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© 2000, Cisco Systems, Inc. 8-1

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© 2000, Cisco Systems, Inc. 8-2

Chöông 3

LIEÂN MAÏNG VÔÙI

TCP/IP

THS.VOÕ TRÖÔØNG SÔN Maïng soá lieäu ” Chöông 2

• Tìm hieåu lôùp giao thöùc Internet, caùc giao thöùc cuûa lôùp ñoù,

giao thöùc IP.

• Söï phaân ñoïan vaø hôïp ñoïan

• Caùc lôùp ñòa chæ IP, ñòa chæ IP, maët naï ñòa chæ, soá löôïng

maïng IP, soá löôïng maïng con vaø soá löôïng Host coù theå coù

• Giao thöùc ARP vaø RARP

• Giao thöùc ICMP

• Lôùp giao thöùc Transport

• Caùc giao thöùc lôùp Transport: TCP vaø UDP

Noäi dung chính


Early protocol suite

Universal

Introduction to TCP/IP

Host

Internet

TCP/IP

Host


TCP/IP Protocol Stack

7

6

5

4

3

2

5

4

3

2

Application

Presentation

Session

Transport

Network

Data Link

Physical1

Application

Transport

Internet

Data Link

Physical

1


Application Layer Overview

*Used by the router

Application

Transport

Internet

Data Link

Physical

File Transfer- TFTP *- FTP *- NFS

E-Mail- SMTP

Remote Login- Telnet *- rlogin *

Network Management- SNMP *

Name Management- DNS*


Transport Layer Overview

Transmission ControlProtocol (TCP)

User Datagram Protocol (UDP)

Application

Transport

Internet

Data Link

Physical

Connection-

Oriented

Connectionless


Internet Layer Overview

OSI network layer corresponds to the TCP/IP internet layer

Internet Protocol (IP)

Internet Control MessageProtocol (ICMP)

Address ResolutionProtocol (ARP)

Reverse AddressResolution Protocol (RARP)

Application

Transport

Internet

Data Link

Physical


IP Datagram

Version

(4)

Destination IP Address (32)

Options (0 or 32 if any)

Data (varies if any)

1Bit 0 Bit 15 Bit 16 Bit 31

Header

Length (4)Priority & Type

of Service (8)Total Length (16)

Identification (16)Flags

(3) Fragment offset (13)

Time to live (8) Protocol (8) Header checksum (16)

Source IP Address (32)

20

Bytes


Determines destination upper-layer protocol

Protocol Field

Transport

Layer

Internet

Layer

TCP UDP

Protocol

Numbers

IP

176



PHAÂN ÑOAÏN VAØ HÔÏP ÑOAÏN

- Khi ñi trong lieân maïng, moät datagram coù theå qua nhieàu maïng maïng

vaät lyù khaùc nhau vôùi caùc daïng khung khaùc nhau.

- Moät IP-Datagram seõ ñöôïc ñoùng goùi trong vuøng data cuûa caùc khung

theo chuaån rieâng cuûa töøng maïng.


PHAÂN ÑOAÏN VAØ HÔÏP ÑOAÏN(TT)



- Moãi maïng vaät lyù coù moät giôùi haïn cöïc ñaïi cho kích thöôùc khung ñi

qua noù, ñöôïc goïi laø Ñôn vò truyeàn daãn cöïc ñaïi (Maximum

Transmisson Unit – MTU).

- Host H2 chæ coù theå phaùt datagram chöùa ≤ 1000 octets vaø router R

coù theå chuyeån caùc datagram naøy sang maïng 1.

- Tuy nhieân, neáu Host H1 phaùt 1 datagram chöùa 1500 octets thì

router R khoâng theå chuyeån caùc datagram naøy sang maïng 2 ñöôïc.



- Khi moät Datagram lôùn hôn MTU cuûa maïng noù phaûi ñi qua, noù seõ

ñöôïc chia thaønh caùc ñoaïn (fragment) nhoû hôn vaø ñöôïc göûi ñi moät

caùch rieâng bieät .



- Ñeå phaân ñoaïn moät Datagram, moät Host hoaëc Router söû duïng MTU

vaø kích thöôùc header cuûa Datagram ñeå tính toaùn xem caàn phaân

thaønh bao nhieâu ñoaïn (boäi cuûa 8 octets- Tröø ñoaïn cuoái).

- Header cuûa Datagram nguoàn ñöôïc copy thaønh header cuûa caùc

ñoaïn vaø thay ñoåi giaù trò caùc tröôøng sau:

+ TOTAL LENGTH: phaûn aùnh kích thöôùc beù hôn.

+ MF: baèng “0” ôû ñoaïn cuoái, baèng “1” ôû caùc ñoaïn coøn laïi.

+ FRAGMENT OFFSET: phaûn aùnh vò trí cuûa ñoaïn trong

Datagram goác.

+ HEADER CHECKSUM!



FRAGMENT OFFSET = Xi(octets) / 8

Ví duï: X1

= 976 octets do ñoù: FRAGMENT OFFSET = 976 / 8 = 122



- Moãi ñoaïn trôû thaønh 1 Datagram môùi, ñöôïc ñònh tuyeán ñoäc laäp.

- Caùc ñoaïn coù theå ñeán ñích khoâng ñuùng theo thöù töï.

- Taïi ñích, quaù trình taùi caáu truùc Datagram goác ñöôïc goïi laø taùi hôïp, vieäc

taùi hôïp söû duïng caùc tröôøng sau:

+ Caùc ñoaïn cuøng giaù trò IDENTIFICATION nhoùm vaøo 1 Datagram

+ FRAGMENT OFFSET giuùp saép xeáp thöù töï caùc ñoaïn.

