Saitin Haɗin TCP
Lokacin da muke lilo a yanar gizo, aika imel, ko kunna wasan kan layi, sau da yawa ba ma tunanin haɗaɗɗiyar hanyar sadarwar da ke bayansa. Duk da haka, waɗannan ƙananan matakai ne ke tabbatar da ingantaccen sadarwa tsakaninmu da uwar garken. Ɗaya daga cikin matakai mafi mahimmanci shine saitin haɗin TCP, kuma ainihin wannan shine musafaha ta hanyoyi uku.
Wannan labarin zai tattauna ƙa'ida, tsari da mahimmancin musafaha ta hanyoyi uku dalla-dalla. Mataki-mataki, za mu bayyana dalilin da yasa ake buƙatar musafaha ta hanyoyi uku, yadda yake tabbatar da kwanciyar hankali da aminci, da kuma yadda yake da mahimmanci don canja wurin bayanai. Tare da zurfin fahimtar hanyar musafiha ta hanyoyi uku, za mu sami kyakkyawar fahimta game da tushen hanyoyin sadarwa na cibiyar sadarwa da kuma kyakkyawar ra'ayi game da amincin haɗin TCP.
TCP Tsarin Hannun Hannu na Hanyoyi uku da Juyin Jiha
TCP ka'idar sufuri ce ta hanyar sadarwa, wacce ke buƙatar kafa haɗin kai kafin watsa bayanai. Ana yin wannan tsarin kafa haɗin kai ta hanyar musafaha ta hanyoyi uku.
Bari mu dubi fakitin TCP da aka aika a kowace haɗi.
Da farko, duka abokin ciniki da uwar garken suna RUFE. Na farko, uwar garken tana saurare sosai akan tashar jiragen ruwa kuma tana cikin yanayin LISTEN, wanda ke nufin cewa dole ne a fara sabar. Na gaba, abokin ciniki yana shirye don fara shiga shafin yanar gizon.Yana buƙatar kafa haɗi tare da uwar garke. Tsarin fakitin haɗin farko shine kamar haka:
Lokacin da abokin ciniki ya ƙaddamar da haɗi, yana haifar da lambar jeri na farko bazuwar (client_isn) kuma ya sanya shi cikin filin "lambar jeri" na taken TCP. A lokaci guda, abokin ciniki yana saita alamar tutar SYN zuwa 1 don nuna cewa fakitin mai fita fakitin SYN ne. Abokin ciniki yana nuna cewa yana son kafa haɗi tare da uwar garken ta hanyar aika fakitin SYN na farko zuwa uwar garken. Wannan fakitin ba ya ƙunshi bayanan Layer na aikace-aikacen (wato, bayanan da aka aiko). A wannan gaba, ana yiwa matsayin abokin ciniki alama azaman SYN-SENT.
Lokacin da uwar garken ta karɓi fakitin SYN daga abokin ciniki, ba da gangan ba ta fara fara lambar serial ɗin ta (server_isn) sannan ta sanya wannan lambar a cikin filin "Serial number" na taken TCP. Bayan haka, uwar garken yana shigar da client_isn + 1 a cikin filin "Acknowledgement Number" kuma ya saita duka SYN da ACK bits zuwa 1. A ƙarshe, uwar garken yana aika fakitin ga abokin ciniki, wanda ba ya ƙunshi bayanan aikace-aikacen-Layer (kuma babu bayanai don uwar garken). a aika). A wannan lokacin, uwar garken yana cikin jihar SYN-RCVD.
Da zarar abokin ciniki ya karɓi fakiti daga uwar garken, yana buƙatar aiwatar da abubuwan haɓakawa masu zuwa don amsa fakitin amsa ta ƙarshe: Na farko, abokin ciniki ya saita ACK bit na taken TCP na fakitin amsa zuwa 1; Na biyu, abokin ciniki ya shigar da ƙimar uwar garken_isn + 1 a cikin filin "Tabbatar da lambar amsa"; A ƙarshe, abokin ciniki yana aika fakitin zuwa uwar garken. Wannan fakiti na iya ɗaukar bayanai daga abokin ciniki zuwa uwar garken. Bayan kammala waɗannan ayyuka, abokin ciniki zai shiga cikin KAFA KAFA.
Da zarar uwar garken ta karɓi fakitin amsawa daga abokin ciniki, ita ma tana canzawa zuwa MATSAYIN JIHAR.
