- Dich Next hop
2.6 Dynamic manet on demand (DYMO)
DYMO IA giao thirc djnh tuyen theo bang min nhat, hien van dang duqc phat trien boi MANET trong IETF. DYMO c6 the coi la sy ket hqp cua AODV va DSR. Muc tieu cua no la thiet ke don gian, giam thieu you au he thong, don gian hem viec thyc thi giao thtic. Meat mat, DYMO cling sir dyng s6 this ti,r de dam bao tranh lap tuyen, mat khac, DYMO dua ra cac dac tinh mei nhu la thyc hien tinh toan tuyen dutmg. Ben canh thong tin tuyen throng ve mOt myc tieu duqc yeu au, mOt nut cling
duqc thOng tin ve tat ca cac nut trong gian clam tren mOt tuyen dtrong mai kham pha duqc. Day la mOt khic biet co ban gigra DYMO va AODV, trong do thi AODV chi
DINH TUYEN TRONG MANG MANET
tao ra entry bang djnh tuyen cho nut dich va nut next-hop, con DYMO thi Itru trfr tuyen throng cho mOi nut trung gian. Dieu nay duqc the hien qua hinh 2.9.
AODV
DYMO
Rink 2.9 Su khdc nhau gitta AODV va DYMO
Khi sir dying AODV, mot nut A chi biet &Ong ten B va D sau khi You eau tuyen duce dap (mg. Trong DYMO, nit A cimg biet a duang ten C. DYMO co the thiet lop ve duy tri cac tuyen duang unicast trong cac kjch ban mang 11Pv4 va IPv6 bing cach sir clang ca the sau:
• Nhim phat hien mot tuyen men den mot nit dich, mot nit gin mot ban tin You au tuyen RREQ tai tit ca hang Vim trong pham vi truyen sing cita no. Dieu nay cling nhOn duqc bing cach girl bitn tin ten 1 dja chi multicast cvc bo rieng. Khi mot nit trung gian nhon duqc mot RREQ no thiet lop tuyen dtrimg ten tit a cac nut ma g6i tin de di qua. Sau di nit se gin (ha chi ciut chinh no vim ban tin va truyen ban tin tai tat ca cac nut Ian an. Bing cach nay thi RREQ duqc quang be mot each hileu qua ten mang va cuoi cling lit den dich cern no.
• Dich dap ling RREQ bing cach giri unicast mot ben tin Tra loi RREP tr .& ve nit ma no ma tir do no nhOn duqc RREQ. Cling nhtr trong qua trinh quang ba RREQ, nit nay lai gin dja chi cis no va ghi chi tit ca ac thong tin djnh tuyen co trong RREP. Cling voi th8ng tin djnh tuyen a co duqc fru& do khi chuyen flip RREQ tuang ling, nit trung gian co kha Wing giri RREP tra ve nit nguen
cua RREQ. Nit nay cling se biet ducm tuytn du?mg ten nit dich duqc yeu au, cling nhu la clueing teri mqi not trung gian, va nguqc lai.
Met nut trung gian ding c6 the too ra RREP neu nhu no hitt tuyen dutmg tai dich. DE phan img tot vtri mpg co mirc dO di chuyen cao, cac lien ket tren tuyen dutmg da biet &Km co the duqc theo doi, bang each sir dung giao thirc nhOn Met hang xOm (Neighboehood Discovery Protocol) ho#c kitm tra phan hoNi Tilton duqc a tang data link. MOt he thiing ding co the Iva chip khong b#t firth nang theo dbi, dun gian chi x6a cac tuyen kh8ng con hoot dOng. Khi !net nut phat hien lien ket 161, no se gni met bin tin RERR de th8ng bao c6 tit ca cac nut Ian con, thong bio cho chimg biet ve
tat ca cac tuyen di dirt.
DINH TUYEN TRONG MANG MANET
TONG KET
Qua viec nghie'n ciru mOt s6 giao that trong MANET to c6 the thAy rang chua c6 giao that nio c6 dAy dpi cac tinh 'tang va kh8ng the khing dinh giao thac nao la thi uu cho MANET. Tuy ration, chac nAng chinh cua cat giao thtic la tun duct throng di tei dich, kh8ng phai dutmg ngAn nhat hay dubng t6i uu nhAt duct dap Ong.