04 internet 2pages
TRANSCRIPT
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CHNG 4 KT NI MNGINTERNET
PGS. TS. Nguyn Hu ThanhB mn K thut thng tinVin in t -Vin thng
HBK H Ni
Email: [email protected]
Ni dungTi sao phi kt ni mng lp
Internetworking?
Khi nim kt ni mng v kin trcInternet
Cu trc a ch IP, lin h gia ach IP, a ch MAC
IP v cc giao thc c lin quannh tuyn trong Internet
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
3CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
t vn
Nhu cu: kt ni nhiu mng con vinhau thnh mt mng ton cu
Kt ni nhiu mng LAN lp MACc kh thi?
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
4CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
t vn (tip) Cc kh khn:
Do a ch MAC khng c cu trc nn khngth s dng nh tuyn phi to ra mtspanning tree
Vic to ra spanning tree kt ni hng chc ngn ntkhng kh thi:
Chn nt gc? Kch thc bng chuyn tip (forwarding table) qu
ln Cc bn tin cu hnh qung b vi s nt ln lm
mng b lt vi cc bn tin iu khin
Vic kt ni cc mng vt l: cu trc vt lkhc nhau v cch nh a ch khc nhau cck phc tp (Ethernet, WiFi, ATM, .v.v.)
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
5CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
t vn (tip) Kt lun:
Cn phi c mt phn lp chung c lp vicc mng vt l kt ni mng lpInternetworking mng Internet
LLC/MAC 802.11)
TCPApplication
Physical
IP
Sender Receiver
LLC/MAC (802.3)
TCPApplication
Physical
IP802.11
IP802.3
Physical
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
6CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Yu cu thit k mng InternetPhi to ra mt lp kt ni lin
mng (Internetworking)a ch mng c cu trc: ph thuc
vo v tr mng thch hp cho nhtuyn
Phn lp chung khng ph thuc vo cs h tng v cng ngh mng phn
cngGiu c s h tng mng pha di
vi cc dch v mng lp trn
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
7CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Yu cu thit k mng Internet(tip)
Ethernet
DSL
3G/4G
ATM
Router
Internet
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
8CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Lch s pht trin ca Internet 1957: M thnh lp c quan ARPA (Advanced Research
Projects Agency) trc thuc B quc phng 1962: M tp trung nghin cu cc phng thc gi d
liu qun s theo phng thc phn tn nguyn lchuyn mch gi
1968: ARPA thnh lp d n ARPANET kt ni UCLA, SRI(ti Stanford), UCSB (Santa Barbara), H Utah. Bngthng 50kbps
1972: Email u tin. ARPA i tn thnh DARPA(Defence Advanced Research Projects Agency). ARPANETs dng NCP (Network Control Protocol) cho php truynd liu gia 2 nt trn cng mng
1973: Vinton Cerf v Bob Kahn (Stanford) bt u phttrin TCP/IP, cho php cc my tnh lin mng trao i
d liu 1974: thut ng Internet c s dng ln u tin 1976: Robert M. Metcalfe pht trin mng Ethernet. Mng
truyn s liu qua v tinh c pht trin. APARNET c hn 23 nt
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
9CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Lch s pht trin ca Internet(tip)
1981: NSF quyt nh xy dng mng CSNET cho nghin cu clp vi ARPANET. Lin kt gia ARPANET v CSNET. Host: 213
1983: thnh lp Internet Activities Board (IAB). TCP/IP thay thhon ton NCP. H Wisconsin a ra DNS u tin. Host: 562
1985: NSF thnh lp mng NSFNET, dung lng: 1,55Mpbs. Host:1962
1986: IETF (Internet Engineering Task Force) c thnh lp.Host: 2308
1990: ngn ng htlm ra i. Host: 330000 1992: s ra i ca World Wide Web. Bng thng mng li:
45Mbps. Host: 2.000.000 1993: Mosaic ra i: web browser u tin vi giao din ha 1996: host: 15.000.000 1998: IPv6 c chun ha bi IETF 1999: 802.11 ra i
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
10CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
c im ca Internet Mi gi c nh tuyn (tm ng) mt cchc lp router khng lu gi trng thi cacc lung d liu
Cho php truyn gi qua nhiu mng vt lkhc nhau
Khng c c ch m bo tr Khng c c ch m bo th t gi Khng c c ch m bo gi s c truyn
n ni nhn Gi c th b mt do trn hng i nt trung gian
Cc chc nng thng minh (truyn li gi, spxp th t gi, iu khin lung, chng tcnghn) c thc hin bi thit b u cui
Giao thc Internet (Internet Protocol IP) cs dng!
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
11CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Chc nng chnh ca lpInternetworking
nh tuyn (routing): tm ng icho mt gi tin t ngun n ch thut ton vo giao thc nh tuyn
Chuyn tip (forwarding): chuynmt gi tin t mt u vo router rau ra thch hp bng chuyn tip(forwarding/routing table)
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
12CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP a ch IP
IPv4: 32 bit (chng ny ch xt IPv4) IPv6: 128 bit
Yu cu: phi c cu trc, cho php nh tuyn a ch IP: Network ID. (a ch mng) Host ID. (a ch my trm)
Mi giao din mng c mt a ch IP a ch IPc tnh duy nht
Cp pht a ch IP: Tnh ng (TD qua DHCP)
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
13CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip)
Biu din a ch IP4 byte c biu din bi 4 ch s thp
phn c chm
TD: a ch DNS ca FPT: 210.245.0.10
X . X . X . X
8 bit (0 - 255)
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
14CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip) Khng gian a ch IP:
Theo l thuytC th l 0.0.0.0 255.255.255.255Mt s a ch c bit (RFC1918)
Private address(khng c nghaton cc)
10.0.0.0/8
172.16.0.0/12
192.168.0.0/16Loopback address 127.0.0.1
Multicast address224.0.0.0
239.255.255.255
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
15CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip)
S my trm ti a trong mt mng:k=2n 2
Trong : n s bit ca Host ID.2 a ch cn li:
a ch ton 0 a ch mng TD: Mng 171.64.15.0
a ch ton 1 a ch qung b trongphm vi mt mng TD: 171.64.15.255 a ch qung b trong
phm vi mng 171.64.15.0
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
16CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip)
Nguyn tc nha ch:Mi mng LAN c
a ch mng ringbit v c ngncch bi router
Cc my trm (kc router) nmtrong mt LAN cchung a chmng, cn a chmy trm khcnhau
C bao nhiu mngLAN trong hnhbn?
