Namuhla sizoqala ukufunda ama-routers. Uma uqedele isifundo sami sevidiyo kusukela kweyokuqala ukuya kwese-17, usuvele ufunde izisekelo zokushintshwa. Manje sidlulela kudivayisi elandelayo - umzila. Njengoba wazi esifundweni sangaphambilini sevidiyo, esinye sezihloko zesifundo se-CCNA sibizwa nge-Cisco Switching & Routing.
Kulolu chungechunge, ngeke sifunde ama-Cisco routers, kodwa sizobheka umqondo womzila ngokujwayelekile. Sizoba nezihloko ezintathu. Esokuqala isifinyezo salokho osuvele ukwazi ngama-routers kanye nengxoxo mayelana nokuthi ingasetshenziswa kanjani ngokuhambisana nolwazi oluzuzile ngesikhathi sokufunda amaswishi. Kudingeka siqonde ukuthi amaswishi namarutha asebenzisana kanjani.
Okulandelayo, sizobheka ukuthi kuyini ukuthungatha, ukuthi kusho ukuthini, nokuthi kusebenza kanjani, bese sidlulela ezinhlotsheni zamaphrothokholi omzila. Namuhla ngisebenzisa i-topology osuvele uyibonile ezifundweni ezedlule.
Sibheke ukuthi idatha ihamba kanjani kunethiwekhi futhi ukuthi ukuxhawula kwe-TCP kwezindlela ezintathu kwenziwa kanjani. Umlayezo wokuqala othunyelwe ngenethiwekhi uyiphakethe le-SYN. Ake sibheke ukuthi ukuxhawula ngezindlela ezintathu kwenzeka kanjani lapho ikhompuyutha enekheli le-IP 10.1.1.10 ifuna ukuxhumana neseva engu-30.1.1.10, okungukuthi, izama ukusungula uxhumano lwe-FTP.
Ukuze uqale uxhumano, ikhompuyutha idala imbobo yomthombo ngenombolo engahleliwe 25113. Uma ukhohlwe ukuthi lokhu kwenzeka kanjani, ngikweluleka ukuthi ubuyekeze izifundo zevidiyo zangaphambili ezixoxisane ngalolu daba.
Okulandelayo, ibeka inombolo yembobo okuyiwa kuyo ohlakeni ngoba iyazi ukuthi kufanele ixhumeke ku-port 21, bese yengeza ulwazi lwe-OSI Layer 3, okuyikheli layo le-IP kanye nekheli le-IP okuyiwa kulo. Idatha enamachashazi ayishintshi ize ifike ekugcineni. Njengoba sezifinyelele iseva, nazo azishintshi, kodwa iseva yengeza ulwazi lwezinga lesibili kuhlaka, okungukuthi, ikheli le-MAC. Lokhu kungenxa yokuthi amaswishi abona ulwazi lweleveli 2 ye-OSI kuphela. Kulesi simo, i-router yiyona kuphela idivayisi yenethiwekhi ecabangela ulwazi Lwesendlalelo sesi-3; ngokwemvelo, ikhompuyutha nayo isebenza ngalolu lwazi. Ngakho-ke, ukushintshwa kusebenza kuphela ngolwazi lwezinga lesi-XNUMX, futhi i-router isebenza kuphela ngolwazi lwezinga lesi-XNUMX.
Iswishi yazi ikheli lomthombo le-MAC XXXX:XXXX:1111 futhi ifuna ukwazi ikheli le-MAC leseva ikhompuyutha efinyelela kuyo. Iqhathanisa ikheli le-IP eliwumthombo nekheli okuyiwa kulo, ibona ukuthi lawa madivayisi atholakala kuma-subnet ahlukene, futhi inquma ukusebenzisa isango ukuze ifinyelele ku-subnet ehlukile.