+ Côø MF giuùp xaùc ñònh ñoaïn cuoái cuûa Datagram ñöôïc taùi hôïp.



- Host H1 göûi 1 datagram 1500 octets (20 octet header vaø 1480 octet

data) tôùi Host H2.

- Router seõ phaân datagram naøy thaønh 2 ñoaïn:

500



Header

20 octet

Data

1480 octet

Identification = a; FRAGMENT OFFSET = 0; DF = 0; MF = 0

DATAGRAM goác = 1500 octets

Header

20 octet

Data

976 octet


Ñoaïn 1 = 996 octets

(Router 1)

Header

20 octet

Data

504 octet



(Router 1)

Phaân ñoaïn taïi Router 1: Datagram goác thaønh 2 ñoaïn



Header

20 octet

Data

480 octet



(Router 2)

Header

20 octet

Data

16 octet



(Router 2)

Header

20 octet

Data

480 octet



(Router 2)

Phaân ñoaïn taïi Router 2: ñoaïn 1 cuõ chia thaønh 3 ñoaïn môùi



Header

20 octet

Data

480 octet



(Router 2)

Header

20 octet

Data

24 octet



(Router 2)

Phaân ñoaïn taïi Router 2: ñoaïn 2 cuõ chia thaønh 2 ñoaïn môùi


• Laø ñòa chæ duy nhaát cho pheùp thoâng tin giöõa caùc traïm ñaàu cuoái.• Vieäc löïa choïn tuyeán ñöôøng ñöôïc giöïa treân cô sôû ñòa chæ traïm ñích

ÑÒA CHÆ IP

172.18.0.2

172.18.0.1

172.17.0.2172.17.0.1

172.16.0.2

172.16.0.1

SADAHDR DATA10.13.0.0 192.168.1.0

10.13.0.1 192.168.1.1


IP Addressing

255 255 255 255

DottedDecimal

Maximum

Network Host

32 bits


IP Addressing

255 255 255 255

DottedDecimal

Maximum

Network Host

128

64

32

16 8 4 2 1

11111111 11111111 11111111 11111111Binary

32 bits

1 8 9 16 17 24 25 32

128

64

32

16 8 4 2 1

128

64

32

16 8 4 2 1

128

64

32

16 8 4 2 1


IP Addressing

255 255 255 255

DottedDecimal

Maximum

Network Host

128

64

32

16 8 4 2 1

11111111 11111111 11111111 11111111

10101100 00010000 01111010 11001100

Binary

32 bits

172 16 122 204ExampleDecimal

ExampleBinary

1 8 9 16 17 24 25 32

128

64

32

16 8 4 2 1

128

64

32

16 8 4 2 1

128

64

32

16 8 4 2 1


Class A:

Class B:

Class C:

Class D: Multicast

Class E: Research

IP Address Classes

Network Host Host Host

Network Network Host Host

Network Network Network Host

8 bits 8 bits 8 bits 8 bits


IP Address Classes

1

Class A:

Bits:

0NNNNNNN Host Host Host

8 9 16 17 24 25 32

Range (1-126)

1

Class B:

Bits:

10NNNNNN Network Host Host

8 9 16 17 24 25 32

Range (128-191)

1

Class C:

Bits:

110NNNNN Network Network Host

8 9 16 17 24 25 32

Range (192-223)

1

Class D:

Bits:

1110MMMM Multicast Group Multicast Group Multicast Group

8 9 16 17 2425 32

Range (224-239)


Host Addresses

172.16.2.2

172.16.3.10

172.16.12.12

10.1.1.1

10.250.8.11

10.180.30.118

E1

172.16 12 12

Network Host

. . Network Interface

172.16.0.0

10.0.0.0

E0

E1

Routing Table

172.16.2.1

10.6.24.2

E0


11111111

Determining Available Host Addresses

172 16 0 0

10101100 00010000 00000000 00000000

16

15

14

13

12

11

10 9 8 7 6 5 4 3 2 1

Network Host

00000000 00000001

11111111 1111111111111111 11111110

...

...

00000000 00000011

11111101

123

655346553565536-

...

2

65534

N

2N-2 = 216-2 = 65534


IP Address Classes Exercise

Address Class Network Host

10.2.1.1

128.63.2.100

201.222.5.64

192.6.141.2

130.113.64.16

256.241.201.10


IP Address Classes Exercise Answers

Address Class Network Host

10.2.1.1

128.63.2.100

201.222.5.64

192.6.141.2

130.113.64.16

256.241.201.10

A

B

C

C

B

Nonexistent

10.0.0.0

128.63.0.0

201.222.5.0

192.6.141.0

130.113.0.0

0.2.1.1

0.0.2.100

0.0.0.64

0.0.0.2

0.0.64.16


Network 172.16.0.0

172.16.0.0

Addressing without Subnets

172.16.0.1 172.16.0.2 172.16.0.3

…...

172.16.255.253 172.16.255.254


Network 172.16.0.0

Addressing with Subnets

172.16.1.0 172.16.2.0

172.16.3.0

172.16.4.0


Subnet Addressing

172.16.2.200

172.16.2.2

172.16.2.160

172.16.2.1

172.16.3.5

172.16.3.100

172.16.3.150

E0

172.16

Network

Network Interface

172.16.0.0

172.16.0.0

E0

E1

New Routing Table

2 160

Host

. .

