Mạng máy tính nâng cao_Chapter01 overview

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Chapter 01: OverviewChapter 01: Overview

MẠNG MÁY TÍNH NÂNG CAO

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Data networks developed as a result of business applications that were written for microcomputers.

Businesses needed a solution that would successfully address the following three problems: • How to avoid duplication of equipment and

resources • How to communicate efficiently • How to set up and manage a network

Data networksData networks

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Network topologyNetwork topology

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Logical TopologiesLogical Topologies

Broadcast

Token Passing

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Local-area networks (LANs)Local-area networks (LANs)

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Local-area networks (LANs)Local-area networks (LANs) LANs consist of the following components:

• Computers • Network interface cards • Peripheral devices • Networking media • Network devices

Some common LAN technologies are: • Ethernet • Token Ring • FDDI

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Wide-area networks (WANs)Wide-area networks (WANs)

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Wide-area networks (WANs)Wide-area networks (WANs) WANs interconnect LANs, which then

provide access to computers or file servers in other locations.

Some common WAN technologies are: • Modems • Integrated Services Digital Network (ISDN) • Digital Subscriber Line (DSL) • Frame Relay • US (T) and Europe (E) Carrier Series – T1,

E1, T3, E3 • Synchronous Optical Network (SONET)

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OSI layersOSI layers Dividing the network into seven layers

provides the following advantages: • It breaks network communication into smaller,

more manageable parts. • It standardizes network components to allow

multiple vendor development and support. • It allows different types of network hardware

and software to communicate with each other. • It prevents changes in one layer from affecting

other layers. • It divides network communication into smaller

parts to make learning it easier to understand.

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TCP/IP modelTCP/IP model

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TCP/IP modelTCP/IP model

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Ethernet and the OSI modelEthernet and the OSI model

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Ethernet and the OSI modelEthernet and the OSI model

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Ethernet Naming – MAC addressEthernet Naming – MAC address

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Ethernet frame fieldsEthernet frame fields

Start Frame Delimiter : 10101011

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Encapsulating DataEncapsulating Data

Transport

Data Link

Physical

Network

Upper Layer Data

Upper Layer DataTCP Header

DataIP Header

DataLLC Header

0101110101001000010

DataMAC Header

Presentation

Application

Session

Segment

Packet

Bits

Frame

FCSFCS

FCSFCS

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De - encapsulating DataDe - encapsulating Data

Upper Layer Data

LLC Hdr + IP + TCP + Upper Layer Data

MAC Header

IP + TCP + Upper Layer Data

LLC Header

TCP+ Upper Layer Data

IP Header

Upper Layer Data

TCP Header

0101110101001000010

Transport

Data Link

Physical

Network

Presentation

Application

Session

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Switches and Bridges

Data Link

OR1 2 3 1 24

• Each segment has its own collision domain• All segments are in the same broadcast domain• Broadcasts are forwarded to all segments

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Ethernet SwitchingEthernet Switching

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Network Device Domains

Hub Bridge Switch Router

Collision Domains:1 4 4 4

Broadcast Domains:1 1 1 4

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Interconnecting Networks Interconnecting Networks with TCP/IPwith TCP/IP

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Introduction to TCP/IPIntroduction to TCP/IP

Host

Internet

TCP/IP

Host

•Early protocol suite•Universal

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OSI Model and TCP/IP Protocol Model OSI Model and TCP/IP Protocol Model

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Application Layer OverviewApplication Layer Overview

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Transport Layer Overview

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Transport Layer Functions

Net

wor

kIPXIP

Tran

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SPXTCP UDP

Distinguishes between upper layer applications

Establishes end-to-end connectivity between applications

Defines flow control

Provides reliable or unreliable services for data transfer

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Reliable Transport Layer Functions

Synchronize

Acknowledge, Synchronize

Acknowledge

Data Transfer(Send Segments)

Sender Receiver

Connection EstablishedConnection Established

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TCP Segment FormatTCP Segment Format

Source port (16) Destination port (16)

Sequence number (32)

Headerlength (4)

Acknowledgement number (32)

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

Checksum (16) Urgent (16)

Options (0 or 32 if any)

Data (varies)

Bit 0 Bit 15 Bit 16 Bit 31

20 byte

s

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Port NumbersPort Numbers

TCP

Port Numbers

FTP

TransportLayer

TELNET

DNS

SNMP

TFTP

SMTP

UDP

ApplicationLayer

2121 2323 2525 5353 6969 161161

RIP

520520

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TCP Port NumbersTCP Port Numbers

SourcePort

SourcePort

Dest.Port

Dest.Port ……

Host A

10281028 2323 ……SP DP

Host ZTelnet Z

Dest. port = 23.Send packet to my

Telnet application.