Ngivame ukubuzwa umbuzo wokuthi ubani onqumayo ukuthi ikheli le-IP lesango kufanele libe yini. Okokuqala, kunqunywa umlawuli wenethiwekhi, odala inethiwekhi futhi anikeze ikheli le-IP kudivayisi ngayinye. Njengomlawuli, unganikeza irutha yakho noma yiliphi ikheli ngaphakathi kwebanga lamakheli avunyelwe ku-subnet yakho. Ngokuvamile leli yikheli lokuqala noma lokugcina elivumelekile, kodwa ayikho imithetho eqinile mayelana nokuyabela. Esimweni sethu, umlawuli unikeze ikheli lesango, noma i-router, 10.1.1.1 futhi wabela yona ku-port F0/0.
Uma usetha inethiwekhi kukhompuyutha enekheli le-IP elimile elingu-10.1.1.10, unikeza imaski ye-subnet engu-255.255.255.0 kanye nesango elizenzakalelayo lika-10.1.1.1. Uma ungasebenzisi ikheli elimile, kusho ukuthi ikhompuyutha yakho isebenzisa i-DHCP, enikeza ikheli eliguqukayo. Akunandaba ukuthi ikhompyutha isebenzisa liphi ikheli le-IP, elimile noma eliguqukayo, kufanele libe nekheli lesango ukuze ifinyelele enye inethiwekhi.
Ngakho, ikhompuyutha 10.1.1.10 iyazi ukuthi kufanele ithumele ifremu kumzila 10.1.1.1. Lokhu kudlulisa kwenzeka ngaphakathi kwenethiwekhi yendawo, lapho ikheli le-IP lingenandaba, ikheli le-MAC kuphela elibalulekile lapha. Ake sicabange ukuthi ikhompuyutha ayikaze ixhumane nomzila ngaphambili futhi ayilazi ikheli layo le-MAC, ngakho-ke kufanele iqale ithumele isicelo se-ARP esibuza wonke amadivaysi ku-subnet: βhey, ubani kini onekheli elithi 10.1.1.1? Ngicela ungitshele ikheli lakho le-MAC! Njengoba i-ARP ingumlayezo osakazwayo, ithunyelwa kuwo wonke amachweba awo wonke amadivayisi, kuhlanganise nomzila.
Ikhompyutha 10.1.1.12, ngemva kokuthola i-ARP, icabanga: βcha, ikheli lami akulona 10.1.1.1,β bese ilahla isicelo, ikhompyutha 10.1.1.13 yenza okufanayo. Umzila, ngemva kokuthola isicelo, uyaqonda ukuthi nguye obuzwayo, futhi ithumela ikheli le-MAC le-port F0/0 - futhi wonke amachweba anekheli elihlukile le-MAC - kukhompyutha 10.1.1.10. Manje, ngokwazi ikheli lesango XXXX:AAAA, kuleli cala okuyikheli lendawo, ikhompuyutha iyengeza ekugcineni kohlaka olubhekiswe kuseva. Ngesikhathi esifanayo, isetha unhlokweni wozimele we-FCS/CRC, okuyindlela yokuhlola iphutha lokudlulisela.
Ngemva kwalokhu, ifreyimu yekhompyutha 10.1.1.10 ithunyelwa phezu kwezintambo kumzila 10.1.1.1. Ngemva kokuthola uhlaka, umzila ususa i-FCS/CRC isebenzisa i-algorithm efanayo nekhompyutha ukuze kuqinisekiswe. Idatha ayilutho ngaphandle kweqoqo elilodwa noziro. Uma idatha yonakalisiwe, okungukuthi, u-1 uba ngu-0 noma u-0 uba omunye, noma kunokuvuza kwedatha, okuvame ukwenzeka lapho kusetshenziswa ihabhu, lapho idivayisi kufanele ithumele kabusha uhlaka futhi.
Uma ukuhlola kwe-FCS/CRC kuphumelela, irutha ibheka umthombo nendawo amakheli e-MAC bese iyawasusa, njengoba lokhu kuwulwazi Lwesendlalelo sesi-2, bese idlulela emzimbeni wohlaka, oluqukethe ulwazi Lwesendlalelo sesi-3. Kuyo ufunda ukuthi ulwazi oluqukethwe kuhlaka luhloselwe idivayisi enekheli le-IP 30.1.1.10.