172.16.3.1

E1


Subnet Addressing

172.16.2.200

172.16.2.2

172.16.2.160

172.16.2.1

172.16.3.5

172.16.3.100

172.16.3.150

172.16.3.1

E0

E1

172.16 2 160

Network Host

. . Network Interface

172.16.2.0

172.16.3.0

E0

E1

New Routing Table

Subnet


Subnet Mask

172 16 0 0

255 255 0 0

255 255 255 0

IP

Address

Default

Subnet

Mask

8-bit

Subnet

Mask

Network Host

Network Host

Network Subnet Host

Also written as ―/16‖ where 16 represents the number of 1s

in the mask.

Also written as ―/24‖ where 24 represents the number of 1s

in the mask.

11111111 11111111 00000000 00000000


Decimal Equivalents of Bit Patterns

0 0 0 0 0 0 0 0 = 0

1 0 0 0 0 0 0 0 = 128

1 1 0 0 0 0 0 0 = 192

1 1 1 0 0 0 0 0 = 224

1 1 1 1 0 0 0 0 = 240

1 1 1 1 1 0 0 0 = 248

1 1 1 1 1 1 0 0 = 252

1 1 1 1 1 1 1 0 = 254

1 1 1 1 1 1 1 1 = 255

128 64 32 16 8 4 2 1


16

Network Host

172 0 0

10101100

11111111

10101100

00010000

11111111

00010000

00000000

00000000

10100000

00000000

00000000

Subnets not in use—the default

00000010

Subnet Mask without Subnets

172.16.2.160

255.255.0.0

Network

Number


Network number extended by eight bits

Subnet Mask with Subnets

16

Network Host

172.16.2.160

255.255.255.0

172 2 0

10101100

11111111

10101100

00010000

11111111

00010000

11111111

00000010

10100000

00000000

00000000

00000010

Subnet

Network

Number128

192

224

240

248

252

254

255


Subnet Mask with Subnets (cont.)

Network Host

172.16.2.160

255.255.255.192

10101100

11111111

10101100

00010000

11111111

00010000

11111111

00000010

10100000

11000000

10000000

00000010

Subnet

Network number extended by ten bits

16172 2 128

Network

Number128

192

224

240

248

252

254

255

128

192

224

240

248

252

254

255


Subnet Mask Exercise

Address Subnet Mask Class Subnet

172.16.2.10

10.6.24.20

10.30.36.12

255.255.255.0

255.255.240.0

255.255.255.0


Subnet Mask Exercise Answers

Address Subnet Mask Class Subnet

172.16.2.10

10.6.24.20

10.30.36.12

255.255.255.0

255.255.240.0

255.255.255.0

B

A

A

172.16.2.0

10.6.16.0

10.30.36.0


Broadcast Addresses

172.16.1.0

172.16.2.0

172.16.3.0

172.16.4.0

172.16.3.255(Directed broadcast)

255.255.255.255(Local network broadcast)

X

172.16.255.255(All subnets broadcast)


Addressing Summary Example

16172 2 160

10101100 00010000 1010000000000010 Host

Mask

Subnet

Broadcast

Last

First

172.16.2.160

255.255.255.192

4

1



10101100

11111111

00010000

11111111 11111111

10100000

11000000

00000010 Host

Mask

Subnet

Broadcast

Last

First

172.16.2.160

255.255.255.192

1

2

16172 2 160



10101100

11111111

00010000

11111111 11111111

10100000

11000000

00000010 Host

Mask

Subnet

Broadcast

Last

First

172.16.2.160

255.255.255.192

1

2

3

7

16172 2 160



10101100

11111111

00010000

11111111 11111111

10100000

11000000

10000000

00000010 Host

Mask

Subnet

Broadcast

Last

First

172.16.2.160

255.255.255.192

1

2

3

4

16172 2 160



10101100

11111111

00010000

11111111 11111111

10100000

11000000

10000000

00000010

10111111

Host

Mask

Subnet

Broadcast

Last

First

172.16.2.160

255.255.255.192

1

2

3

4

5

6

16172 2 160



10101100

11111111

00010000

11111111 11111111

10100000

11000000

10000000

00000010

10111111

10000001

Host

Mask

Subnet

Broadcast

Last

First

172.16.2.160

255.255.255.192

1

2

3

4

5

6

16172 2 160



10101100

11111111

00010000

11111111 11111111

10100000

11000000

10000000

00000010

10111111

10000001

10111110

Host

Mask

Subnet

Broadcast

Last

First

172.16.2.160

255.255.255.192

1

2

3

4

5

6

7

16172 2 160



10101100

11111111

10101100

00010000

11111111

00010000

11111111

00000010

10100000

11000000

10000000

00000010

10101100 00010000 00000010 10111111

10101100 00010000 00000010 10000001

10101100 00010000 00000010 10111110

Host

Mask

Subnet

Broadcast

Last

First

172.16.2.160

255.255.255.192

1

2

3

4

5

6

7

8

16172 2 160



10101100

11111111

10101100

00010000

11111111

00010000

11111111

00000010

10100000

11000000

10000000

00000010

10101100 00010000 00000010 10111111

10101100 00010000 00000010 10000001

10101100 00010000 00000010 10111110

Host

Mask

Subnet

Broadcast

Last

First

172.16.2.160

255.255.255.192

172.16.2.128

172.16.2.191

172.16.2.129

172.16.2.190

1

2

3

4

5

6

7

89

16172 2 160


IP Host Address: 172.16.2.121Subnet Mask: 255.255.255.0

Subnet Address = 172.16.2.0

Host Addresses = 172.16.2.1–172.16.2.254

Broadcast Address = 172.16.2.255

Eight bits of subnetting

Network Subnet Host

10101100 00010000 00000010 11111111

172.16.2.121:

