HC VIN K THUT QUN S

Trn Xun Nam, Nguyn Thnh, inh Th Cng

TI LIU

HNG DN TH NGHIM OPNET

H Ni 12 / 2008

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MC LC

TrangMc lc 1Li ni u 3Phn 1: Gii thiu v phn mm OPNET IT GURU 5Phn 2: C s l thuyt m phng 9

2.1 Mng LAN Ethernet 92.2 Hub v Switch 102.3 Cc giao thc nh tuyn 102.4 QoS: nh hng ca c ch xp hng 10

Phn 3: Cc module m phng 123.1 Module m phng 1: M phng nh gi hiu nng mng

LAN Ethernet 12

3.2 Module m phng 2: So snh Hub v Switch 223.3 Module m phng 3: Cc giao thc nh tuyn 303.4 Module m phng 4: C ch hng i 41

Kt lun Ti liu tham kho

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LI NI U Mng Truyn S liu l mt trong nhng ni dung c bn trong cu trc chng trnh o to i hc v sau i hc cc chuyn ngnh thng tin, k thut in t v raa dn ng. Bn cnh khi lng kin thc l thuyt bao qut mt phm vi rt rng, t cp phn t cho n h thng ln, rt phc tp, mn hc cn t ra yu cu phi c iu kin cho hc vin c th tip cn thc tin h thng so snh, kim nghim vi l thuyt c trang b. Trong iu kin hin nay, vic trang b mt phng th nghim vi quy m nh vy cc k tn km, hn na, v nhiu l do khc nhau, cc cng ty vin thng cng khng to iu kin d dng hc vin c th tip cn, kho st, iu chnh cc h thng ca h.

Trong iu kin nh vy, cch thc hiu qu gii quyt vn l s dng cc phn mm mnh thc hin vic m hnh ho, m phng, nh gi cht lng ca cc mng vin thng. Gii php ny v ang c rt nhiu cc trng i hc k thut danh ting trn th gii c chuyn ngnh ny s dng.

Trong phm vi ti nghin cu ny, trn c s l thuyt v mng truyn s liu, nhm tc gi xy dng 4 module m phng da trn phn mm m phng mng OPNET Academic IT Guru. Cc module m phng xy dng c bao gm :

1. Mng Ethernet: Phn tch hot ng ca mng chia s mi trng

truyn, nh gi cht lng (hiu nng) ca mng khi ti lu lng thay i.

2. Switch v Hub: Tm hiu nguyn l hot ng ca Switch v Hub, nh hng ca n n thng lng ca mng.

3. Th tc nh tuyn: Nguyn cu hot ng ca giao thc Thng tin nh tuyn RIP (Routing Information Protocol), m phng hot ng ca mt s router s dng giao thc RIP, xc nh s thay i ca bng thng tin nh tuyn cng nh tc gi tin nhn c trong cc trng thi khc nhau ca mng.

4. QoS: nh hng ca c ch x l hng i: Kho st mt s tham s cht lng ca mng nh t l mt gi tin, tr xp hng, bin thin tr, khi p dng nhng c ch x l hng i khc nhau.

Thng qua 4 module m phng ny ngi s dng c th tin hnh m phng nh gi cht lng c cc giao thc mng c bn nh a truy nhp MAC, giao thc nh tuyn, mng LAN, v cc th tc nh tuyn trong mng chuyn mch gi. Ngoi 4 module m phng, thng qua phng php gii

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thiu ngi dng c th t tin hnh xy dng cho mnh cc module m phng phc v cho mc ch hc tp v nghin cu mt cch d dng.

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Phn 1:

Gii thiu v phn mm OPNET IT GURU S bng n ca mng Internet trong nhng nm gn y t ra yu cu cho cc nh khoa hc v cc k s trong lnh vc vin thng v cng ngh thng tin phi c kh nng bo tr, iu chnh, g li, i mi v pht trin h tng mng. Vic nm vng cc k thut ny i hi c kin thc l thuyt v thc hnh. Vi ngha gip hc sinh cng c cc khi nim l thuyt ng thi hiu c kh nng ng dng trong thc t ca tng vn , cc chuyn gia trong ngnh c bit khuyn co vic kt hp hot ng phn tch vi thc nghim trc quan trong cc kha hc v mng. Cn phi nhn mnh thm l hc phn th nghim thc s l yu cu bt buc i vi mt chng trnh hc v mng v kh nng hiu bit su v h thng i hi cc phng tin th nghim phi c kh nng cho php xy dng, quan st, thc hnh v o c. c rt nhiu cch khc nhau pht trin cc kha hc v mng da trn cc th nghim trc quan. Mt s kha hc thc hnh tp trung vo iu hnh v cu hnh mng hay c lnh vc qun tr mng. Mt s kha khc th nhn mnh ti mt lp c th trong tp cc giao thc mng nh phn tch lu lng mng lp lin kt d liu, ng dng cc giao thc lp truyn ti, vv S t cc chng trnh o to mng quy m ln cung cp cc phn cng chuyn dng trn hc vin c th thc hnh vi mt s mng thc v pht trin tnh nng mng mc li. Tuy nhin nhng chng trnh nh vy i hi lng ti nguyn cc ln khi to v qun l, chi ph cao mua sm trang thit b chuyn dng lm n tr thnh bt kh thi v mt ti chnh cho phn ln cc chng trnh o to.

Phn ln cc kha hc thc hnh mng c a ra nh l kha hc th hai v mng my tnh. Tuy nhin do gii hn bi trang thit b v nhn lc, phn ln cc trng i hc v cao ng ch thc hin c mt kha hc v mng, m i a phn trong khng c bt k mt hc phn th nghim no. Yu cu cp thit hin nay l phi tch hp c cc kha hc mang tnh gii thiu v mng vi cc hc phn th nghim. Mt li gii cho bi ton ny l a thm cc bi th nghim m phng vo bn cnh chng trnh hc l thuyt. M phng mng cho ngi dng kim chng cc bi ton vi lng cng sc ti thiu nhng quy m v phm vi th ln hn rt nhiu so vi vic thc hnh trn thit b phn cng. Trong trng hp ny, mt cng c c sn l chng trnh m phng mng ca OPNET, cung cp cc phng tin m

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hnh ha, thit k, m phng, thu thp d liu v phn tch. OPNET c th m phng rt nhiu loi mng khc nhau c kt ni vi nhau. Do , ch vi mt my tnh, sinh vin c th thc hnh rt nhiu cc ty chn c sn trong mng v xem xt mt cch trc quan cc tc ng do vic thay i ca mnh. Lung tin d liu, cc s kin mt gi tin, lung tin iu khin/nh tuyn, s c ng truyn, li bit, vv c th c rt ra quan st mt cch trc tip. y c th coi l gii php c bit kinh t cho cc trng i hc minh ha trng thi ca cc mng cng nh cc giao thc khc nhau.

Ti liu ny s m t qu trnh pht trin cc module m phng s dng phn mm OPNET ca nhm tc gi cng nh tng kt cc kinh nghim bc u trong qu trnh a cc module m phng vo phc v nghin cu v o to. Mc tiu o to cng nh l do la chn phn mm OPNET trong s rt nhiu cc gi phn mm m phng khc s c cp trc tin. Vn l thuyt cho nhng bi ton c bn ca mng vin thng sau c bn ti. Tip theo, cc bi thc hnh m phng c gii thiu mc chi tit ngi dung c th tin hnh cc bc tin hnh m phng tng i d dng m khng gp phi cn tr no ln.

1.1. Tiu ch la chn phn mm m phng mng

p ng c cc yu cu m phng cc tnh nng ca mng truyn s liu, cng c phn mm m phng mng c s dng phi tha mn cc tnh nng sau:

Kh nng m phng mt s lng ln cc cng ngh mng: Phn mm m phng phi bo m kh nng m hnh ha ton mng, bao gm trong n l cc router, switch, giao thc, server v cc ng dng c th m chng h tr. Phn mm phi h tr mt s ln cc h thng thng tin t mc ca mt mng LAN n mc ca cc mng v tinh ton cu.

D dng s dng: Phn mm m phng c th c ci t v khai thc khng my kh khn. Hc vin c th s dng phn mm hon tt cc bi th nghim m phng mt cch c lp, khng cn phi c o to s dng mt cch cng phu, bi bn.