Irutha ngandlela thize iyazi ukuthi le divayisi ikuphi. Asizange sixoxe ngalolu daba uma sibheka ukuthi amaswishi asebenza kanjani, ngakho-ke sizoyibheka manje. I-router inamachweba angu-4, ngakho-ke ngengeze okunye ukuxhumana okumbalwa kuyo. Ngakho-ke, i-router yazi kanjani ukuthi idatha yedivayisi enekheli le-IP 30.1.1.10 kufanele ithunyelwe nge-port F0/1? Kungani ingazithumeli nge-port F0/3 noma F0/2?
Iqiniso liwukuthi i-router isebenza ngetafula lomzila. I-router ngayinye inetafula elinjalo elikuvumela ukuthi unqume ukuthi iyiphi ichweba ongadlulisela uhlaka oluthile.
Kulokhu, imbobo ye-F0/0 ilungiselelwe ekhelini le-IP elithi 10.1.1.1 futhi lokhu kusho ukuthi ixhunywe kunethiwekhi 10.1.1.10/24. Ngokufanayo, imbobo ye-F0/1 ilungiselelwe ekhelini elithi 20.1.1.1, okungukuthi, lixhunywe kunethiwekhi 20.1.1.0/24. I-router iwazi womabili lawa manethiwekhi ngoba axhumeke ngqo kumachweba ayo. Ngakho, ulwazi lokuthi ithrafikhi yenethiwekhi 10.1.10/24 kufanele idlule ku-port F0/0, kanye nenethiwekhi engu-20.1.1.0/24 nge-port F0/1, iyaziwa ngokuzenzakalelayo. I-router yazi kanjani ukuthi yiziphi izimbobo okufanele zisebenze namanye amanethiwekhi?
Siyabona ukuthi inethiwekhi engu-40.1.1.0/24 ixhunywe ku-port F0/2, inethiwekhi 50.1.1.0/24 ixhunywe ku-port F0/3, futhi inethiwekhi 30.1.1.0/24 ixhuma umzila wesibili kuseva. I-router yesibili nayo inetafula lomzila, elithi inethiwekhi 30. ixhunywe echwebeni layo, ake siyisho 0/1, futhi ixhunywe kumzila wokuqala nge-port 0/0. Le router iyazi ukuthi ichweba layo elingu-0/0 lixhunywe kunethiwekhi 20., futhi imbobo 0/1 ixhunywe kunethiwekhi 30., futhi ayazi lutho olunye.
Ngokufanayo, i-router yokuqala iyazi mayelana namanethiwekhi 40. no-50. axhunywe kumachweba 0/2 no-0/3, kodwa awazi lutho ngenethiwekhi 30. Iphrothokholi yomzila inikeza ama-routers ulwazi abangenalo ngokuzenzakalelayo. Indlela lawa ma-routers axhumana ngayo iyisisekelo somzila, futhi kunomzila oguquguqukayo nomile.
Umzila omile ukuthi i-router yokuqala inikezwa ulwazi: uma udinga ukuxhumana nenethiwekhi 30.1.1.0/24, udinga ukusebenzisa i-port F0/1. Kodwa-ke, lapho i-router yesibili ithola ithrafikhi evela kuseva ehloselwe ikhompuyutha 10.1.1.10, ayazi ukuthi yenzeni ngayo, ngoba ithebula layo lomzila liqukethe ulwazi mayelana namanethiwekhi 30 no-20. Ngakho-ke, le router nayo idinga ukubhalisa umzila omile : Uma ithola ithrafikhi yenethiwekhi 10., kufanele iyithumele ngembobo engu-0/0.