255.255.255.0:

10101100

11111111

Subnet: 10101100 00010000

00010000

11111111

00000010

00000010

11111111

01111001

00000000

00000000

Class B Subnet Example

Broadcast:

Network


Subnet Planning

Other subnets

192.168.5.16

192.168.5.32 192.168.5.48

20 subnets

5 hosts per subnet

Class C address:

192.168.5.0


11111000

IP Host Address: 192.168.5.121Subnet Mask: 255.255.255.248

Network Subnet Host

192.168.5.121: 11000000

11111111

Subnet: 11000000 10101000

10101000

11111111

00000101

00000101

11111111

01111001

01111000

255.255.255.248:

Class C Subnet Planning Example

Subnet Address = 192.168.5.120

Host Addresses = 192.168.5.121–192.168.5.126

Broadcast Address = 192.168.5.127

Five Bits of Subnetting

Broadcast:

NetworkNetwork

11000000 10101000 00000101 01111111


Broadcast Addresses Exercise

Address Class Subnet Broadcast

201.222.10.60 255.255.255.248

Subnet Mask

15.16.193.6 255.255.248.0

128.16.32.13 255.255.255.252

153.50.6.27 255.255.255.128


Broadcast Addresses Exercise Answers

153.50.6.127

Address Class Subnet Broadcast

201.222.10.60 255.255.255.248 C 201.222.10.63201.222.10.56

Subnet Mask

15.16.193.6 255.255.248.0 A 15.16.199.25515.16.192.0

128.16.32.13 255.255.255.252 B 128.16.32.15128.16.32.12

153.50.6.27 255.255.255.128 B 153.50.6.0


Internet Layer Overview

OSI network layer corresponds to the TCP/IP internet layer

Internet Protocol (IP)

Internet Control MessageProtocol (ICMP)

Address ResolutionProtocol (ARP)

Reverse AddressResolution Protocol (RARP)

Application

Transport

Internet

Data Link

Physical





Address Resolution Protocol

172.16.3.1 172.16.3.2

IP: 172.16.3.2 = ???

I need the

Ethernet

address of

176.16.3.2.



172.16.3.1 172.16.3.2

IP: 172.16.3.2 = ???

I heard that broadcast.

The message is for me.

Here is my Ethernet

address.

I need the

Ethernet

address of

176.16.3.2.



172.16.3.1

IP: 172.16.3.2

Ethernet: 0800.0020.1111

172.16.3.2

IP: 172.16.3.2 = ???



Here is my Ethernet

address.

I need the

Ethernet

address of

176.16.3.2.



Map IP MAC

Local ARP

172.16.3.1

IP: 172.16.3.2

Ethernet: 0800.0020.1111

172.16.3.2

IP: 172.16.3.2 = ???



Here is my Ethernet

address.

I need the

Ethernet

address of

176.16.3.2.







8:0:20:7a:49:68




Proxy ARP

Machine A wishes to communicate with machine F. It sends out an ARP request for machine F’s MAC address.

The router intercepts the request from A and replies with its own MAC address.



Reverse ARP

Ethernet: 0800.0020.1111 IP = ???

What is

my IP

address?


Reverse ARP

Ethernet: 0800.0020.1111 IP = ???

What is

my IP

address?

I heard that

broadcast.

Your IP

address is

172.16.3.25.


Reverse ARP

Ethernet: 0800.0020.1111

IP: 172.16.3.25

Ethernet: 0800.0020.1111 IP = ???

What is

my IP

address?

I heard that

broadcast.

Your IP

address is

172.16.3.25.


Reverse ARP

Map MAC IP

Ethernet: 0800.0020.1111

IP: 172.16.3.25

Ethernet: 0800.0020.1111 IP = ???

What is

my IP

address?

I heard that

broadcast.

Your IP

address is

172.16.3.25.


Internet Control Message Protocol

Application

Transport

Internet

Data Link

Physical

Destination

Unreachable

Echo (Ping)

Other

ICMP

1


Internet Control Message Protocol (ICMP)


Moät soá loãi ñöôïc baùo veà nguoàn baèng caùch:

Router göûi thoâng baùo veà nguoàn baèng ICMP

Thoâng baùo coù chöùa thoâng tin veà loãi

Ví duï: loãi checksum

Phaùt hieän loãi vaø thoâng baùo

ICMP ñöôïc ñoùng goùi trong IP datagram

Lôùp Internet phaùt hieän ra caùc Datagram coù loãi


Caùc daïng baûn tin ICMP

Caùc baûn tin thoâng tin bao goàm:

Yeâu caàu traû lôøi vaø ñaùp öùng (ping)

Yeâu caàu maët naï ñòa chæ vaø ñaùp öùng

Yeâu caàu boä ñònh tuyeán (Router discovery)

ICMP ñònh nghóa caùc baûn tin baùo loãi vaø baûn tin thoâng

tin.

Caùc baûn tin loãi bao goàm:

Nguoàn döøng laïi

Heát thôøi gian chôø Datagram

Khoâng tôùi ñích ñöôïc

Yeâu caàu ñònh tuyeán laïi

Yeâu caàu phaân maûnh


Truyeàn taûi baûn tin ICMP

ICMP ñöôïc ñoùng goùi trong IP

Baûn tin ICMP thoâng baùo coù chöùa thoâng tin veà Datagram coù

loãi.

