn cung cp dch v chuyn giao thng tin tin cy s dng TCP bi n cung cp dch v kim tra ng n v d liu c truyn vi mt s phi hp thch hp. Mt s c im ca dch v tin cy m TCP cung cp l:

Hng dng (Stream Orientation): TCP coi d liu n gi i l mt dng byte khng phi l gi tin. Do , TCP m bo s th t ca cc byte gi nhn. Trng Sequency number v Acknowledgment number trong header ca TCP gi du ca cc byte trong ton b dng d liu truyn. TCP khng bt h thng phi s dng mt s c bit no nh s dng byte, mi h thng chn mt s m n s dng lm im bt u. Mi trm cui phi bit s th t m trm kia dng. Chng phi trao i mt s segment ng b h thng s s c s dng (Synchronize sequence number SYN) trong qua trnh bt tay. Trng Sequent number trong SYN segment cha s bt u (ISN) ca dng s nh th t, s ny c chn ngu nhin . Mi byte trong d liu c gi du bi ISN do byte u tin ca d liu mng s ISN + 1. Sequent number cha v tr ca dng byte trong gi tin nu ISN = 0 v 4000 byte c chuyn giao th con s tip theo s l 4001.

Chuyn giao b m (Buffered Transfer): gim s lng truyn thng, giao thc c gng s dng s lng ti thiu cc segment truyn ti thng tin. Do vy, giao thc s dng ti a di c th ca segment. Trng Window trong TCP header cho bit s byte ti a m trm ch c th nhn c, nu trm ch c kh nng chp nhn 6000 byte th trng window s l 6000, trm gi c th iu chnh li d liu cho ph hp. Nu trng Window mang gi tr 0 ngha l trm gi phi ch ti khi nhn c mt s khc 0.

Kt ni hai chiu (Full Duplex Connection): TCP/IP cung cp kt ni cho c hai u ca lin kt. iu ny c ngha l tng pha di cung cp kh nng gi tr thng bo t trm ch tr li trm ngun. TCP l giao thc hng kt ni. N thit lp quan h logic gia hai trm tham gia lin kt. Thng tin iu khin gi l handshake c trao i gia hai trm thit lp hi thoi trc khi thng tin c truyn. TCP ch dn chng trnh iu khin ca mt segment bng cch t mt bit dnh ring ca c ti word th 4 ca segment header.

Kiu bt tay ca TCP gi l three way handshake bi v 3 segment c trao i. Trm A bt u kt ni bng cch gi mt segment vi bit SYN. Segment ny bo cho trm B th t trm A s s dng cho nhng segment ca n gi, s th t ny bo m cho d liu mt trt t thch hp. Trm A p li trm B vi bit Acknownledgment (ACK) v SYN c t. Segment ca B thng bo rng n nhn c thng bo ca A v bo cho A bit s th t m n s s dng. Cui cng, A gi mt segment bo cho B n nhn c thng bo v truyn gi d liu u tin. Ch rng, gi tin th nht cha bit SYN v cc gi tip theo cha bit ACK. Sau khi trao i, trm A xc nh hin nhin trm ch tn ti v sn sng nhn d liu. Ngay sau khi kt ni c thit lp, d liu c th truyn. Khi kt thc hp tc truyn giao d liu, chng s trao i three way handshake cha bit thng bo ht d liu truyn No more data from sender gi l ( FIN) kt thc kt ni. l s trao i gia hai trm cung cp mt kt ni logic gia hai h thng.

TCP cung cp dch v tin cy vi mt c ch gi l Positive Ackownledgement with Retransmission (PAR). n gin l trm ngun tip tc gi thng tin i cho ti khi n nhn c thng bo d liu c nhn chnh xc ti trm ch. n v thng tin chuyn giao gia cc ng dng gi l segment, mi segment cha checksum m bo rng segment khng b ph hu trn ng truyn, nu segment b ph hu, trm nhn hu b n v sau mt thi gian no , trm gi s gi li gi tin m n khng nhn c thng bo xc nhn. 0 15 1631Source PortDestination Port

Sequence Number

Acknowledgment Number

OffsetReservedFlagsWindow

ChecksumUrgent Pointer

OptionPadding

Data

Destination AddressSourse AddressType FieldIP HeaderTCP DataCRC

Hnh 2. 11 : Cu trc gi tin TCP.

Source Port Cng ngun. Destination Cng ch. Sequency Number S th t ca gi tin.

Offset S th t ca byte u tin.

Reserved dnh. Flags C ch dn.

Window S byte ti a trm ch c th nhn.

Checksum Checksum kim tra tnh ton vn. Urgent Pointer di d liu khn i sau.

Option Tu chn.

Padding Phn in thm vo cc con s 0.

Data D liu bt u t y.

Tuy cng dng cc Port number nh danh cho cc ng dng nhng mt cng khng nh danh cho mt thc t duy nht trn mng. TCP l mt giao thc hng kt ni do n cn phi nh danh cho c hai u ca lin kt. TCP a ra nh ngha endpoin l mt cp s nguyn ( host, port) trong , host l a ch IP ca mt my tnh cn port l port number m my tnh s dng.2.2.6 Tng ng dng:

Phn ln ngi s dng ch quan tm n cc dch v thng tin c cung cp trn Internet. Cc ng dng c sm nht ca Internet l Telnet, FTP, SMTP, DNS ngoi ra ngy nay c hng ngn ng dng khc ang pht trin v ngy mt nhiu. Sau y ta tm hiu mt s ng dng ca Internet:a.Dch v tn min DNS:

Vic nh v cc my tnh trn mng bng cc a ch IP c nhiu li im, tuy nhin vi ngi s dng, vic nh cc con s l mt vic t nht kho chu. Hn na, a ch IP khng mang thng tin v a l, t chc hay ngi dng. V th, ngi ta xy dng h thng t tn gi l Domain Name Server cung cp cho ngi dng cch t tn cho cc my tnh vi cch t tn thng thng quen thuc.