Kamar yadda kake gani daga tsarin da ke sama, lokacin yin musafiha ta hanyoyi uku, musafaha na uku yana ba da izinin ɗaukar bayanai, amma musafaha biyu na farko ba. Wannan tambaya ce da ake yawan yi a cikin hira. Da zarar an kammala musabaha ta hanyoyi uku, sai bangarorin biyu su shiga ESTABLISHED jihar, wanda ke nuni da cewa an samu nasarar kafa hanyar sadarwa, inda abokin ciniki da uwar garken za su iya fara aika bayanai ga junansu.
Me yasa musafiha uku? Ba sau biyu ba, sau hudu?
Amsar gama-gari ita ce, "Saboda musafaha ta hanyoyi uku yana ba da tabbacin ikon karɓa da aikawa." Wannan amsar daidai ce, amma dalili ne kawai, bai gabatar da babban dalili ba. A cikin wadannan, zan yi nazari kan dalilan musafaha da musabaha sau uku daga bangarori uku domin zurfafa fahimtar wannan batu.
Hannun hannu guda uku na iya guje wa farawar haɗin kai da aka maimaita a tarihi (babban dalili)
Hannun hannu guda uku yana ba da tabbacin cewa ɓangarorin biyu sun sami amintaccen lambar jerin farko.
Hannun hannu guda uku yana guje wa ɓarna albarkatu.
Dalili na 1: Guji Haɗin Rubutun Tarihi
A taƙaice, babban dalilin yin musafaha ta hanyoyi uku shi ne don guje wa ruɗani da ke haifar da tsohuwar haɗin haɗin gwiwa. A cikin mahalli mai sarƙaƙƙiya, ba koyaushe ana aika watsa fakitin bayanai zuwa mai masaukin baki daidai da ƙayyadadden lokacin, kuma tsofaffin fakitin bayanai na iya isa wurin masaukin da farko saboda cunkoson cibiyar sadarwa da wasu dalilai. Don guje wa wannan, TCP yana amfani da musafaha ta hanyoyi uku don kafa haɗin gwiwa.
Lokacin da abokin ciniki ya aika fakitin kafa haɗin SYN da yawa a jere, a yanayi kamar cunkoson hanyar sadarwa, mai zuwa na iya faruwa:
1- Tsofaffin fakitin SYN sun isa uwar garken kafin sabbin fakitin SYN.
2-Server zai amsa fakitin SYN + ACK ga abokin ciniki bayan ya karɓi tsohuwar fakitin SYN.
3- Lokacin da abokin ciniki ya karɓi fakitin SYN + ACK, yana ƙayyade cewa haɗin haɗin haɗin gwiwa ne na tarihi (lambar lamba ta ƙare ko ƙarewa) gwargwadon yanayinta, sannan a aika fakitin RST zuwa uwar garken don cire haɗin.
Tare da haɗin gwiwar hannu biyu, babu wata hanyar da za a iya tantance ko haɗin na yanzu haɗin tarihi ne. Hannun hannu guda uku yana bawa abokin ciniki damar tantance ko haɗin yanzu haɗin gwiwa ne na tarihi dangane da mahallin lokacin da ya shirya don aika fakiti na uku:
1- Idan haɗin tarihi ne (lambar lamba ta ƙare ko ƙarewa), fakitin da aka aiko ta hannun musafaha na uku fakitin RST ne don soke haɗin tarihi.
2- Idan kuma ba alakar tarihi ba ce, fakitin da aka aika a karo na uku fakitin ACK ne, kuma bangarorin biyu sun samu nasarar kulla alaka.
Saboda haka, babban dalilin da TCP ke amfani da musafiha ta hanyoyi uku shine ya fara haɗin gwiwa don hana haɗin tarihi.
Dalili 2: Don daidaita lambobin farko na ɓangarorin biyu
Duk bangarorin biyu na yarjejeniyar TCP dole ne su kula da lambar jeri, wanda shine mabuɗin mahimmanci don tabbatar da ingantaccen watsawa. Lambobin jeri suna taka muhimmiyar rawa a haɗin TCP. Suna yin haka:
Mai karɓa zai iya kawar da kwafin bayanai kuma ya tabbatar da daidaiton bayanan.
Mai karɓa zai iya karɓar fakiti a cikin tsari na lambar jeri don tabbatar da amincin bayanan.
Lambar jeri na iya gano fakitin bayanan da ɗayan ɓangaren ya karɓa, yana ba da damar ingantaccen watsa bayanai.
