Ukuqonda i-UDP nokuthi ihluke kanjani ku-TCP
I-Protocol Datagram Protocol (UDP) yasungulwa ngo-1980 futhi ingenye yezinhlelo zokuqala zenethiwekhi ezikhona. Kuyindlela elula yokuthutha yokuthutha ye- OSI yezinhlelo zokusebenza zenethiwekhi yamakhasimende / iseva, isekelwe kwi- Inthanethi Protocol (IP) , futhi iyindlela ehlukile ye- TCP .
Incazelo encane ye-UDP ingase ichaze ukuthi kuyindlela yokwethenjwa engathembeki uma kuqhathaniswa ne-TCP. Nakuba lokho kuyiqiniso, njengoba kungekho siphambeko sokuhlola noma ukulungisa okuhilelekile ekuthunyeleni kwedatha, kuyiqiniso futhi ukuthi kukhona izicelo zokusebenza kule protocol ukuthi i-TCP ayikwazi ukufanisa.
U-UDP (ngezinye izikhathi obizwa ngokuthi i-UDP / IP) uvame ukusetshenziswa emisebenzini yezinkomfa zevidiyo noma imidlalo yekhompiyutha eyenziwa ngokuqondile ukusebenza kwesikhathi sangempela. Ukufeza ukusebenza okuphezulu, le protocol ivumela amaphakethe ngamunye ukuba ahlehliswe (ngaphandle kokuzama) namaPhakethe we-UDP ukuthi atholakale ngendlela ehlukile kunalokho ayithunyelwe, njengoba kuchazwa isicelo.
Le ndlela yokudlulisela, uma kuqhathaniswa ne-TCP, ivumela idatha encane ngaphezulu futhi ibambezelekile. Njengoba amaphakethe athunyelwa kungakhathaliseki ukuthi yikuphi, futhi akukho ukubuka okuphutha okubandakanyekayo, kuphumela ekusebenziseni umkhawulokudonsa ongaphansi.
Ingabe i-UDP ingcono kuneTCP?
Impendulo yalo mbuzo ixhomeke kumongo ngoba iDP ivumela ukusebenza okungcono, kodwa izinga elibi kakhulu, kune-TCP.
Isibonelo esihle lapho u-UDP angase ukhethwe ngaphezu kwe-TCP uma kuziwa kwisicelo esenza kangcono nge- latency encane, njengokudlala kwe-intanethi, ukuxoxa ngevidiyo, noma ukuthumela ngezwi. Amaphakethe angahle alahleke, kodwa ngokunciphisa okuncane ukunciphisa ikhwalithi, akukho ukulahleka kwekhwalithi okuningi okubonakalayo.
Ngokudlala kwe-intanethi, ukuhamba kwe-UDP kuvumela umdlalo ukuthi uqhubeke ngisho noma uxhumano lulahlekile okwesikhashana, noma uma amanye amaphakethe elahliwe nganoma yisiphi isizathu. Uma ukulungiswa kwephutha kuhilelekile, ukuxhumeka kuzolahlekelwa isikhathi ngoba amaphakethe azama ukufaka kabusha lapho ayeke khona ukwenza amaphutha, kodwa akudingekile emidlalweni yevidiyo ebukhoma. Kuyafana nokusakaza bukhoma.
Kodwa-ke, isizathu sokuthi u-UDP akakhulu kakhulu uma kuziwa ekudlulisweni kwefayela ukuthi udinga ifayela lonke ukuze ulisebenzise kahle. Nokho, awudingi iphakethe ngalinye lomdlalo wevidiyo noma ividiyo ukuze ujabulele.
Kokubili i-TCP ne-UDP kuzinhlaka ezingu-4 ze-OSI model bese usebenza nezinsizakalo ezifana ne- TFTP , i-RTSP, ne- DNS .
Ama-UDP Datagrams
Idrayivu ye-UDP isebenzisa lokho okubizwa ngokuthi i-datagrams, nayo yonke imininingwana ehlanganisa i-unit unit eyodwa. Imininingwane yekhanda igcinwe kuma-bytes ayisishiyagalombili okuqala, kodwa okunye okugcina umyalezo wangempela.
Ingxenye ngayinye yenhloko ye-UDP datagram, efakwe lapha, yi- bytes amabili:
- Inombolo yesipredithi yomthombo
- Inombolo yesibalo sokufika
- Usayizi weDatagram
- I-Checksum
Izinombolo zezinombolo ze- UDP zivumela izinhlelo zokusebenza ezahlukene ukugcina iziteshi zabo zedatha, efana ne-TCP. Izinhloko ze-port ze-UDP ziyi-bytes ezimbili eside; Ngakho-ke, izinombolo zezindiza ze-UDP ezisukela ku-0 kuya ku-65535.
Usayizi we-datagram we-datagram ubalwa inani eliphelele lama-bytes equkethwe ezihlokweni zenhloko kanye nedatha. Njengoba ubude bekhanda buyingayizi ehleliwe, le nsimu ilandelela ngokuphumelelayo ubude besabelo sezinombolo eziguquguqukayo (ngezinye izikhathi esibizwa nge-payload).
Ubukhulu bama datagram buhluka kuye ngokuvumelana nemvelo yokusebenza, kodwa banamaphesenti angama-65535 bytes.
Ama- checksums e- UDP avikela idatha yomlayezo kusuka ekudambiseni. Inani le-checksum limelela ikhodi yedatha ye-datagram ebalwa kuqala ngomthumeli futhi kamuva ngomamukeli. Uma i-datagram ngayinye inganqotshwa noma ilahlekelwe ngesikhathi sokudluliselwa, i-protocol ye-UDP ithola ukungahambisani kokubala kokuhlola.
E-UDP, ukuhlolwa kokuzikhethela kuyindlela yokuzikhethela, ngokuphambene ne-TCP lapho kuhlolwa khona ama-checksums.