Abin da ba ya aiki a matakin cibiyar sadarwa? Bisa ga tambayar da ta gabata, ka rubuta mahallin da ke ɗauke da amsar. Zai iya zama jumla 1 - 20. Abubuwan da ke ciki:
Dukansu X.25 da Frame Relay samar da connection-daidaitacce aiki. Amma X.25 ya aikata shi a cibiyar sadarwa Layer na OSI Model. Frame Relay ya yi shi a mataki na biyu, da bayanan link Layer. Wani babban bambanci tsakanin X.25 da Frame Relay shine cewa X.25 yana buƙatar musafiha tsakanin ɓangarorin sadarwa kafin a watsa kowane fakitin mai amfani. Frame Relay ba ya bayyana irin wannan hannun hannu. X.25 ba ya ayyana kowane aiki a cikin hanyar sadarwar fakiti. Yana aiki ne kawai a mai amfani-cibiyar sadarwa dubawa (UNI). Saboda haka, mai ba da hanyar sadarwa yana da 'yanci don amfani da duk wata hanya da yake so a cikin hanyar sadarwa. X.25 yana ƙayyade wasu ƙayyadaddun hanyoyin sake watsawa a UNI, kuma yarjejeniyar haɗin haɗin (LAPB) tana ba da hanyoyin haɗin haɗin haɗin HDLC na al'ada. Frame Relay sigar gyare-gyare ce ta ISDN ta Layer biyu yarjejeniya, LAPD da LAPB. Saboda haka, ayyukansa na mutunci sun shafi kawai tsakanin nodes a kan hanyar haɗi, ba ƙarshen-zuwa-ƙarshe ba. Duk wani retransmissions dole ne a za'ayi ta hanyar mafi girma Layer ladabi. Yarjejeniyar X.25 UNI wani ɓangare ne na yarjejeniyar yarjejeniyar X.25, wanda ya ƙunshi ƙananan matakan uku na OSI Model. An yi amfani da shi sosai a UNI don hanyoyin sadarwa na canzawa a cikin 1980s da farkon 1990s, don samar da daidaitaccen hanyar shiga da fita daga hanyoyin sadarwa. Wasu aiwatarwa amfani da X.25 a cikin cibiyar sadarwa da, amma ta connection-daidaitacce fasali sanya wannan saitin m da kuma rashin inganci. Frame relay yana aiki da farko a Layer biyu na OSI Model. Koyaya, ana iya amfani da filin adireshinsa (ID ɗin Haɗin Haɗin Bayanai, ko DLCI) a layin cibiyar sadarwar OSI, tare da ƙaramin tsari. Ta haka ne, yana kawar da kansa da yawa na X.25 Layer 3 masu ɗaukar nauyi, amma har yanzu yana da DLCI a matsayin ID fiye da yarjejeniya ta hanyar haɗin gwiwa na biyu. Sauƙin Frame Relay ya sa ya fi sauri da inganci fiye da X.25. Saboda Frame relay ne mai data link Layer yarjejeniya, kamar X.25 shi ba ya ayyana ciki cibiyar sadarwa routing ayyukan. Domin X.25 da fakiti IDs --- da rumfa kewaye da rumfa tashar lambobin da za a correlated to...