Gi thnh thp hoc min ph: Phn mm phi c th c tip cn m khng i hi chi ph qu ln trong iu kin kinh ph bo m o to hn ch nh hin nay. Hn na, c th em li mt hc phn th nghim m, hc vin phi c th download v ci t phn mm (ch cn) vi my tnh c nhn ca mnh, khng cn n h thng my tnh vi my ch mnh h tr.

Cht lng m phng cao: Vi mi module m phng, ngi dng s c yu cu t khi to ly m hnh mng, chy m phng, phn tch

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kt qu v vit bo co th nghim. Do nht thit cn n mt cng c m phng cht lng cao cc m phng ca phn ln cc bi m phng c th c hon thnh trong thi gian ngn (di 30 pht). Nhiu loi tham s, kt qa c th rt ra c t m phng, biu din nhiu dng khc nhau nh th, bng, vn bn, vv

Ngoi ra phn mm m phng nn c thm cc thuc tnh mong mun khc nhng khng phi l thit yu nh:

Kh nng thch hp ca phn mm cho vic nghin cu: Phn mm m phng c th c dng cho cc nghin cu v mng da trn m phng. y l lnh vc hc thut cha c pht trin trong phm vi ca khoa chuyn nghnh.

Kh nng trin khai din rng: Phn mm phi c cng ng s dng ng o v phi c s dng rng ri trong ngnh, sao cho, trong qu trnh hc, hc vin c iu kin tham kho tip cn cc ngun ti liu phong ph t nhiu c s o to khc nhau v hn na, sau khi tt nghip, hc vin c th p dng trc tip kin thc va c trang b vo cng vic.

1.2. La chn phn mm m phng mng

Hin ti, trn th trng c rt nhiu cc gi phn mm m phng mng. Mt s trong nhm ti tng lnh vc quan tm nghin cu ring mt loi mng hay mt giao thc c th, nh cc mng khng dy bi GloMoSIM. S khc, nh x-Sim v Maise, tp trung vo vic cho php to ra ngn ng c th va chy m phng va thc hin c trn cc mng thc. OPNET v NS-2 l hai phn mm m phng mng ph dng nht, hng ti rt nhiu loi mng v giao thc. NS-2, pht trin t REAL, l cng c m phng mng m ngun m, c s dng rng ri cho nghin cu v o to v, y l phn mm min ph. Tuy nhin NS-2 kh hc hn v thiu giao din ngi dng. N buc ngi dng phi hc v s dng cc giao din son tho phi chun (nh Tcl) v phi cn kh nhiu thi gian thng thuc. C th ni OPNET l phn mm m phng mng hng u p ng cc mc tiu o to cng nh tiu ch la chn phn mm ra vi cc l do sau:

OPNET d s dng hn nhiu so vi NS-2. N h tr giao din ngi dng ha GUI rt thn thin v n gin.

OPNET c th c s dng m hnh ha ton mng, bao gm router, switch, giao thc, server v cc ng dng ring m chng h tr. Rt nhiu loi mng khc nhau t mc cc b n ton cu cng c h tr.

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Phn mm OPNET c sn min ph cho lnh vc ging dy v nghin cu khoa hc. Hc vin c th download v ci t OPNET IT Guru ti nh thng qua mt my tnh ni mng Internet.

Cng c bin c ri rc cho cc m phng mng ca OPNET l gii php nhanh nht, c kh nng m rng tt nht v hiu qu kinh t. N ch cn mt vi pht hon tt phn ln cc m phng thng thng.

OPNET c cng ng s dng ng o. Phn mm OPNET c s dng bi hn 500 cng ty, nh cung cp dch v v t chc chnh ph ton cu. Hc vin c kinh nghim vi OPNET s c nhiu c hi vic lm trong ngnh.

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Phn 2:

C s l thuyt m phng 2.1 Mng LAN Ethernet

2.1.1 Gii thiu Trong mt mng Ethernet chia s, cc thit b u cui thng c kt ni vi nhau thng qua mt hub trung tm. Hub ny s pht li bt k khung d liu no m n nhn c ( li vo) ra tt c cc ng ra, to thnh mt mi trng qung b cho tt c cc thit b trong mng. Trong mi trng ny, giao thc a truy cp th cm sng mang c pht hin xung t ca lp iu khin truy cp mi trng MAC (Media Access Control) c dng xc nh nt mng no c quyn pht mt thi im xc nh v x l xung t khi c nhiu hn hai nt mng cng pht ng thi.

2.1.2 Mc tiu m phng Xc nh thng lng ca mt mng Ethernet chia s trong cc iu kin khc nhau ca ti d liu. 2. 2 Hub v Switch

2.2.1 Gii thiu Cc hub Ethernet lm vic lp vt l, ch n gin pht li cc khung m chng nhn c ra cc cng khc. Do , chng cn c gi l trm lp a cng. Tt c cc nt mng ni vo cng mt hub u c coi l mt phn ca mi trng qung b ng nht. Ni cch khc, bt k khung d liu no c pht i t mt trong s cc nt mng u c thu bi tt c cc nt cn li. Nguyn tc hot ng ny c th gii hn thng lng ca ton mng, do tt c cc nt mng u phi chia s dung lng ca mng LAN.

Trong khi cc switch ch chuyn tip cc khung ra ng cng tng ng vi a ch ch trn khung. V cc switch chuyn tip cc khung ch trn mt ng ra nht nh, chng to ra khng phi mt m nhiu mi trng truyn lan; iu ny cho php tng ng k thng lng. Tuy nhin, thng lng ca mt switch th li b hn ch bi tc x l, tc m ti n c th chuyn tip cc khung ra ng ra mt cch chnh xc.

1.2.2 Mc tiu m phng Kho st s thay i ca thng lng trong mt mng cc b khi nng cp t hub ln switch.

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2.3 Cc giao thc nh tuyn

2.3.1 Gii thiu Giao thc thng tin nh tuyn RIP (Routing Information Protocol) l mt v d v thut ton nh tuyn vector khong cch ng. Giao thc ny la chn cc ng i trong mt mng sao cho khong cch ca cc ng l cc tiu. Cc thit b nh tuyn (router) thch ng theo cc thay i (hng kt ni hoc router) ca hnh mng bng cch trao i thng tin vi cc router c kt ni trc tip xung quanh. Trong iu kin bnh thng, thng tin v bng nh tuyn c c cp nht theo chu k (thng thng l 30 giy). Tuy nhin, nu hnh mng c thay i th lp tc c ch cp nht kch hot (triggered update) s vn hnh. Nu mt router nhn c thng tin nh tuyn mi, thay v i trong 30 giy, n s ch i (ngu nhin) t 1 n 5 giy trc khi chuyn tip thng tin ti cc router xung quanh. C ch cp nht kch hot gip cho thng tin v hnh truyn lan qua mng nhanh hn nhiu so vi trng hp thng thng vn hnh theo nguyn tc ht hn thi gian (timeout).

2.3.2 Mc tiu m phng M phng trng thi ca mt s router s dng giao thc nh tuyn RIP v tm hiu cch thc s dng cc bng nh tuyn tm ng i qua mt mng. 2.4 QoS: nh hng ca c ch xp hng

2.4.1 Gii thiu Trong mt mng lu-v-chuyn, cc router duy tr mt hay nhiu hng ch cho mi ng ra. Vic duy tr (cc) hng ch ny l rt cn thit v mt gi tin c th n ri c chuyn tip ti mt ng ra trong khi n ang thc s bn. Mt c ch xp hng s xc nh mt tp cc quy tc t cc gi tin vo (cc) hng ch v ly chng ra khi chuyn tip. C ch xp hng nguyn thu l Vo trc-Ra trc (First-In, First-Out FIFO) i x vi tt c cc lung d liu nh nhau v do kh n gin trong vic thc hin. Mt gi tin va mi ti s c xp cui hng v phi ch n lt c chuyn tip. Tuy nhin, ngy nay khi mng Internet cn c dng truyn c cc lung thoi cng nh video th cc c ch FIFO n gin l khng . Cc ng dng thoi v video i hi cc yu cu kh cao v tr v bin thin tr (jitter) truyn ti. Mt cch p ng cc ch tiu ny l i x vi cc gi tin theo cch khc nhau trong cc hng ch ca router. i vi c ch Xp hng Cng bng Trng s (Weighted Fair Queuing WFQ), mi cp u tin s s dng

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mt hng ch. Cc trng s c gn vi cc hng u tin khc nhau da trn mc quan trng ca n. Cc hng ch s c phc v (hay cc gi tin s c ly ra t cc hng v c gi ti ng ra) vi tc da vo trng s ca chng. V d, nu hng ch A c gn trng s bng 1 cn hng ch B c gn trng s l 2 th c 2 gi tin ca hng B c chuyn i th s c 1 gi tin ca hng A c phc v. Bng cch gn cc lung thoi v video vo 1 hng ch c trng s cao, chng s c chuyn tip vi tc cao hn ti tin tiu chun. i vi c ch xp hng u tin, nhiu hng ch c duy tr da trn cp u tin m gi tin c gn. Trong trng hp ny, ton b cc gi tin c mc u tin cao s c chuyn tip trc mi gi tin c mc u tin thp. Gi thit chng ta c hai hng ch, mt hng dnh cho ti lu lng c mc u tin mt, cn mt hng cho ti lu lng mc u tin hai, hng ch mc u tin hai s c x l cho n ht, sau hng ch u tin mt mi c phc v. Nu c gi tin mc u tin hai n th vic pht gi tin mc u tin mt s b chn li phc v gi tin mi n c mc u tin cao hn trc.