223.1.1.1
223.1.1.3
223.1.1.4
223.1.2.2223.1.2.1
223.1.2.6
223.1.3.2223.1.3.1
223.1.3.27
223.1.1.2
223.1.7.2
223.1.7.1
223.1.8.2223.1.8.1
223.1.9.1
223.1.9.2
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
17CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip)
Cu hi:Lm sao phn bit c a ch mng
v a ch my trm trong 32 bit a chIP?
Phn loi a ch IP:C phn lp (classful addressing)Khng phn lp (classless addressing):
Subnetting
Supernetting (CIDR)
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
18CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip) a ch IP c phn lp: 5 lp (A, B, C, D,
E)
Class A 0
Class B 1 0
Class C 1 1 0
Class D 1 1 1 0
Class E 1 1 1 1 Reserve for future use
Multicast
5
7
6bit
H
N
H H
H H
N N H
8bits 8bits 8bits 8bits
A B C D0 232-1
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
19CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip)# of network # of hosts
Class A 128 2^24
Class B 16384 65536
Class C 2^21 256
a ch IP c phn lp: (tip)Th d:
18.181.0.31 class A 171.64.74.155 class B
Nhn xt: a ch c phn lp gy lng ph
khng gian a ch
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
20CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip)Th d:18.181.0.31 (www.mit.edu) ?
171.64.74.155 (stanford) ?
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
21CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip)
Nhn xt: nh a ch c phn lpc mt s nhc imCng nhc, lp C qu nh, lp B qu
ln khng tn dng hiu qu mina ch
Cc router trong mng ni b cn phic a ch mng (network ID.) ring bitcho tng giao din
Th d: mt c quan c tng cng 300my tnh tm c ch nh a ch?
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
22CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip) Subnetting: chia nh mt mng thnh nhiu
mng con vi nhiu a ch mng con
CLASS Be.g. Company
10 Net ID Host-ID2 14 16
10 Net ID Host-ID
2 14 16
0000
Subnet ID (20) SubnetHost ID (12)
10 Net ID Host-ID
2 14 16
1111
Subnet ID (20) SubnetHost ID (12)
10 Net ID Host-ID
14 16
000000
Subnet ID (22) SubnetHost ID (10)
10 Net ID Host-ID
14 16
1111011011
Subnet ID (26) SubnetHost ID (6)
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
25CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip)
Subnetting (tip): Th d: subnetting ti Stanford Gii thch s mng bn di?
Gates-rtr 171.64.74.58
171.64.74.0/24
171.64.1.178
yuba
border2-rtr
bbr2-rtr
171.64.1.161
171.64.1.160/27171.64.0.0/16AS 32
Stanford Class BAddress
171.64.74.1
171.64.1.131To: cenic.net
To: cogentco.com
171.64.1.152
171.64.1.148
171.64.1.133
171.64.1.144/28
171.64.1.132/30hpr1-rtr
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
26CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip) Supernetting:
Classless Inter-Domain Routing (CIDR) addressing:
Ton b vng a ch IP c chia thnh cc segmentc c trng bi mt tin t(prefix)
TD: 128.9.0.0/16 th hin mt segment vi vng a cht 128.9.0.0 128.9.255.255 (2^16 a ch)
0 232-1128.9.0.0/16
128.9.0.0
216
142.12.0.0/19
65.0.0.0/8
128.9.17.1
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
27CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip) Supernetting (tip):
ng i n mt a ch IP xc nh cc router nhtuyn da trn nguyn tc longest prefix match
TD: a ch IP 129.9.17.1 thuc v mng no trong ccmng sau:
128.9.16.0/20 128.9.16.0/21 128.9.24.0/21
0 232-1
128.9.0.0/16
128.9.17.1
128.9.16.0/20 128.9.176.0/20
128.9.16.0/21
128.9.24.0/21
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
28CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip)Supernetting (tip):Cho php nhm nhiu segment con
thnh mt segment ln hnMc ch ca supernetting:
Tit kim vng a chGim s bn ghi trong bng nh tuyn
Ch : supernetting ch c php khitt c cc segment con cng nm trnmt hng
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
29CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip)
Supernetting (tip):Th d: ti bng nh tuyn ca R1
128.9.16.0/22 = 10000000 00001001 00010000 00000000
128.9.20.0/22 = 10000000 00001001 00010100 00000000
128.9.24.0/22 = 10000000 00001001 00011000 00000000128.9.28.0/22 = 10000000 00001001 00011100 00000000
/22
/20
128.9.16.0/20
12
3128.9.16.0/22
128.9.20.0/22
128.9.28.0/22
128.9.32.0/20
128.9.48.0/20
R1 R2
12 3
4
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
30CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
a ch IP (tip)Mi lin h gia giao thc nh tuyn v
phng thc nh a ch:Cc giao thc nh tuyn ch h tr phng
thc nh a ch c phn lp (classfuladdressing): RIP-1 (Routing InformationProtocol)
Cc giao thc nh tuyn h tr nh a chkhng phn lp: RIP-2, OSPF (Open ShortestPath First), EIGRP (Enhanced Interior GatewayRouting Protocol), IS-IS
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
NAT
NAT: Network Address Translation
IETF RFC 1631
Phng thc nh x a ch IP private thnha ch IP public, cung cp s nh tuyntrong sut gia cc host.
Gateway router cn phi c mt bng NAT Phn loi:
Static NAT
Dynamic NAT
NPAT (Network Port Address Translation)
31CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
Static NAT L qu trnh nh x 1-1 t a ch IP private
thnh a ch IP public.S dng khi s lng IP trong LAN bng s lng
NAT-IP.n gin.