Baûn tin ICMP khoâng göûi thoâng baùo loãi cho baûn tin ICMP


Frame ICMP

Caáu truùc header baûn tin ICMP

“ Type: Kieåu baûn tin

” Echo, Timestamp, Destination Unreachable, ...

“ Code: Moâ taû chuùc naêng baûn tin, theo Type

“ Checksum: Toång kieám tra cuûa header ICMP

Type Code Checksum

0 8 16 31


Type trong ICMP

Type Moâ taû

0 Echo reply

3 Destination unreachable

4 Source quench

5 Redirect

8 Echo request

11 Time exceeded

12 Parameter unintelligible

13 Time-stamp request

14 Time-stamp reply

Type Moâ taû

15 Information request

16 Information reply

17 Address mask request

18 Address mask reply


Type trong ICMP

Type Moâ taû Type Moâ taû

0 Yeâu caàu (Yc) traû lôøi 13 Yc cung caáp thôøi gian

3 Khoâng theå tôùi ñích 14 Tl cung caáp thôøi gian

4 Nguoàn chaäm laïi 15 Yc cung caáp thoâng tin

5 Ñònh tuyeán laïi 16 Tl cung caáp thoâng tin

8 Traû lôøi (Tl) Type=0 17 Yc cung caáp maët naï

11 Heát thôøi gian 18 Tl cung caáp maët naï

12 Khoâng hieåu tham soá


Baûn tin ICMP trong IP datagram


A. Caùc baûn tin ICMP baùo loãi

Type Code Checksum

0 8 16 31

Unused (Must be Zero)

IP Header + First 64 bits of IP data (loãi)

.........


Type trong caùc ICMP baùo loãi

Type Moâ taû

3 Khoâng theå tôùi ñích

4 Nguoàn chaäm laïi (ñieàu khieån luoàng)

5 Ñònh tuyeán laïi (yeâu caàu ñoåi höôùng ñònh

tuyeán)

11 Heát thôøi gian (TTL = 0) hoaëc heát thôøi

gian chôø caùc maûnh taùi hôïp.

12 Khoâng hieåu tham soá


Loãi khoâng theå tôùi ñích ñöôïc

Type = 3 Code Checksum

0 8 16 31



.........

“Söû duïng khi coù moät loãi vaø Router hoaëc Host göûi baùo loãi veà

nguoàn.


Khoâng tôùi ñöôïc ñích (Type = 3) -

Code

Code Moâ taû

0 Khoâng tôùi ñöôïc maïng

1 Khoâng tôùi ñöôïc Host

2 Khoâng tôùi ñöôïc Protocl

3 Khoâng tôùi ñöôïc Port

4 Caàn phaân maûnh nhöng côø DF = 1

5 Router nguoàn bò loãi

6 Khoâng bieát maïng ñích (khoâng toàn taïi)

7 Khoâng bieát Host ñích (khoâng toàn taïi)

8 Host nguoàn bò caùch ly

9 Truyeàn thoâng vôùi Maïng ñích bò Admin ngaên caám

10 Truyeàn thoâng vôùi Host ñích bò Admin ngaên caám

11 Khoâng tôùi ñöôïc Maïng do kieåu dòch vuï

12 Khoâng tôùi ñöôïc Host do kieåu dòch vuï


Destination Unreachable -Code






TYPE = 3, CODE = 4

Type=3 Code=4 Checksum

0 8 16 31

Unused (Must be Zero) Link MTU


.........

“Söû duïng khi Datagram caàn phaân maûnh nhöng DF = 1

“Linh MTU laø MTU cuûa maïng caàn phaân maûnh


Ñieàu khieån luoàng Host nguoàn

Type = 4 Code=0 Checksum

0 8 16 31



.........

“Khi Router bò ngheõn (hoaëc Host ñích bò traøn), noù göûi cho

thoâng baùo veà nguoàn cho töøng Datagram bò traøn.

“Host nguoàn giaûm daàn taàn xuaát göûi datagram cho tôùi khi

khoâng coøn nhaän ñöôïc thoâng baùo loãi.

“Sau ñoù Host nguoàn taêng daàn taàn xuaát göûi datagram.


Yeâu caàu ñònh tuyeán laïi

Type = 5 Code=0,1,2,3 Checksum

0 8 16 31

Router IP Address


.........

“Router 1 nhaän ñöôïc 1 datagram, noù tham khaûo baûng ñònh

tuyeán vaø tìm ra ñöôøng ñi tieáp tôùi Router 2.

“Neáu Router 2 vaø Host nguoàn cuøng maïng, Router 1 thoâng

baùo veà nguoàn ‚khuyeân‛ neân phaùt tröïc tieáp theo höôùng ñöôïc

chæ ra ôû Router IP address.

“Router 1 vaãn tieáp tuïc göûi Datagram goác ñi.


Ví duï: ICMP Redirect

1. Host sends IP data packet to default gateway R1

2. Default gateway R1 redirects IP data packet to

another router R2

3. Default gateway sends ICMP Redirect to inform host

to send to router R2 next time

Gateway

Router R1

Gateway

Router R2

To Internet To Internet

Host1.

2.

3.