2.4.2 Mc tiu m phng Kho st cc nh hng khi p dng cc c ch xp hng khc nhau router. T l mt gi tin do trn b m ti router cng nh tr xp hng v bin thin tr (jitter) s c kho st mt cch chi tit mi loi c ch khc nhau.

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Phn 3:

Cc module m phng 3.1 Module 1: M phng nh gi hiu nng mng LAN Ethernet

3.1.1 Thit lp module m phng Bc 1: Xy dng hot cnh

1. Khi ng OPNET IT Guru Academic Edition. 2. Chn tab File New 3. Trn ca s mi m New chn Project ri nhp chut OK 4. Trong ca s Enter Name, thay i Project Name thnh Shared_Ethernet. i tn Scenario Name thnh Low_load ri nhp OK.

5. Trn ca s Initial Topology, chn Create Empty Scenario ri nhp Next. 6. Trn ca s Choose Network Scale, chn Office ri nhp Next. 7. Trn ca s Specify Size, gi nguyn cc tham s, ch nhp Next. 8. Trn ca s Select Technologies, ko thanh cun xung, chn h m hnh

Ethernet ri nhp Next. 9. Trn ca s Review, nhp OK.

Hnh 3.1.1. Hp thoi Review ca cng c Startup Wizard.

Bc 2: Thit lp cu hnh mng LAN Ethernet Trc ht, cn xy dng mt mng LAN trong cc my trm c ni vi nhau qua mt Hub trung tm. Cch n gin to ra mt mng vi mt s lng ln cc nt l s dng b cng c Rapid Configuration.

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1. Trn ca s Project: Shared_Ethernet: Low_load, chn tab Topology Rapid Configuration.

2. t Configuration v kiu Star v nhp OK t Center Node Model l ethernet16_hub. t Periphery Node Model l ethernet_station. t Link Model l 10BaseT. t Number l 12, ri nhp OK khi to mng LAN.

Hnh 3.1.2. Hp thoi Rapid Configuration: Star.

3. Nhp phi chut trn hub ri chn View Node Description. Hub ny c th h tr ti a 16 Ethernet links vi cc tc 10, 100, 1000 Mbps. l thi gian x l trong hub ny c coi bng khng, hub pht li cc khung m n nhn c trn tt c cc u ra. Nhp biu tng Close ng ca s ny li.

4. Nhp phi chut trn hub v chn Set Name. t Name l Hub. Nhp OK ng ca s li.

5. Nhp phi chut trn mt my trm Ethernet bt k v chn View Node Description. Cc my trm ny pht v thu cc khung Ethernet tc c ci t. l cc chc nng pht hin v x l xung t c thc hin trn hub trung tm. Nhp biu tng Close ng ca s ny li.

Bc 3: Xy dng m hnh lu lng cho my trm Ethernet xy dng m hnh lu lng cho cc trm trong mng LAN Ethernet, thc hin cc bc sau y:

1. Nhp phi chut ln mt trm bt k v chn Select Similar Node. Sau kch phi chut ln mt trong s cc my trm v chn Edit Attributes.

2. nh du la chn (3) vo hp chn checkbox nm bn cnh Apply Changes to Selected Objects pha di bn tri ca ca s.

3. Bung th mc Traffic Generation Parameters v Packet Generation Arguments. t ON State Time l constant (1000) (bng cch nhp chut ln exponential (10) v thay i cc tham s trn ca s mi m ri nhp OK), v OFF State Time l constant (0). Vic thit lp tham s nh vy s buc cc my trm lun pht d liu.

4. t Interarrival Time (seconds) l exponential (0.004) v Packet Size

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(bytes) l constant (100). Nhp OK xc nh cc thay i ny v ng ca s tng tc.

Hnh 3.1.3. Ci t tham s cho cc my trm.

Nh vy mi my trm by gi s to ra lung d liu vi tc trung bnh l bn mili giy mt gi 100-byte. Do , c th tnh c lu lng trung bnh m mi nt mng s to ra t cc tham s thi gian n v kch thc gi. V d, 100 (bytes/packet) * 8 (bits/byte) * 1 (packet/0.004 sec) = 200 Kbps / trm Nh vy, mng LAN c xy dng xong, dng ca n c minh ho trn hnh 2.4.

Hnh 3.1.4. M hnh mng LAN vi hub trung tm.

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Bc 4: Thit lp tham s kt qu m phng Cc kt qu c th thu c t m hnh m phng bao gm: S ln va chm (Collsion Count), Ti lu lng [Load (bits/sec)], Ti lu lng chuyn tip [Traffic Forwarded (bits/sec)], Ti lu lng nhn [Traffic Received (bits/sec)] v Hiu sut [Utilization].

Hnh 3.1.5. Chn kt qu m phng.

c th thu c cc tham s ni trn thc hin cc bc sau y:

1. Chn tab Simulation chn Choose Individual Statistics 2. Bung cc th mc Global Statistics/Ethernet, ri chn tham s Delay (sec). 3. Bung th mc Traffic Sink v chn tham s Traffic Received (bits/sec). 4. Bung th mc Traffic Source v chn tham s Traffic Sent (bits/sec). 5. Bung cc th mc Node Statistics/Ethernet ri chn cc tham s Collsion

Count, Load (bits/sec), Traffic Forwarded (bits/sec), Traffic Received (bits/sec) v Utilization.

6. Nhp OK ng ca s Choose Results. Ton b thao tc chn ny c biu din trn hnh 2.5 3.1.2 Tin hnh m phng

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Bc tip theo sau khi thit lp xong module m phng l tin hnh m phng thu nhn kt qu. Cc bc tin hnh m phng bao gm: Bc 5: Ci t tham s m phng

1. Chn tab Simulation Configure Discrete Even Simulation 2. Trong tab Common, thay i tham s Duration v 20 vi n v l

second(s). 3. Nhp OK ng ca s tng tc.

Hnh 3.1.6. Ci t tham s m phng. Bc 6: Nhn bn hot cnh Tip theo hy xy dng mt hot cnh khc trong mi my trm Ethernet to ra lu lng d liu ln hn rt nhiu. Nh c th so snh cht lng ca mng LAN trong nhng iu kin khc nhau.

1. Chn Scenarios Duplicate Scenario v gi hot cnh mi l High_load. Nhp OK khi to hot cnh.

2. Nhp phi chut ln bt k my trm no ri chn Select Similar Nodes. Tip theo, nhp phi chut ln mt my trm ri chn Edit Attributes. nh du la chn (3) vo hp chn checkbox nm bn cnh Apply Changes to Selected Objects.

3. Bung cc th mc Traffic Generation Parameters v Packet Generation Arguments. t Interarrival Time (seconds) l exponential (0.001). Nhp OK xc nh cc thay i ny v ng ca s tng tc. Thi gian n ngn hn c ngha l cc gi c to ra vi tn xut ln hn.

Bc 7: Chy chng trnh m phng

1. Chn tab Scenarios Manage Scenarios...

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2. Nhp chut ln trng Results trn c hai hng v chn tham s hoc .

3. Nhp OK chy ln lt c hai hot cnh. Khi m phng kt thc, nhp biu tng Close ng hp thoi tng tc Simulation Sequence.

Hnh 3.1.7. Tp hp cc hot cnh chy m phng.

