DSR lien quan den, viOe chophdp may chit Ulm tiep tra km lugng tray cop ma khong th8ng qua b0 can bang tai. Bang cach ;thong th8ng qua b0 can bang tai, thong ta co the co dirge hieu suet tot han neu b0 can bang tai la nth c8 ehai, bai vi bay gia ,b0 can bang tai chi phai xir19 cac luu lugrig you eau, cat giam doge so lugng the goi tin can phai xir 19. Qua trinh thiet lap de that hiOn DSR, b0 can bang tai se khong chuyen dia chi IP dich thanh IP cita may chit ma van gift nguyen la ilia chi VIP (IP public). BO can bang tai chi dOi dia chi MAC dich thinh dia chi MAC cita may chit de gai tin co the den dugc may chit. Van de con 13i la lam sao de khi may chit nhan gal tin you eau tir 116 dinh tuyen chuyen den se khong tir ch6i, vi dja chi IP dich kh8ng phai la IP cita may chit, ma la dia chi VIP. MOt each dim gian, ta cau hinh de dia chi VIP la dja chi cita loopback interface tren mot may chit. BO dinh tuyen dung cach nay vi lqi dung nhUng tinh chat thti vi sau day cita loopback interface:
• Co the gin bat Ict dia chi IP nao, khong bit buOc phai bit dAu bang 127.x.x.x • Vi loopback interface khong phai la mOt thiet bi that, no kh8ng co dia chi MAC,
nen hg thong se khong tra lai cho cac yeu cau ARP. Do 66 se khong co hg thiing ben ngoiti nit° ilia dirge dja chi IP cita loopback interface. Tuy nhien, hg thong van nhan you cau den IP cita loopback interface va tra leti tutu la cac interface Ichic. Nhu vay, bang mOt chit thin thuat vii cac dja chi, may chit thfrc khong an dja chi IP public van co the nhan you cau va tra Itri trip tiep cho may khach.
Chuang 2: May ch6 can bang tai DO Van Thjnh — A13439 Hinh 2.10 the hien luting gal tin khi sir dung DSR. Dim tien, b0 can bing . titi gift nguyen dja chi IP dich van nhu la dja chi VIP trong gei tin yeu ceu, nhtmg thay doi dia chi MAC dich cua may chit da duqc chqn Itra. BO chuyen mach lap 2 gifta bo can bang tai va may chit chuyen ti .ep g6i tin den dung may chi' dua tren dia chi MAC dich. May chit thuc se chap nhan gai tin bai vi dia chi IP dich caa goi tin vi dja chi VIP da duqc djnh nghia nhu la dia chi IP loopback tren may chit. Khi may chit tra 16i, dia chi VIP bay gibt trot thkh dja chi IP nguon, va dja chi IP dm may khkh tra thank Elia , chi IP dich. ,Goi tin duqc chuyen tiep thong qua b0 chuyen mach lap 2 den b0 djnh tuyen, vi sau do den may khach ma Ichong can phai sir dung NAT.
Chen • HS 1.1 100