Thd: a ch 192.168.1.2 s lun lun nh xsang a ch 200.18.123.15
32CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
192.168.1.2
192.168.1.5
192.168.1.6
200.18.123.15
200.18.123.14
200.18.123.12
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
Dynamic NAT L qu trnh nh x mt a ch IP private thnh mt a ch
IP public t mt di cc a ch IP c ng k. Mi kt ni tbn trong mun ra ngoi s c cung cp mt
a ch trong di. Nu di a ch ny c cp pht ht th cc kt ni s
khng thra ngoi na. Thd:
My tnh vi a ch IP 192.168.1.2 s chuyn i sang a chu tin cha c s dng trong di a ch public200.18.123.10 n 200.18.123.20
33CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
192.168.1.2
192.168.1.5
192.168.1.6
200.18.123.10
200.18.123.20
.
.
.
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
NPAT Cc a ch IP trong mng LAN c du di mt ach NAT-IP.Mi gi tin c gi ra ngoi bng a ch NAT-IP v
port ngun c thay th bng mt cng no chac dng NAT (thng ln hn 1024).
Khi nhn c gi tin, router s kim tra a ch IP vport trong bng NAT v chuyn n n host.
Thd: Cc a ch private u chuyn thnh a ch200.18.123.10 nhng vi cc port khc nhau
34CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
192.168.1.2
192.168.1.5
192.168.1.6
200.18.123.10:1211
200.18.123.10:1212
200.18.123.10:1213
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
35CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Lin h gia a ch MAC va ch IP
Trong mng vt l,cc trm trao i dliu thng qua cckhung lp MAC IPdatagram c nggi vo MAC frame
A B:A gi 1 gi IP vi a
ch ngun l IP addr.ca A, ia ch ch lia ch IP ca B
Gi IP c ngvo mt khung MACvi a ch ngun lAs MAC addr, ach ch l Bs MACaddr
Thng thng A chbit a ch IP ca B
223.1.1.1
223.1.1.2
223.1.1.3
223.1.1.4 223.1.2.9
223.1.2.2
223.1.2.1
223.1.3.2223.1.3.1
223.1.3.27
A
BE
Lm th no A bita ch MAC ca B?
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
36CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Lin h gia a ch MAC v
a ch IP (tip)
Giao thcARP (Address Resolution Protocol): tm ach MAC tng ng vi mt a ch IP cho trc Mi nt mng (my trm, router) u chy giao thc ARP Lu gi bng ARP (ARP table): nh x gia a ch IP v a
ch MAC {IP addr., MAC addr., TTL} TTL: thi gian sng ca mt bn ghi (thng thng 20
pht)
Bs MAC
addr
As MAC
addr
frame
dest. addr
frame
src addr
Bs IP addr As IP addr IP payload
IP
dest. addrIP
src. addr
IP datagram
MAC frame
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
37CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Lin h gia a ch MAC va ch IP (tip)
A
B: 1: A kim tra a ch IP ca B nhn ra B nm trong cngmt LAN vi A
2: A tm a ch MAC ca Btrong bng ARP (tng ngvi a ch IP ca B)
3: nu tm thy: A ng gi IPvo khung MAC vi a chMAC ngun ca A v a chMAC ch ca B
4: nu khng tm thy: Aqung b bn tinARP requestvi a ch MAC ch l a chqung b (FF-FF-FF-FF-FF-FF)km theo a ch IP ca mycn tm B
5: Cc my trm trong LANnhn c bn tinARPrequest. Ch B tr li bng bntinARP reply ti A c chaa ch MAC ca B
IP: 223.1.1.1MAC: 1A-23-F9-CD-06-9B
IP: 223.1.1.3
MAC: 5C-66-AB-90-75-B1
IP: 223.1.1.4
MAC: 88-B2-F2-54-1A-0F
IP:2
23.1.2.2
MAC
:1A-2B-EF-60-A3-5F
A
BE
6: A nhn c bn tinARP replytB cp nht bng ARP, gi gi IPtrong khung MAC
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
38CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Lin h gia a ch MAC v
a ch IP (tip) A E:
1: A kim tra a ch IP ca B nhn ra B nm trn mngkhc (LAN2) quyt nh gigi ti default router (R1)
2: A tm a ch MAC ca R1trong bng ARP (tng ngvi a ch IP ca B)
3: nu tm thy: A ng gi IPvo khung MAC vi a chMAC ch l R1
4: nu khng tm thy: Aqung b bn tinARP requestvi a ch MAC ch l a chqung b (FF-FF-FF-FF-FF-FF)km theo a ch IP ca mycn tm R1
5: Cc my trm trong LAN
nhn c bn tinARPrequest. Ch R1 tr li bngbn tinARP reply ti A ccha a ch MAC ca R1
6: A nhn c bn tinARPreplyt R1 cp nht bngARP, gi gi IP trong khungMAC
IP: 223.1.1.1
MAC: 1A-23-F9-CD-06-9B
IP: 223.1.1.3
MAC: 5C-66-AB-90-75-B1
IP: 223.1.1.4
MAC: 88-B2-F2-54-1A-0F
IP:223.1.2.2
MAC:1A-2B
-EF-60-A3-5F
A
BE
R1
LAN1
LAN2
LAN3
7: R1 nhn c khung MAC tA ly gi IP, tm chng tip theo gi gi (LAN2)8: R1 li thc hin c ch ARPtrn LAN 2 nh cc bc 1 - 6
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
39CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Lin h gia tn min v ach IP
Tn min Domain Name System L mt h thng t tn cho my trm, dch v, router, cc
loi ti nguyn khc nhau trm mng Mc ch: d nh v thun tin
a ch mng tn min (domain name) a ch my trm tn my (host name)
mail.hut.edu.vn 202.191.57.199
c im ca DNS: Tn my hoc tn min c cu trc phn lp: mt tn c th
thuc v mt tn min cp cao hn mail.hut.edu.vn thuc v hut.edu.vn
Nhng tn min hay s dng: Theo lnh vc: .com, .edu, .net, .gov., .org Theo a l: .us, .vn, .ru, .au, .de
Tn min cp cao nht c cp pht bi ICANN (InternetCorporation for Assigned Names and Numbers)
Tn min .vn c cp pht bi VNNIC Mt tn min s tng ng vi mt t chc duy nht
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
40CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Lin h gia tn min v a
ch IP (tip) M hnh truy vn DNS:
Client server C s d liu tn min c lu ti DNS server DNS server
Phn tn C cu trc phn tng Mi min u c mt server gc
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
41CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Lin h gia tn min v ach IP (tip)
M hnh truy vn DNS (tip): DNS query:
ng dng gi mt DNS query n DNSserver gn nht (local DNS server) TD:web browser gi DNS server v a ch IPca www.wikipedia.org
DNS server kim tra, nu khng c thngtin cn tm th s chuyn tip DNS queryn DNS server cp cao hn .v.v.
