El Imodeli ye-OSI Kubaluleke kakhulu kumanethiwekhi ekhompyutha. Ngakho-ke, kulesi sihloko, sizochaza ukuthi iyini le modeli yenethiwekhi, isebenza kanjani, isetshenziselwa ini, izendlalelo ezifanele ezakhayo, nokuningi.
Iyini imodeli ye-OSI?
El Imodeli ye-OSI (Open Systems Interconnection)., noma i-Open Systems Interconnection, iyimodeli eyireferensi yezivumelwano zokuxhumana zenethiwekhi yekhompyutha. Le modeli yasungulwa ngeminyaka yawo-80 yi-ISO (International Standards Organisation).
I-OSI Model yaqale yashicilelwa yi-ITU (International Telecommunication Union). Kodwa-ke, lokhu bekungeke kuze kufike ngo-1983, njengoba ngonyaka olandelayo yanikezwa yi-ISO ngokwayo, njengendinganiso. Eqinisweni, inhloso ye-OSI uku qinisa ukuxhumana kwe-inthanethi ukwenza kube lula futhi kufune ukusebenzisana kwawo wonke amadivaysi enethiwekhi nesoftware.
Njengoba i-OSI Model iyi-a imodeli yohlobo olujwayelekile, ungathi umqondo wetiyori, nakuba usebenza ukwenza izinto ezibonakalayo ukuze unike amandla ubuchwepheshe obuhlukahlukene nabakhiqizi emhlabeni wezokuxhumana ukuze benze umsebenzi wabo ngendlela efanele.
Ngokuhamba kweminyaka, imodeli ye-OSI iye yathuthukiswa. Okwamanje inikeza izendlalelo ezingu-7 ukuchaza izigaba ezahlukene ulwazi oludlula kuzo lapho ukuxhumana kwenziwa phakathi kwamanodi amabili noma amadivaysi kunethiwekhi. Kungakhathalekile ukuthi yiluphi uhlobo lolwazi, uhlobo lwedivayisi exhunyiwe, ubuchwepheshe bayo, noma indawo yayo, izendlalelo ezifanayo zizohlala zihilelekile.
Umlando omncane: Isendlalelo
Kumele kushiwo ukuthi i- ukunwetshwa kwamanethiwekhi ekhompyutha Kwaqala ngeminyaka yawo-80s, lapho isidingo sokuxhumanisa amadivaysi ahlukene sasakazwa emhlabeni wonke ukuze kudluliswe ulwazi nokuhlala kuxhumekile saduma. Amanethiwekhi, ngakolunye uhlangothi, adalwe kudala ngaphambi kwaleyo minyaka eyishumi.
Impela uyayikhumbula i- umlando womsuka we-inthanethi kanye nabandulelayo, njengenethiwekhi eyaziwa ngokuthi i-ARPANET. Nokho, ngaleso sikhathi, i-OSI Model yayingekho, futhi inkinga abahlangabezane nayo yayiwukuthi izinhlelo eziningi zenethiwekhi noma amadivaysi ayenenkinga yokuxhumana. Kungakho ukumiswa kwe-ISO bekudingeka ukuze kunqunywe isethi yemithetho esebenza kuwo wonke amanethiwekhi ukuze lezi zinkinga zokusebenzisana zingabi khona.
Isebenza kanjani imodeli ye-OSI?
Njengoba ngishilo ekuqaleni, i-OSI Model yenziwe ngezingqimba ezi-7 ezihlukene okuncike kuzo. I ukusebenza kuhlukaniswe ngezinyathelo, njengoba isendlalelo ngasinye sifeza umsebenzi othize, wesigaba kwezokuxhumana. Ngakho-ke, izivumelwano zokuxhumana zizosebenzisa zonke noma ezinye zalezi zingqimba ukuze kuqinisekiswe ukuxhumana kwenethiwekhi.
Isetshenziselwa ini imodeli ye-OSI?
I-OSI Model iyithuluzi ngokuyisisekelo lokuhlela ezokuxhumana. Lokho elikwenzayo qinisa indlela ulwazi oludluliswa ngayo kumanethiwekhi ikhompuyutha.
Kumele kushiwo ukuthi i-OSI Model ayiyona i-topology yenethiwekhi, noma imodeli yenethiwekhi ngokwayo, noma imininingwane noma izivumelwano. Kuyithuluzi elichaza ukusebenza ukuze abakhiqizi nabathuthukisi ingakha imikhiqizo engasebenzisana ngaphandle komthungo njengoba beyenza ngaphambilini.
I-OSI Model Layers noma i-OSI Stack
I-Las izendlalelo noma amazinga akha imodeli ye-OSI, eyaziwa nangokuthi i-OSI Stack, yilezi:
- Isendlalelo esibonakalayo: Ingqimba yezinga eliphansi kakhulu lemodeli ye-OSI. Iphatha yonke into ehlobene ne-topology yenethiwekhi, ukuxhumana ngokomzimba, ukusayinda, nokudluliswa kanambambili. Ngamanye amazwi, ilinganisa izinga lomzimba (izinhlobo zekhebula, amaza amagagasi okuxhumana okungenantambo, izixhumanisi zenethiwekhi, i-voltage kagesi, njll.).