Mt Domainname thng thng c dng:

Tn_ngi_dng@tnmin.

Vi tn min c phn lm cc cp ni vi nhau bi du chm ..Tn min c NIC cung cp.

b. ng nhp t xa Telnet:

Telnet cho php ngi s dng t mt trm lm vic ca mnh c th ng nhp vo mt mng xa nh mt u cui ni trc tip vi trm xa .

ng nhp vo mt my tnh ta nh lnh:

telnet[domain name / IP address].

c.Th in t Email:

y l mt dch v ph bin nht trn Internet trc khi word wide web ra i, thng qua dch v ny, ngi s dng trn mng c th trao i cc thng bo cho nhau trn phm vi th gii. y l mt dch v m hu ht cc mng din rng u ci t v cng l dch v c bn nht ca mt mng khi ra nhp Internet. Nhiu ngi s dng my tnh tham gia mng ch dng duy nht dch v ny. Dch v ny s dng giao thc SMTP (Simple Mail Transfer Protocol) trong h giao thc TCP/IP.

d.Giao thc truyn tp FTP:

y l mt phng thc sao chp tp t mt my tnh xa v my tnh ca ngi dng. Ta c th ngi ti my tnh ca mnh truyn hoc ly file trn mt my ch no .

2.2.7 C ch a ch Internet:

Mi thit b TCP/IP c nhn dng bi mt a ch IP. a ch IP l a ch lp mng, n khng ph thuc vo a ch lp lin kt d liu. Mi a ch IP xc nh duy nht mt Host vo mt thit b mng.

Mi a ch IP bao gm Network ID v Host ID: Network ID ( c th xem nh l a ch mng ) dng nhn dng cc h thng t trong cng mt mng vt l c chia bi cc Router. Cc h thng cng mng vt l phi c cng Network ID. Network ID phi l duy nht trn mng tng tc. Host ID ( c th xem nh l a ch Host) c dng nhn dng mt workstation, server, router, hay thit b TCP/IP khc trn mng. a ch ca mi Host l duy nht i vi mi Network ID. Mng Internet s dng h thng a ch IP 32 bits xc nh v tr cc my tnh kt ni vi n. C 2 cch nh a ch, ph thuc vo cch lin kt ca tng my tnh c th. Nu cc my tnh c kt ni trc tip vi mng Internet th trung tm thng tin Internet ( Network Information Centre NIC) s cp cho cc my tnh mt a ch IP ( tuy nhin cng di s cho php ca NIC).

H thng a ch ny c thit k mm do qua mt s phn lp, c 5 lp a ch IP l: A, B, C, D, E. S khc nhau c bn gia cc lp a ch ny l kh nng t chc cc cu trc con ca n.

Hnh 2. 12: Cc lp a ch IP.

Trong 5 lp a ch IP trn, ch c 3 lp a ch A, B, C l c s dng rng ri trn mng.

a. a ch lp A:

Lp A s dng byte u tin nh a ch mng, 3 byte cn li dng nh a ch my trong mng. Lp A c nhn ra d dng bi bit du tin trong byte u tin c gi tr 0.

Mt khc, do ngi ta khng s dng a ch ton 0 hay ton 1 nh a ch mng cng nh a ch my trong mng nn lp A c 2 2 = 126 a ch nm trong khong 1 n 126 v s my tnh ti a i vi mi a ch lp A s l 2 2 = 16.777.214 a ch lp A thng c cp cho cc t chc c s lng my tnh ln.

a ch lp A c dng: .

b.a ch lp B:

a ch lp B c nhn ra bi 2 bit u tin ca byte u tin c gi tr 10. Lp B s dng 2 byte u tin nh a ch mng v 2 byte cui nh a ch trong mng.

Lp B c 2 2 = 16.382 a ch v mi a ch c ti a 2 2 = 65.534 my tnh. Byte u tin ca a ch lp B nm trong khong 128 n 191.

a ch lp B c dng: .

c. a lp C:

a ch lp C c phn bit bi 3 bit u tin ca byte u tin c gi tr 110. Lp C dng 3 byte u tin nh a ch mng v byte cui nh a ch my ch trong mng. a ch lp C thng c cp cho cc t chc c quy m nh. Lp C c 2 2 = 2.097.150 a ch, mi lp C c ti a 2 2 = 254 my ch. Gi tr lp C c dng: .

2.2.8 Subnet v Subnet Mask

Mng Internet s dng a ch IP 32 bit v phn chia ra cc lp rt mm do. Tuy nhin, vi mt h thng a ch nh vy vic qun l vn rt kho khn. Nu nh mt mng c cp cho mt a ch lp A th c ngha n cha ti 16.777.214 my tnh, do vy ngi ta dng mt n bit phn chia mng ra thnh nhng mng con gi l Subnet Mask.Subnet Mask l mt s 32 bit bao gm n bit 1 (cc bit cao nht) dng nh a ch mng con v m bit 0 (cc bit cn li) dng nh a ch my trong mng con vi n + m = 32.

0 16Network NumberHost Number

Network NumberSubnet NumberHost Number

11111111111111111111111100000000

Subnet Mask phi c cu hnh cho mi my trong mng v phi c nh ngha cho mi Router. Nh vy, ta pha dng mt Subnet Mask cho ton b mng vt l cng chung mt a ch Internet.

