mmt- 04-2.pdf
TRANSCRIPT
-
Trng i Hc Bch Khoa Tp.HCM Khoa Khoa Hc v K Thut My Tnh
ThS. NGUYN CAO T
E-mail:[email protected]
Bi ging
Mng my tnh
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
2
Bi ging 9: Tng Mng(t.t)
Tham kho:
Chng 4: Computer Networking A top-down approach
Kurose & Ross, 5th ed., Addison Wesley, 2010.
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
3
Chng 4: Tng Mng
4.1 Gii thiu
4.2 Bn trong b nh tuyn l g?
4.3 IP: Internet Protocol
nh dng gi tin
nh a ch IPv4
ICMP
IPv6
4.4 Cc gii thut nh tuyn Trng thi lin kt
Vc-t Khong cch
nh tuyn phn cp
4.5 nh tuyn trong Internet
RIP
OSPF
BGP
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
4
ICMP: Giao thc thng ip kim sot Internet
s dng bi my tnh v bt lin lc thng tin tng-mng
bo co li: my, mng, cng, giao thc khng lin lc c
yu cu/phn hi gi echo (s dng bi ping)
nm tng trn IP:
th/ip ICMP c mang trong gi tin IP
thng ip ICMP: loi, m cng vi 8 byte u ca gi tin IP m gy ra li
Loi M Ch gii 0 0 phn hi echo (ping) 3 0 mng ch ko lin lc c 3 1 my ch ko lin lc c 3 2 g/thc ch ko lin lc c 3 3 cng ch ko lin lc c 3 6 mng ch khng bit 3 7 my ch khng bit 4 0 gim tc ngun (kstn khng dng) 8 0 truy vn echo (ping) 9 0 qung b tuyn ng 10 0 tm tuyn ng 11 0 TTL ht hn 12 0 mo u IP b li
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
5
Traceroute v ICMP
Ngun gi mt lot khc UDP cho ch
khc u tin c TTL =1
khc th 2 c TTL=2, v.v.
s cng khng c nh
Khi gi tin th n n bt n:
BT loi b gi tin
V gi li ngun mt thng ip ICMP (loi 11, m 0)
Thng ip bao gm c tn v a ch IP ca bt
Khi thng ip ICMP ti, ngun s tnh RTT
Traceroute thc hin vic ny 3 ln
iu kin ngng li
Khc UDP n c my ch
My tr v gi ICMP my ch khng ti c (loi 3, m 3)
Khi ngun nhn c nhng ICMP ny, n s dng li.
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
6
Chng 4: Tng Mng
4.1 Gii thiu
4.2 Bn trong b nh tuyn l g?
4.3 IP: Internet Protocol
nh dng gi tin
nh a ch IPv4
ICMP
IPv6
4.4 Cc gii thut nh tuyn Trng thi lin kt
Vc-t Khong cch
nh tuyn phn cp
4.5 nh tuyn trong Internet
RIP
OSPF
BGP
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
7
IPv6
ng lc ban u: khng gian a ch 32-bit s c cp pht ht trong t/g ngn.
ng lc khc: nh dng mo u s gip tng tc x l/chuyn tip gi tin
thay i mo u h tr QoS
nh dng gi tin IPv6:
mo u c di c nh 40 byte
khng cho php phn khc
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
8
Mo u IPv6 (tt)
Mc u tin: xc nh mc u tin gia cc gi tin Nhn lung: xc nh cc gi tin trong cng lung. (khi nim lung cha thc s chun). Mo u tip theo: xc nh d liu ca giao thc tng trn
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
9
Nhng thay i khc t IPv4
Tng kim tra: c loi b hon ton gim thi gian x l ti mi thit b
Ty chn: cho php, nhng nm ngoi phn mo u, ch nh bi trng Next Header
ICMPv6: phin bn mi ca ICMP nhng thng ip b sung, vd: Gi tin qu ln
nhng chc nng qun l nhm gi-nhiu-ch (multicast)
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
10
Chuyn tip T IPv4 Ti IPv6
Khng th nng cp tt c bt ngay mt lc c Lm sao mng c th lm vic vi c cc b nh tuyn IPv4
v IPv6?