3.1.3 Thu thp v phn tch kt qu m phng 1. Chn tab Scenarios Switch to Scenario v chn hot cnh Low_load.

Chn tab Results View Results 2. Chn v bung th mc Global Statistics, tip theo chn mc Traffic

Source / Traffic Sent (bits/sec). xem lu lng thu, bung th mc Traffic Sink / Traffic Received (bits/sec)

Hnh 3.1.8 Kt qu Traffic Sent, Traffic Received ca hot cnh Low_load.

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3. Quan st cc kt qu m phng ch As Is. Vi mc ti ny, tc bit thu xp x bng tc bit pht i. Nhp li chut ln mc Traffic Sent (bits/sec) v Traffic Received (bits/sec) ng ca s preview. C th kch ln tab Show quan st th mc chi tit hn. Nhp chut ln biu tng Close ng ca s View Results.

Hy xem xt kt qu m phng trong hot cnh High_load. 1. Lp li cc bc trn bao gm c vic chuyn sang hot cnh High_load,

chn, xem cc kt qu. Trong trng hp ny, c th quan st thy lu lng pht ln hn rt nhiu lu lng thu. Hub trung tm nhanh chng b qu ti v khng th phn phi ton b lu lng m n nhn c.

2. Nhp biu tng Close ng ca s View Results.

Hnh 3.1.9. Kt qu Traffic Sent, Traffic Received ca hot cnh High_load. Tip theo chng ta hy so snh cc kt qu to ra t hai hot cnh.

1. Chn tab Results Compare Results 2. Chn v bung cc th mc Object Statistics, Office Network, node_0,

Ethernet. Chn kt qu Load (bits/sec) v xem ch As Is. Nhp chut ln tab Show xem chi tit. Kt qu ny cho bit lu lng c to ra t my trm tng ng. C th thy gi tr quan st c kh gn vi cc tnh ton thu c phn trc thng qua cc tham s ci t. Trong trng hp Low_load, 100 (bytes/packet) * 8 (bits/byte) * 1 (packet/0.004 sec) = 200 Kbps/trm. Cc tnh ton tng t c th c p dng cho trng hp High_load.

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Hnh 3.1.10. So snh kt qu Ethernet.Load ca hai hot cnh.

3. Nhp vo biu tng Close v chn Delete ng ca s ha. Nhp li chut ln th mc Load(bits/sec) ng ca s preview.

Khc bit gia cc tc pht, thu c th c xem xt thng qua kt qu m phng Collision Count.

1. Bung cc th mc Hub v Ethernet. Chn kt qu Collision Count. Nhp chut ln tab Show xem chi tit. Vic pht li cc gi b xung t r rng s lm gim thng lng ca mng. iu ny ng cho c hai trng hp, nhng hot cnh High_load to ra s xung t ln hn rt nhiu.

2. Nhp chut ln biu tng Close v Delete ng ca s ha. Nhp li chut ln tn th mc ny xo th preview.

Hnh 3.1.11. So snh kt qu Ethernet.Colision Count ca hai hot cnh.

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Hiu nng (Utilization) ca hai hot cnh c kho st qua kt qu m phng Utilization.

1. Chn th mc Utilization. 2. Nhp chut ln biu tng Show quan st th mc chi tit.

Hiu nng, v c bn, l o phn trm thng lng ca mng c s dng.

Hnh 3.1.12. So snh kt qu Ethernet.Utilization ca hai hot cnh.

V cc ng truyn 10BaseT c dng ni cc my trm vi hub trung tm, dung lng do bng 10 Mbps. C th thy rng ti lu lng ca hot cnh High_load khai thc dung lng ca hub tt hn rt nhiu so vi trng hp Low_load.

3. Nhp chut ln biu tng Close v Delete. Nhp li chut ln tn th mc Utilization ng ca s preview.

Cui cng, chng ta s xem xt n tr ca cc gi tin trong tng trng hp.

1. Bung th mc Global Statistics v Ethernet, chn th mc con Delay (sec).

2. Nhp chut ln biu tng Show xem chi tit. Tham s thng k ny cho bit tr m tt c cc gi phi tri qua trc khi c pht thnh cng.

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Hnh 3.1.13. So snh kt qu Ethernet.Delay ca hai hot cnh.

C th thy rng tr l kh n nh trong trng hp Low_load nhng, do ti lu lng qu cao, tng khng ngng trong hot cnh High_load.

3. Nhp chut ln biu tng Close v Delete ng ca s Compare Results.

4. Lu li project bng lnh Save ri ng tt c cc ca s.

22

3.2 Module 2: So snh Hub v Switch 3.2.1 Thit lp module m phng Bc 1: Xy dng hot cnh Khi ng OPNET IT Guru Academic Edition.

1. Chn tab File New 2. Chn Project ri nhp OK. Thay i Project Name thnh

xx_Switch_vs_Hub (xx l s khi u). t Scenario Name l Hub v nhp OK.

3. Trn ca s Initial Topology, chn Create Empty Scenario ri nhp Next. 4. Trn ca s Choose Network Scale, chn Office ri nhp Next. 5. Trn ca s Specify Size, cc gi tr mc nh ri nhp Next. 6. Trn ca s Select Technologies, chn h m hnh Ethernet v

Ethernet_advanced, nhp Next. 7. Trn ca s Review, nhp OK.

Hnh 3.2.1. Hp thoi Review ca cng c Startup Wizard.

Trc ht, hy xy dng mt mng LAN trong cc my trm c ni vi nhau qua mt hub trung tm. Cch lm nhanh l s dng b cng c Rapid Configuration.

1. Chn tab Topology Rapid Configuration. 2. t Configuration l Star, v nhp OK. 3. t Center Node Model l ethernet16_hub. t Periphery Node Model

l ethernet_station. t Link Model to 10BaseT. t Number l 12, nhp OK khi to mng LAN.

4. Nhp phi chut trn hub v chn Set Name. Khai trng tn Name l Hub. Nhp OK ng ca s tng tc.

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Hnh 3.2.2. Hp thoi Rapid Configuration: Star.

Tip theo cn ci t m hnh lu lng cho cc my trm Ethernet. 1. Nhp phi chut ln mt my trm bt k v chn Select Similar Nodes. 2. Sau nhp phi chut ln mt my trm ri chn Edit Attributes. t

du la chn (3) vo hp chn checkbox bn cnh Apply Changes to Selected Objects.

3. Bung cc th mc Traffic Generation Parameters v Packet Generation Arguments. t ON State Time l Constant (1000) v OFF State Time l constant (0). Vi cu hnh ny cc my trm s pht d liu lin tc.

Hnh 3.2.3. Ci t tham s cho cc my trm.

4. t Interarrival Time (seconds) l exponential (0.005) v Packet Size (bytes) l constant (1000).

5. Nhp OK xc nhn cc thay i ny v ng ca s tng tc Attributes. Mi my trm theo s to ra ti lu lng vi tc trung bnh l mi 5

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mili giy mt gi d liu kch thc 1000 byte. Do c th tnh c ti lu lng trung bnh ca mi my trm,

1000 (bytes/packet) * 8 (bits/byte) * 1 (packet/0.005 sec) = 1.6 Mbps/trm Nh vy mng LAN dng hub trung tm c thit lp xong. M hnh s c dng nh hnh 3.2.4.

Hnh 3.2.4. M hnh mng LAN vi hub trung tm.

Bc 2: Chn tham s kt qu m phng 1. Chn tab Simulation Choose Individual Statistics 2. Bung cc th mc Global Statistics/Ethernet, chn th mc con Delay

(sec). 3. Bung th mc Traffic Sink v chn Traffic Received (bits/sec). Bung th

mc Traffic Source ri chn Traffic Sent (bits/sec). Bung th mc Node Statistics / Ethernet v chn Collision Count.

4. Nhp OK ng ca s tng tc Choose Results. Cc tham s chn c minh ho trn hnh 3.2.6.

Hnh 3.2.5. Ci t tham s m phng.

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Hnh 3.2.6. Chn kt qu m phng.

Bc 3: t cu hnh m phng 1. Chn tab Simulation Configure Discrete Event Simulation 2. Trn tab Common, t Duration l 2, n v l minutes(s). 3. Nhp OK ng ca s tng tc Configure Simulation.

Thao tc t cu hnh m phng c minh ha trn hnh 3.2.5.

Bc 4: Nhn bn hot cnh Hy to mt hot cnh khc trong hub trung tm ca mng c thay th bng switch. Vi hai cu hnh khc nhau, cht lng ca mng c th c kho st, so snh qua m phng.

Hnh 3.2.7. M hnh mng LAN vi switch trung tm.