V d:

Ta c mt a ch lp B 128.001.000.000 v cn chia n thnh 254 mng con vi 254 my trong mi mng, ta gii quyt vn ny bng Subnet Mask nh sau:Network No 10000000 00000001 00000000 00000000 = 128.001.000.000Subnet Mask 11111111 11111111 11111111 00000000 = 255.255.255.000Subnet Mask trn nh ngha 254 mng con vi a ch nh sau:

Subnet#1 10000000 00000001 00000001 00000000 = 128.001.001.000

Subnet#2 10000000 00000001 00000010 00000000 = 128.001.002.000Subnet#3 10000000 00000001 00000011 00000000 = 128.001.003.000

.

Subnet#254 10000000 00000001 11111110 00000000 = 128.001.254.000S my trong mng con th nht s nm trong khong sau:

Subnet#1 10000000 00000001 00000001 00000000 = 128.001.001.000Low Address 10000000 00000001 00000001 00000001 = 128.001.001.001High Address 10000000 00000001 00000001 11111110 = 128.001.001.254

Ch rng mt a ch cha ton s 1 dng cho broadcasting, cha ton s 0 dnh cho Subnet Mask. Do vy, a ch IP ca Host khng bao gi cha cc s 0 hoc 1.

2.3 Vn nh tuyn trong mng IP:

nh tuyn l vic x l truyn cc gi tin IP da vo a ch IP ch, Internet l mt mng chuyn mch gi, chuyn cc gi tin IP trn mng ngi ta s dng thut ton nh tuyn. nh tuyn l mt tin trnh tm ng i truyn gi tin v vic inh tuyn c thc hin bi my tnh trn mng. C 2 kiu nh tuyn: Trc tip v gin tip. nh tuyn trc tip ( Direct routing): nh tuyn trc tip t my tnh ny sang my tnh kia ch thc hin c khi c hai my tnh kt ni vo mt mng vt l. nh tuyn gin tip (Indirect routing): Khi trm ch khng cng nm trong mt mt mng vi trm gi, cn thng qua Gateway truyn i.2.3.1 nh tuyn trc tip:

Mi my tnh cng nm trn mt mng c cng mt Network ID v cc my tnh trn cng mt mng vt l c th gi frame vt l trc tip cho nhau nn vic truyn thng tin gia hai my tnh trong cng mt mng vt l khng cn s dng Gateway. Trm gi ch vic kt ni d liu vo frame, chuyn a ch IP ca trm ch thnh a ch vt l v gi trc tip n ti my nhn.

Mt c ch s dng truyn a ch IP thnh a ch vt l l ARP (Address Rosolusion Protocol). Khi hai my tnh cng ni vo mt mng vt l, chng phi bit a ch vt l ca nhau. ARP gii quyt vn chuyn t a ch IP 32 bit sang a ch Ethernet 48 bit. Ngi ta s dng hai c ch l: Chuyn giao trc tip: a ch vt l l mt hm ca a ch IP (kiu chuyn giao ny thng s dng cho cc mng cho php t a ch IP v a ch vt l t do). V d ta c th t a ch IP l 192.5.48.3 v a ch vt l l 3 khi ta c Chuyn giao a ch ng: c thc hin bng cch my tnh mun gi thng bo ti ton b cc my tnh trn mng, trong thng bo c cha a ch IP ca my n cn lin lc, mi my s nhn c thng bo v my no thy a ch IP ca mnh th tr li mt thng bo cha a ch vt l. Khi hai my c th ni chuyn vi nhau.

Hnh 2. 13: Qu trnh chuyn giao a ch ng.

Ngoi ra, ngi ta cn s dng bng nh tuyn lu tr tm thi cc a ch s dng mi nht tng tc ca vic chuyn giao a ch.

Trong trng hp my trm khng bit a ch IP ca chnh mnh khi khi ng, ngi ta s dng c ch c tn RARP gii quyt vn ny l: C mt my ch cha bng a ch IP ca cc my trm, khi my trm khi ng, n gi mt request ti tt c cc my v my ch tr li n bng mt gi tin cha a ch IP ca n.

2.3.2 nh tuyn gin tip:

Nu trm gi v nhn nm trn cc mng khc nhau th trm gi phi ng gi thng tin v gi t mt Gateway ny ti mt Gateway khc n khi n c th c truyn trc tip ti my nhn. Thut ton nh tuyn thng s dng bng nh tuyn ( Internet routing table IP routing table) trn mi my tnh cha thng tin v cc my tnh v cch i n chng. V vic nh tuyn c thc hin bi cc Host v Gateway, nn mi thit b u cha mt bng nh tuyn. Bng nh tuyn cha thng tin v cc mng v Gateway kt ni n .

Mt k thut c s dng che du thng tin v gim thiu kch thc ca mng nh tuyn l s dng default Gateway. Nu my tnh khng tm thy a ch ch trong bng nh tuyn ca n, th gi tin c chuyn i n mt thit b l default Gateway. K thut ny c bit thch hp vi trng hp mng my tnh c ni vo Internet thng qua mt my tnh duy nht.CHNG 3: TNG QUAN V MOBILE IP3.1 Gii thiu v cng ngh Mobile IP:

T Internet gi y thng dng, quen thuc vi mi ngi. Internet kt ni ton b th gii my tnh. Hng ngy, c thm hng nghin ngi dng mi kt ni vo Internet. Cc cng ty s dng Internet kinh doanh, qung co v thc hin cc dch v thng mi khc. Thi i ngy nay l thi i bng n Internet.