Khi nhn c DNS reply, ng dng lugi a ch IP trong cache.
Phng thc gi bn tin DNS query: Linux/Unix: host [tn min] Windows: nslookup [tn min] C/C++: gethostbyname() TD: host vnexpress.net
Ch : DNS c th c s dng vinhiu mc ch TD: cn bng ti:
cng vi mt DNS query DNS serverc th tr li vi cc a ch IP khcnhau
sales.fpt.vn test.fpt.vn rd.fpt.vn
fpt.vn
DNS query (host1.rd.fpt.vn)
DNS reply
(IP address)
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
42CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Internet Protocol IP:
Version 4 hin ti ang c s dng rng riVersion 6 l giao thc ca tng lai Phin bn IP c th hin trong trng version ca
IP header
App
Host-to-Host
Internetwork
Network Access
TCP / UDP
IP
Data Hdr
Data Hdr
TCPSegment
IP Datagram
Protocol Stack
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
43CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Internet Protocol (tip) Tip u IP (IP header)
ver length
32 bits
data(variable length,typically a TCP
or UDP segment)
16-bit identifier
Internetchecksum
time tolive
32 bit source IP address
IP protocol version
header length(bytes)
max numberremaining hops
(decremented ateach router)
forfragmentation/reassembly
total datagramlength (bytes)
upper layer protocolto deliver payload to
head.len
DSCP
type of data flgsfragment
offset
upperlayer
32 bit destination IP address
Options (if any) E.g. timestamp,record routetaken, pecifylist of routers
to visit.
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
44CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Phn mnh gi tin Vn : truyn IP datagram qua nhiu mng vi kchthc gi cho php ln nht khc nhau (TD: Ethernet:1500byte)
Phn mnh (Fragmentation)
Gii php: R1 phn mnh IP datagram thnh nhiu datagramngn hn
AEthernet MTU=1500 bytes MTU=1500 bytes
B
Source Destination
MTU0More Frag=0
Offset=0More Frag=1
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InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
45CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Phn mnh gi tin (tip)
Vic ghp mnh (assemble) ch c thc hin thit b u cui
Nn trnh phn mnh trong mng thit b ucui c th c lng chiu di gi nh nht(Maximum Transmission Unit - MTU) cho phptrn ng i
Bn pht c th gi cc gi c kch thc khcnhau, khng phn mnh tm path MTU traceroute F www.hut.edu.vn 1500
traceroute F www.hut.edu.vn 1501
(DF=1 trong IP header; router gi bn tin ICMP li)
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
46CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Phn mnh gi tin (tip) Phn mnh s dng cc trng: identification,
flags, fragment offset Identification: 16 bit - cc offset ca cng 1 gi ln c
cng mt ID. Flags: 3 bit
#1 bit: khng s dng #2 bit Dont fragment (DF) bit:
DF=1: Khng c php phn mnh DF=0: c php phn mnh
#3 bit More fragment (MF) bit: nu DF=0 MF=1: hy cn phn mnh tip theo
MF=0: phn mnh cui cng Offset: 13 bit V tr ca gi tin phn mnh trong gi tin ban u Theo n v 8 bytes
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
47CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Phn mnh gi tin (tip)
Th d:
0 3999
0 1399
1400 2799
2800 3999
ID=2356
Flag=0.0.1
Offset = 0/8 = 0
ID=2356
Flag=0.0.1
Offset = 1400/8 = 175
ID=2356
Flag=0.0.0
Offset = 2800/8 = 350
1400 2800
ID=2356
Flag=0.0.0Offset=0
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
48CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Cc trng khc Version: 4 bit 4: IPv4 6: IPv6
IHL (Internet Header Length): 4 bit th hin chiu dica header theo n 1 dword (32bit)
DSCP (Differentiated Service Code Point): 8 bit Tn c: type of service (TOS) Hin ti c s dng trong qun l cht lng dch v
(Quality-of-Service: QoS) (TD: cc dch v thi gian thc.v.v.)
DiffServ (RFC2474)
ECN (Explicit Congestion Notification): 2 bit bo hiumng b tc nghn, ch dng khi thit b u cui h tr
c ch ny Total length: 16 bit - di ton b, tnh c phn u
Tnh theo bytes Max: 65536
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
49CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Cc trng khc (tip)
TTL (Time-To-Live): 8 bit thi gian sng di ng i gi tin c th i quaMax: 255
Router gim TTL i 1 n v khi nhn v chuyn tip gitin
Gi tin b hy nu TTL bng 0 Protocol: 8 bit cho bit cc giao thc c ng
gi vo IP datagram: Giao thc tng host-to-host: TCP (6), EGP (8), IGP (9),
UDP (17), OSPF (89), SCTP (132)
Giao thc tng internetworking: ICMP (1), IGMP (2), IP
(IP in IP) (4)
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
50CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Cc trng khc (tip)Header Checksum: 16 bit Kim tra
li cho headerOptions:
di thay i, c th ln n 40 bytec s dng thm cc chc nng
mi
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
51CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
ICMP ICMP Internet Control Message Protocol RFC 792 ICMP c s dng tng mng trao i thng tin
Bo li: bo gi tin khng n c mt my trm, schng vt qu gii hn cho php (TTL=0), kch thcgi tin qu di .v.v.