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TCP Three Way HandshakeTCP Three Way Handshake

Send SYN (seq=100 ctl=SYN)

SYN received

Host A Host B

11

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SYN received

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

Host A Host B

SYN received

11

22

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SYN received

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

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

Host A Host B

11

22

33

SYN received

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DenialDenial--ofof--Service AttacksService Attacks Denial-of-service (DoS) attacks are designed to deny

services to legitimate hosts attempting to establish connections. In a DoS attack, the hacker initiates a synchronization but the receiving device replies to a non-existent, unreachable IP address and then is placed in a wait-state while waiting to receive the final ACK from the initiator.

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TCP Simple AcknowledgmentTCP Simple Acknowledgment

•Window size = 1

Sender Receiver

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Sender ReceiverSend 1 Receive 1

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TCP Simple AcknowledgmentTCP Simple AcknowledgmentSender Receiver

Send 1 Receive 1

Send ACK 2

Send 2Receive 2

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•Window size = 1


Send ACK 2

Send 2Receive 2

Send ACK 3

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•Window size = 1


Receive ACK 2 Send ACK 2

Send 2Receive 2

Receive ACK 3Send ACK 3

Send 3Receive 3

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•Window size = 1


Receive ACK 2 Send ACK 2

Send 2Receive 2

Receive ACK 3Send ACK 3

Send 3Receive 3

Receive ACK 4

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TCP Sequence and Acknowledgment NumbersTCP Sequence and Acknowledgment Numbers

SourcePort

SourcePort

Dest.Port

Dest.Port

……Sequence#

Sequence#

Acknowledgement#

Acknowledgement#

Source Dest. Seq. Ack.1028 23 10 1

I justsent #10.

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

SourcePort

SourcePort

Dest.Port

Dest.Port ……Sequence

#Sequence

#Acknowledgement

#Acknowledgement

#

10281028 2323Source Dest.

101010Seq.

11Ack.

102810282323Source Dest.

111111Seq.

11Ack.

I justsent #10.

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SourcePort

SourcePort

Dest.Port

Dest.Port ……Sequence

#Sequence

#Acknowledgement

#Acknowledgement

#


111111Seq.

22Ack.


101010Seq.

11Ack.

102810282323Source Dest.

111111Seq.

11Ack.

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

I justsent #11.

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TCP Basic WindowingTCP Basic Windowing

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TCP Sliding WindowingTCP Sliding Windowing

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TCP Sliding WindowingTCP Sliding Windowing

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UDP Segment FormatUDP Segment Format

•No sequence or acknowledgment fields

Source port (16) Destination port (16)

Length (16)

Data (if any)

1Bit 0 Bit 15 Bit 16 Bit 31

Checksum (16)

8Bytes

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Network Layer Functions

Net

wor

k

IP, IPX

Dat

a Li

nkPh

ysic

alEIA/TIA-232

v.35Et

hern

e t

Fram

e R

e la y

HD

LC

802.2

802.3

• Defines logical source and destination addresses associated with a specific protocol

• Defines paths through network

• Interconnects multiple data links

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Network Layer Functions

DataSourceaddress

Destination addressIP Header

172.15.1.1NodeNetwork

Network Layer End Station Packet

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Network Layer FunctionsNetwork Layer Functions

11111111 11111111 00000000 00000000

10101100 00010000 01111010 11001100

172.16.122.204 255.255.0.0

172 16 122 204

255

Address Mask

255 0 0

Network Host

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Internet Layer OverviewInternet 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

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IP DatagramIP Datagram

Version(4)

Destination IP Address (32)

Options (0 or 32 if any)

Data (varies if any)

1Bit 0 Bit 15 Bit 16 Bit 31Header

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)

20Bytes

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Protocol FieldProtocol Field

TransportLayer

InternetLayer

TCP UDP

ProtocolNumbers

IP

176

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Internet Control Message ProtocolInternet Control Message Protocol

Application

Transport

Internet

Data Link

Physical

Destination Unreachable

Echo (Ping)

Other

ICMP1

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Address Resolution ProtocolAddress Resolution Protocol

172.16.3.1 172.16.3.2

IP: 172.16.3.2 = ???IP: 172.16.3.2 = ???

I need the Ethernet address of 176.16.3.2.

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172.16.3.1 172.16.3.2

IP: 172.16.3.2 = ???IP: 172.16.3.2 = ???

I heard that broadcast. The message is for me. Here is my Ethernet address.




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172.16.3.1

IP: 172.16.3.2 Ethernet: 0800.0020.1111 IP: 172.16.3.2 Ethernet: 0800.0020.1111

172.16.3.2

IP: 172.16.3.2 = ???IP: 172.16.3.2 = ???





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•Map IP MAC

172.16.3.1

IP: 172.16.3.2 Ethernet: 0800.0020.1111 IP: 172.16.3.2 Ethernet: 0800.0020.1111

172.16.3.2

IP: 172.16.3.2 = ???IP: 172.16.3.2 = ???