Vic h tr kh nng di ng cho cc thit b Internet tr nn rt quan trng, do in ton ng (mobile computing) ngy cng pht trin rng ri. S lng my tnh ng d kin s tng ln nhanh chng. Hn th na , c nhng sn phm v in thoi Cellular h tr cc dch v IP da trn WAP hay GPRS, v s lng ca chng ngy cng tng trong thi gian ti. Cc tht b Cellular ca th h 3G s l cc thit b chuyn mch gi , thay v chuyn mch knh nh trc y. Do cc dch v IP s tr thnh mt b phn tch hp trn cc thit b Cellular 3G.

Hin nay chng ta phi ng u vi nhiu vn khin cho vic roaming ca cc t01hit b Internet gp nhiu kh khn. Vn ny bt u ny sinh nu mt ngi no ngt thit b di ng ra khi Internet kt ni n t mt ni khc. Bnh thng th ngi s khng th kt ni nu khng cu hnh li h thng vi mt a ch IP mi, mt mt n mng chnh xc v mt b nh tuyn mc nh mi. Nguyn nhn l do cc c ch nhot ng tuyn ang c s dng hin nay. Cc a ch IP nh ngha mt kiu quan h v cu hnh mng gia cc my tnh c lin kt. Cc phin bn gn y ca giao thc Internet ngm nh rng mi trm ch c mt im lin kt vi Internet. Ngoi ra a ch IP ca trm nh danh mt lin kt n trm (ch khng phi l nh danh trm).Nu mt trm di chuyn m khng thay i a ch IP, s khng c thng tin no trong a ch ch ra rng l mt im lin kt Internet mi. Do cc giao thc Internet ang tn ti s khng c kh nng phn phi cc gi tin mt cch chnh xc. Trn hnh 5.1, cc gi tin c nh tuyn n trm vi tin t mng con l B s lun c chuyn n B. Nu trm ny chuyn n mt ni khc n s khng nhn c gi tin ny, trong khi cc gi tin vn c chuyn n mng B. Cc giao thc nh tuyn hin ti yu cu phi thay i a ch mng khi mt trm di chuyn n mt v tr mi.

Hnh 3. 1: Mt trm di chuyn v khng thay i a ch IP.

T chc IETF chun ho mt giao thc h tr cc thit b internet di ng gi l Mobile IP (ngha l giao thc IP h tr kh nng di ng). Giao thc ny cho php cc thit b c th t cu hnh im truy cp Internet ca n. C 2 phin bn giao thc Mobile IP l Mobile IPv4 da trn IPv4 v Mobile IPv6 da trn IPv6, chng ta s ln lt tm hiu v hai giao thc ny. 3.2 Cc khi nim v thut ng c bn dng trong giao thc:

a ch gc (Home Address): l a ch IP c gn c nh cho MN trn mng gc.

a ch tm (Care of Address): l a ch IP c phn b cho MN khi thit b ny chuyn n mt mng ngoi. Tin t mng con ca a ch IP ny l mt tin t ca mng ngoi. Trong s cc a ch tm v mt MN c th c ti mt thi im th ch c mt a ch c ng k vi a ch gc v c coi l a ch tm c bn.

Lin kt di ng (Mobility Binding): l s kt hp ca mt b ba gi tr: a ch gc ca MN, a ch tm v thi gian tn ti cn li ca kt hp ny.

Thit b tng ng: thit b ngang hng vi mt MN khi trao i thng tin thit b tng ng c th l mt MN hay mt thit b c nh.

ng gi(Encapsulation): l qu trnh st nhp mt gi IP gc vo trong mt gi IP khc lm cho cc trng tiu ca gi IP c tm thi mt i tc dng ca chng.

Mng gc (HN Home Network): l mng m tin t mng con gc ca trm di ng c nh ngha. Cc c ch nh tuyn IP chun s chuyn cc gi tin, c ch l a ch gc ca MN, n mng gc ca n.

Mng ngoi (FN Foreign Network): l bt k mng no khng phi mng gc ca trm di ng.

Tin t mng con gc (Home Subnet Prefix): l bt k tin t mng con no khng phi l tin t ca mng con gc ca MN.

i l di ng (Mobility Agent): l mt thit b ( thng l b nh tuyn ) phc v cho trm di ng. i l di ng c th l i l gc hoc i l ngoi.

i l gc (Home Agent): l mt thit b ( thng l b inh tuyn) trn mng gc ca MN, ni m MN ng k a ch tm hin thi khi thit b di chuyn n mt mng mi, i l gc s nhn cc gi tin gi ti MN trn mng gc, ng gi v chuyn cc gi tin n a ch tm m MN ng k.

i l ngoi (Foreign Agent): l bt k thit b no (thng l b nh tuyn) trn mng ngoi, ni m MN c c da ch tm. N tr gip cho MN nhn cc gi tin ny c chuyn ti a ch tm. Khi nim i l ngoi ch c trong giao thc Mobile Ipv 4.

ng k (Home Regitration): l qu trnh qua MN thng bo cho i l gc v a ch tm c bn hinh thi ca n.

S di chuyn (Movement): l s thay i im kt ni Internet n mt mng khc vi mng trc . Nu mt trm di ng khng c ni vo mng gc ca n th trm di ng c gi l ri khi mng gc (away from home).

ng ngm (Tunnel): l qu trnh cc gi tin t ngun c ng gi mt ln na v chuyn n ch trung gian ( trong mt s trng hp, ch trung gian cng chnh l ch cui cng). Ti y gi c m ra v chuyn n ch cui cng.3.3 Cc yu cu v mc tiu ca Mobile IP:

Trong cc mng s dng giao thc IP hin nay a ch IP ca cc thit b phn bit duy nht qua im m thit b ni vi mng. Chnh v vy m mt thit b phi ni vo chnh mng c quy nh bi a ch IP ca n th mi c th nhn c cc gi IP. Khi m mt thit b thay i im kt ni ca n vo mng m khng mun mt kh nng gi v nhn d liu th trc y c 2 cch gii quyt vn ny:

Thit b thay i a ch IP khi thay i im kt ni vi mng.

