Kungani i-multicast ingaweli i-VPN ngaphandle kohlelo

Iziza ezimbili zingafinyelelana ngokuphelele nge-unicast futhi ziphathwe sengathi enye yazo ayiboni isimemezelo sokutholakala kwephrinta, ukugeleza kwe-IPTV noma ukushaya kwenhliziyo kweqoqo. Lona akulona umhubhe ophukile; umehluko phakathi kwendawo ekuyiwa kuyo neqembu. Ukulethwa kwe-multicast kudinga imodeli yobulungu, isimo sokudlulisa endaweni yonke yomzila kanye nesixhumi esibonakalayo esizimisele ukuthwala ithrafikhi, futhi akukho kulokhu okuvela emzileni we-unicast. Ukusuka eqenjini lohlelo lokusebenza kuya kumamukeli oyedwa osebenzayo kuwumzila omfushane kakhulu wokuphendula.

Qala ngeqembu kanye nohlelo lokusebenza

Buza ukuthi uhlelo lokusebenza lusebenzisa yiphi ikheli leqembu nokuthi ithrafikhi iyenzeni. Iphrothokholi yokutholakala ekhangisa izinsizakalo, ukugeleza kokusakaza kanye namaphakethe okuhalalisela ephrothokholi yomzila kuyizinkinga ezintathu ezihlukene ezinezimpendulo ezintathu ezihlukene ezamukelekayo. Ikheli leqembu ngokwalo lisho ububanzi: amakheli akublokhi yokulawula inethiwekhi yasekhaya awenzelwe ukudluliselwa ngaphandle kwesixhumanisi ngomzila ojwayelekile, futhi izinhlelo ezisebenzisa wona ngokuvamile zithatha isizinda esisodwa sokusakaza. Ukugeleza kokusakaza eqenjini elinobubanzi bomhlaba wonke kuwumklamo ohlukile kunephrothokholi yokutholakala elindele ukuthi idivayisi ngayinye izwe umbuzo ngamunye, futhi eyokugcina kuphela ekhathazekayo ngosayizi wesizinda sokusakaza.

Nquma ukuthi isidingo umsebenzi noma indlela yokutholakala, ngoba lezo zimpendulo zihluke ngezindleko ngezinga elilodwa. Enye icela ikheli elingashintshi; enye icela isizinda sokusakaza esinwetshwe phezu kwesixhumanisi sendawo ebanzi kanye nakho konke okulandela lokho.

Ukutholakala kwasekhaya kufanele kume

I-Multicast DNS njengoba ichaziwe ku-RFC 6762 yakhelwe isixhumanisi esisodwa: imibuzo iya eqenjini eliqinile, izimpendulo zithunyelwa eqenjini elifanayo, futhi iphrothokholi incike ekutheni umhlanganyeli ngamunye ezwe wonke umuntu. Amaroutha awakudlulisi lokho kugeleza ngokuzenzakalela, futhi lokho kuyisinqumo somklamo hhayi ukukhohlwa. Umngcele ukhona ukuze idivayisi esakhiweni esisodwa ingakwazi ukuzimemezela ngokukhululekile kwesinye. Umhubhe obonakala ulungisa ukutholakala ngokuthwala iqembu yonke indawo usususe lowo mngcele kuhlelo lokusebenza ngalunye, hhayi kuphela lolo olwaludinga usizo.

Izimpinda kanye nezibonisi zikhona, futhi ziyizinsizakalo zangempela ezinemiphumela yangempela: yonke igama elimenyezelwa endaweni eyodwa ibonakala kwenye, kuhlanganise namagama edivayisi akhomba abantu noma izinto zokusebenza. Uma isidingo sangempela siwukuthi insizakalo ethile itholakale, irekhodi lensizakalo elishicilelwe ku-DNS ngokuvamile wushintsho oluncane, futhi lethula igama elilodwa esikhundleni sokugeleza kwamagama.