Saboda haka, bayan kafa haɗin TCP, abokin ciniki ya aika fakitin SYN tare da lambar jerin farko kuma yana buƙatar uwar garken ya ba da amsa tare da fakitin ACK da ke nuna nasarar karɓar fakitin SYN na abokin ciniki. Sa'an nan, uwar garken aika fakitin SYN tare da farkon jerin lambar ga abokin ciniki da kuma jira abokin ciniki ya ba da amsa, sau ɗaya kuma gaba ɗaya, don tabbatar da cewa farkon jerin lambobin an daidaita aiki tare.
Kodayake musafaha ta hanyoyi huɗu kuma yana yiwuwa a dogara aiki tare da lambobi na farko na ɓangarorin biyu, ana iya haɗa matakai na biyu da na uku zuwa mataki ɗaya, yana haifar da musafaha ta hanyoyi uku. Sai dai musafaha biyu na iya ba da tabbacin cewa lambar farko ta ɗaya jam'iyya ta samu nasarar karɓo daga ɗayan ɓangaren, amma babu tabbacin cewa za a iya tabbatar da adadin farkon jerin bangarorin biyu. Saboda haka, musafiha ta hanyoyi uku shine mafi kyawun zaɓi don ɗauka don tabbatar da kwanciyar hankali da amincin haɗin TCP.
Dalili na 3: Gujewa Almubazzaranci
Idan kawai akwai "musafaha biyu", lokacin da aka toshe buƙatar SYN abokin ciniki a cikin hanyar sadarwa, abokin ciniki ba zai iya karɓar fakitin ACK da uwar garken ya aika ba, don haka SYN za ta yi fushi. Koyaya, tunda babu musafaha na uku, uwar garken ba zai iya tantance ko abokin ciniki ya sami amincewar ACK don kafa haɗin. Don haka, uwar garken na iya kafa haɗin kai da ƙarfi bayan an karɓi kowace buƙatar SYN. Wannan yana haifar da abubuwa masu zuwa:
Sharar da albarkatu: Idan an toshe buƙatar SYN na abokin ciniki, yana haifar da maimaita watsa fakitin SYN da yawa, uwar garken zai kafa haɗin kai mara inganci da yawa bayan karɓar buƙatar. Wannan yana haifar da asarar albarkatun uwar garke mara amfani.
Riƙewar saƙo: Saboda rashin musafaha na uku, uwar garken ba ta da hanyar sanin ko abokin ciniki ya sami amincewar ACK daidai don kafa haɗin. Sakamakon haka, idan saƙonnin sun makale a cikin hanyar sadarwar, abokin ciniki zai ci gaba da aika buƙatun SYN akai-akai, yana sa uwar garke ta kafa sabbin hanyoyin sadarwa koyaushe. Wannan zai ƙara cunkoson cibiyar sadarwa da jinkiri kuma yana tasiri mara kyau ga aikin cibiyar sadarwa gabaɗaya.
Don haka, don tabbatar da kwanciyar hankali da amincin haɗin yanar gizon, TCP yana amfani da musafaha ta hanyoyi uku don kafa haɗin gwiwa don guje wa faruwar waɗannan matsalolin.
Takaitawa
TheDillalan Fakitin hanyar sadarwaAna yin kafa haɗin TCP tare da musafaha ta hanyoyi uku. Yayin musafaha ta hanyoyi uku, abokin ciniki ya fara aika fakiti mai alamar SYN zuwa uwar garken, yana nuna yana son kafa haɗin gwiwa. Bayan karɓar buƙatun daga abokin ciniki, uwar garken yana amsa fakiti tare da tutocin SYN da ACK ga abokin ciniki, yana nuna cewa an karɓi buƙatar haɗin kai, kuma ta aika lambar jerin farkon ta. A ƙarshe, abokin ciniki yana ba da amsa da tutar ACK zuwa uwar garken don nuna cewa an sami nasarar kafa haɗin. Don haka, bangarorin biyu suna cikin KAFARAR KAFA kuma suna iya fara aika bayanai ga junansu.
Gabaɗaya, tsarin musafaha na uku don kafa haɗin haɗin TCP an tsara shi don tabbatar da kwanciyar hankali da aminci, guje wa rikicewa da ɓarna albarkatu akan haɗin gwiwar tarihi, da kuma tabbatar da cewa bangarorin biyu sun sami damar karɓa da aika bayanai.
Lokacin aikawa: Janairu-08-2025