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1. Chn Scenarios Duplicate Scenario, t tn cho hot cnh mi ny l Switch.

2. Nhp OK khi to hot cnh. Nhp phi chut ln hub trung tm v chn Edit Attributes.

3. Nhp tri chut ln thuc tnh model v chn ethernet16_switch_adv t thc n.

4. Nhp OK xc nhn thay i. 5. Nhp phi chut ln switch v chn Set Name. t Name l Switch ri

nhp OK ng ca s tng tc.

Hnh 3.2.8. i tn switch trung tm.

3.2.2 Tin hnh m phng Bc tip theo sau khi thit lp xong module th nghim l tin hnh m phng thu nhn kt qu. Cc bc tin hnh m phng bao gm:

1. Chn tab Scenarios Manage Scenarios... 2. Thay i trng Results trong c hai hng vi gi tr chn l

hoc . 3. Nhp OK chy ln lt tng hot cnh. 4. Khi m phng kt thc, nhp OK ng ca s m phng.

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Hnh 3.2.9. Tp hp cc hot cnh chy m phng. 3.2.3 Thu thp v phn tch kt qu m phng Trc ht hy kho st tham s tr ca cc gi tin trong mng ca hai hot cnh. ly c th v kt qu ny, chng ta thc hin cc thao tc sau.

1. Chn tab Results Compare Results 2. Chn v bung th mc Global Statistics/Ethernet, chn tham s Delay

(sec). Xem kt qu m phng ch As Is.

Hnh 3.2.10. So snh kt qu Ethernet. Delay ca hai hot cnh.

3. Nhp biu tng Show xem th trn mt ca s ring. th trn hnh 3.10 biu din tr thi gian ca cc khung Ethernet c pht i. C th thy rng tr ca mng s dng switch l tng i nh v n nh, trong khi tr ca mng hub tng khng ngng. Nhc li l mi my trm to ra ti lu lng 1.6 Mbps. Vi 12 nt trong h thng, ti tng cng l 19.2 Mbps. Trong khi hub li lm vic tc 10 Mbps

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(10BaseT). 4. Nhp chut ln biu tng Close v Delete ng ca s. Nhp li

chut ln tn th mc xo th preview. Tip theo chng ta s so snh lu lng gi tin nhn ca hai hot cnh. Tin hnh cc bc sau:

1. Bung th mc Traffic Sink, chn tham s Traffic Received (bits/sec). Xem th ch As Is.

Hnh 3.2.11. So snh kt qu Traffic Sink. Traffic Recieved ca hai hot cnh.

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Hnh 3.2.12. Hp thoi Compare Results vi th Traffic Sent ca hai hot cnh.

2. Nhp Show xem chi tit. th trn mn hnh biu din ti lu lng tng cng thu c trn tt c cc my trm ca mng LAN. C th quan st thy ti lu lng trong trng hp mng LAN dng hub t xp x 10 Mbps, tc danh nh ca hub. Mt khc, switch d dng phn pht ti lu lng gp i trng hp ca hub.

3. Nhp chut ln biu tng Close v Delete ng ca s th. Nhp li chut ln tn th mc xo th preview.

V ton b cc my trm ca hai mng c cu hnh ging ht nhau nn ti lu lng m chng to ra phi nh nhau. Kt qu ny c kim chng khi quan st th so snh c ly ra bng cc thao tc nh sau:

1. Bung th mc Traffic Source, chn tham s Traffic Sent (bits/sec). Xem th ch As Is.

2. Nhp Show xem chi tit. Kt qu ny cho bit lu lng tng cng ca ton b cc trm trong mng LAN pht i. C th thy rng ti lu lng c to ra trong c hai hot cnh l nh nhau. Tuy nhin, switch thc t l x l tt ti ny.

3. Nhp chut ln biu tng Close v Delete ng ca s th. Nhp li chut ln tn th mc xo th preview.

Cui cng, hy kho st tham s ch p dng cho trng hp hub. 1. Chn tab Scenarios Switch to Scenario ri chn hot cnh Hub. 2. Chn tab Results View Results... 3. Bung cc th mc Object Statistics, Office Network, Hub, Ethernet. 4. Chn tham s Collision Count. Xem kt qu ch As Is. Tham s ny

biu din s xung t xut hin trn hub trong qu trnh m phng. D dng quan st thy c xp x 2000 xung t/giy xy ra. Nguyn nhn l do ti lu lng trn hub qu nng.

5. Nhp ln biu tng Close ng ca s View Results. 6. Lu li m hnh v ng ton b cc ca s.

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3.3 Module th nghim 3: Cc giao thc nh tuyn 3.3.1 Thit lp module th nghim Bc 1: Xy dng hot cnh

Hnh 3.3.1. Hp thoi Review ca cng c Startup Wizard. Khi ng OPNET IT Guru Academic Edition

1. Chn thc n File New 2. Chn Project ri nhp OK. 3. Thay i Project Name l xx_RIPNetwork (trong xx l s khi u) v

nhp OK. 4. Trong ca s Initial Topology, chn Create Empty Scenario v nhp vo

Next. 5. Trong ca s Choose Network Scale, chn Logical v nhp Next. 6. Trong ca s Review, nhp OK.

Trc ht, chng ta c th c hng dn s dng m hnh ca giao thc RIP. Hng dn s din gii cch thc cu hnh cc nt mng s dng RIP v xc nh ngha ca cc tham s. Nhp chut ln tab Protocol RIP Model Usage Guide. Sau khi c xong hng dn th tt ca s xem file PDF. Chng ta s xy dng mt mng con gm cc router v ci t cc tham s RIP.

1. Chn biu tng ethernet4 slip8-gtwy trong th vin Object Palette v t n vo ca s lm vic workspace. Nhp phi chut ln biu tng v chn View Node Description. l gateway ny c trng b bn giao din Ethernet v tm giao din SLIP. ng ca s ny li.

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2. Nhp phi chut ln router ri chn Edit Attributes, t thuc tnh name l Router1. Bung th mc thuc tnh RIP Parameter v Timers. Lu l Update Interval (seconds) c t l 30 giy. iu ny ngha l mi router s trao i bng nh tuyn ca n vi cc router ln cn theo tng khong thi gian 30 giy, ngay c khi khng c thng tin mi v s thay i hnh ca mng. Nhp OK ng ca s ny.

Hnh 3.3.2. Ci t tham s cho router. 3. Nhp tri chut ln router v chn Copy t thc n Edit phi trn ca

ca ca s. Chn Paste t thc n Edit 5 ln to ra 5 bn sao ca router gc trong ca s lm vic workspace. Sp xp cc router ny theo mt vng trn.

4. Ni cc router va sp bng cc ng truyn dn PPP_DS1 ly t th vin Object Palette. Mi router s kt ni vi hai router k bn.

5. Copy thm hai router na vo workspace bng lnh Paste. 6. S dng hai ng truyn PPP_DS1 ni hai router ny thnh mt nhnh

gn vo mng vng v tr ca router 6. Mng thit k s c dng nh hnh 3.3.3.

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Giao thc nh tuyn c s dng trong m phng l RIP, vic gn giao thc ny cho cc router c thc hin nh sau:

1. Chn thc n Protocol IP Routing Configure Routing Protocols

2. Nhp vo cc hp chn bn cnh RIP. Apply the above selection to subinterfaces v Visualize Routing Domains.

3. Nhp vo nt chn bn cnh All interfaces (including loopback). 4. Nhp OK ng ca s.

Cc thao tc va ri cho php giao thc RIP s c dng nh tuyn cc gi qua tt c cc giao din c trn cc router. thy k hiu RIP xut hin trn cc ng truyn xc nhn giao thc c khai bo s dng.

Hnh 3.3.3. M hnh mng m phng.

Tip theo chng ta s ci t mt trong s cc ng truyn PPP s b hng trong qu trnh m phng.

1. Chn utilities t thc n ko xung trong th vin Object Palette hin th ton b cc phn t c trong th vin.

2. Chn v t mt phn t Failure Recovery vo ca s lm vic workspace.

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3. Nhp phi chut ln biu tng ny v chn Edit Attribute. 4. t tn i tng l Link Failure. 5. Nhp chut bung thuc tnh Link Failure/Recovery Specification ri t

rows bng 1 v t Name l Logical Network.Router 1 Router 6. 6. t Time l 300. Lu trng Status c t v Fail. Thao tc ci t

va ri s buc ng truyn dn gia router 1 v router 6 ri vo trng thi hng sau khi tin trnh m phng bt u c 300 giy.