Inkinga ngomzila omile ukuthi kufanele ngilungise ngesandla irutha yokuqala ukuze isebenze nenethiwekhi 30. futhi irutha yesibili ukuze isebenze nenethiwekhi 10. Lokhu kulula uma nginamarutha angu-2 kuphela, kodwa uma nginamarutha angu-10, ngiyamisa. umzila omile uthatha isikhathi esiningi. Kulokhu, kunengqondo ukusebenzisa umzila oguquguqukayo.
Ngakho-ke, ngemva kokuthola uhlaka oluvela kukhompyutha, i-router yokuqala ibheka itafula layo lomzila bese inquma ukuyithumela nge-port F0/1. Ngesikhathi esifanayo, yengeza ikheli le-MAC elingumthombo XXXX.BBBB kanye nekheli le-MAC okuyiwa kulo XXXX.CCSS kuhlaka.
Ngemva kokuthola lolu hlaka, irutha yesibili "isika" amakheli e-MAC ahlobene nosendlalelo sesibili se-OSI bese idlulela kulwazi lwesendlalelo sesithathu. Ubona ukuthi ikheli le-IP okuyiwa kulo 3 lingelenethiwekhi efanayo nembobo engu-30.1.1.10/0 yomzila, wengeza ikheli lomthombo we-MAC kanye nekheli le-MAC okuyiwa kulo kuhlaka futhi ithumela uhlaka kuseva.
Njengoba ngishilo kakade, khona-ke inqubo efanayo iphindaphindiwe ngokuphambene, okungukuthi, isigaba sesibili sokuxhawula siyenziwa, lapho iseva ibuyisela umlayezo we-SYN ACK. Ngaphambi kokwenza lokhu, ilahla lonke ulwazi olungadingekile futhi ishiya iphakethe le-SYN kuphela.
Ngemva kokuthola leli phakethe, i-router yesibili ibuyekeza ulwazi olutholiwe, ingezelele futhi ithumele.
Ngakho-ke, ezifundweni ezedlule sifunde ukuthi iswishi isebenza kanjani, futhi manje sesifundile ukuthi ama-routers asebenza kanjani. Ake siphendule umbuzo wokuthi kuyini umzila ngomqondo womhlaba wonke. Ake sithi uhlangana nophawu lomgwaqo olunjalo olufakwe empambanweni yomgwaqo. Ungabona ukuthi igatsha lokuqala liholela eRAF Fairfax, elesibili esikhumulweni sezindiza, elesithathu eningizimu. Uma uthatha indlela yesine ephumayo uzobe ungasekho, kodwa okwesihlanu ungakwazi ukushayela unqamule enkabeni yedolobha uye eBraxby Castle.
Ngokuvamile, umzila yikho okuphoqa irutha ukuthi yenze izinqumo mayelana nokuthi izoyithumela kuphi ithrafikhi. Kulokhu, wena, njengomshayeli, kufanele unqume ukuthi iyiphi indlela ephuma ezimpambanweni yomgwaqo ozoyithatha. Kumanethiwekhi, amarutha kufanele enze izinqumo mayelana nokuthi azowathumela kuphi amaphakethe noma amafreyimu. Kufanele uqonde ukuthi umzila ikuvumela ukuthi udale amathebula ngokusekelwe kulokho amarutha athatha lezi zinqumo.
Njengoba ngishilo, kukhona umzila omile futhi oguquguqukayo. Ake sibheke umzila omile, engizodweba kuwo amadivaysi angu-3 axhunywe komunye nomunye, ngedivayisi yokuqala neyesithathu exhunywe kumanethiwekhi. Ake sicabange ukuthi inethiwekhi eyodwa 10.1.1.0 ifuna ukuxhumana nenethiwekhi 40.1.1.0, futhi phakathi kwama-routers kukhona amanethiwekhi 20.1.1.0 no-30.1.1.0.