To ng hm: IPv6 c mang nh l d liu ca gi tin IPv4 gia cc bt IPv4
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
11
To ng hm
A B E F
IPv6 IPv6 IPv6 IPv6
ng hm Gc nhn lun l:
Gc nhn vt l: A B E F
IPv6 IPv6 IPv6 IPv6 IPv4 IPv4
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
12
To ng hm
A B E F
IPv6 IPv6 IPv6 IPv6
ng hm Gc nhn lun l:
Gc nhn vt l: A B E F
IPv6 IPv6 IPv6 IPv6
C D
IPv4 IPv4
Flow: X Src: A Dest: F data
Flow: X Src: A Dest: F data
Flow: X Src: A Dest: F data
Src:B Dest: E
Flow: X Src: A Dest: F data
Src:B Dest: E
A-ti-B: IPv6
E-ti-F: IPv6
B-ti-C: IPv6 bn trong
IPv4
B-ti-C: IPv6 bn trong
IPv4
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
13
Chng 4: Tng Mng
4.1 Gii thiu
4.2 Bn trong b nh tuyn l g?
4.3 IP: Internet Protocol
nh dng gi tin
nh a ch IPv4
ICMP
IPv6
4.4 Cc gii thut nh tuyn Trng thi lin kt
Vc-t Khong cch
nh tuyn phn cp
4.5 nh tuyn trong Internet
RIP
OSPF
BGP
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
14
1 2 3
0111
gi tr trong mo u ca gi ti
gii thut nh tuyn
bng chuyn tip cc b
gtr mo u u ra
0100
0101
0111
1001
3
2
2
1
Tng tc gia nh tuyn, chuyn tip
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
15
u
y x
w v
z 2
2 1
3
1
1
2
5 3
5
th: G = (N,E) N = tp cc bt = { u, v, w, x, y, z } E = tp cc g lin kt ={ (u,v), (u,x), (v,x), (v,w), (x,w), (x,y), (w,y), (w,z), (y,z) }
Tru tng ha bng th
Lu : Tru tng ha bng th cng hu dng trong nhng phm tr mng khc V d: P2P, vi N l tp cc thnh vin v E l tp cc kt ni TCP
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
16
Tru tng ha bng th: chi ph
u
y x
w v
z 2
2 1
3
1
1
2
5 3
5 c(x,x) = chi ph ca ng (x,x) - vd: c(w,z) = 5 chi ph c th lun bng 1, hoc nghch o vi bng thng, hoc nghch o vi tc nghn
chi ph ca ng i c(x1, x2, x3,, xp) = c(x1,x2) + c(x2,x3) + + c(xp-1,xp)
Cu hi: ng i no t chi ph nht gia u v z ?
Gii thut nh tuyn: tm ra ng i t tn km nht
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
17
Phn loi gii thut nh tuyn
Thng tin tng qut hay phn tn?
Tng qut:
tt c bt u c thng tin y v hnh mng v chi ph lin kt
g/thut trang thi kt ni
Phn tn:
bt bit hng xm kt ni vt l ti n, chi ph ti h
qu trnh tnh ton, trao i thng tin vi hng xm c lp i lp li
g/thut vc t khong cch
Tnh hay ng?
Tnh:
tuyn ng chm thay i theo t/gian
ng:
tuyn ng thay i nhanh hn cp nht theo chu k
phn nh li s thay i trong chi ph ng lin kt
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
18
Chng 4: Tng Mng
4.1 Gii thiu
4.2 Bn trong b nh tuyn l g?
4.3 IP: Internet Protocol
nh dng gi tin
nh a ch IPv4
ICMP
IPv6
4.4 Cc gii thut nh tuyn Trng thi lin kt
Vc-t Khong cch
nh tuyn phn cp
4.5 nh tuyn trong Internet
RIP
OSPF
BGP
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
19
Mt g/thut trng thi-lin kt
gii thut Dijkstra tt c nt u bit hnh
mng, chi ph lin kt
thc hin bi pht tn trng thi lin kt
mi nt c cng th/tin
tnh tuyn ng r nht t 1 nt ti tt c nt khc
to bng chuyn tip cho nt
lp: sau k ln lp, bit c tuyn ng r nht ti k ch
K hiu:
c(x,y): chi ph t nt x ti y; = nu khng phi hng xm trc tip
D(v): gi tr hin ti ca chi ph ca tuyn ng t ngun ti ch v
p(v): nt lin trc trn ng i t ngun ti v
N': tp cc nt m bit c ng i xc nh r nht ti chng
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
20
Gii thut Dijsktra
1 Khi to: 2 N' = {u}
3 vi mi nt v 4 nu v k vi u 5 th D(v) = c(u,v) 6 ngoi ra D(v) = 7
8 Lp 9 tm w khng thuc N' sao cho D(w) l min 10 thm w vo N' 11 cp nht D(v) cho tt c v k vi w v ko thuc N' : 12 D(v) = min( D(v), D(w) + c(w,v) )
13 /* chi ph mi ti v hoc l chi ph c ti v hoc l chi ph 14 tuyn ngn nht ti w cng vi chi ph t w ti v */ 15 ti khi tt c cc nt u thuc N'
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
21
Gii thut Dijkstra: V d
Bc 0
1
2
3
4
5
N'
u
ux
uxy
uxyv
uxyvw
uxyvwz
D(v),p(v)
2,u
2,u
2,u
D(w),p(w)
5,u
4,x
3,y
3,y
D(x),p(x)
1,u
D(y),p(y)
2,x
D(z),p(z)
4,y
4,y
4,y
u
y x
w v
z 2
2 1
3
1
1
2
5 3
5
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
22
Gii thut Dijkstra: v d (2)
u
y x
w v
z
Kt qu cy ng i ngn nht t u:
v
x
y
w
z
(u,v)
(u,x)
(u,x)
(u,x)
(u,x)
ch lin kt
Kt qu bng chuyn tip ti u:
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
23
Gii thut Dijkstra, tho lun
phc tp gii thut: n nt
mi ln lp: phi kim tra tt c n nt, w, ko thuc N
thc hin n(n+1)/2 ln so snh: O(n2)
c kh nng hin thc tt hn: O(nlogn)
Dng khc:
vd, chi ph lin kt = lng lu lng s dng
A
D
C
B
1 1+e
e 0
e
1 1
0 0
A
D
C
B
2+e 0
0 0 1+e 1
A
D
C
B
0 2+e
1+e 1 0 0
A
D
C
B
2+e 0
e 0 1+e 1
khi u tnh li nh tuyn
tnh li tnh li
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
24
Chng 4: Tng Mng
4.1 Gii thiu
4.2 Bn trong b nh tuyn l g?
4.3 IP: Internet Protocol
nh dng gi tin
nh a ch IPv4
ICMP
IPv6
4.4 Cc gii thut nh tuyn Trng thi lin kt
Vc-t Khong cch
nh tuyn phn cp
4.5 nh tuyn trong Internet
RIP
OSPF
BGP
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
25
Gii thut Vc t-Khong cch
Phng trnh Bellman-Ford (lp trnh ng)
Xc nh
dx(y) := ch ph ca tuyn ng r nht t x ti y
Khi
dx(y) = min {c(x,v) + dv(y) }
vi min c ly trn tt c hng xm v ca x
v
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
26
V d Bellman-Ford
u
y x
w v
z 2
2 1
3
1
1
2
5 3
5 R rng, dv(z) = 5, dx(z) = 3, dw(z) = 3
du(z) = min { c(u,v) + dv(z), c(u,x) + dx(z), c(u,w) + dw(z) } = min {2 + 5, 1 + 3, 5 + 3} = 4
node m t c gi tr min s l node tip theo trong tuyn ng ngn nht bng chuyn tip
phng trnh B-F:
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
27
Gii thut Vc t-Khong cch
Dx(y) = chi ph thp nht t x ti y
node x bit chi ph ti mi hng xm v: c(x,v)
node x duy tr vc t khong cch Dx = [Dx(y): y N ]