Cc tuyn c bit (bao gm cc thng tin chi tit v ng i ca gi tin ti c my nhn) s c truyn ti cc b nh tuyn trn mng. Tuy nhin c hai hng gii quyt u c nhng nhc dim nht nh ca n.

Cch 1: Lm thit b mt kt ni lp giao vn v cc lp cao hn.

Cch 2: S gy ra cc vn nghim trng khi tin hnh m rng mng v c bit l khi s lng cc thit b mng tng cao.

Mobile IP chnh l gii php c a ra khc phc nhc im cho c hai phng php trn.3.2.1 Cc yu cu m Mobile IP phi p ng: Cc thit b di ng phi c kh nng lin lc vi tt c cc thit b khc khi thay i im kt ni m khng lm thay i a ch IP. Cc thit b di ng cng phi c kh nng lin lc vi cc thit b thng thng khc (cc thit b khng hiu Mobile IP). Tt c cc bn tin s dng cp nht thng tin v v tr ca thit b di ng cn phi c xc thc nhm m bo tnh an ton ca thng tin.

Mobile IP cho php cc trm di chuyn t mt subnet ny sang mt subnet khc. Do ch hot ng trn lp mng v m khng b bt c yu cu no ln lp lin kt d liu (lp 2 m hnh OSI). Mobile IP h tr kh nng di chuyn qua mi trng ng nht cng nh mi trng khng ng nht. Ngha l Mobile IP to iu kin thun li cho trm di chuyn t mt vng Ethernet ny sang vng Ethernet khc cng nh h tr trm di chuyn t mt vng Ethernet ti mt mng LAN khng dy, v a ch IP ca trm di ng vn khng thay i sau khi di chuyn.

3.2.2 Cc mc tiu ca Mobile IP:

Mobile IP c th c s dng trn cc link c bng thng nh t l li truyn cao hn cc kt ni hu tuyn truyn thng. Vn tiu th nng lng ca cc thit b di ng l ht sc quan trng v vy trong qu trnh xy dng cc th tc trong Mobile IP cn gim thiu cc bn tin trao i cng nh kch thc ca chng ti mc ti thiu.3.4 Tng quan v Mobile IP:

Giao thc Mobile IP cho php mt thit b ri khi mng gc m vn duy tr mi kt ni hin ti cng nh kh nng kt ni n phn cn li ca Internet. iu ny c thc hin bng cch xc nh a ch gc (hay a ch tnh) ca mi thit b m khng quan tm n im truy cp Internet hin thi ca n. Khi mt thit b di ng ngoi mng gc, n s gi cc thng tin v v tr hin thi n i l trn mng gc, gi l i l gc (HA Home Agent). i l gc s ng ra nhn cc gi tin gi cho cc thit b di ng, thay i mt s thng tin v chuyn tip nhng gi tin ny n v tr hin thi ca thit b di ng.C ch ny hon ton trong sut i vi cc lp trn lp IP nh: TCP, UDP, cc lp ng dng .. do cc phn t DNS ch cn nh x n a ch gc ca thit b di ng v khng thay i cho d thit b di ng c thay i im truy nhp. Thc t Mobile IP c tc ng n qu trnh nh tuyn, xong giao thc ny hon ton c lp vi cc giao thc c nh tuyn (RIP).Gii php Mobile IP a ra l to ra mt loi a ch gi l a ch tm (COA Care of Address). Thit b di ng lun c nhn dng bi a ch gc ca n v khng quan tm n im kt ni vi Internet. Khi chuyn n mng mi, thit b di ng s c thm mt mt a ch tm, xc nh v tr hin ti ca thit b. Thit b di ng phi gi a ch tm ny ti mt i l trn mng gc. i l ny ng nhn cc gi tin gi n a ch gc ca thit b di ng v s dng cch ng gi IP In IP lp knh cho cc gi tin i n a ch tm.Nu thit b di ng chuyn ri na, n s tm c a ch tm th 2 v thng bo cho i l gc v v tr mi ny. Khi tr v mng gc, thit b di ng phi lin h vi i l gc hu b vic ng k. hnh di minh ho mt thit b di ng chuyn t mng A n mng B. Trn mng mi, thit b di ng c cp mt a ch tm ni phn tin t l mng B.

Hnh 3. 2: Thit b di ng sang mng khc v c cp a ch tm.3.4.1 Cc thnh phn chnh ca mng Mobile IP:

Mobile IP bao gm ba thnh phn chnh sau y:

Thit b di ng: Mobile Node (MN).i l gc: Home Agent ( HA ).

i l ngoi: Foreign Agent (FA).

Hnh 3. 3: Cc thnh phn ca Mobile IP v mi quan h ca chng.

Trong :

Thit b di ng (MN) l mt thit b nh cell phone, PDAs, (personal digital asisstant) hoc l my tnh xc tay.i l gc (HA) l mt thit b nh tuyn trn mng ch, phc v nh l mt im neo trong qu trnh truyn thng tin ca MN.HA tip nhn thng tin gi cho MN v gi tip ti MN thng qua mt ng ngm c thit lp gia HA v FA.i l ngoi (FA) l mt thit b nh tuyn c chc nng nh mt im gn kt ca MN khi n di chuyn vo mng ngoi (Foreign Network).

