KỸ THUẬT CHUYỂN MẠCH GÓI

8/7/2019 K THUT CHUYN MCH GI

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Gio vin hng dn:guyn Vn Trng

Sinh vin thc hin:Trn Th T NhiNguyn Hong PhngPhm Th T NyLng Nht TnDng Tun Quang


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I. Gii thiu1. Khi nim

2.

So snh chuyn mch gi v chuyn mch knhII. Cc dng chuyn mch gi1. Chuyn mch Datagram

2. Chuyn mch knh o

III. Gi tin trong chuyn mch gi1. Cu trc tng qut ca gi tin2. Qu trnh ng gi trong m hnh OSI

IV. nh tuyn


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1. Khi nim:

L k thut gi d liu t my ngun nmy ch qua mng di dng gi (packet).

Gi tin cha cc thng tin iu khin, thngtin a ch ngun v a ch ch.

Mi gi tin c nh s th t.


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1. Khi nim:

Cc gi tin c gi qua mng c th nch bng nhiu con ng khc nhau.

Pha thu s tp hp cc gi tin li theo th t D liu ban u.


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1 2 3 4

1 2 3 4

1

2

3

4


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2. So snh c im ca chuyn mch knh vchuyn mch gi:

Chuyn mch gi Chuyn mch knh

Thng tin truyn theo cu trc gi Khng c cu trc gi

Bng thng cho mt lin kt c ththay i

Bng thng c nh

tr ln v c th bin i tr nh v c th thay i

p ng s t bin lu lngKhng ph hp vi t bin lu

lng

C iu khin lu lng v kim trali

Khng c


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2. So snh c im ca chuyn mch knh vchuyn mch gi:

Chuyn mch gi Chuyn mch knh

Khng cn thit phi thit lp ktni

Phi thit lp kt ni

Hai thu bao c th hot ng haitc khc nhau

Hai thu bao phi hot ng tc c nh ca knh thng tin

Khng lng ph bng thng C kh nng lng ph bng thng


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C 2 dng chuyn mch gi:

Chuyn mch Datagram

Chuyn mch knh o VC (VirtualCircuit)


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1. Chuyn mch Datagram:

S dng trong mng khng lin kt(Connectionless).

Mi gi tin c lu chuyn v x l clp, khng cn tham chiu n gi tin gitrc.

V d: Ethernet, IP, UDP


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c im:

Giai on thit lp v gii phng lin kt c bqua.

Ph hp d liu khng ln, thi gian tn ti ngn.

Kh nng nh tuyn linh hot ra khi vng nghn.

Nu node hng, t tm hng khc di chuyn,phn pht gi tin.


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2. Chuyn mch knh o VC:

S dng trong mng hng lin kt

Trc khi trao i thng tin , hai thc ththam gia truyn thng m phn vi nhau vcc tham s truyn nh kch thc gi tin,ng truyn Mt knh o hnh thnhthng qua lin mng v tn ti cho n khithc th ngng trao i vi nhau.


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2. Chuyn mch knh o VC:

Ti mt thi im, c th c nhiu knh o i

v n t nhiu hng khc nhau. Cc gi tin c m ti mi node v xp

hng u ra trn ng truyn.

Cc gi tin ca cc d liu khc nhau c thchia s s dng ng truyn.

V d: X.25, Frame Relay, ATM, MPLS, TCP


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c im: Cc gi tin i trn cng mt tuyn s n theo

cng mt th t. Gi tin lu chuyn nhanh v khng phi nh

tuyn ti cc node.

Hu ch vi cc lu lng thi gian thc, thigian tn ti di.

Kh thch ng vi tc nghn. Nu node hng knh o b mt truyn hng.


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1. Cu trc tng qut ca gi tin: Gm 3 phn: Tiu (Header) Ti tin (Payload)

Phn ui (Trailer)


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1. Cu trc tng qut ca gi tin:


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2. Qu trnh ng gi trong m hnh OSI: M hnh OSI gm 7 tng Qu trnh phn mnh d liu c thc hin

tng Vn chuyn. Qu trnh ng gi c thc hin tng

Mng.


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1. nh ngha:

nh tuyn (routing) l s la chn mt con

ng truyn mt n v d liu (v.d. gitin) t trm ngun n trm ch.

Mt k thut nh tuyn phi thc hin 2

chc nng chnh sau: Quyt nh chn ng

Cp nht thng tin chn ng


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2. Phn loi cc k thut nh tuyn: Da vo cc yu t lin quan n hai chc nng

trn: S thch nghi vi trng thi hin hnh ca mng

K thut nh tuyn thch nghi & k thut nh tuynkhng thch nghi.

S phn tn cc chc nng nh tuyn trn cc nt

mng K thut nh tuyn tp trung & k thutnh tuyn phn tn.

Cc tiu chun nh tuyn ( tr truyn, anton,)


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3. K thut nh tuyn tp trung & k thutnh tuyn phn tn:

K thut nh tuyn tp trung: Trung tm iu khin mng thc hin vic chn

ng Gi cc bng chn ng ti cc nodetrn con ng chn.

Cc node ch gi thng tin trng thi theo nh k Trung tm cp nht bng chn ng da trncc thng tin .


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3. K thut nh tuyn tp trung & k thutnh tuyn phn tn:

K thut nh tuyn phn tn: Khng tn ti cc trung tm iu khin.

