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C huong GIAO THLfC DIEU KHIEN CONG PHUONG TIEN - MEGACO/H.248 6.1 G l l THI$U CHUNG vfi GIAO THtfC Bltu KHlfhs c6 n G PHUONG TlfN Dfiu nam 1998 nhidu nha nghien curu cung nhu cac nha dieu hanh m ang da dua mdt so giao thirc didu khien cong phuang tidn khac (M GCP cua IETF, M DCP cua ITU-T )- M ac du nhu c5u ve m dt giao thurc didu khidn cdng phuang tidn ia r&l ro rang nhung khdng co giao thurc nao nhan duac su ung hd hoan toan Tdi cud'i nam 1998, IETF lap nhom nghien cun v i giao thurc di6u khien cdng phuang tidn M EGACO (M Egaco GAteway Control working group) vdi nhidm vu xay dung m dt tidu chuan md trdn co sd IP dua trdn nguydn ly chu/td de’ di6u khien cac cdng phuang tidn, Nortel Network la td chuc dung ddu nhom Nhom nghien curu da lira chon cac uu diem cua hai giao thurc tidn than M GCP va MDCP, ddng thdi bo sung cac tfnh nang tang cudng, tdi thang nam 1999, Nortel Network chinh thurc cdng bd ve m dt giao thurc dieu khien c6ng phuang tien mdi MEGACO Song song vdi cac nd luc cua IETF viec xay dung giao thurc M EGACO, vao thang nam 1999 nhom nghien curu 16 (S G I6 - study group 16) cua ITU -T cung khdi xudng mdt du an xay dung giao thurc dieu khien cdng phuang tidn GCP, sau la giao thurc H.248 Cung vao m ua he nam dd, hiep dinh ve vide xay dung m dt chu£n quoc td' M EGACO/H.248 cung duac ky ket giua hai td churc Tdi thang nam 2000, M EGACO/H.248 chinh thuc dugc phe chuan bdi hai td chuc IETF va ITU-T Trong qua trinh xay dung M EG A C O /H 248, nhung ngudi ung ho M GCP van yeu cau IETF dua m ot RFC ve giao thuc MGCP V ao thang 10 nam 1999, van ban dugc ban hanh nhung day khdng phai la tidu chuan chinh thuc cua IETF, RFC cung khdng dugc S G I6 cua ITU -T thira nhan mac dii hidn ISC ung hd MGCP Vao thdi diem hidn M EG A CO la giao thurc chuan qudc td' nhat danh cho dieu khien moi loai cdng phuang tien theo c a che' chu/td M EGACO se tiep tuc dugc cai tien va phat trien han nua nhd nd luc khong ngimg cua IETF, ITU-SG16 va cac td chuc tieu chuan hoa khac Chuong 6: Giao thiic dieu khien tdng phucmg tien M EGACO/H.248 - 99 6.2 G IA O THCTC M EG A C O /H 248 6.2.1 Tdng quan ve giao thurc M EG AC O/H 248 M EGACO la giao thurc didu khidn cdng phucmg tien noi chung, bao gdm cdng noi hat, trung k£ mang PSTN, giao didn ATM , giao didn thoai va ducmg day tuong tu, didn thoai IP, cac loai may chu Vdi tfnh nang hd trp rdng rai cac urng dung mdt cach mdm deo, don gian va hidu qua d mure chi phi hop ly, M EGACO se la chuan dupe su dung mang thd' hd sau NGN M EGACO khdng bi rang budc vdi ba't ky mdt giao thurc didu khidn cudc gpi ngang ca'p nao (vf du nhu SIP hay H.323) va hoan toan thudc v&o thid't kd' cua ngudi quan tri mang Kid'n true cua M EGACO dua trdn ldp: ldp MGC, ldp M G Vci ldp M EGA CO (Hinh 6.1) • Ldp M GC chura tat ca cac phdn mdm didu khidn, xu ly cudc gpi Ldp thuc hidn cac dac didm d mure cudc gpi nhu phat tridn cudc gpi, chuydn cudc gpi, hdi thoai hay giS cudc gpi Ldp M GC cQng thuc hidn giao ti£p vdi cac MGC cung nhu cac thuc thd ngang ca'p hay cap dudi khac, MGC quan ly moi thuoc tinh qua trinh giao tid'p • Ldp M G thuc hidn cac kd't ndi luu lupng di va tdi cac m ang khac, tuong tac vdi cac ludng luu lupng qua urng dung bao hidu va sir kidn Ldp MG cung dieu khien 100 Chuyen mach mem va itng dung mang vien thdng the he sau cac thudc tinh thia't bi cua c