Cac boat dOng co ban cim mOt b0 chuyEn mach la nhon get tin tren moat cong veto, xac djnh cac giao din dau ra, gui cac g6i tin tren cong ra. Lam the nao dE bo chuy . En mach xac dinh duqc giao din ra cho mOt gel tin can phy thuOc vao tong loai chuyEn doi.
Ethernet lap 2 chuyen d6i sir dung dia chi MAC c6 sin trong lop lien ket da lieu coa met g6i tin (16p 2 trong m8 hinh OSI) de xac dinh cac cong giao din dau ra cho mOt g6i tin. MOt b0 chuyen mach 16p 3, ding dugc biet den nhu mOt bo djnh tuyen, sir dung thong tin lop mang (16p 3 dugc the hi'en trong mo hinh OSI) de xac dinh cac cong giao din dau ra dm met g6i tin. Khi sir dung giao thirc intemet, bo chuyen mach 16p 3 sir dung thong tin dia chi IP trong g6i tin de xac dinh cac giao din dau ra cac gal tin.
May lchach va may chit thubng dugc ggi nhu la cac host, tra den b0 dinh tuyen qua mOt default gateway c6 dirt chi IP duce cung cep bed ngueri quart tri mang. Khi Wit host can phai girt mOt g6i tin den mOt, dia chi IP ma kh8ng c6 trong cling mot dja chi mang con cim ne, host se giri cac g6i tin den default gateway cim ne, default gateway dm be) dinh tuyen se sir dung melt giao thirc dinh tuyen d'E' xac dinh nai girl g6i da lieu du tren cac thong tin dia chi IP.
BO can bang tai hoat dOng o lop 4 hoac cao hcrn phu thuOc vim cac tinh nang ma chin ta sir dung, Nhu da de cap, khi be) can bang tai nhan dugc mOt gel tin, g6i tin co dja chi VIP nhu la dja IP va dia chi MAC dm can bang tai la dia chi MAC dich. BO can bang tai se
Cliental, 166.1.1.100
0
141.149.65.1 MAC-MI MAC-MI
Chuang 4: Thiel k'e mang veri b0 can bimg tai DO Van Thinh — A13439
xem xet thong tin tai lop 4 vi b ben trong g6i tin de xac dinh loai chirc nang can bang tai can [him hien. Bang each sir dung the thong tin trong cac g6i di lieu cling veri viec kiem tra tinh trang sire kh6e may chit va dieu kien tai may chit, b0 Gang bang , tai se xic dinh may dich cho you cAu. BO can . bang tai sfra &di cac throng can thiet trong goi tin, chang han ram dja chi IP dich va so ding TCP hoAc UDP. MOt khi &Ai tin da duqc sin ded, b0 can bang tai ,an phai xic dinh giao din dAu ra vi chuyen tiep gel tin. BO can bing tai co the chuyen tiep cac goi tin neu n6 la mOt Ns) chuyen mach holm mOt bo dinh tuyen tny thuOc vio no duqc cau hinh nhu the nao.
Hinh 4.1 cho thay luu luqng goi tin va dia chi IP qua b0 can bang ma kitting thqc hien
dinh tuyen lop 3. Default gateway cho the may chi' va b0 can bing tai da dutyc thiet l'Ap den b0 dinh tuyen tren. Cac may chu trong cling mot mang con, va do do c6 the giao tiep veri nhau thong qua viec can bang tai ma Ichong an phii lien quan den cac b0 dinh tuyen. Dieu quan frog la phai chu y IuOng cac gel tin to Rn lai cho may khich tir may chil dia chi MAC dich den Ml, dia chi MAC dm bij dinh tuyen. Tuy nhien ac may ch8 ce dia
chi IP public n6i chung thutmg kh8ng dirge mong muon bed vi chting ta khong the brio
ton doge kW:Mg gian dirt chi. Vies sir dung IP public tren cac may chi thirc se kitting the ngan chan mOt ngutri nio d6 muon truy cop tut tiep vao cac may chit, trir khi co cac chinh sach kiem soat truy cAp thich hqp dirge thuc thi tren bo can bang tai hoAc tren b0 dinh tuyen. Chung ta cling co the sir dung dirt chi IP private cho the may chit, nhung bAy gitr echang ta se co hai mang con khac nhau ket not ten cling mOt interface cia b0 dinh tuyen. BO can bang tai veri dia chi VIP public la mOt mang con vi the may chi WA dia chi IP private li cac mang con ;chic nhau. Ching ta can phai xac dinh hai dja chi IP tren b0 dinh tuyen ket not veri can bang tai: mOt Ii dirt chi IP trong mane con cia dia chi VIP va cac dia chi khac trong mang con dm the may chi. MOt s6 sin pham can bing tai c6 the cung cap cac tinh Ming nham tranh sir can thiet khi xac dinh dia chi W tren interface cia b0 dinh tuyen.
VIP 141.146.66 MAC-642 MAC-642
Source IP Oset IP Soures Dee MAC 1 106.1.1.100 141 .149.66.3 ml 142 2 110.1.1.100 141.14985.11 11411 M4 9 141 14966.11166 1 1 100 644 MI
4 141.i49.65.3i96.1.1 100 614 MI
Dealt gamey for servers is at