Thng tin phn hi nh dng bn tin ICMP: Type, Code, cng vi 8 bytes u
tin ca gi tin IP b li
Type Code Checksum
Rest of the header
Data
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
52CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
ICMP (tip)Mt s dng bn tin ICMP:
Type Code description
0 0 echo reply (ping)
3 0 dest. network unreachable3 1 dest host unreachable
3 2 dest protocol unreachable3 3 dest port unreachable
3 6 dest network unknown
3 7 dest host unknown4 0 source quench (congestion
control - not used)
8 0 echo request (ping)9 0 route advertisement
10 0 router discovery11 0 TTL expired
12 0 bad IP header
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
53CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
ICMP (tip)
Ping:S dng kim tra kt niGi gi tin ICMP echo requestBn nhn tr v ICMP echo replyMi gi tin c mt s hiu gi tinTrng d liu cha thi gian gi gi tin
Tnh c thi gian i v v - RTT (round-trip time)
C php: ping [a ch IP/tn host] ping www.google.com
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
54CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
ICMP (tip) Traceroute Tm ng i (cc router trung gian) t ngun ti ch C php:
Linux: traceroute [a ch IP/tn host] Windows: tracert [a ch IP/tn host]
C:\Documents and Settings\tnh>tracert www.jaist.ac.jp
Tracing route to www.jaist.ac.jp [150.65.5.208]over a maximum of 30 hops:
1 1 ms
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
55CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
ICMP (tip) Traceroute (tip): Bn gi truyn gi tin cho bn nhn
Gi th nht c TTL =1 Gi th 2 c TTL=2,
Khi gi tin th n n router th n: Router hy gi tin gi mt gi tin ICMP (type 11, code 0) c cha tn v a ch IP ca router
khi nhn c gi tin tr li, bn gi s tnh ra RTT Khi ngun nhn c gi tin ICMP ny s dng liMi gi tin lp li 3 ln
3 probes3 probes
3 probes
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
56CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Tng quan v nh tuynBn Internet 1999:
Ngun: http://www.lumeta.com
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
57CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Tng quan v nh tuyn(tip)
Bn Internet 2006:
Ngun: http://www.lumeta.com
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
58CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Tng quan v nh tuyn (tip) S bn ghi trong bng nh tuyn ti
mng li Internet
Ngun: http://www.cidr-report.org/
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
59CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Tng quan v nh tuyn (tip)
Phn b cc bn ghi
0
20000
40000
60000
80000
100000
812
16
20
24
Prefix length (bits)
Numberofentries
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
60CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Tng quan v nh tuyn
(tip)Vn : A B
A B
R1
R2
R3
R4R1 chn chng tiptheo i n B ntn?
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
61CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Tng quan v nh tuyn(tip)
Bng nh tuyn (routing table) :Bng nh tuynnm trong cc routerCho php vi mt a ch mng ch th phi
gi gi tin ra giao din mng no ca routerBng nh tuyn c to ra do cc router trao
i bn tin nh tuyn thng qua cc giao thcnh tuyn (routing protocols)
Nguyn l nh tuyn ca router: longestprefix match
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
62CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Tng quan v nh tuyn
(tip) Bng nh tuyn (tip)
dest.network
net. mask next hop interface metrics
10.0.0.0 255.255.255.0 A IP addr. 1 1
172.16.0.0 255.255.255.0 C IP addr. 2 1
Router B Router CRouterA
10.0.0.0/24 192.168.0.0/24 172.16.0.0/24
10.0.0.0/24 172.16.0.0/241 2
3
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
63CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Tng quan v nh tuyn (tip)
Mc tiu: Tm ng i ngn nht t mt nt gc ti cc ntcn li xy dng cy theo ng ngn nht(shortest path tree - SPT)
Cc thut ton xy dng cy SPT: Thut ton Bellman-Ford distance vector routing
(RIP, IGRP) Thut ton Dijkstra link state routing (OSPF)
Cu hi: S khc nhau gia cy bc cu ti thiu (Minimum
Spanning Tree) v cy theo ng ngn nht? Ti sao nguyn tc nh tuyn trong Internet li tun
theo cy SPT?
Ch : Xem li mn C s mng thng tin hiu chi titv l thuyt nh tuyn
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
64CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Tng quan v nh tuyn (tip)Cc giao thc nh tuyn:Cc giao thc nh tuyn ni min
(Intra-AS routing):OSPF, RIP-1, RIP-2IS-IS, EIGRP, IGRP
Cc giao thc nh tuyn lin min
(Inter-AS routing):BGP
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
65CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Tng quan v nh tuyn (tip)
Cho R8l nt gc, tm ng i ngnnht t R8n cc nt cn li
R5R3
R7
R6R4R2R11 1 4
2
4
2 2 3
2 3
R8
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
66CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Thut ton Bellman-Ford phntn
1: Gi Xn=(C1,C2,,C7) l cc khong cch t Ri R8(i=1 - 7), n s bc lp
2: X0=(, )
3: Router igi Xk ti cc nt hng xm ca itheochu k T vector khong cch (distance vector)
4: Nu router inhn c bn tin vi khongcch Cinh hn khong cch hin ti Ri cpnht Xn.
5: Lp li bc 3 cho n khi Xn+1=Xn 6: Dng
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
67CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Thut ton Bellman-Ford phntn (tip)
R5R3
R7
R6R4R2R11 1 4
2
4
2 2 3
23
R8 0
R5R3
R7
R6R4R2R11 1 4
2
4
2 2 3
23
R84
2 3
2
0
R1 Inf
R2 Inf
R3 4, R8
R4 Inf
R5 2, R8
R6 2, R8
R7 3, R8
n=1
n=2
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
68CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Thut ton Bellman-Ford phn tn (tip)
R5R3
R7
R6R4R2R11 1 4
2
4
2 2 3
23
R84
23
26
46
0
R1 6, R3
R2 4, R5
R3 4, R8
R4 6, R7
R5 2, R8
R6 2, R8
R7 3, R8
R5R3
R7
R6R4R2R11 1
2
4
2
23
R84
23
25
45
0
R1 5, R2
R2 4, R5
R3 4, R8R4 5, R2
R5 2, R8
R6 2, R8
R7 3, R8
n=3
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
69CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Thut ton Bellman-Ford phn tn (tip)
Nhn xt:Cc bn tin DS c gi theo chu k, khng
ph thuc vo trng thi ng truyn
Cc vn :S bc lp ca thut ton? (thut ton s
chy bao lu)Thut ton c lun hi t hay khng (n< )?iu g s xy ra khi mt nt/lin kt b hng
hoc khi khong cch thay i?