Kulokhu, izimbobo ze-router kufanele zibe ngama-subnet ahlukene. Umzila 1 ngokuzenzakalelayo wazi kuphela ngamanethiwekhi 10. no-20. futhi awazi lutho ngamanye amanethiwekhi. Umzila 2 wazi kuphela ngamanethiwekhi 20. kanye 30. ngoba axhumeke kuyo, futhi umzila 3 wazi kuphela amanethiwekhi 30. kanye 40. Uma inethiwekhi 10. ifuna ukuxhumana nenethiwekhi 40., kufanele ngitshele umzila 1 mayelana nenethiwekhi 30 nokuthi uma efuna ukudlulisa uhlaka kunethiwekhi 40., kufanele asebenzise isixhumi esibonakalayo senethiwekhi 20. futhi athumele uhlaka kunethiwekhi efanayo 20.
Kumele nginikeze imizila emi-2 kumzila wesibili: uma ifuna ukudlulisa iphakethe kusuka kunethiwekhi 40. kuya kunethiwekhi 10., kufanele isebenzise i-port yenethiwekhi 20., nokudlulisa iphakethe kusuka kunethiwekhi 10. kuya kunethiwekhi 40. - inethiwekhi port 30. Ngokufanayo, kufanele nginikeze ulwazi lwe-router 3 mayelana namanethiwekhi 10. kanye ne-20.
Uma unamanethiwekhi amancane, khona-ke ukusetha umzila omile kulula kakhulu. Kodwa-ke, lapho inethiwekhi ikhula, izinkinga eziningi ziyavela ngomzila omile. Ake sicabange ukuthi udale uxhumano olusha oluxhuma ngokuqondile irutha yokuqala neyesithathu. Kulokhu, isimiso somzila esiguquguqukayo sizobuyekeza ngokuzenzakalela ithebula lomzila le-Router 1 ngokulandelayo: "uma udinga ukuthinta Umzila 3, sebenzisa umzila oqondile"!
Kunezinhlobo ezimbili zamaphrothokholi omzila: I-Internal Gateway Protocol IGP kanye ne-External Gateway Protocol EGP. Iphrothokholi yokuqala isebenza kusistimu ehlukile, ezimele eyaziwa ngokuthi isizinda somzila. Cabanga ukuthi unenhlangano encane enamarutha angu-5 kuphela. Uma sikhuluma kuphela mayelana nokuxhumana phakathi kwalawa ma-routers, khona-ke sisho i-IGP, kodwa uma usebenzisa inethiwekhi yakho ukuxhumana ne-Inthanethi, njengoba abahlinzeki be-ISP benza, bese usebenzisa i-EGP.
I-IGP isebenzisa izivumelwano ezi-3 ezidumile: i-RIP, i-OSPF ne-EIGRP. Ikharikhulamu ye-CCNA ikhuluma kuphela ngamaphrothokholi amabili okugcina ngoba i-RIP isiphelelwe yisikhathi. Lokhu kulula kakhulu kumaphrothokholi omzila futhi kusasetshenziswa kwezinye izimo, kodwa akunikezeli ngokuvikeleka kwenethiwekhi okudingekayo. Lesi ngesinye sezizathu ezenza iCisco ikhiphe i-RIP esifundweni sokuqeqesha. Nokho, ngizokutshela ngakho noma kunjalo ngoba ukufunda kukusiza ukuthi uqonde izisekelo zomzila.
Ukuhlukaniswa kwephrothokholi ye-EGP kusebenzisa izivumelwano ezimbili: i-BGP kanye nephrothokholi ye-EGP ngokwayo. Esifundweni se-CCNA, sizofaka i-BGP, OSPF, ne-EIGRP kuphela. Indaba emayelana ne-RIP ingathathwa njengolwazi lwebhonasi, oluzobonakala kwesinye sezifundo zevidiyo.
Kukhona ezinye izinhlobo ezi-2 zezinqubo zomzila: Izivumelwano zeVector yebanga kanye nemithethonqubo yomzila ye-Link State.