7. Nhp OK ng ca s ci t. Bc 2: Chn tham s kt qu m phng Ti lu lng thu l mt trong cc tham s quan trng nht ca m phng ny, n phn nh kt qu ca th tc nh tuyn trong iu kin trng thi ca mng b thay i. Tham s ny c tp hp nh minh ho trn hnh 3.3.4.

Hnh 3.3.4. Chn kt qu m phng.

1. Chn tab Simulation Choose Individual Statistic 2. Nhp tri chut bung ln lt cc mc Global Statistics, RIP ri chn

Traffic Received (bits/sec)

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Hnh 3.3.5. Tp hp chi tit kt qu m phng. c th tp hp kt qu y hn, chng ta thc hin thm cc thao tc:

1. Chn tab Simulation Choose Individual Statistic (advanced) 2. Bung cc th mc Global Statistics Probes v RIP Traffic Received ri

chn Collect all values. Thao tc chn ny s cho php OPNET cung cp mt th chi tit hn.

3. ng ca s tng tc Probe Model. 3.3.2 t cu hnh v chy m phng

Hnh 3.3.6. t cu hnh chy m phng.

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1. Chn Simulation Configure Discrete Event Simulation 2. Trong giao din ca tab Common, t trng Duration l 10, chn n v

l minute(s). 3. Nhp tri chut ln tab Global Attributes, t trng IF Interface

Addressing Mode v Auto Address/Export. 4. t trng IP Routing Table Export/Import v Export. Thao tc ci t

ny cho php cc bng nh tuyn c ghi li trong mt file vn bn sau khi m phng kt thc.

5. t RIP Sim Efficiency v Disable. 6. t RIP Stop Time l 1000. Khi cc router vn thng xuyn duy tr

vic trao i thng tin nh tuyn ngay c khi cc bng nh tuyn n nh (khng thay i).

7. Nhp tri chut ln Run khi ng m phng. Khi m phng kt thc, nhp Close ng ca s tng tc. 3.3.3 Thu thp v phn tch kt qu m phng Kt qu m phng c kho st khi m th Traffic Received nh sau.

1. Chn Results View Results 2. Nhp tri chut bung cc th mc Global Statistics v RIP ri chn

Traffic Received (bits/sec). Tham s thng k ny cho bit mc ti lu lng c to ra bi thut ton nh tuyn dng trong m phng.

Hnh 3.3.7. Hp thoi View Results vi th Traffic Received.

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3. Nhp tri chut ln Show to mt ca s mi biu din th nh hnh 4.8. Chng ta s thy ti lu lng ca giao thc nh tuyn c cc nh phn b u n chu k 30 giy ngoi tr hai im, mt ti thi im bt u v mt ti thi im gia ca tin trnh m phng. Chn trc thi gian l hai pht u tin ca th quan st cn cnh. Chng ta s nhn thy c nhiu ln cp nht ngu nhin v thi gian c thc hin rt nhanh ti qung thi gian bt u m phng. Cc cp nht ti thi im ban u ny c thc hin nh c ch cp nht kck hot c ci t trong R11. Cc cp nht bt thng cn li l do s c t tuyn truyn dn to ra, xy ra sau 300 giy.

4. Nhp chut tt ca s th v chn Delete. 5. ng ca s View Results bng nt Close.

Hnh 3.3.8. th Traffic Received trong 300 giy u.

Tip theo, d dng thc hin cc so snh, phn tch, chng ta s to thm mt hot cnh mi trong mng hot ng m khng gp s c no.

1. Chn Scenarios Duplicate Scenario 2. Nhp OK chp nhn tn mc nh ca hot cnh l scenario2. 3. Nhp tri chut nn biu tng Failure ri chn Edit Cut loi

nt hng ra. 4. Chn Simulation Run Discrete Event Simulation to ra cc kt qu

ca hot cnh ny trong ton mng hot ng bnh thng, khng c s c t tuyn.

5. Khi m phng kt thc, nhp OK ng ca s tng tc. Bng cc thao tc chn ci t trc, chng ta c th kho st mng truyn d liu ny mc chi tit hn. xem thng tin v a ch IP m

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OPNET t ng gn cho cc router trong qu trnh m phng, chng ta thc hin cc bc sau:

1. Chn File Model Files Refresh Model Directories. 2. Chn File Open tm v m Generic Data File, trong danh sch lit k,

chn xx_RIP Network-scenario2-ip addresses: File ny ghi li cc a ch IP v subnetwork mask c OPNET gn cho mi giao din. rng mi router c mt giao din c gi l giao din vng hi tip m khng c gn vo bt k ng truyn no. Cc giao din lgic ny thng c dng cho chc nng kim tra hay cho hai chng trnh c chc nng thu pht truyn thng vi nhau khi ang chy trn cng mt thit b. Hnh 4.9 ch biu din mt phn ca file d liu.

3. Nhp chut ng hp thoi -ip_addresses.

Hnh 3.3.9. File d liu cha a ch IP ca cc router.

Tip theo chng ta s tm hiu bng nh tuyn ca cc nt mng. 1. Chn Select Open 2. Tm v chn li Generic Data File, t danh sch hin th, chn

xx_RIP_Network-scenario2-ip_routes.

Hnh 3.3.10. File d liu cha bng nh tuyn cc router.

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File d liu ny cha cc bng nh tuyn, c duy tr ti mi router, vi cc gi tr tng ng vi trng thi ca mng thi in kt thc m phng. Cu trc ca file gm hai phn.

Phn th nht lit k cc mng kt ni trc tip vi mi router. Mt mng c kt ni trc tip vi mt router nu mt trong s cc giao din ca router ny c a ch trng vi a ch mng trong ton b di ca subnetwork mask. V d, Router1 c mt giao din l 192.0.2.1 vi mt subnetwork mask l 255.255.255.0 s cn 24 bit u tin trong a ch IP ca n trng vi a ch ca cc mng khc cc phn t ny kt ni trc tip c vi nhau. Do a ch mng 192.0.2.0 trng vi a ch giao din 192.0.2.1 v Router1 c kt ni trc tip vi mng 192.0.2.0.

Phn th hai ca file ip_routes biu din cc tuyn trong mng khng c kt ni trc tip. Hnh minh ho di ch th hin mt phn ca file d liu bng nh tuyn tng ng vi Router 1. File d liu y bao gm nhiu bng nh tuyn, mi bng tng ng vi mt router. Lu l a ch trn bng nh tuyn c th khc vi hnh minh ha tu thuc vo th t t router trong workspace.

Hnh 3.3.11. S dng ip_routes tm ng i trong mng.

S dng file ip_routes, chng ta c th xc nh ng i m mt gi tin s truyn qua trong mng. Xt v d tm ng i t router 1 n router 8. Trong file xx_RIP_Network-scenario1-ip_addresses, tm mt giao din trn mi router (khng phi l cc giao din vng kn loopback). Router1: 192.0.1.1

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Router8: 192.0.13.2 a ch 192.0.13.2 thuc v mng 192.0.13.0 v vy chng ta s tm hiu giao

din ny trong cc bng nh tuyn. l gim kch thc ca cc bng nh tuyn, thao tc nh tuyn c thc hin da trn cc a ch mng thay cho cc a ch IP c th.

Bt u vi bng nh tuyn ca router 1, chng ta xc nh c mng ch (trng Dest Network trong bng) l 192.0.13.0, ly ra trng Next Hop Addr. Trong trng hp ny Next Hop Addr l 192.0.1.2. Tip theo, quan st phn Interface Information ca file d liu ny hoc trong file xx_RIP_Network-scenariolip_addresses xc nh router no c mt giao din vi a ch ny. Trong tnh hung ny th l router 6. Sau tin hnh tm a ch mng ch, 192.0.13.0, trong bng nh tuyn ca router 6, ly ra a ch ca chng tip theo (192.0.11.2), v xc nh router c a ch ny (router 7). Thc hin lin tip cc bc nh vy cho ti khi ti c router kt ni trc tip vi mng ch. Router 7 c mt giao din (192.0.13.1) trn mng ch, c ngha l n c mt kt ni trc tip vi router 8 (192.0.13.2). C th thy rng router 7 v router 8 trong cng mt mng v a ch IP ca chng ging nhau trong ton b phn subnetwork mask (24 bit) Trong v d ny, ng i ca gi tin s l Routerl (192.0.1.1) Router2 (192.0.2.1) Router3 (192.0.5.1) Router6 (192.0.7.1) Router7 (192.0.8.1) Router8 (192.0.8.1)

3. ng ca s ip_routes.

