04 Internet 2pages

7/22/2019 04 Internet 2pages

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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



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



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



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



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



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



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



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



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



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



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



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



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



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



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



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



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



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



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



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


10 Net ID Host-ID

14 16

000000


10 Net ID Host-ID

14 16

1111011011



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Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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



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



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



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



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


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


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


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



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



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



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



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



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



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



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



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



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



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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Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


24/582

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


25/582

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


26/582

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


27/582

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


28/582

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



Tng quan v nh tuynBn Internet 1999:

Ngun: http://www.lumeta.com


29/582

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



Tng quan v nh tuyn (tip) S bn ghi trong bng nh tuyn ti

mng li Internet

Ngun: http://www.cidr-report.org/


30/583

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



Tng quan v nh tuyn

(tip)Vn : A B

A B

R1

R2

R3

R4R1 chn chng tiptheo i n B ntn?


31/583

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


32/583

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn




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



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


33/583

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn




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



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


34/583

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


35/583

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn




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




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


36/583

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn




Khc phc vn phn k caBellman-Ford (counting to infinityproblem):t s bc ti a, TD: Ci


37/583

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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 - - - - - - -


38/583

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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?


39/583

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


40/584

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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 )


41/584

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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

.


42/584

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


43/584

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


44/584

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


45/584

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


46/584

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


47/584

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


48/584

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



Quan h khch hng nh

cung cp (tip)

IP trafficprovider customer


49/584

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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



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


50/585

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn



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


51/585

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn

101


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


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


52/585

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn

103


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



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


53/585

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


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


S bn ghi trong router li(Ngun: http://www.cidr-report.org/)

Phn b di network prefix trongrouter li


54/585

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


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



55/585

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


Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn

Th dXt bng nh tuyn:


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?


56/585

Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn

Th d (tip)

Gii p:P1 = 010011110 a

P2 = 111000110 h


Khi nim

InternetProtocol

Cc giaothc khc

a ch IP

nh tuyn

Binary Trie


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


57/585

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


58/58

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.