Iphasi lokuqala libheka ibanga kanye nama-vectors aqondisayo. Ngokwesibonelo, ngingakwazi ukusungula uxhumano ngokuqondile phakathi kwerutha i-R1 ne-R4, noma ngingenza uxhumano endleleni engu-R1-R2-R3-R4. Uma sikhuluma ngamaphrothokholi omzila asebenzisa indlela ye-vector yebanga, khona-ke kulokhu ukuxhumana kuzohlala kwenziwa ngendlela emfushane kakhulu. Akunandaba ukuthi lokhu kuxhumana kuzoba nesivinini esincane. Esimweni sethu, lokhu kungu-128 kbps, okuhamba kancane kakhulu kunokuxhumeka kumzila we-R1-R2-R3-R4, lapho isivinini siyi-100 Mbps.
Ake sicabangele iphrothokholi yevekhtha yebanga i-RIP. Ngizodweba inethiwekhi 1 phambi kwe-router R10, kanye nenethiwekhi 4 ngemuva kwe-router R40. Ake sicabange ukuthi kunamakhompyutha amaningi kulawa manethiwekhi. Uma ngifuna ukuxhumana phakathi kwenethiwekhi 10. R1 kanye nenethiwekhi 40. R4, ngizobe senginikeza umzila omile ku-R1 njengathi: βuma udinga ukuxhuma kunethiwekhi 40., sebenzisa uxhumano oluqondile kumzila u-R4.β Ngesikhathi esifanayo, kufanele ngilungiselele ngesandla i-RIP kuwo wonke ama-routers angu-4. Khona-ke ithebula lomzila u-R1 lizosho ngokuzenzakalelayo ukuthi uma inethiwekhi 10. ifuna ukuxhumana nenethiwekhi 40., kufanele isebenzise uxhumano oluqondile R1-R4. Noma ngabe i-bypass ibonakala ishesha, i-Distance Vector protocol isazokhetha indlela emfushane enebanga elifushane kakhulu lokudlulisela.
I-OSPF iyisivumelwano somzila wesifunda esihlala sibheka isimo sezigaba zenethiwekhi. Kulokhu, ihlola ijubane lamashaneli, futhi uma ibona ukuthi ijubane lokudluliswa kwezimoto esiteshini i-R1-R4 liphansi kakhulu, ikhetha umzila ngejubane eliphezulu R1-R2-R3-R4, noma ngabe ubude budlula indlela emfushane kakhulu. Ngakho-ke, uma ngilungiselela iphrothokholi ye-OSPF kuwo wonke ama-routers, lapho ngizama ukuxhuma inethiwekhi 40. kunethiwekhi 10., ithrafikhi izothunyelwa ngomzila R1-R2-R3-R4. Ngakho-ke, i-RIP iyiphrothokholi ye-vector yebanga, futhi i-OSPF iyiphrothokholi yomzila wombuso wokuxhumanisa.
Kukhona enye iphrothokholi - i-EIGRP, iphrothokholi ye-Cisco yokuphathelene. Uma sikhuluma ngamadivaysi enethiwekhi avela kwabanye abakhiqizi, isibonelo, iJuniper, ayisekeli i-EIGRP. Lena iphrothokholi yomzila enhle kakhulu esebenza kahle kakhulu kune-RIP ne-OSPF, kodwa ingasetshenziswa kuphela kumanethiwekhi asekelwe kumadivayisi e-Cisco. Kamuva ngizokutshela ngokuningiliziwe ukuthi kungani le protocol inhle kangaka. Okwamanje, ngizoqaphela ukuthi i-EIGRP ihlanganisa izici zephrothokholi yevekhtha yebanga kanye nemithethonqubo yokuxhumanisa isimo, emele iphrothokholi eyingxube.
Esifundweni esilandelayo sevidiyo sizosondela ekucatshangelweni kwamarutha e-Cisco; ngizokutshela kancane mayelana nesistimu yokusebenza ye-Cisco IOS, ehloselwe kokubili ukushintsha namarutha. Ngethemba, ngoSuku lwe-19 noma uSuku lwama-20, sizongena emininingwaneni eyengeziwe mayelana nezivumelwano zomzila, futhi ngizobonisa indlela yokulungisa amarutha e-Cisco kusetshenziswa amanethiwekhi amancane njengezibonelo.
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