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
70CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Thut ton Bellman-Ford phn tn (tip)
Tnh khong cch n R4:
R4R3R2R11 1 1
5,R24,R35,R233,R24,R33,R22
3,R22,R33,R21
1, R42,R33,R20
R3R2R1Bc lp
Counting to infinity
R3 R4 hng
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
71CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Thut ton Bellman-Ford phn tn (tip)
Khc phc vn phn k caBellman-Ford (counting to infinityproblem):t s bc ti a, TD: Ci
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
73CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Thut ton Dijkstra (tip)
C ch qung b trong Dijkstra: Gi tin trng thi lin kt (Link State Packet - LSP)bao gm:
ID ca router Rigi bn tin LSP Danh sch cc hng xm ca Ricng vi khong cch
tng ng t Ri S th t TTL
Khi router Rjnhn c bn tin LSP: Nu s th t ch ra bn tin mi nht gi LSP trn tt
cc cc giao din cn li (qung b) Nu khng hy gi tin
Cc router gi bn tin hello n cc nt hng xm nhn bit c trng thi knh truyn
Xy dng cy SPT: Da trn bn tin LSA cc router t xy dng cySPT da trn thut ton Dijkstra
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
74CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Thut ton Dijkstra (tip)Bc {S} P(R1),d(R1)
P(R2),
d(R2)
P(R3),
d(R3)
P(R4),
d(R4)
P(R5),
d(R5)
P(R6),
d(R6)
P(R7),
d(R7)
0 R8 4, R8 2,R8 2,R8 3,R8
1 R8,R5 4,R5 4,R8 - 2,R8 3,R8
2 R8,R5,R6 4,R5 4,R8 6,R6 - - 3,R8
3 R8,R5,R6,R7 4,R5 4,R8 6,R6 - - -
4 R8,R5,R6,R7,R2 5,R2 - 4,R8 5,R2 - - -
5 R8,R5,R6,R7,R2,R3 5,R2 - - 5,R2 - - -
6 R8,R5,R6,R7,R2,R3,R1 - - - 5,R2 - - -
7 R8,R5,R6,R7,R2,R3,R1,R4 - - - - - - -
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
75CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Thut ton Dijkstra (tip)
R5R7
R6
2
2 3
R80
R80
R5 2R8
0
R5
R6
2
2
R80
R5R3
R7
R6R4R2R11 1
2
4
2
2 3
R8
n=0 n=1
n=2n=3
n=7
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
76CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
So snh
Bn tin nh tuyn:Kch thcS lng bn tin trao i
Lng thng tin cn lu ti router n nh (khi cc bn tin b li)
Thi gian hi tGi : trong LS c hin tngcounting-to-infinity khng?
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
77CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
So snh (tip)
Bn tin nh tuyn:Kch thc: DV: ln (gi ton b thng tin v kt ni t 1
router ti tt c cc router khc) LS: nh (ch c thng tin t 1 router ti cc router
hng xm ca n)
S lng bn tin trao i DV: t (ch gi n cc nt hng xm) LS: nhiu (qung b ti ton mng)
Lng thng tin cn lu ti router:DV: ch lu gi trng thi cc router hng
xmLS: lu gi hnh ton mng
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
78CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
So snh (tip) n nh:
DV: 1 router c th gi cc bn tin vi khong cchkhng ng ti cc hng xm lan ra ton mng
LS: 1 router c th qung b cc bn tin LSA khngng/li cho ton mng
Tuy nhin cc router khc vn c th xy dng c hnh mng da vo cc bn tin LSA ti t cc router khc
Thi gian hi t: DV: cc bn tin DV c gi c chu k, khng ph
thuc vo trng thi ng truyn thi gian hi tlu, ngoi ra c th to vng lp (routing loop) (nh li
gii php split horizon!) LS: cc bn tin LSA c gi ch khi trng thi ngtruyn thay i thi gian hi t nhanh hn
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
79CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
nh tuyn trong mngInternet
Internet thc hin nh tuyn c phntng (hierarchical routing):Internet c phn thnh cc h t tr - AS
(Autonomous System)
Mi AS do c qun tr ring bit bi ccqun tr mng
Trong mt AS: s dng mt giao thc nhtuyn ni min (interior gateway protocol)
Gia cc AS: s dng giao thc nh tuyn lin
min (exterior gateway protocol)
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
80CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
nh tuyn trong mngInternet (tip)
3b
1d
3a
1c2aAS3
AS1
AS21a
2c2b
1b
3c
3a
1c2a
1b
Interior Gateway Protocol
(OSPF, RIP)
Exterior Gateway Protocol
(BGP )
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
81CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
EGP v IGP
AS3
EGP
IGP
EGPEGP
IGP
IGP
IGP
EGP
EGP
AS1
AS4
AS2
AS5OSPF domain
RIP domain
RIP domain
RIP domain
OSPF domain
RIP domain
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
82CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
H t trMi h t tr c mt s hiu ring AS
number (ASN - 16 bits hay 32 bits)
2914 NTT-COMMUNICATIONS-2914 - NTT America, Inc.
3491 BTN-ASN - Beyond The Network America, Inc.
4134 CHINANET-BACKBONE No.31,Jin-rong Street
6453 GLOBEINTERNET Teleglobe America Inc.
24087 VNGT-AS-AP Vietnam New Generation Telecom
24066 VNNIC-AS-VN Vietnam Internet Network Information Center
17981 CAMBOTECH-KH-AS ISP Cambodia
.
