Ukubala iphakethe elilodwa le-G.729 ngomhubhe we-IPsec

Izwi phezu kwe-IPsec lisho i-bitrate ye-codec, futhi lelo nombolo alilungile emngceleni ngamunye ngaphandle komngcele we-codec ngokwayo. Umsindo ngu-8 kbit/s, iphakethe eliwuthwalayo likhulu, umgqomo we-ESP mkhulu nakakhulu, futhi uhlaka lwe-Ethernet lwengeza ukufakwa kozimele okungeke kuboniswe yinoma ikuphi ukubanjwa emhubheni. Ukubala iphakethe elilodwa kusukela kufomethi eshiwo yiyo kuphela indlela yokwazi ukuthi isixhumanisi somzimba kufanele sithwale ini ngempela. Ukuhamba ngezansi kwenza lokho ngendlela eyodwa kuphela, futhi yonke inombolo lapha iwukubala, hhayi isilinganiso.

Qala ngokukhetha ukupakisha, hhayi ngenombolo ye-codec

Ithebula le-codec linikeza izinga lomthwalo futhi akukho okunye: i-G.729 ikhipha u-8 kbit/s, okuyibhayithi ezingu-30 zomsindo njalo nge-30 ms. Ayisho lutho mayelana namakhanda, ukuvikelwa noma ukufakwa kozimele, futhi lezi zintathu zilawula umphumela. Isikhala siwukukhetha kwenqubomgomo okufanele kuvunyelwane ngakho yizinhlangothi zombili, ngakho-ke kukhethe kuqala futhi ukusho, ngoba yonke inombolo elandelayo incike kuleso sinqumo esisodwa.

Lesi sibonelo sisebenzisa u-30 ms, ngakho-ke izinga lamaphakethe lingu-33.3 ngomzuzwana. Sicabanga ikhanda le-RTP lamabhayithi angu-12, ikhanda le-UDP lamabhayithi angu-8 kanye nekhanda le-IPv4 langaphakathi lamabhayithi angu-20 ngaphandle kwezinketho, futhi akukho i-SRTP, ukucindezelwa kwamakhanda noma ukugcwaliswa kokuyimfihlo kokugeleza kwethrafikhi; noma yiluphi ushintsho luhambisa isabelomali kanye nalo, ngakho-ke izicabango kufanele zibe eceleni kwempendulo.

Engeza amakhanda angaphakathi, bese kuba umgqomo we-ESP

Uhlelo luthumela umthwalo kanye ne-RTP kanye ne-UDP kanye ne-IP, okuyibhayithi ezingu-70 kulokhu kupakisha. Lokho kugeleza kwangaphakathi kuphuma ku-18.7 kbit/s, kakade ngaphezu kokuphindwe kabili kwezinga le-codec, ngoba amakhanda hhayi umsindo akha ingxenye enkulu yephakethe. Akukho nelilodwa kulawa mabhayithi okuyizwi; ayintengo yokukhomba nokuhlela. Ukubanjwa okuthathwe ngaphezulu komhubhe kubonisa ngqo le nombolo, futhi yiyo abantu abayicaphunayo uma bethi ucingo luncane.

Iphinde ibe yinombolo engafiki ocingweni. Imodi yomhubhe ye-ESP yengeza i-SPI kanye nenombolo yokulandelana yamabhayithi angu-8, i-IV ecacile yamabhayithi angu-8 ye-AES-GCM, umsila wamabhayithi angu-2 kanye nomaka wokuqinisekisa wamabhayithi angu-16. Umthwalo wamabhayithi angu-70 kanye nomsila kufinyelela ku-72, osekuvele kuhlangabezana nokulinganiswa kwamabhayithi amane, ngakho-ke akudingeki ukugcwaliswa okwengeziwe lapha.RFC 4106 ichaza osayizi be-IV nomaka we-GCM, futhi kokubili kungokokubala, hhayi umbhalo waphansi:

30  payload, G.729 at 30 ms
12  RTP
 8  UDP
20  inner IPv4
--
70  inner IP packet
 8  ESP SPI and sequence
 8  explicit IV
 2  pad length and next header
16  authentication tag
--
104 ESP packet