Yeâu caàu ñònh tuyeán laïi - Code

192.168.5.16

192.168.6.32

R1

R2R0


Yeâu caàu ñònh tuyeán laïi - Code

Code Moâ taû

0 Ñoåi höôùng cho maïng hoaëc maïng con

1 Ñoåi höôùng cho Host

2 Ñoåi höôùng cho maïng vaø dòch vuï

3 Ñoåi höôùng cho Host vaø dòch vuï


Heát thôøi gian

Type=11 Code=0, 1 Checksum

0 8 16 31


Internet Header + First 64 bits of datagram

.........

Code Moâ taû

0 TTL = 0 nhöng chöa tôùi ñích (Router)

1 Heát thôøi gian chôø taùi hôïp nhöng vaãn thieáu

moät vaøi ñoaïn (Host).


Khoâng hieåu tham soá

Type = 12 Code=0, 1 ,2 Checksum

0 8 16 31

Pointer Unused (Must be Zero)


.........

“Router hoaëc Host phaùt hieän datagram coù loãi ôû Header.

“Chæ thoâng baùo veà nguoàn khi loãi gaây huûy datagram.


Khoâng hieåu tham soá

Code Moâ taû

0 Pointer chæ ra vò trí cuûa octec loãi ñöôïc phaùt

hieän (loãi khoâng roõ raøng)

1 Maát moät Option caàn phaûi coù

2 Sai ñoä daøi (giaù trò ñoä daøi Header hoaëc toång

ñoä daøi khoâng ñuùng)


B. Caùc baûn tin ICMP truy vaán

thoâng tin

Type Code Checksum

0 8 16 31

Identifier Sequence Number

Depends on Query Message Type

“Ñöôïc söû duïng ñeå caùc phaàn töû maïng truy vaán vaø hoài ñaùp caùc thoâng tin

treân maïng.

“Identifier: duøng ñeå phaân bieät caùc baûn tin göûi ñi caùc Host khaùc nhau.

Lôøi ñaùp phaûi duøng ñuùng chæ soá cuûa baûn tin Request ñaõ nhaän.

“Sequence Number: duøng ñeå phaân bieät caùc baûn tin göûi ñeán cuøng moät

Host.


Caáu truùc chung baûn tin ICMP truy

vaán thoâng tin


Caùc giaù trò Type trong caùc ICMP

truy vaán thoâng tin

Type Moâ taû

8 / 0 ECHO request / reply

13 / 14 Timestamp request / reply

15 / 16 Information request / reply

17 / 18 Address Mask request / reply


Baûn tin ECHO Request / Reply

Type=8, 0 Code=0 Checksum

0 8 16 31


Data (Ping: UNIX - 56 bytes; WINDOW = 32 bytes)

“Type = 8 : yeâu caàn traû lôøi.

“Type = 0 : traû lôøi yeâu caàu.

“Söû duïng ñeå 1 Host coù thoâng vôùi 1 Host khaùc hay khoâng.


Yeâu caàu vaø ñaùp öùng thôøi gian


0 8 16 31


Origiante Timestamp (thôøi gian beân yeâu caàu phaùt)

Receive Timestamp (thôøi gian beân ñaùp öùng nhaän ñöôïc baûn tin)

Transmit Timestamp (thôøi gian beân ñaùp öùng phaùt ñaùp öùng)

“Thôøi gian (32 bit) ñöôïc tính laø soá mili giaây tính töø nöûa ñeâm,

theo giôø GMT.

“Söû duïng ñeå 1 Host tham khaûo thôøi gian cuûa 1 Host khaùc.


Yeâu caàu vaø ñaùp öùng thoâng tin maïng


0 8 16 31


“Söû duïng cho caùc Host trong caùc heä thoáng khoâng coù ñóa taïi

thôøi ñieåm Boot, ñeå truy vaán ñòa chæ maïng.

“Baûn tin naøy ñöôïc ñaët trong IP-datagram. Khi yeâu caàu, ñòa chæ

IP ñích (vaø coù theå caû nguoàn) laø 32 bit ‘0’.

“Khi traû lôøi, ñòa chæ IP nguoàn (vaø coù theå caû ñích) laø ñòa chæ IP

cuûa maïng.


Yeâu caàu vaø ñaùp öùng maët naï ñòa chæ


0 8 16 31


Maët naï ñòa chæ maïng con

“ 1 Host ñaõ coù ñòa chæ IP muoán bieát maët naï, noù göûi baûn tin naøy

vôùi ñòa chæ ñích trong IP datagram laø 255.255.255.255. Host

ñöôïc chæ ñònh tröôùc seõ traû lôøi baûn tin naøy.

“Söû duïng cho caùc Host trong caùc heä thoáng khoâng coù ñóa taïi

thôøi ñieåm Boot, ñeå truy vaán maët naï ñòa chæ maïng con.

“Hoaëc söû duïng cho caùc Router truy vaán maët naï ñòa chæ cuûa

caùc giao tieáp.


Transport Layer Overview

Transmission ControlProtocol (TCP)

User Datagram Protocol (UDP)

Application

Transport

Internet

Data Link

Physical

Connection-

Oriented

Connectionless


TCP Segment Format

Source port (16) Destination port (16)

Sequence number (32)

Header

length (4)

Acknowledgement number (32)

Reserved (6) Code bits (6) Window (16)

Checksum (16) Urgent (16)

Options (0 or 32 if any)

Data (varies)

20

Bytes

Bit 0 Bit 15 Bit 16 Bit 31


Port Numbers

TCP

Port

Numbers

FTP

Transport

Layer

TELNET

DNS

SNMP

TFTP

SMTP

UDP

Application

Layer

21 23 25 53 69 161

RIP

520


TCP Port Numbers

Source

Port

Dest.

