Chuyn mch IP v VoIPGio vin hng dn: Trn Th Tr Vinh
I. Cng ngh chuyn mch IP 1. nh ngha IP l giao thc chuyn tip gi tin theo c ch phi kt ni. IP nh ngha c cu nh s,c cu chuyn tin, c cu nh tuyn v cc chc nng iu khin mc thp (ICMP Internet Control Message Protocol). Gi tin IP gm a ch ca bn nhn, a ch l s duy nht trong ton mng v mang y thng tin cn cho vic chuyn gi ti ch.
2. Nguyn l lm vic
D liu truyn qua h thng chuyn mch IP s c x l qua cc bc sau: - u tin iu khin b x l nh tuyn IP c ghp vi chuyn mch ATM v cho php chuyn mch IP nh mt giao thc ca b nh tuyn IP thng thng v thc hin truyn gi trn nguyn tc tng chng. - Tip theo, khi lung d liu ln xut hin gim st b x l nh tuyn IP s bo hiu cho lung truyn trm k tip pha trn gn nhn ca mt tuyn o/ lung o cho cc t bo ca lung v sau s cp nht vo bng nh tuyn chuyn mch ATM c lin quan. Gi giao thc IFMP Ipsilon Flow Management Protocol ti trm pht.
- Nu lung n c bin dch, n s gi tip cc gi ca lung trn mt knh o ri vi mt nhn dng knh o. Tin trnh ny xy ra c lp gia cc cp chuyn mch IP ph thuc vo tuyn kt ni. - Lung ra c th gim st trn cng mt lung v yu cu chuyn mch IP hin thi s dng mt VCI cho n. - Sau b iu khin chuyn mch IP ch dn chuyn mch ATM to bn cng cho lung . Cc s liu tip theo s c chuyn mch trc tip trn phn cng ca chuyn mch ATM .
3. u, nhc im- u im Thit k linh hot trong vic thit k m rng mng. - Nhc im Do IP hot ng lp 3 nn tc chuyn mch gi tin chm hn so vi chuyn mch lp 2 ca ATM. Do s phc tp ca nh tuyn gi tin IP ti mi router m tc hi t s chm.
II/ Cng ngh VoIP1. nh ngha
Voice Over Internet Protocol (VoIP) l mt cng ngh cho php truyn thoi s dng giao thc mng IP, trn c s h tng sn c ca mng internet.2. Nguyn l hot ng VoIP chuyn tn hiu thoi Analog thnh tn hiu s Digital ri ng gi thnh gi tin truyn i trn lin mng. Khi ti ch, cc gi tin c sp xp theo th t ban u, c gii m v phc hi ting ni ban u. Cc qu trnh din ra ln lt nh sau:
- S ha tn hiu analog: ging ni khi i qua microphone to ra tn hiu tng t v c chuyn thnh tn hiu s thng qua cc thit b VoIP nh IP phone, softphone. Sau tn hiu analog tin hnh qua 4 bc: ly mu, lng t ha, m ha v nn ging ni.- Chuyn cc gi tin ging ni s ha trn thnh cc gi tin IP: khi ti ch, gi tin VoIP s c m v qu trnh thnh dng tn hiu thoi din ra ngc li vi qu trnh trn. - Thnh phn, chc nng v m hnh ng dng h thng tng i thoi IP PBX.
3. c im - Cng ngh VoIP cho php truyn d liu voice trn mt mng d liu. N thc hin mt cch hiu qu chc nng ca mt h thng thoi analog truyn thng. - Mt in thoi bnh thng c th c dng a cc d liu thoi ca ngi gi vo h thng VoIP. Mt lot cc chuyn i t analog sang digital v cc tin trnh khc trn my tnh thay i tn hiu thoi sang data, sau c truyn trn mng cc b LAN hoc mng din rng WAN hoc trn internet.
Mun s dng h thng VoIP ta cn c tng i IP PBX(Private Branch Exchange). Thc cht PBX l mt chuyn mch dng kt ni gia cc in thoi vi nhau hay mt hoc nhiu ng line khc. Trong trng hp ny tng i IP PBX l mt IP Gateway.
4. ng dng VoIP c th va thc hin mi cuc gi nh trn mng in thoi knh truyn thng PSTN ng thi truyn d liu trn c s mng truyn d liu. - Chuyn i a ch. iu khin chp nhn cuc gi. iu khin bng thng. Qun l mng. Bo hiu iu khin cuc gi. Cp quyn cuc gi. Qun l bng thng
5.u, nhc ima) u im - Gim chi ph - Tch hp nhiu dch v: do thit k c s h tng tch hp nn c kh nng h tr tt c cc hnh thc thng tin cho php chun ha tt hn v gim thiu s cc thit b. - Thng nht: con ngi l mt nhn t quan trng nhng cng d sai lm nht trong mng vin thng, mi c hi hp nht thao tc, loi b cc im sai st, vic thng nht cc im thanh ton s rt c ch. Vic thng nht giao thc IP cho tt c cc ng dng ha hn gim bt phc tp v tng cng tnh mm do.
- Qun l bng thng: bng thng c qun l mt cch m do hn - Nng cao ng dng v kh nng m rng: thoi v Fax ch l cc ng dng khi u ca VoIP, cc li ch trong thi gian di hn c mong i t cc ng dng a phng tin v a dch v. Tnh linh hot ca mng IP cho php to ra nhiu tnh nng mi trong dch v thoi
- b) Nhc im - Cht lng dch v cha cao. - Vn ting vng: do tr ln nn ting vng nh hng nhiu n cht lng thoi. - K thut phc tp. - Cht lng dch v cha cao. - Vn ting vng: do tr ln nn ting vng nh hng nhiu n cht lng thoi. - K thut phc tp.