Engeza amakhanda angaphandle adingwa ukudlula kwe-NAT

Ngaphandle komgqomo we-ESP kukhona ikhanda le-IPv4 langaphandle lamabhayithi angu-20 kanye nekhanda le-UDP lamabhayithi angu-8 lokudlula kwe-NAT, ngakho-ke iphakethe liba amabhayithi angu-132. Ukufakwa kwe-UDP kukhona ngoba iphakethe kufanele lidlule idivayisi yokuhumusha phakathi kozakwabo, futhi lishintsha isimo sangaphandle ngaphandle kokuthinta umthwalo ovikelwe. Ku-33.3 amaphakethe ngomzuzwana, amabhayithi angu-132 acishe abe ngu-35.2 kbit/s, okungaphezu kokuphindwe kane kwezinga elijwayelekile le-codec.

Noma umaka noma i-IV akukwazi ukususwa esilinganisweni ukuze kwenziwe lincane, ngoba kokubili kuyingxenye yalokho isixhumanisi esizokuthwala ngempela. Isilinganiso esishiya ngaphandle kukho sichaza iphakethe umamukeli angalilahla. Kuyafana nomsila, okhona ukumaka umngcele womthwalo kanye nekhanda elilandelayo ngaphakathi kwesifunda esivikelwe.

Qamba umngcele ngaphambi kokucaphuna inombolo

Inombolo ye-IP yangaphandle ayikafaki ukufakwa kozimele kwe-Ethernet. Isixhumanisi sokufinyelela esinethegi noma esingenalo sengeza ikhanda le-MAC lamabhayithi angu-14 kanye nokulandelana kokuhlola uhlaka kwamabhayithi angu-4, lenze uhlaka lube amabhayithi angu-150, okuyisilinganiso esibalwa yimbobo yesishintshi. Ngezinga elifanayo lamaphakethe lokho ngu-40 kbit/s, ngokuphindwe kahlanu kwezinga le-codec, futhi umehluko awukona ukumosha kodwa yintengo yokuthutha.

Inombolo engu-40 kbit/s ayikafaki isandulela, isikhala phakathi kwezinhlaka, amathegi e-VLAN, ukufakwa komhlinzeki, i-RTCP, ukusayina kanye nomsindo ohamba ngakolunye uhlangothi. Lesi isilinganiso ngendlela ngayinye, hhayi ukubekelwa isixhumanisi, futhi ukusicaphuna njengokubekelwa kudlulela ekutheni isixhumanisi kufanele sigcine kangakanani endaweni eyodwa ngenkathi sinciphisa kwenye. Ukubanjwa kusibungu nakho kungaphuthelwa ukufakwa kozimele okwengezwa isixhumanisi, ngakho-ke umngcele kufanele uqanjwe eceleni kwenombolo, futhi yingakho ithebula lemigcele liwusizo ukudlula inombolo eyodwa yesihloko. Gcina ngokwehlukile uhlangothi ongalubalanga.

Hlola ukubala ngokumelene ne-interface

Ngaphambi kokuthemba isilinganiso, siqhathanise nalokho i-interface ekubikayo ngenani elaziwayo lamaphakethe. Bhanga ku-interface yomzimba hhayi kudivayisi yomhubhe, ukuze ukufakwa kozimele ozama ukukubala kufakwe, futhi ulindele umehluko omncane hhayi ukuvumelana okuphelele.

sudo tcpdump -ni eth0 -c 50 'udp port 4500'
ip -s link show eth0

Ukubanjwa kuqinisekisa usayizi wephakethe langaphandle, kuyilapho izibali ze-interface zibonisa izinga kufakwe nokufakwa kozimele. Uma zombili zehluka cishe ngokwesilinganiso se-Ethernet, ukubala kulungile futhi umngcele kuphela owaqanjwa kabi. Umehluko omkhulu kakhulu kunekhanda elilodwa lohlaka ukhomba kokunye okusixhumanisini, njengokuthumela kabusha noma okunye ukugeleza okwabelana nge-interface. Bhala isikhala sokupakisha, isethi yokuvikelwa kanye nomngcele eceleni kwenombolo, ngoba isilinganiso esingenakho lokho kuthathu sicashunwa njengesilinganiso ngumfundi olandelayo.