Izinto ezintathu ezidingwa yi-multicast enomzila

I-multicast enomzila idinga izinto ezintathu ezisebenza ndawonye: abamukeli abajoyina iqembu, amaroutha agcina isimo sokudlulisa salo, kanye nomhubhe obheka amakheli eqembu njengethrafikhi okufanele ithwalwe. Umhubhe onomgomo obala kuphela ama-subnet e-unicast uzowisa ithrafikhi yeqembu emngceleni wokubethela, yingakho uphawu lokuqala ngokuvamile luwukuthula hhayi iphutha. Isixhumi esisekelwe emizileni esifana nomhubhe we-GRE noma we-VTI sithwala lokho okuthunyelwa yithebula yomzila kuso, okwenza iqembu lifinyeleleke uma isimo se-multicast sikhona.

Ukufinyeleleka komthombo ingxenye yesibili. Amaphrothokholi omzila we-multicast afana ne-PIM akha izihlahla zokusabalalisa ngokuhlola ukuthi indlela ebuyela emthonjeni yileyo elindelekile, ngakho umzila we-unicast okhomba kwenye indawo uphula isihlahla ngisho lapho ubulungu beqembu bulungile. Ukufaka umzila womamukeli akusizi lutho kulokho kuhlola, futhi yilona phutha elikhiqiza i-ping esebenzayo nokugeleza okwehlulwayo. Qinisekisa kuqala indlela yokubuya yomthombo, bese wengeza ubulungu, futhi bese ubheka uhlelo lokusebenza ngemuva kwalokho.

ip maddr show dev tun0
ip mroute show
ss -gnu | grep 239.255.0.10
ip route get 10.20.5.20

Imigqa emibili yokuqala ibonisa ukuthi isibungu sijoyine ini nokuthi i-kernel idlulisa ini, owesithathu ubonisa ubulungu bohlelo lokusebenza ngokwalo, futhi owokugcina ubonisa umzila we-unicast ozosetshenziswa ukuhlola komzila ophambene. Ukuzifunda ndawonye kuhlukanisa uhlelo lokusebenza olungakaze lujoyine kunethiwekhi engakaze idlulise.

Kufakazele ngomthombo owodwa nomamukeli oyedwa

Ngaphambi kokuthinta ukucushwa, qinisekisa ukuthi uhlelo lokusebenza lusebenza esigabeni esisodwa. Uma lwehluleka endaweni, umzila we-multicast akulona inkinga futhi akukho shintsho lomhubhe oluzosiza. Bese uphinda ngomamukeli oyedwa unqamula umhubhe futhi ubheke amaphakethe ezinhlangothini zombili zomngcele wokubethela.

tcpdump -ni tun0 -c 10 'ip multicast'
tcpdump -ni eth0 -c 10 'ip multicast and host 239.255.0.10'

Amaphakethe abonakala ngaphakathi komhubhe kodwa engekho ngaphandle abonisa ukugoqa noma umgomo; amaphakethe abonakala ezinhlangothini zombili kodwa uhlelo lokusebenza lungaqhubeki abonisa ubulungu bomamukeli noma ukubopha kohlelo lokusebenza. Gcina ukuthwebula kufushane futhi kuhlungiwe, ngoba ukuthwebula kwe-multicast okubanzi esigabeni esimatasa ngokuvamile umsindo.

Khetha ikheli lomsebenzi uma kudingeka umsebenzi kuphela

Ukutholakala kukhona ukuze kutholakale into ehambayo. Iseva enegama elizinzile ayidingi ukutholakala, futhi ikheli elibhalwe ku-DNS yangasese liphendula umbuzo wangempela womsebenzisi ngaphandle kokunweba isizinda sokusakaza phezu kwesixhumanisi sendawo ebanzi. Umqondo ofanayo usebenza kumaphrinta, izinto zokusebenza kanye nezinsizakalo zewebhu zangaphakathi. Igama eliku-DNS lifinyeleleka kusuka kuyo yonke indawo elidingayo ngenkathi lingamemezeli lutho izindawo ezingalidingi, futhi liyaqhubeka nokusebenza uma idivayisi ishintshwa ngenye enekheli elihlukile.

Uma iphrothokholi idinga ngempela i-multicast, yikhawulele eqenjini nasezindaweni ezilidingayo, bhala ukuthi kungani, futhi uphinde ubuyekeze isinqumo uma uhlelo lokusebenza lushintsha. Ukunweba ukutholakala yonke indawo kulula kanye, futhi kunzima ukukuhoxisa ngemuva konyaka wedivayisi ezincike kukho buthule.