node x cng duy tr cc vc t khong cch ca hng xm Cho mi hng xm v, x duy tr
Dv = [Dv(y): y N ]
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
28
Gii thut Vc t-Khong cch
tng cn bn:
Qua thi gian, mi node gi o c VTKC ca n ti cc hng xm
Khng ng b
Khi mt node x nhn c DV mi t hng xm, n cp nht DV ca n s dng p/trnh B-F:
Vi vi iu kin nh, gi tr ca Dx(y) s hi t ti gi tr chi ph nh nht thc t dx(y)
Dx(y) minv{c(x,v) + Dv(y)} vi mi node y N
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
29
Gii thut Vc t-Khong cch (5)
Lp, khng ng b: mi vng lp cc b gy ra bi:
thay i chi ph lin kt cc b
thng ip cp nht DV t hng xm
Phn tn: mi node thng bo cho
hng xm ch khi DV ca n thay i
hng xm khi s li thng bo cho hng xm ca chng, nu cn
ch cho (thay i trong chi ph ca lin kt cc b hoc t/ip t hng xm)
tnh li cc o c
nu DV ti bt k ch no thay i, thng bo cho hng xm
Mi node:
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
30
x y z
x
y
z
0 2 7
t
c.ph ti
t
t
x y z
x
y
z
0
t
c.ph ti
x y z
x
y
z
c.ph ti
x y z
x
y
z
7 1 0
c.ph ti
2 0 1
2 0 1
7 1 0
t
x z
1 2
7
y
bng node x
bng node y
bng node z
Dx(y) = min{c(x,y) + Dy(y), c(x,z) + Dz(y)}
= min{2+0 , 7+1} = 2
Dx(z) = min{c(x,y) +
Dy(z), c(x,z) + Dz(z)}
= min{2+1 , 7+0} = 3
3 2
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
31
x y z
x
y
z
0 2 7
t
c.ph ti
t
t
x y z
x
y
z
0 2 3
t
c.ph ti x y z
x
y
z
0 2 3
t
c.ph ti
x y z
x
y
z
c.ph ti
x y z
x
y
z
0 2 7
t
c.ph ti
x y z
x
y
z
0 2 3
t
c.ph ti
x y z
x
y
z
0 2 3
t
c.ph ti
x y z
x
y
z
0 2 7
t
c.ph ti
x y z
x
y
z
7 1 0
c.ph ti
2 0 1
2 0 1
7 1 0
2 0 1
7 1 0
2 0 1
3 1 0
2 0 1
3 1 0
2 0 1
3 1 0
2 0 1
3 1 0
t
x z
1 2
7
y
bng node x
bng node y
bng node z
Dx(y) = min{c(x,y) + Dy(y), c(x,z) + Dz(y)} = min{2+0 , 7+1} = 2
Dx(z) = min{c(x,y) + Dy(z), c(x,z) + Dz(z)} = min{2+1 , 7+0} = 3
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
32
VTKC: chi ph lin kt thay i
Chi ph lin kt thay i: node nhn ra s thay i chi ph trong lin
kt cc b
cp nht t/tin nh tuyn, tnh li vc t KC
nu DV thay i, thng bo hng xm
tin tt truyn nhanh
x z 1 4
50
y 1
ti t0, y pht hin thay i chi ph lk, cp nht DV ca n, v thng bo hng xm. ti t1, z nhn c cp nht ca y v cp nht bng ca n. N tnh chi ph thp nht ti x v gi cho hng xm DV ca n. ti t2, y nhn c cp nht ca z v cp nht DV ca n. tuyn ng chi ph thp nht ca y khng i v vy n khng gi thng ip no cho z.
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
33
Vc t KC: chi ph lin kt thay i
Chi ph lin kt thay i: tin tt truyn nhanh
tin xu truyn chm vn m ti v cng!
44 vng lp trc khi gii thut n nh
S nhim c ngc: Nu Z i qua Y ti X:
Z ni Y khong cch ca n ti X l v tn (vy Y s khng i qua Z ti X)
liu cch ny c gii quyt hon ton vn m ti v cng khng?
x z 1 4
50
y 60
-
Trng i Hc Bch Khoa Tp.HCM
Khoa Khoa Hc v K Thut My Tnh
2011
MNG MY TNH CN BN
Bi ging 3 - Chng 4: Tng Mng
34
So snh cc gii thut LS v DV
S phc tp ca th/ip LS: vi n node, E lin kt, O(nE)
th/ c gi
DV: ch trao i gia hng xm vi nhau
t/gian hi t thay i
Tc hi t LS: O(n2) gii thut cn O(nE)
thng ip
c th c dao ng
DV: thi gian hi t thay i
c th c vng lp nh tuyn
vn m-ti-v-cng
Sc chu ng: nu bt trc trc?
LS:
node c th qung b chi ph lin kt sai
mi node ch tnh ton bng ca ring n
DV:
node DV c th qung b chi ph tuyn ng sai
mi bng ca node c dng bi cc node khc
li lan truyn trong mng