CC KIN TRC MNG (TOPOLOGY)1. Khi nim. Network topology l s dng biu din cc kiu sp xp, b tr vt l ca my tnh, dy cp v nhng thnh phn khc trn mng theo phng din vt l. C hai kiu kin trc mng chnh l: kin trc vt l (m t cch b tr ng truyn thc s ca mng), kin trc logic (m t con ng m d liu tht s di chuyn qua cc node mng)

2. Cc kiu kin trc mng chnh.a.Mng Bus (tuyn) - Kin trc Bus l mt kin trc cho php ni mng cc my tnh n gin v ph bin nht. N dng mt on cp ni tt c my tnh v cc thit b trong mng thnh mt hng. Khi mt my tnh trn mng gi d liu di dng tn hiu in th tn hiu ny s c lan truyn trn on cp n cc my tnh cn li, tuy nhin d liu ny ch c my tnh c a ch so khp vi a ch m ha trong d liu chp nhn. Mi ln ch c mt my c th gi d liu ln mng v vy s lng my tnh trn bus cng tng th hiu sut thi hnh mng cng chm. - Hin tng di tn hiu: l hin tng khi d liu c gi ln mng, d liu s i t u cp ny n u cp kia. Nu tn hiu tip tc khng ngng n s di ti lui trong dy cp v ngn khng cho my tnh khc gi d liu. gii quyt tnh trng ny ngi ta dng mt thit b terminator (in tr cui) t mi u cp hp thu cc tn hiu in t do. - u im: kin trc ny dng t cp, d lp t, gi thnh r. Khi m rng mng tng i n gin, nu khong cch xa th c th dng repeater khuch i tn hiu. - Khuyt im: khi on cp t i hoc cc u ni b h ra th s c hai u cp khng ni vi terminator nn tn hiu s di ngc v lm cho ton b h thng mng s ngng hot ng.Nhng li nh th rt kh pht hin ra l hng ch no nn cng tc qun tr rt kh khi mng ln (nhiu my v kch thc ln).

Hnh Kin trc mng Bus

b.Mng star (sao) - Trong kin trc ny, cc my tnh c ni vo mt thit b u ni trung tm (Hub hoc Switch).Tn hiu c truyn t my tnh gi d liu qua hub tn hiu c khuch i v truyn n tt c cc my tnh khc trn mng. -u im: kin trc star cung cp ti nguyn v ch qun l tp trung. Khi mt on cp b hng th ch nh hng n my dng on cp , mng vn hot ng bnh thng. Kin trc ny cho php chng ta c th m rng hoc thu hp mng mt cch d dng. - Khuyt im: do mi my tnh u phi ni vo mt trung tm im nn kin trc ny i hi nhiu cp v phi tnh ton v tr t thit b trung tm. Khi thit b trung tm im b hng th ton b h thng mng cng ngng hot ng.

Hnh Kin trc mng Star.

c.Mng Ring (vng) - Trong mng ring cc my tnh v cc thit b ni vi nhau thnh mt vng khp kn, khng c u no b h. Tn hiu c truyn i theo mt chiu v qua nhiu my tnh. Kin trc ny dung phng php chuyn th bi (token passing) truyn d liu quanh mng. - Phng php chuyn th bi l phng php dng th bi chuyn t my tnh ny sang my tnh khc cho n khi ti my tnh mun gi d liu. My ny s gi th bi v bt u gi d liu i quanh mng. D liu chuyn qua tng my tnh cho n khi tm c my tnh c a ch khp vi a ch trn d liu. My tnh u nhn s gi mt thng ip cho my tnh u gi cho bit d liu c nhn. Sau khi xc nhn my tnh u gi s to th bi mi v th ln mng. Vn tc ca th bi xp x vi vn tc nh sng.

Hnh Kin trc mng Ring.

d.Mng Mesh (li). Tng cp my tnh thit lp cc tuyn kt ni lin im do s lng tuyn kt ni nhanh chng gia tng khi s lng my tnh trong mng tng ln nn ngi ta t dng cho cc mng li ln.

Hnh Kin trc mng Mesh

Mng Cellular (t bo). Cc mng t bo chia vng a l ang c phc v thnh cc t bo, mi t bo c mt trm trung tm phc v. Cc thit b s dng cc tn hiu radio truyn thng vi trm trung tm, v trm trung tm s nh tuyn cc thng ip n cc thit b. V d in hnh ca mng t bo l mng in thoi di ng.

3. Cc kin trc mng kt hp.a.Mng star bus. Star bus l mng kt hp gia mng star v mng bus. Trong kin trc ny mt vi mng c kin trc hnh star c ni vi trc cp chnh (bus). Nu mt my tnh no b hng th n khng nh hng n phn cn li ca mng. Nu mt Hub b hng th ton b cc my tnh trn Hub s khng th giao tip c.

b.Mng Star Ring tng t nh mng Star Bus. Cc Hub trong kin trc Star Bus u c ni vi nhau bng trc cp thng (bus) trong khi Hub trong cu hnh Star Ring c ni theo dng hnh Star vi mt Hub chnh

Hnh Kin trc mng Star-Ring