-
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
83CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
H t tr (tip)
ASN c cp pht bi IANA (InternetAssigned Numbers Authority)
Source: http://www.potaroo.net/
2008
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
84CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
nh tuyn ni vngIntra-AS routing = Interior Gateway
Routing (IGP)
Cc giao thc nh tuyn ni vngthng dng:RIP (Routing Information Protocol)
OSPF (Open Shortest Path First)
IGRP (Interior Gateway RoutingProtocol) Ch s dng cho cc routerca Cisco
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
85CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
RIP
c im:RIP Routing Information Protocol
L giao thc nh tuyn theo vector khongcch s dng thut ton Bellman-Ford phntn
c pht trin ln u di h iu hnhBSD Unix nm 1982
Trc y c s dng rng ri, hin nay tc s dng
Khong cch l s chng ti mng chS chng ti a: 15 chng
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
86CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
RIP (tip) Trao i thng tin: nh k
Cc vector khong cch c trao i nh k - 30s Mi thng ip cha ti a 25 mc Trong thc t, nhiu thng ip c s dng
S kin Gi thng ip cho nt hng xm mi khi c thay i Nt hng xm s cp nht bng chn ng ca n
Cc b m thi gian: Update timer
Dng trao i thng tin c 30s Invalid timer
Khi to li mi khi nhn c thng tin chn ng Nu sau 180s khng nhn c thng tin -> trng thi hold-down
Hold down timer Gi trng thi hold-down trong 180s Chuyn sang trng thi down
Flush timer Khi to li mi khi nhn c thng tin chn ng Sau 240s, xa mc tng ng trong bng chn ng
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
87CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
RIP (tip)
0 30 60 90 120 150 180 210 240 270 300 330 360 390 420
update
update
noupdate
Invalid timer
Hold down timer
Flush timer
When it is timeout,
hold down timer starts
When it is timeout,
Routing info will be deletedfrom routing table
When it is timeout,
This info will be deleted
from RIP database
When it receives update,
Invalid timer restarts
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
88CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
RIP (tip) RIP
RIPv1: ch h tr nh tuyn trong cc mngnh a ch IP c phn lp (classful)
Bn tin cp nht: thng tin mng ch, khong cchti mng ch
RIPv2: h tr nh tuyn trong c mng nha ch khng phn lp (classless)
Bn tin cp nht: thng tin mng ch, subnet mask
ca mng ch, khong cch ti mng ch
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
89CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
OSPF
c im:OSPF Open Shortest Path First
Thng tin v trng thi lin kt - LSA (linkstate advertisement) c qung b trn ton
AS
Vi cc AS ln: OSPF c phn cp thnhnhiu min OSPF nh
Cc router s dng thut ton Dijkstra thitlp bng nh tuyn
Khong cch (gi): 100Mbps/dung lng knh
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
90CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
OSPF (tip)Phn vng trong OSPF:Trong vic chn ng, ti sao phi
chia mng thnh cc vng nh hn?Nu c qu nhiu router
Thng tin trng thi lin kt c truynnhiu ln hn
Phi lin tc tnh ton li
Cn nhiu b nh hn, nhiu ti nguynCPU hnLng thng tin phi trao i tng lnBng chn ng ln hn
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
91CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
OSPF (tip)
3b
1d
3a2aAS3
AS1
AS21a
2b
1b
3c2c
1c
Ga
Gb
GcBackbone
Area border router
internal router
backbone router
boundary router
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
92CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
OSPF (tip)ABR - Area border routers: Qun l 1 vng
v kt ni n cc vng khcASBR - Autonomous system boundary
router: Ni n cc AS khc BR - backbone routers: thc hin OSPF
routing trong vng backbone
Internal Router Thc hin OSPF bntrong mt vng
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
93CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
RIP v OSPF So snh
RIP OSPF
c im Router bnh ng Cu hnh d dng Mng c nh
Phn cp Cu hnh phc tp Mng c va v ln
Kh nng m rng Khng C
phc tp tnh ton Nh Ln
Hi t Chm Nhanh
Trao i thng tin Bng chn ng Trng thi lin kt
Gii thut Distant vector Link-state
Cp nht hng xm 30s 10s (Hello packet)
n v chi ph S nt mng Bng thng
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
94CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
nh tuyn lin min BGP (Border Gateway Protocol): giao thc nh
tuyn lin min thng dng nht hin nay BGP-4
Vn ny sinh trong nh tuyn lin min: hnh: mng Internet c hnh phc tp, khng cu
trc
Tnh t tr ca cc AS: cc AS nh ngha khong cchhoc gi khc nhau kh tm c ng i thc sti u
tin cy (trust): mt s AS khng mun gi lu lngca mnh ti mt s AS xc nh
Chnh sch (policy): Mi AS c mt chnh sch nhtuyn khc nhau
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
95CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Quan h khch hng nhcung cp
Khch hng (customer) Nh cung cp (provider) Khch hng tr tin cho nh cung cp Internet c
truy nhp vo mng
provider
customer
IP trafficprovider customer
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
96CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Quan h khch hng nh
cung cp (tip)
IP trafficprovider customer
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
97CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
Quan h khch hng nhcung cp (tip)
peer peer
customerprovider
trafficallowed
traffic NOTallowed
-Lu lng thng c trao i giacc AS theo quan h providercustomer- Cc AS cng cp khng mong mun
trao i lu lng (khi khng c hpng trao i lu lng)
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
98CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
BGP c im:
Khng s dng phng thc vector khongcch v trng thi knh truyn s dngvector ng dn (path vector)
Cho php mt AS bit c thng tin i n AS khc BGP trao i cc bn tin path vector:AS_PATH
Gi thng tin ny vo bn trong AS Xc nh ng i tt nht da trn thng tin
v cc chnh sch chn ng
Cho php thit lp cc chnh sch Chn ng ra Qung b cc ng vo
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
99CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
BGP (tip)
eBGP v iBGP: External BGP vs. Internal BGP
Phn tn thng tin chn ng1. 3a gi ti 1c bng eBGP2. 1c gi thng tin ni b ti (1b, 1d, ) trong AS1 bng iBGP3. 2a nhn thng tin t 1b bng eBGP
3b
1d
3a
1c
2aAS3
AS1
AS21a
2c
2b
1b
3ceBGP session
iBGP session
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
100
CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
BGP (tip)p dng chnh sch nh tuyn vi
BGP:
Khi cc router gi v nhn thng tinchn ng:BGP c th t cc chnh sch
Cho ng vo Cho ng ra
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
101
CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
BGP (tip)
Cc bn tin BGP:Open: Thit lp mt phin BGP gia 2
router.
Keep Alive: Bt tay theo chu k.
Notification: Hy b phin BGP sau khitrao i thng tin.