- Isendlalelo Sesixhumanisi Sedatha: iphathelene nokuqondisa kabusha ngokomzimba, ukutholwa kwamaphutha, ukufinyelela kwemidiya, nokulawula ukugeleza phakathi nokuxhumana. Isibonelo, amakheli e-MAC nawe-LLC azochazwa kulesi sendlalelo.
- Isendlalelo senethiwekhi: Inesibopho sokukhuluma ngendlela enengqondo kanye nokunquma umzila. Okungukuthi, ukuhlonza umzila okhona phakathi kwamanethiwekhi ahililekile. Amayunithi edatha ayisisekelo abizwa ngokuthi "amaphakethe" futhi angahlukaniswa ngokuya ngephrothokholi yomzila noma iphrothokholi eshintshekayo ayisebenzisayo. Eyangaphambili ikhetha imizila (RIP, IGRP, EIGRP, phakathi kokunye) kanye nohambo lwakamuva namaphakethe (IP, IPX, AppleTalk, njll.). Inhloso yalesi sendlalelo wukuqinisekisa ukuthi idatha ifinyelela lapho iya khona, ngisho noma ihlanganisa ukusebenzisa amadivayisi aphakathi nendawo, njengamarutha.
- Isendlalelo sezokuthutha: Ibophezelekile ekuxhumekeni ekupheleni kuya ekupheleni kanye nokuthembeka kwedatha edlulisiwe. Lapha kulapho idatha equkethwe phakathi kwephakethe ngalinye ithuthwa isuka endaweni eyodwa iye kwenye, okungukuthi, isuka kudivayisi yomthombo iye kudivayisi okuyiwa kuyo, kungakhathaliseki ukuthi iyiphi indlela ebonakalayo esetshenzisiwe. Umsebenzi wayo wenziwa ngokusebenzisa amachweba anengqondo futhi ulolonge okuthiwa Izisekelo ze-IP: Imbobo.
- Isendlalelo seseshini: Iwukuxhumana phakathi kwamadivayisi akunethiwekhi ngokwayo. Inesibopho sokulawula nokugcina isixhumanisi phakathi kwamadivayisi axhunyiwe ashintshanisa idatha. Kufanele futhi iqinisekise ukuthi, uma ukuxhumana phakathi kwazo zombili izinhlelo sekusunguliwe, isiteshi sokudlulisa idatha singaqalwa kabusha uma siphazamiseka. Lawa masevisi angase akhipheke ngokwengxenye noma ngokuphelele, kuye ngecala. Kungakho ngike ngasho phambilini ukuthi akuzona zonke izingqimba eziyisi-7 ezihlala zisetshenziswa...
- Isendlalelo sephrezentheshini: Njengoba igama layo liphakamisa, isetshenziselwa ukwethula idatha edlulisiwe. Okusho ukuthi, lawa maphakethe aqoqiwe "ahunyushwa" ukuze abonakale noma abe wusizo ohlelweni. Isibonelo, uchungechunge lwamaphakethe lungaholela kumlayezo, ifayela, njll. Iphinde ivumele ukubethelwa kwedatha kanye nombhalo wekhodi, kanye nokucindezelwa nokuzivumelanisa nomshini owamukelayo.
- Isendlalelo sohlelo lokusebenza: Lesi isendlalelo sezinga eliphezulu. Khumbula ukuthi izivumelwano ezintsha zokuxhumana zisathuthukiswa ngokuqhubekayo njengoba kuvela izinhlelo ezintsha. Ngakho-ke, lesi sendlalelo sokugcina sichaza imigomo esetshenziswa izinhlelo zokusebenza ukushintshanisa idatha. Lesi sendlalelo singase sibangele inqubo umsebenzisi agcine eyibona, nakuba lokhu kungenzeki ngaso sonke isikhathi. Nokho, kufanele kuqashelwe ukuthi umsebenzisi akavamile ukusebenzisana nesendlalelo sohlelo lokusebenza; zisebenzisana nezinhlelo zokusebenza ezisebenzisana nesendlalelo sohlelo lokusebenza. Isibonelo, kungaba uhlelo lokusebenza lokuxoxa, isiphequluli sewebhu, njll.
Ekugcineni, abanye abantu basebenzisa umthetho we-mnemonic ukuze bakhumbule izingqimba eziyisi-7 ze-OSI Model, futhi lowo mthetho uthi I-FERTSPA (I-Physics, Isixhumanisi Sedatha, Inethiwekhi, Ezokuthutha, Iseshini, Isethulo kanye Nokusebenza).