3.4.2 Cc c tnh ca Mobile IP:

Mobile IP cung cp kh nng di ng cho cc thit b IP vi cc c tnh sau:

Kh nng m rng: Mobile IP c kh nng m rng linh hot bi v ch c cc thit b u cui mi cn hiu Mobile IP, tt c cc thit b trung gian nh cc b nh tuyn u khng cn c s thay i.

Hnh 3. 4: Tnh trong sut ca Mobile IP.

Tnh trong sut: Mobile IP trong sut vi cc ng dng chy trn n v n c thc hin lp mng, c lp vi lp vt l v lin kt d liu.

Tnh bo mt: mobile IP mang tnh bo mt cao bi v tt c cc gi tin gi i theo hai chiu u c xc thc.

Tnh chuyn ng v m (Macro mobility): Thay v c gng x l vic nh v nhanh chng nh trng hp ca h thng Cellular khng dy th Mobile IP tp trung vo vn dch chuyn trong qu trnh di, chng hn nh trong vi gi.

Cng hot ng trong IP: Cc my tnh s dng Mobile IP c th tng tc cc my tnh bn s dng phn mm IP thng thng cng nh vi cc tnh ng khc. Hn na, Mobile IP khng i hi phi c vic cu hnh a ch c bit, cc a ch gn cho my tnh ng khng khc g vi cc a ch gn cho my tnh c nh.

C th Mobile IP c thit k cho nhng di chuyn trong phm vi ln ch khng phi nhng dch chuyn tc cao, v cng vic qun l i hi nhiu thi gian v cng on. Sau khi di chuyn, trm di ng phi nhn bit n ang di chuyn, no phi thng tin vi mng mi ly a ch ph, ri sau lin h vi mt i l mng gc qua Internet b tr vic chuyn d liu.CHNG 4: HOT NG CA MOBILE IPv4

4.1 Tng quan v giao thc Mobile IP:

Phn ny s gii thiu mt s khi nim v hot ng ca giao thc Mobile IPv4. Mobile IPv4 c xy dng da trn giao thc IPv4 cho php cc nt mng tip tc nhn c cc gi tin d kt ni vi Internet bt k v tr no. Nhng b xung bao gm cc bn tin iu khin v cc th tc dnh ring cho giao thc. Cc th tc c bn ca giao thc Mobile IPv4 gm c: qung co trm, ng k, v chuyn tip.

4.1.1 Khi nim a ch care of:

Khi mt trm di ng ra khi mng gc, Mobile IP s dng c ch ng hm (tuneling) gi a ch gc ca trm di ng khng b nhm nhm gia mng gc v v tr hin ti ca trm. a ch care of l im cui ca ng hm. N c th l a ch ca mt i l trn mng ngoi hay cng c th l a ch ph ca trm di ng. Ti y, gi tin c thit lp li v c gi ti trm di ng nh khi ang mng gc.

Giao thc Mobile IPv4 cung cp hai phng thc nhn a ch care of.

a ch care of ca i l ngoi: L a ch care of c cp bi i l ngoi thng qua bn tin qung co i l. Trong trng hp ny, a ch care of l a ch IP ca i l ngoi. Khi , i l ngoi s l im cui ca ng hm. Ngay khi nhn c gi tin gi ti t i l gc, i l ngoi s tin hnh m gi to li gi tin ban u ri chuyn n trm di ng. Cch nhn a ch care of nh trn c nhiu u im bi n cho php nhiu trm di ng c th s dng chung mt a ch care of, nh s tit kim c ti nguyn khng gian a ch IPv4 ang ngy cng cn kit.

a ch colocated care of: L a ch care of m trm di ng nhn c thng qua mt s phng tin trn mng ngoi. Trm di ng c th nhn c a ch ny thng qua giao thc DHCP. Khi s dng a ch colocated care of, trm di ng s hot ng vi t cch l im cui ca ng hm v pha thc hin vic m/thit lp li gi tin tunneled ti trm. Vic s dng li a ch colocated care of c u im l cho php trm di ng c th hot ng m khng cn ti i l ngoi. Tuy nhin, phng php ny i hi phi cp mt a ch IP (t danh sch cc a ch IP m mng ngoi c cp) cho mi trm di ng.

4.1.2 Nguyn l hot ng ca Mobile IPv4:

1. Cc i l di ng ( bao gm i l gc v i l ngoi) thng bo s hin din ca chng qua bn tin qung co i l. Trm di ng khi mi n, c th gi mt bn tin tm kim i l yu cu cc i l di ng, trong mng m n ang kt ni ti, gi bn tin qung co i l.

2. Trm di ng nhn bn tin qung co i l v xc nh xem liu n ang mng gc hay trong mt mng ngoi.

3. Khi trm di ng pht hin ra rng n ang mng gc, trm di ng s hot ng m khng s dng cc chc nng di ng Nu trm di ng tr v mng gc t bt k mt mng ang c ng k no , trm di ng s hu b vic ng k vi i l gc thng qua th tc ng k thng thng.

4. Khi trm di ng pht hin ra rng n chuyn ti mt mng ngoi, trm di ng s nhn mt a ch care of trn mng ngoi. a ch care of ny c th l a ch care of ca i l ngoi (nhn c t bn tin qung co i l) hay a ch colocated care of (nhn c thng qua giao thc DHCP).

5. Khi hot ng ngoi mng gc, trm di ng s ng k a ch care of hin thi vi i l gc thng qua vic trao i cc bn tin yu cu v tr li ng k. Tu thuc vo phng thc lin kt, trm di ng c th ng k trc tip vi i l gc ca n hoc thng qua mt i l ngoi.