Update: cp nht cc tuyn mi hochy b cc tuyn c
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
102
CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
BGP (tip) Bn tin cp nht: cha cc thuc tnh ca tuyn Thuc tnh ca tuyn: c s dng chn
ng ti u khi c nhiu tuyn cng i n mtch ORIGIN
Ngun ca thng tin (IGP/EGP/incomplete)AS_PATH
NEXT_HOP
MED (MULTI_EXIT_DISCRIMINATOR)
LOCAL_PREFATOMIC_AGGREGATE
AGGREGATOR
COMMUNITY
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
103
CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
BGP (tip)
Cc mc u tin khi chn tuyn
Highest Local Preference
Shortest ASPATH
Lowest MED
i-BGP < e-BGP
Lowest IGP costto BGP egress
Lowest router ID
traffic engineering
Enforce relationshipsE.g. prefer customer routesover peer routes
Throw up hands andbreak ties
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
104CHNG 4 KT NI MNG INTERNET
PGS. TS. Nguyn Hu Thanh
BGP (tip)
AS 7018135.207.0.0/16
AS Path = 6341
AS 1239Sprint
AS 1755
Ebone
AT&T
AS 3549Global Crossing
135.207.0.0/16AS Path = 7018 6341
135.207.0.0/16AS Path = 3549 7018 6341
AS 6341
135.207.0.0/16
AT&T Research
Prefix Originated
AS 12654RIPE NCCRIS project
AS 1129Global Access
135.207.0.0/16AS Path = 7018 6341
135.207.0.0/16AS Path = 1239 7018 6341
135.207.0.0/16AS Path = 1755 1239 7018 6341
135.207.0.0/16AS Path = 1129 1755 1239 7018 6341
Pick shorterAS path
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
Cc thut ton tm bn ghi trongbng nh tuyn
Cc vn lin quan n tm bn ghitrong bng nh tuyn (tablelookup):Trong nh a ch c phn lp:
Exact prefix match: hashing
Trong nh a ch khng phn lp:longest prefix match:
Binary triePatricia tree
105CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
Cc thut ton tm bn ghi
trong bng nh tuyn (tip) t vn :
S bn ghi trong bng nh tuyn trong mngli Internet tng theo hm m
Phn b chiu di ca network prefix (CIDR)thay i bt k
106CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
S bn ghi trong router li(Ngun: http://www.cidr-report.org/)
Phn b di network prefix trongrouter li
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
Cc thut ton tm bn ghi trongbng nh tuyn (tip)
t vn (tip):Router li tip nhn lung bit c tc
Gbit/s, cn phi gi khong 1 triugi/s/port tc x l nhanh
Bng nh tuyn thay i lin tc:100 ln/s vi chc ms phi cp nht
bng nh tuyn 1 ln
107CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
Cc thut ton tm bn ghi trong
bng nh tuyn (tip)Yu cu:
Cc bn ghi trong bn nh tuyn phi c spxp sao cho:
Cp nht cc bn ghi (table entry) nhanh v d dng Tc tm kim nhanh (table lookup) Kch thc b nh cha bng nh tuyn nh Thch hp vi c ch nh a ch khng phn lp
(classless addressing - CIDR)longest prefix match
Gi:W: di ca a ch IP
IPv4: W=32N: Sbit a ch mng (prefix)
Trong CIDR: Nthay i
108CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
Cc thut ton tm bn ghi trongbng nh tuyn (tip)
Cc thut ton lookup (longest prefixmatch) cho CIDR:
Binary triePatricia tree
109CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
Th dXt bng nh tuyn:
110CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
dest. network (b in.)/subnet mask next hop
a: 0/1
b: 01000/5
c: 011/3
d: 1/1
e: 100/3
f: 1100/4
g: 1101/4
h: 1110/4
i: 1111/4
a ch mng: P1 = 010011110 P2 = 111000110
thuc v prefix no bng trn?
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Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
Th d (tip)
Gii p:P1 = 010011110 a
P2 = 111000110 h
111CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
Khi nim
InternetProtocol
Cc giaothc khc
a ch IP
nh tuyn
Binary Trie
112CHNG 4 KT NI MNG INTERNETPGS. TS. Nguyn Hu Thanh
Nt mc Lth hin chiu di Lbit Cc prefix trong bng nh tuyn c nh du bng nt mu thm Thut ton tm kim:
i theo cy nh phn theo nhnh ph hp Ghi nh nt prefix va i qua (a) i cho ti khi khng gp nt ph hp na th dng prefix cui cng i qua l bn
ghi thch hp
a: 0
b: 01000
c: 011
d: 1
e: 100
f: 1100
g: 1101
h: 1110
i: 1111
(01000)
a
0
1
c
1
b
0
0
0
(0)
(011)
d
1
(1)
0
e
0
(100)
1
f
0
(1100)
0
g
1
(1101)
h
0
1
(1110)
h
1
(1111)
P1 = 010011110
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Bi tp
Bi tp 1: Cho bng nh tuyn ti router R1 R1 s gi gi n mng no khi nhn c cc gi tin
c a ch ch nh sau: 192.138.32.1 192.138.32.100
dest. network/subnet mask next hop
192.138.32.0/26 10.1.1.1
192.138.32.0/24 10.1.1.2
192.138.32.0/19 10.1.1.3
Bi tp (tip) Bi tp 2:
Cng ty A xy dng mt mng LAN bao gm1000 host c nhm theo kiu supernet.Trc tin qun tr mng ca cng ty ny phiyu cu ISP B cung cp mt di a ch IPthuc lp C.Cng ty A c th chn mt vi ach nm trong di sau:
La chn 1 gm 5 a ch: di 200.1.15.0,200.1.16.0, 200.1.17.0, 200.1.18.0, 200.19.0.
La chn 2 gm 5 a ch: 215.3.31.0, 215.3.32.0,215.3.33.0, 215.3.34.0, 215.3.35.0
Hy trnh by cch thc la chn a ch v tmsupernet mask tng ng
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Bi tp (tip)
Bi tp 3:Cho mt mng cc b thuc cng ty A
c phn a ch 220.130.15.0. Mngny c chia thnh 7 mng nh:Mng th nht v 2 c 62 host.Mng th 3 v 4 c 30 hostMng th 5, 6, 7 mi mng c 14 host
Hy thit k mng ny.
Ti liu tham kho Internetworking with TCP/IP, Vol 1, Douglas Comer,
Prentice Hall Computer Networking: a top-down approach featuring the
Internet, James F. Kurose, Keith W. Ross, AddisonWesley, 4thed, 2006
Computer Networks, Andrew S. Tanenbaum, PrenticeHall, 4th Edition
Computer Networks, Nick McKeown, StanfordUniversity
M. Sanchez, E. Biersack, and W. Dabbous, "Survey andTaxonomy of IP address lookup algorithms," IEEE
Network, 15(2):8-23, 2001. M. Waldvogel, G. Varghese, J. Turner, and B. Plattner,Scalable High Speed IP Routing Lookups, Proc. ACMSIGCOMM 97, Sept. 1997, pp.2536.