Quyt nh chn ng c thc hin ti minode.

i hi trao i thng tin gia cc node.


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4. K thut nh tuyn thch nghi & k thutnh tuyn khng thch nghi:

K thut nh tuyn khng thch nghi (Kthut nh tuyn tnh): Vic nh tuyn ch phi thc hin mt ln khi

xy dng mng.

Thng tin nh tuyn c lu trong cc bngnh tuyn.

Ph hp vi cc mng tng i n nh.


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K thut nh tuyn thch nghi (K thutnh tuyn ng): p ng nhanh chng vi cc thay i trn mng.

Vic tnh ton ng truyn ti u c thc hinnhiu ln trong khi mng hot ng.

Mc thch nghi c c trng bi s trao ithng tin chn ng trong mng.


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K thut nh tuyn thch nghi (K thutnh tuyn ng): n gin nht l khng trao i g ht Cc

node hot ng c lp vi thng tin ring camnh nh tuyn thch nghi cch ly.

mc cao hn, thng tin trng thi ng truync cung cp bi cc node khc.


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5. Gii thut Dijsktra cho k thut nh tuyntp trung:

Tm ng c di cc tiu t mt ntcho trc (ngun) ti mi nt cn li camng (ch).

Gii thut s tng bc kin thit mt cyng ngn nht, c gc ti nt ngun, choti khi nt xa nht trong mng c a vo.


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5. Gii thut Dijsktra cho k thut nh tuyntp trung:

Gi: l(i,j): di ca ng ni trc tip hai nt i v j

l(i,j) = nu ng ni khng tn ti Nkl tp hp to thnh bi k+1 phn t ngun v

k nt gn ngun nht sau k bc thc hin giithut Dk(n) l di t ngun ti nt n theo con

ng ngn nht bao hm trong Nk.


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Thut ton thc hin nh sau: Bc 0:

N0

= {1}D0(v) = l(1,v) v khng thuc N0

Bc k:Nk= Nk-1 U {v}

Vi w tha mn: Dk-1(v) = min Dk-1(v)Dk(v) = min [Dk-1(v), Dk-1(w) + l(w,v)]v khng thuc Nk

Thut ton dng li khi tt c cc nt nm trong N


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6. Gii thut Ford & Fulkerson cho k thutnh tuyn phn tn:

Cho php tm tt c cc con ng ngn nhtt tt c cc nt ti mt ch chung.

Mi node c nh du bi cc cp(nk(v),Dk(v)), trong :

Dk(v) l di cc tiu (hin ti) t nt v tich; nk(v) l nt tip theo hin ti trn con ng ti

u t nt v ti ch.


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Thut ton thc hin nh sau: Bc 0 (khi ng):

D0(1) = 0 v tt c cc nt c nh du (., ) Bc k (tnh v cp nht)

Vi mi v 1 (ch):Dk(v) = min [Dk-1(w) + l(v,w)], w Nv

nk(v) c cp nht nh sau:

nk(v) = w1 , vi w1 tha mn:Dk-1(w1) + l(v, w1) = min [Dk-1(w) + l(v,w)]

Qu trnh dng li khi cp gi tr nh du ca mi ntgi nguyn khng thay i na.


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192.168.1.100A-10

192.168.1.0/24 192.168.2.0/24 192.168.3.0/24

192.168.3.100B-20

00-10

.1 .1 .2 .1

0C-22

Dest. IP

192.168.3.10

Source IP192.168.1.10

IPfields

Data TrailerDest. MAC00-10

Source MAC0A-10

Gi tin tng 3Khung tng 2

R1 R2

PC1sARP Cache for R1

IP Address MACAddress

192.168.1.1 00-10

00-20 0B-31


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192.168.1.100A-10

192.168.1.0/24 192.168.2.0/24 192.168.3.0/24

192.168.3.100B-20

00-10

.1 .1 .2 .1

0C-22

Dest. IP

192.168.3.10

Source IP192.168.1.10

IPfields

Data TrailerDest. MAC00-10

Source MAC0A-10


00-20 0B-31

Dest. MAC Source MACDest. MAC0B-31

Source MAC00-20

R1 R2

Bng nh tuyn ti R1

Network Hop Next-hop-IP

192.168.1.0/24 0 ir . Co ect

192.168.2.0/24 0 ir . Co ect

192.168.3.0/24 1 192.168.2.2

R1s ARP Cache


192.168.2.2 0B-31


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192.168.1.100A-10

192.168.1.0/24 192.168.2.0/24 192.168.3.0/24

192.168.3.100B-20

00-10

.1 .1 .2 .1

0C-22

Dest. IP

192.168.3.10

Source IP192.168.1.10

IPfields

Data TrailerDest. MAC0B-31

Source MAC00-20


00-20 0B-31

Dest. MAC Source MACDest. MAC0B-20

Source MAC0C-22

R1 R2

Bng nh tuyn ti R2

Network Hop Next-hop-IP

192.168.1.0/24 1 192.168.2.1

192.168.2.0/24 0 Dir . Connect

192.168.3.0/24 0 Dir. Connect

R2sARP Cache


192.168.3.10 0B-20


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192.168.1.100A-10

192.168.1.0/24 192.168.2.0/24 192.168.3.0/24

192.168.3.100B-20

00-10

.1 .1 .2 .1

0C-2200-20 0B-31R1 R2

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