Chng ta cng c th truy cp trc tip vo file d liu nh tuyn. S dng Windows Explorer, tm trong th mc gc th mc con op-models, chuyn ti th mc ny v m file xx_RIP_Network-scenariol-ip_routes.gdf. y chnh l file va c kho st trong OPNET. C th s dng h tr tm kim bng cch sau, chn Edit Preference, ri tm thuc tnh mod_dirs. Gi tr i km l ng dn ti th mc op_models. Lu m hnh va khi to v ng tt c cc ca s.

40

3.4 Module 4: C ch hng i 3.4.1 Thit lp module m phng Bc 1: Xy dng hot cnh Khi ng OPNET IT Guru Academic Edition

1. Chn thc n File New 2. Chn Project ri nhp OK. 3. Thay i Project Name l xx_QoS_Queuing (trong xx l s khi u), t tn hot cnh Scenario Name l PQ ri nhp OK.

4. Trong ca s Initial Topology, chn Create Empty Scenario v nhp vo Next.

5. Trong ca s Choose Network Scale, chn Choose From Maps v nhp Next.

6. Trong ca s Choose Map chn usa ri nhp Next. 7. Trong ca s Choose Technologies nhp Next. 8. Trong ca s Review, nhp OK.

Hnh 3.4.1. Hp thoi Review ca cng c Startup Wizard.

u tin chng ta s cu hnh hai ng dng nn FTP tng t nhau ngoi tr mc u tin.

1. Chn biu tng Application Config t th vin cng c Object Palette v ri t n vo khng gian thit k workspace.

2. Nhp phi chut ln biu tng ri chn Edit Attributes. t thuc tnh name l Applications.

3. Bung th mc Application Definitions, t gi tr v Default.

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Hnh 3.4.2. Khai bo thuc tnh Applications.

4. Tip tc bung th mc Application Definitions, t thuc tnh rows l 2. 5. Bung th mc row 0, t trng tn Name l

FTP_Low_Priority_Application. a. Bung th mc thuc tnh Description, tip theo phi t thuc tnh

Database v Off c th ci t gi tr cho thuc tnh Ftp. b. Nhp phi chut vo v tr Off ngang hng vi thuc tnh Ftp, chn

Edit c. Trong ca s (Ftp) Table va hin ra, t cc tham s cho thuc tnh

Inter-Request Time (sec) nh sau, Distribution Name l exponential, Mean Outcome l 5. Lu l cn t trng Special Value v Not Used c th thay i cc tham s thuc tnh. Nhp OK ng ca s Inter-Request Time.

d. Tng t, t thuc tnh File Size (bytes) l constant (500000). e. Trng Type of Service c t v Best Effort (0). Best Effort l mc u tin thp nht. ng dng va c ci t s truyn lin tc cc file c kch thc 500 KB vi khong thi gian trung bnh gia mi ln truyn l 5 giy.

f. Nhp OK ng ca s (Fpt) Table.

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Hnh 3.4.3. Hp thoi (FTP) Table ca ng dng Low_Priority. 6. Tip theo, bung thuc tnh row 1 v t tn l

FTP_High_Priority_Application. a. t Inter-Request Time (sec) l exponential(5) v File Size (bytes) l

constant (500000). b. Thay i trng Type of Service v Exellent Effort (3). Exellent Effort

cho php mc u tin cao hn Best Effort. c. Nhp OK hai ln ng ca s.

Hnh 3.4.4. Hp thoi (FTP) Table ca ng dng High_Priority. Tip theo profile ca m hnh mng s c nh ngha thng qua cc thao tc sau:

1. Chn i tng Profile Config t th vin cng c Object Palette ri t vo workspace.

2. Nhp phi chut ln i tng v chn Edit Atttributes. t thuc tnh name l Profiles.

3. Bung thuc tnh Profile configuration v t rows l 2. 4. Bung thuc tnh row 0 ri t Profile Name l FTP_Low_Priority_Profile.

a. Bung thuc tnh Applications v t row l 1. b. Bung thuc tnh row 0, t trng Name l

FTP_Low_Priority_Application. c. t Duration (seconds) l End of Last Task.

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d. Bung thuc tnh Repeatability v t Inter-repeatition Time (seconds) l constant (0).

Hnh 3.4.5. Ci t tham s cho profiles.

5. Bung thuc tnh row 1, t Profile Name l FTP_High_Priority_Profile. a. Bung thuc tnh Applications v t rows l 1. b. Bung thuc tnh row 0 ri t trng Name l

FTP_High_Priority_Application. c. t Duration (seconds) l End of Lask Task. d. Bung thuc tnh Repeatability v t Inter-repetition Time (seconds) l

constant(0). 6. Nhp OK ng ca s (Profiles) Attributes.

Cc ci t va ri cho chng ta cc profile cn dng cho m phng. Tip theo chng ta s xy dng mt mng truyn d liu s dng cc profile ny.

1. Chn thit b ppp_wkstn t th vin cng c Object Palette v t n vo workspace. a. Nhp phi chut ln my trm ny v chn Edit Atributes.

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b. t trng name l FTP Low Client. c. Bung thuc tnh Application: Support Profiles, t thuc tnh row l 1. d. Bung row 0 ri chn Profile Name l FTP_Low_Priority_Profile. e. Nhp OK ng ca s tng tc.

2. Chn thit b ppp_wkstn t th vin cng c Object Palette v t n vo workspace. a. Nhp phi chut ln my trm ny v chn Edit Atributes. b. t trng name l FTP High Client. c. Bung thuc tnh Application: Support Profiles, t thuc tnh row l 1. d. Bung row 0 ri chn Profile Name l FTP_High_Priority_Profile. e. Nhp OK ng ca s tng tc.

Hnh 3.4.6. Ci t tham s cho FTP Low Client. Tip theo chng ta s ci t my ch server h tr c hai ng dng FTP va c nh ngha.

1. Chn thit b ppp_server trong th vin i tng Object Palette ri t n vo workspace.

2. Nhp phi chut ln thit b ri chn Edit Attributes. 3. Thay i thuc tnh name ca server thnh FTP Server. 4. Nhp phi chut ln thuc tnh () ngang hng vi Application:

Supported Services, chn Edit.

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5. Ca s (Application: Supported Services) Table xut hin. t thuc tnh Rows l 2.

6. t trng Name trong hng th nht l FTP_Low_Priority_Application. 7. t trng Name trong hng th hai l FTP_High_Priority_Application. 8. Nhp OK hai ln ng cc ca s giao din.

Hnh 3.4.7. Ci t tham s cho FTP Server.

Hnh 3.4.8. Ci t tham s cho Application: Supported Services. Vic chn hai router v to cc kt ni trong mng ny c thc hin nh sau:

1. Chn hai thit b ethernet4_slip8_gtwy trong th vin i tng v t chng vo workspace.

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2. Nhp phi chut ln mt router ri chn Set Name. t tn ca router ny l Router 1.

3. Lm tng t t tn router cn li l QoS Router. 4. Chn ng truyn PPP_DS1 trong th vin i tng, dng n ni

hai my trm FTP vi Router 1 v ni hai router vi nhau. 5. Chn ng truyn PPP_DS3 trong th vin i tng v dng n ni

my ch FTP vi QoS Router. Tip theo chng ta cn thit lp cc c ch xp hng s c dng trong cc router. Nhp phi chut ln QoS Router v chn Select Similar Nodes c th p dng cc thay i cho c hai router ng thi.

Hnh 3.4.9. M hnh mng truyn s liu m phng.

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Hnh 3.4.10. Ci t c ch xp hng PQ. 1. Trn ca s workspace, chn tab Protocols IP QoS Configure

QoS 2. t QoS Scheme l Priority Queuing. 3. l thuc tnh QoS Profile c t ToS Based, ngha l cc router

s dng cc mc u tin Type of Service va c ci t thng qua vic s dng trng nh ngha ny.

4. Nhp phi chut ln khoanh chn bn cnh Interfaces on selected router(s).

5. Nhp OK ng ca s QoS Configuration. Chng ta va ci t QoS Router s dng c ch xp hng ph hp cc giao din ca chng. Lu l mt i tng QoS Parameters s t ng xut hin trong workspace. Nguyn nhn l do chng ta cu hnh QoS Router s dng cc c ch xp hng va c nh ngha trc . Tip theo chng ta s tin hnh kim tra tn giao din c gn cho QoS Router.