Port…

Host A

1028 23 …

SP DP

Host ZTelnet Z

Dest. port = 23.

Send packet to my

Telnet

application.


Code bits

Code Moâ taû

U (URG) Chæ ra tröôøng Con troû khaån caáp (Urgent

pointer) coù hieäu löïc.

A (ACK) Tröôøng ACK number coù hieäu löïc

P (PSH) Ñöa ngay leân lôùp treân

R (RTS) Reset laïi keát noái

S (SYN) Ñoàng boä (khôûi taïo) chæ soá tuaàn töï

F (FIN) Khoâng coøn döõ lieäu ñeå göûi


Sequence number, ACK number & Header length

“ Sequence number: laø soá tuaàn töï cuûa octet ñaàu tieân trong

ñoaïn naøy (tröø tröôøng hôïp côø SYN = 1).

“ Neáu côø SYN = 1: soá tuaàn töï laø soá ñöôïc khôûi taïo (ISN) vaø

octet data ñaàu tieân ñöôïc tính laø ISN+1 .

“ Acknowledgment number: neáu côø ACK = 1, tröôøng naøy

chöùa giaù trò Sequence number maø ñaàu göûi ñang chôø nhaän.

“ Header length (data offset): ñoä daøi Header, tính theo

words (32 bits).


Swindow & Urgent Pointer

“ Window (Window size): laø soá octet data toái ña maø ñaàu göûi

segment naøy coù theå nhaän, tính töø giaù trò ôû ACK number.

“ Urgent number: neáu côø URG = 1, tröôøng naøy chæ ra soá

octec döõ lieäu khaån caáp tính töø octec ñaàu tieân trong vuøng

data. Luùc naøy Sequence number laø chæ soá tuaàn töï cho octet

ñaàu tieân ngay sau döõ lieäu khaån caáp.


Send SYN (seq=100 ctl=SYN)

SYN received

Host A Host B

TCP Three Way Handshake/Open Connection

1



SYN received

Send SYN, ACK (seq=300 ack=101 ctl=syn,ack)

Host A Host B

SYN received

1

2




SYN received

Send SYN, ACK (seq=300 ack=101 ctl=syn,ack)

Established(seq=101 ack=301 ctl=ack)

Host A Host B

1

2

3

SYN received



TCP Simple Acknowledgment

Window size = 1

Sender Receiver



Window size = 1

Sender Receiver

Send 1Receive 1



Window size = 1

Sender Receiver

Send 1Receive 1

Receive ACK 2 Send ACK 2



Window size = 1

Sender Receiver

Send 1Receive 1


Send 2Receive 2



Window size = 1

Sender Receiver

Send 1Receive 1


Send 2Receive 2

Receive ACK 3Send ACK 3



Window size = 1

Sender Receiver

Send 1Receive 1


Send 2Receive 2


Send 3Receive 3


Window size = 1

Sender Receiver

Send 1Receive 1


Send 2Receive 2


Send 3Receive 3




TCP Sequence and Acknowledgment Numbers

Source

Port

Dest.

Port

…Sequence

#

Acknowledgement

#

Source Dest. Seq. Ack.

1028 23 10 1

I justsent #10.



I just got #10,now I need #11.

Source

Port

Dest.

Port…

Sequence

#

Acknowledgement

#

1028 23Source Dest.

10Seq.

1Ack.

102823Source Dest.

11Seq.

1Ack.

I justsent #10.



Source

Port

Dest.

Port…

Sequence

#

Acknowledgement

#

1028 23

Source Dest.

11

Seq.

2

Ack.

1028 23Source Dest.

10Seq.

1Ack.

102823Source Dest.

11Seq.

1Ack.


I justsent #11.



Source

Port

Dest.

Port…

Sequence

#

Acknowledgement

#

1028 23

Source Dest.

11

Seq.

101

Ack.

1028 23Source Dest.

10Seq.

100Ack.

102823Source Dest.

11Seq.100

Ack.

102823Source Dest.

12Seq.101

Ack.


I justsent #11.


TCP Windowing

Sender Receiver


TCP Windowing

Window size = 3Send 2

Sender ReceiverWindow size = 3Send 1




TCP Windowing

Sender Window size = 3Send 1


ACK 3Window size = 2

Packet 3 is

Dropped

Receiver



TCP Windowing




Packet 3 is

Dropped



Receiver



TCP Windowing




Packet 3 is

Dropped




ReceiverWindow size = 3


No sequence or acknowledgment fields

UDP Segment Format

Source port (16) Destination port (16)

Length (16)

Data (if any)

1Bit 0 Bit 15 Bit 16 Bit 31

Checksum (16)

8

Bytes

“ Length: ñoä daøi (soá octet) cuûa UDP segment, bao goàm caû

Header vaø data.