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Reverse ARPReverse ARP

Ethernet: 0800.0020.1111 IP = ???Ethernet: 0800.0020.1111 IP = ???

What is my IP address?

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I heard that broadcast. Your IP address is 172.16.3.25.

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Ethernet: 0800.0020.1111IP: 172.16.3.25

Ethernet: 0800.0020.1111IP: 172.16.3.25




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• Map MAC IP

Ethernet: 0800.0020.1111IP: 172.16.3.25

Ethernet: 0800.0020.1111IP: 172.16.3.25




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Introduction to TCP/IP AddressesIntroduction to TCP/IP Addresses

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

• Unique addressing allows communication between end stations

• Path choice is based on destination address

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IP AddressingIP 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 204ExampleDecimalExampleBinary

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

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IP Address ClassesIP Address Classes

•Class A:

•Class B:

•Class C:

•Class D: Multicast

•Class E: Research

NetworkNetwork HostHost HostHost HostHostNetworkNetwork HostHost HostHost HostHost

NetworkNetwork NetworkNetwork HostHost HostHostNetworkNetwork NetworkNetwork HostHost HostHost

NetworkNetwork NetworkNetwork NetworkNetwork HostHostNetworkNetwork NetworkNetwork NetworkNetwork HostHost

8 bits 8 bits 8 bits 8 bits

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IP Address ClassesIP Address Classes1Bits:0NNNNNNN0NNNNNNN HostHost HostHost HostHost

8 9 16 17 24 25 32

Range (1-126)1Bits:10NNNNNN10NNNNNN NetworkNetwork HostHost HostHost

8 9 16 17 24 25 32

Range (128-191)1Bits:110NNNNN110NNNNN NetworkNetwork NetworkNetwork HostHost

8 9 16 17 24 25 32

Range (192-223)1Bits:1110MMMM1110MMMM Multicast GroupMulticast Group Multicast GroupMulticast Group Multicast GroupMulticast Group

8 9 16 17 2425 32

Range (224-239)

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Host AddressesHost 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 12Network Host

. . Network Interface

172.16.0.010.0.0.0

E0E1

Routing Table

172.16.2.1

10.6.24.2

E0

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Determining Available Host AddressesDetermining Available Host Addresses

11111111

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 0000001111111101

123

655346553565536-

...

265534

N

2N-2 = 216-2 = 65534

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Addressing without SubnetsAddressing without Subnets

•Network 172.16.0.0

172.16.0.0

172.16.0.1 172.16.0.2 172.16.0.3

…...

172.16.255.253 172.16.255.254

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Addressing with SubnetsAddressing with Subnets

•Network 172.16.0.0

172.16.1.0 172.16.2.0

172.16.3.0

172.16.4.0

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Subnet AddressingSubnet 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

172.16Network

Network Interface

172.16.0.0172.16.0.0

E0E1

New Routing Table2 160Host

. .

172.16.3.1E1

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Subnet AddressingSubnet 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

172.16.3.1

E0E1

172.16 2 160Network Host

. . Network Interface

172.16.2.0172.16.3.0

E0E1

New Routing Table

Subnet

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Subnet MaskSubnet Mask

172172 1616 00 00172172 1616 00 00

255255 255255 00 00

255255 255255 255255 00255255 255255 255255 00

IPAddress

DefaultSubnet

Mask

8-bitSubnet

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

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Decimal Equivalents of Bit PatternsDecimal 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

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Subnet Mask without SubnetsSubnet Mask without Subnets

16

Network Host

172 0 0

10101100

11111111

10101100

00010000

11111111

00010000

00000000

00000000

10100000

00000000

00000000

•Subnets not in use—the default

00000010172.16.2.160172.16.2.160

255.255.0.0255.255.0.0

NetworkNumber

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Subnet Mask with SubnetsSubnet Mask with Subnets

•Network number extended by eight bits

16

Network Host

172.16.2.160172.16.2.160

255.255.255.0255.255.255.0

172 2 0

10101100

11111111

10101100

00010000

11111111

00010000

11111111

00000010

10100000

00000000

00000000

00000010

Subnet

NetworkNumber

128

192

224

240

248

252

254

255

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Subnet Mask with SubnetsSubnet Mask with SubnetsNetwork Host

172.16.2.160172.16.2.160

255.255.255.192255.255.255.192

10101100

11111111

10101100

00010000

11111111

00010000

11111111

00000010

10100000

11000000

10000000

00000010

Subnet

•Network number extended by ten bits

16172 2 128NetworkNumber

128

192

224

240

248

252

254

255

128

192

224

240

248

252

254

255

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Broadcast AddressesBroadcast Addresses

172.16.1.0172.16.2.0

172.16.3.0

172.16.4.0

172.16.3.255(Directed broadcast)

255.255.255.255(Local network broadcast)XX

172.16.255.255(All subnets broadcast)