6. Cc gi tin c gi ti a ch gc ca trm di ng s c i l gc chn li, ng gi v chuyn n a ch care of hin thi ca trm di ng theo c ch ng hm. Ti y, gi tin c thit lp li v c gi ti trm di ng.

7. Theo hng ngc li, cc gi tin c gi i t trm di ng s c chuyn ti ch theo cc c ch nh tuyn IP chun, khng cn i qua i l gc.Trong trng a ch ngun ca tt c cc gi tin IP gi i t trm di ng s l a ch gc ca trm.

Hnh 4. 1: M hnh nh tuyn gi tin trong IPv4.

Nu trm di ng ang s dng a ch colocated care of th trm di ng pha c nh v trn tuyn c nh danh bi phn tin t mng ca a ch care of. Nu khng cc gi tin hng ti a ch care of ny s khng th chuyn c.

Hnh 5.3 miu t l trnh cc gi tin i v n trm di ng khi trm di ng nm ngoi mng gc v thc hin ng k vi i l gc ca n. Trong v d ny, trm di ng s dng a ch care of ca i l ngoi. M hnh ny cn c gi l m hnh nh tuyn tam gic.

Gi tin gi cho trm di ng c chuyn n mng gc theo giao thc IP chun.

i l gc nhn gi tin, ng gi v chuyn ti a ch care of ca trm di ng. Gi tin c thit lp li v c gi ti trm di ng. T trm di ng cc gi tin s c chuyn trc tip ti ch theo c ch nh tuyn IP thng thng. Trn hnh v, i l ngoi chnh l b nh tuyn mc nh ca trm di ng.4.1.3 Cu trc chung ca cc bn tin s dng trong giao thc.

thc hin th tc ng k, Mobile IP nh ngha mt tp hp cc bn tin iu khin mi c gi i bng giao thc truyn ti UDP trn cng 434. Hin ti, c hai loi bn tin sau y c nh ngha l yu cu ng k v tr li ng k.

pht hin cc i l, Mobile IP sa i bn tin qung co b nh tuyn (Router Advertisement) v tm kim b nh tuyn (Router Solicitation), c nh ngha s dng trong c ch pht hin b nh tuyn ICMP.

Mobile IP cng nh ngha mt c ch m rng cho php cc thng tin tu chn c th c truyn ti trn cc bn tin iu khin hay trn cc bn tin pht hin b nh tuyn ICMP. Mi phn m rng ny c m ho theo cu trc Kiu di Gi tr (TLV: Type Length Value) nh ch ra trn hnh.

0 7 8 15 16

TypeLengthData

Hnh 4. 2: Cu trc ca m rng TLV.

Trong , trng kiu ch th kiu ca m rng. Trng di xc nh kch thc (tnh theo bytes) ca phn d liu. Trng ny c th c gi tr ln hn hay bng khng. Cu trc v di trng s liu c quy nh bi trng kiu v trng di.

C hai tp ring r cc s xc nh trng kiu ca phn m rng s dng trong IPv4. Tp th nht bao gm cc m rng c th xut hin trong cc bn tin iu khin. Hin ti, nhng kiu sau y xc nh s xut hin phn m rng trong cc bn tin ng k:

32. Nhn thc Mobile home.

33. Nhn thc Mobile foreign.

34. Nhn thc foreign home.

Tp th hai bao gm nhng phn m rng c th xut hin trong cc bn tin pht hin b nh tuyn ICMP:

0. m 1 byte (khng c trng kiu v trng gi tr).

16. Qung co i l di ng.

19. di tin t.

C th tm tt nh sau: Mobile IP s dng mt c ch cung cp cc thng tin nh tuyn cn thit cho i l gc ca mt trm di ng. Nh i l gc c th nh hng lu lng t mng gc ti a ch care of hin thi ca trm di ng. C ch c thc hin bng vic i l ngoi qung co s c hin din ca mnh, v chuyn tip cc bn tin ng k trao i gia trm di ng v i l gc. Cc bn tin qung co i l chnh l cc bn tin qung co b nh tuyn ICMP c b xung thm phn m rng, cn cc bn tin ng k c truyn trn cc gi tin UDP trnh nhng phc tp ca giao thc TCP.

4.2 Phng php pht hin i l.

Pht hin i l (Agent Discovery) l phng php m qua trm di ng xc nh c n ang kt ni vi mng gc hay vi mng ngoi, nh vy trm di ng c th bit c khi no n chuyn t mt mng ny n mt mng khc. Phn ny gii thiu v cc phng php qua trm di ng c th nhn a ch care of ca i l ngoi trn mng ngoi m n ang kt ni n.

Phn ny cng miu t chi tit cc bn tin c s dng bi cc trm v cc i l di ng pht hin s hin din ca nhau. Vic trao i cc bn tin ny c thc hin da trn giao thc ICMP v c ch pht hin b nh tuyn thng thng, trong c b xung thm mt s phn m rng. iu c ngha l Mobile IPv4 s dng phn m rng qung co i l di ng (Mobile Agent Advert. Extension) trong cc bn tin pht hin b nh tuyn ICMP lm c ch pht hin i l.4.2.1 Qung co i l.

Cc i l di ng s nh k gi cc bn tin qung co i l thng bo v cc im dch v trn mng. Trm di ng s s dng bn tin qung co ny xc nh im kt ni hin ti ca n vi internet. Bn tin qung co i l c hnh thnh t:

Bn tin qung co b nh tuyn ICMP.

Phn m rng qung co i l di ng.