1. Nhp phi chut ln ng truyn PPP ni QoS Router vi Router 1, chn Edit Attributes.

2. Kim tra cc thuc tnh port a v port b xem giao din no ang c s dng trn QoS Router (trong v d ny l IF10). Khi xy dng bi th nghim, chng ta c th nhn c tn giao din khc tu thuc vo cch t ng truyn PPP.

3. Nhp OK ng ca s (Router 1 QoS router) Attributes.

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Hnh 3.4.11. Tn giao din c gn cho QoS Router. Chng ta s s dng thng tin va tm c thay i kch thc b m ca giao din ny sao cho trn b m nhanh chng xy ra.

1. Nhp phi chut ln QoS Router v chn Edit Attributes. 2. Bung th mc IP Routing Parameters, ri th mc Interface Information

v th mc hng i vi giao din va tm c, row 10 trong v d ny. 3. Tip tc bung th mc QoS Information, t thuc tnh Buffer Size

(bytes) l 100000. Bng cch t kch thc b m trn giao din ny tng i nh, trn b m s nhanh chng xy ra, cho php chng ta quan st cc kt qu ca cc c ch xp hng khc nhau d dng hn. l d th no th trn b m cui cng cng s xy ra v my ch FTP Server sn sinh ra ti lu lng kh ln, c truyn trn ng truyn DS3 ni vi QoS Router, nhng QoS Router ch s dng ng truyn DS1 chuyn tip cc gi tin ti cc my trm.

4. Nhp OK ng ca s (QoS Router) Attributes.

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Hnh 3.4.12. Thay i kch thc b m ca giao din c gn cho QoS Router.

Bc 2: Chn tham s kt qu m phng 1. Nhp phi chut ln QoS Router v chn Choose Individual Statistics. 2. Bung th mc IP Interface, chn Buffer Usage (packets), Queuing Delay

Variation (sec), Queuing Delay (sec) v Traffic Dropped (packets/sec). 3. Nhp OK ng ca s Choose Results.

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Hnh 3.4.13. Chn tham s kt qu m phng.

3.4.2 Thc hin m phng 1. Chn Simulation Configure Discrete Event Simulation 2. Trong tab Common, t Duration l 10, chn n v thi gian l minute(s). 3. Nhp Run chy m phng. 4. Khi m phng kt thc, nhp Close ng ca s Simulation Sequence.

Hnh 3.4.14. t cu hnh chy m phng.

3.4.3 Thu thp v phn tch kt qu m phng Trc tin chng ta s xem xt lu lng rt ca hai hng ch.

1. Chn tab Results View Results 2. Chn v bung cc th mc Object Statistics, Choose From Maps

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Network, QoS Router v IP Interface. 3. Nhp phi chut chn cc tham s kt qu PQ Traffic Dropped

(Packets/sec) IF10 Q1 v PQ Traffic Dropped (Packets/sec) IF10 Q1 (Default Queue). Lu l giao din 10 (IF10) l giao din trn QoS Router ni vi Router 1. Nu trong qu trnh xy dng m hnh m phng chng ta gp mt giao din c tn khc th phi thay ng giao din trong cc bc phn tch kt qu tip theo. S dng ch As Is xem cc ton b cc kt qu. Cc tham s kt qu c chn cho bit c bao nhiu gi tin b nh mt do trn b m. Q1 tng ng vi ti lu lng c mc u tin cao trong khi Q0 tng ng vi ti tin mc u tin thp. l hng ch mc u tin cao c t l mt gi tin thp hn so vi hng ch mc u tin thp.

Hnh 3.4.15. Hp thoi View Results vi cc th Traffic Dropped ca hai hng ch c cp u tin khc nhau.

4. Nhp phi chut ln cc kt qu mt ln na tt th preview. th tr ca hai hng ch, minh ho trn hnh 3.5.16, c ly ra nh sau:

1. Chn kt xem qu PQ Queue Delay (sec) IF10 Q1 v PQ Queue Delay (sec) IF10 Q0 (Default Queue). Cc kt qu ny cho bit lng thi gian cc gi tin phi i trong hng ch trc khi c gi i. C th quan st thy ti tin c mc u tin thp (Q0) phi ch lu hn ng k so vi cc gi tin c mc u tin cao hn (Q1).

2. Nhp phi chut ln cc th mc ny tt th preview.

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Cng nh tr, bin thin tr cng thay i tu theo cp u tin ca hng ch nh biu din ca hnh 3.4.17.

Hnh 3.4.16. Hp thoi View Results vi cc th Queuing Delay ca hai hng ch c cp u tin khc nhau.

Hnh 3.4.17. Hp thoi View Results vi cc th Queuing Delay Variation ca hai hng ch c cp u tin khc nhau.

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1. Chn xem kt qu PQ Queue Delay Variation (sec) IF10 Q1 v PQ Queue Delay Variation (sec) IF10 Q0 (Default Queue). Cc gi tr ny cho bit mc bin thin tr (jitter) trong hng ch m cc gi tin phi tri qua. Nhn thy ngay rng cc gi tin c mc u tin cao hn chu lng jitter t hn nhiu so vi cc gi tin c mc u tin thp.

2. Nhp phi chut li cc th mc ny tt th preview. Cui cng, y b m c kho st theo cc bc sau:

1. Chn xem PQ Buffer Usage (packets) IF10 Q1 v PQ Buffer Usage (packets) IF10 Q0 (Default Queue). Cc kt qu ny cho bit s gi tin phi i trong hng ch ti mi thi im trong thi gian m phng. D dng quan st thy c rt nhiu gi tin c mc u tin thp phi ng trong hng ch ti mi thi im trong khi rt t gi tin mc u tin cao phi xp hng ch.

2. Nhp li chut ln cc th mc ny tt th preview. 3. Lu m hnh va xy dng v tt ht cc ca s giao din.

Hnh 3.4.18. Hp thoi View Results vi cc th Buffer Usage ca hai hng ch c cp u tin khc nhau.

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KT LUN

Thng qua kt qu nghin cu trnh by ni trn, chng ti nhn thy vic ng dng phn mm m phng mng Opnet IT Guru cho php xy dng mt s lng ln cc module m phng bao ph phn ln phm vi nghin cu v mng truyn s liu. Bn module m phng xy dng c p ng c yu cu t ra ca ti. S dng phn mm m phng Opnet IT Guru, ngoi 4 module th nghim gii thiu, ngi dng c th hon ton xy dng c cc module th nghim phc v cho nghin cu v hc tp mt cch d dng. Chng ti cng xut a cc module m phng xy dng c vo s dng cho o to v nghin cu.

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TI LIU THAM KHO 1. URL: http://www.ietf.org/rfc/rfc2001.txt?number=2001 (2008-05-31) 2. URL: http://www.ietf.org/rfc/rfc2581.txt?number=2581 (2008-05-31) 3. Kevin Brown & Leann Christianson Opnet Lab Manual to accompany Data &

Computer Communications by W. Stallings. Pearson, 2005. ISBN 0-13-148252-1. 4. Jinhua Guo, Weidong Xiang, and Shengquan Wang - Reinforce Networking

Theory with OPNET Simulation. Journal of Information Technology Education. Volume 6, 2007.

5. Tommy Svensson, Alex Popescu. OPNET Modeler - Development of laboratory exercises based on OPNET Modeler. Master thesis MEE 03:24, Blekinge Institute of Technology, 2003.

6. William Stallings. Computer Networking with Internet Protocols and Technology, 7nd Ed. Upper Saddle River, NJ: Prentice Hall Inc., 2004. ISBN: 0131006819.

7. Bertsekas, Dimitri, and Robert Gallager. Data Networks. 2nd Ed. Upper Saddle River, NJ: Prentice Hall, 1991. ISBN: 0132009161.

8. Peterson and Davie. Computer Networks. 2nd Ed. San Francisco, CA: Morgan Kaufmann Publishers, 1999. ISBN: 1558605142 .

9. Tanenbaum, A. S. Computer Networks. 4th Ed. Upper Saddle River, NJ : Prentice Hall, 2003. ISBN: 0130661023.

10. Alberto Leon-Garcia, Indra Widjaja. Computer Networks Fundemental Concepts and Key Architectures. 2nd Ed. NY: McGraw Hill, 2003. ISBN: 0071198482.