Switch IP Address Configuration

• Assigns an address and subnet mask

• Starts IP processing on a switch

Switch(config)#ip address ip-address subnet-mask

Switch(config)#ip default-gateway ip-address

• Specifies a default gateway


Router IP Address Configuration

• Assigns an address and subnet mask

• Starts IP processing on a router interface

Router(config-if)#ip address ip-address subnet-mask


Router IP Address Configuration

Router(config-line)#ip netmask-format

{bitcount | decimal | hexadecimal}

• Sets format of network mask for a specific line

Router#term ip netmask-format {bitcount|

decimal | hexadecimal}

• Sets display format of network mask forcurrent session


• Defines static host name to IP address mapping

• Hosts/interfaces selectable by name or IP address

Router IP Host Names

Router(config)#ip host name [tcp-port-number]address [address]

ip host Norine 172.16.3.1 192.168.3.1

ip host Roger 172.16.4.3


• Specifies one or more hosts that supplyhost name to logical address resolution

Router Name Server Configuration

Router(config)#ip name-server server-address1 [[server-address2]...[server-address6]]

DNS Server


• DNS enabled by default

Router Name System

Router(config)#ip domain-lookupRouter(config)#endRouter#patTranslating ”pat"...domain server (255.255.255.255)% Unknown command or computer name, or unable to find computer addressRouter#config tRouter(config)#no ip domain-lookupRouter(config)#endRouter#patTranslating ”pat"% Unknown command or computer name, or unable to find computer addressRouter#


Router Display Host Names

Router#show hostsDefault domain is not setName/address lookup uses domain serviceName servers are 255.255.255.255

Host Flags Age Type Address(es)Norine (perm, OK) 0 IP 172.16.100.100Roger (perm, OK) 0 IP 172.16.100.101Frank (perm, OK) 0 IP 172.16.200.200

Bob (perm, OK) 0 IP 172.16.200.201

• Shows the host table


VLAN to VLAN Overview

VLAN 1 VLAN 2

ISL

10.1.1.2 10.2.2.2

Network layer devices combine multiple broadcast domains

Router on

a stick

Application

TCP

IP

ISL

Ethernet

Fa0/0


Dividing a Physical Interface into Subinterfaces

FastEthernet 0/0

FastEthernet 0/0.2FastEthernet 0/0.3

FastEthernet 0/0.1

Physical interfaces can be divided into multiple subinterfaces


ISL Encapsulation

• Enables ISL on a subinterface

Router(config-subif)#encapsulation isl vlan identifier


Routing Between VLANs

VLAN 1 VLAN 2

ISL

interface fastethernet 0/0no ip address!interface fastethernet 0/0.1ip address 10.1.1.1 255.255.255.0encapsulation isl 1interface fastethernet 0/0.2ip address 10.2.2.1 255.255.255.0encapsulation isl 2

Fast

E0/0

10.1.1.2 10.2.2.2


Routing Between WANs

ISL

interface Serial0ip address 172.16.1.1 255.255.255.0

Application

TCP

IP

HDLC

Serial

S0

172.16.1.1172.16.1.2

VLAN 1 VLAN 2

10.1.1.2 10.2.2.2


Visual Objective

core_ server

wg_sw_a

10.1.1.10

wg_sw_l

10.1.1.120

...

e0/1fa0/26

(port A)

e0/1fa0/26

(port A)

fa0/1 fa0/12

fa0/24

core_sw_a

10.1.1.2

core_sw_b

10.1.1.4

fa0/12 fa0/1

fa0/13 fa0/13

fa0/27

(port B)

fa0/27

(port B)

wg_pc_a

10.2.2.12

wg_pc_l

10.13.13.12

Core_ro

fa0/23

fa0/0

fa0/14fa0/14

VLAN2

VLAN13

SUBNET VLAN POD

10.1.1.0 1 wg_ro_x, wg_sw_x, core_sw_a, core_sw_b

10.2.2.0 2 wg_pc_a, core_server, core_ro

10.3.3.0 3 wg_pc_b, core_server, core_ro

10.4.4.0 4 wg_pc_c, core_server, core_ro

10.5.5.0 5 wg_pc_d, core_server, core_ro

10.6.6.0 6 wg_pc_e, core_server, core_ro

10.7.7.0 7 wg_pc_f, core_server, core_ro

10.8.8.0 8 wg_pc_g, core_server, core_ro

10.9.9.0 9 wg_pc_h, core_server, core_ro

10.10.10.0 10 wg_pc_i, core_server, core_ro

10.11.11.0 11 wg_pc_j, core_server, core_ro

10.12.12.0 12 wg_pc_k, core_server, core_ro

10.13.13.0 13 wg_pc_l, core_server, core_ro

SUBNET VLAN POD

10.1.1.0 1 wg_ro_x, wg_sw_x, core_sw_a, core_sw_b

10.2.2.0 2 wg_pc_a, core_server, core_ro

10.3.3.0 3 wg_pc_b, core_server, core_ro

10.4.4.0 4 wg_pc_c, core_server, core_ro

10.5.5.0 5 wg_pc_d, core_server, core_ro

10.6.6.0 6 wg_pc_e, core_server, core_ro

10.7.7.0 7 wg_pc_f, core_server, core_ro

10.8.8.0 8 wg_pc_g, core_server, core_ro

10.9.9.0 9 wg_pc_h, core_server, core_ro

10.10.10.0 10 wg_pc_i, core_server, core_ro

10.11.11.0 11 wg_pc_j, core_server, core_ro

10.12.12.0 12 wg_pc_k, core_server, core_ro

10.13.13.0 13 wg_pc_l, core_server, core_ro


Summary

After completing this chapter, you should be able to perform the following tasks:

• Identify the TCP/IP protocol stack and the functions of each layer

• Separate an IP address into its subcomponents: the network, subnet, and host portions

• Configure IP addresses on Cisco router and switch interfaces

• Interconnect VLANs using a layer three device such as a ―router on a stick‖


Review Questions

1. What is the difference between the TCP and UDP transport layer protocols?

2. Given a host with IP address, 192.168.20.1 255.255.255.240, how many other hosts can you have in that network?

3. What is required to interconnect separate VLANs?

Documents

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