C th thm phn m rng prefix length hoc phn m mt byte hay cng c th l cc m rng khc c nh ngha sau ny.

0 7 8 15 16 23 24 31

VerIHLType of ServiceTotal Length

IdentificationFlagFragment Offset

TTLProtocolHeader Checksum

Source Address

Destination Address

TypeCodeICMP Checksum

Num AddrsAddr Entry SizeLifetime

Router Address(1)

Prefered Value(1)

.

Extensions

Hnh 4. 3: Cu trc bn tin qung co i l.

Cn lu rng, bn tin ICMP c t trong trng d liu ca gi tin IP. Do vy, cc trng nh a ch ngun, a ch ch, ca bn tin qung co i l s c xc nh trong phn tiu ca gi tin IP.Trng a ch ch c th l a ch multicast n ton b h thng (224.0.0.1) hoc a ch broadcast trc tip (255.255.255.255) trn ton b h thng. Trng hp bn tin qung co l tr li cho bn tin tm kim i l th trng a ch ch s l a ch unicast ca trm yu cu. Trng TTL (Time To Live) cn phi c thit lp 1 cho tt c cc bn tin qung co i l.Cc trng ICMP:

Kiu (Type): 9. M (Code): Trng m ca bn tin qung co a l c cc gi tr.0 i l di ng ch ng vai tr nh cc b nh tuyn cho cc gi tin IP, khng c lin quan g ti cc trm di ng.

1 i l di ng c th khng thc hin vic nh tuyn cc lu lng IP thng thng. Tuy vy, cc i l ngoi 2 phi chuyn tip ( c th l ti mt b nh tuyn mc nh) bt k gi tin no m n nhn c t mt trm di ng ng k.

ICMP Checksum: l s b 1 ca ton b bn tin ICMP, bt u t trng kiu. tnh checksum, gi tr ca trng ny cn phi c thit lp 0.

Thi gian tn ti (Lifetime) l khong thi gian ti a m mt bn tin qung co c xem l hp l, khi cha xut hin cc bn tin qung co tip theo.

S lng a ch (Num Addrs) chi ra s lng a ch ca cc b nh tuyn c qung b trn bn tin ny. Trng ny c th c gi tr l 0.

Kch thc ca mi a ch (Addr Entry Size): C gi tr l 32 ch trng a ch b nh tuyn l 32 bit.

a ch ca mi b nh tuyn qung b trong bn tin ny thng km theo mt gi tr u tin biu th kh nng cung cp dch v cho cc trm mi. Thng thng b nh tuyn no c mc u tin cao s c chn.

Cc bn tin qung co i l c th c gi i theo nh k. Khi khong cch gi cc ln gi nn c thit lp bng 1/3 thi gian tn ti ca bn tin. iu ny cho php trm di ng b qua 3 bn tin qung co i l lin tip trc khi xo mt i l khi danh sch cc i l hp l ca n. Ngoi ra thi gian truyn thc t ca mi qung co nn c thc hin mt cch ngu nhin trnh s trng lp v ng vi qung co ca cc i l hay cc b nh tuyn khc. Cn lu rng, trng Lifetime khong lin quan g ti thi gian tn ti ca ng k (Reg.Lifetime) trong phn m rng qung co i l di ng, c nh ngha di y.a.M rng qung co i l di ng.

Phn m rng qung co i l di ng (Mobile Agent Advert. Extension) c t tip theo sau bn tin qung co b nh tuyn ICMP v c i l di ng s dng thng bo s c mt ca n. Khng c mt kiu bn tin ICMP ring no dnh dnh cho m rng ny. Thay vo , trm di ng s bit rng c s m rng nu chiu di ca gi tin, xc nh trong phn u IP, ln hn di ca bn tin qung co b nh tuyn ICMP. Hnh 5 6 miu t khun dng ca m rng ny.

0 7 8 15 16 23 24 31

TypeLengthSequence Number

Registration LifetimeRBHFMGV

Hnh 4. 4: M rng qung co i l di ng.

ngha ca mi trng trong m rng ny c nh ngha nh sau:

Kiu (Type): 16.

di (Length): C gi tr l (6+4*N) bytes, trong N l s lng a ch care of c qung co.

S th t (Sequence number): S hu ca bn tin qung co i l c gi i k t khi i l c khi to.

Thi gian tn ti ca ng k: l khong thi gian ti a ( tnh bng giy) m i l ny sn sng nhn bt k yu cu ng k no. Nu tt c cc bt ca trng ny u c gi tr l 1, n biu th thi gian tn ti ca ng k l v tn.

R: Yu cu ng k. Bit ny ch th rng trm di ng phi thc hin ng k vi i l ngoi ny ( hoc vi vi mt i l ngoi khc trn cng tuyn) thay cho vic s dng a ch colocated care of.

B: Bn. Nu bit ny c thit lp, i l ngoi s khng chp nhn vic ng k thm bt k mt trm di ng no na.

H: i l gc. i l ny s thc hin chc nng ca mt i l gc trn tuyn m bn tin qung co c gi i.

F: i l ngoi. i l ny s thc hin chc nng ca mt i l ngoi trn tuyn m bn tin qung co c gi i.

M: ng gi ti thiu. i l ny s nhn cc gi tin c gi i (tunnel) theo phng php ng gi ti thiu.

G: ng gi GRE. i l ny s nhn cc gi tin c gi i (tunnel) theo phng php ng gi GRE.

V: Nn tiu Van Jacobson. i l ny h tr vic s dng nn tiu ca Van Jacobson trn cng tuyn vi trm di ng ng k.

D tr (Reserved): Trng ny c thit lp 0 khi gi v c b qua khi nhn.

Cc a ch