1

Computer Networks:Hands On Experience

Pongpisit Wuttidittachotti, Ph.D.Faculty of Information Technology

King Mongkut's University of Technology North Bangkok (KMUTNB)pongpisitw@kmutnb.ac.th

http://www.it.kmutnb.ac.th/pongpisit

2

Outline• What is a Network?• Network Components• Putting It all Together• LAN & WAN• LAB #1: Testing the network

connectivity• LAB #2: Connect 2 computers

using a cable

3

What is a Network?

• A Network is two or more devices connected to a common medium.

Network Components• All networks have 4 basic elements

in common:

Rules (protocols) to govern the handling of the message.

Messages that travel from one device to another.

Medium that is used to interconnect devices and can transport the messages from one device to another.

Devices on the network that exchange messages.

DevicesDevices on a network – Common Symbols

MessagesMessages take many forms.

MediaMedia on a network can be varied.

Guided(wired)

Unguided(wireless)

•Twisted Pair Cable•Coaxial Cable•Fiber Optic Cable

AIR WATER

Rules (Protocols)Rules on a network seem almost endless – but they’re not.

• Other Application Protocols:• DNS, DHCP, FTP

• Some Other Protocols:• TCP/IP Protocol Suite, Ethernet, Routing Protocols

Communications – What is it?• We establish rules, or protocols, for

communicating with each other:– Identify the sender and receiver.– Agree on the method.– Common language.– Speed and delivery of the message.– Confirmation that the message was received.

• Communications between individuals is successful if the meaning of the received message is the same as the meaning of the message that was sent.

Putting It all Together1. Converted to Binary.

2. NIC generates signals.

3. Passed among LAN devices.

4. Exit the local area (router).

Putting It all TogetherThe many interconnected devices worldwide are often represented by a cloud.

5. Bits are transmitted to devices that interconnect the networks.

Putting It all Together

6. Passed among local devices at the destination.

7. The destination device converts the bits into human readable form.

Putting It all Together

1 2 3 4

5

6 7

At each of these steps, there are protocols that define the rules for device communication.

14

LAN & WAN

Local Area Networks• An individual network usually spans

a single geographical area, providing services and applications to people within a common organizational structure, such as a single business, campus or region.

Wide Area Networks• Networks that connect LANs in

geographically separated locations. Usually implemented with leased connections through a telecommunications service provider (TSP) network.

• A TSP traditionally transports voice and data on different networks. Now, providers are offering converged network services.

HDLC, PPP, T1, DS3, OC3, ISDN, Frame Relay

LAB #1: Testing the network connectivity

• Ping• Traceroute (tracert)

Testing the Network Layer

19

“ipconfig” command • ipconfig is a commmand line utility. • This utility allows you to get the IP address information of

a Windows computer.

Testing the Network Layer

C:>ping 10.0.0.1Verifies that the local IP configuration is correct.

C:>ping 10.0.0.254Verifies that the host can reach the gateway.

Testing the Network Layer

C:>ping 10.0.1.2

Testing the Network Layer

23

LAB #2: Connect 2 computers using a cable

24

What do you need to know?

• IPv4• Cable types

Anatomy of an IPv4 Address

• Each device on a network must be uniquely identified at the Network layer.

• For IPv4, a 32 bit source and destination address is contained in each packet.

Anatomy of an IPv4 Address

• Devices use binary logic and work with strings of binary numbers. For us, the decimal equivalent is much easier to use and remember.

32 bit Binary String

Expressed in DOTTED DECIMAL NOTATION

Divided into OCTETS

Anatomy of an IPv4 Address

• To identify a path or "route" through a network, the addressmust be composed of two parts:– Network portion– Host portion

1.1

1.2

1.3

2.1

2.2

3.1 3.2

Anatomy of an IPv4 AddressIP Address 192. 168. 1. 2

Binary IP Address 11000000 10101000 00000001 00000010

• Network Portion:– Some portion of the high-order bits

represents the network address.– We define a network as a group of

hosts that have identical bit patterns in the network address portion of their addresses.192.168.1.2 11000000 10101000 00000001 00000010

192.168.1.67 11000000 10101000 00000001 01000011

192.168.1.204 11000000 10101000 00000001 11001100

Anatomy of an IPv4 AddressIP Address 192. 168. 1. 2

Binary IP Address 11000000 10101000 00000001 00000010

• Host Portion:– There are a variable number of bits

that are called the host portion of the address.

– The number of bits used in this host portion determines the number of hosts that we can have within the network.

192.168.1.2 11000000 10101000 00000001 00000010

192.168.1.67 11000000 10101000 00000001 01000011

192.168.1.204 11000000 10101000 00000001 11001100

Binary to Decimal Conversion

• In all number systems, the digits start with 0.• A Base-n number system has n number of digits:

– Decimal:• Base-10 has 10 digits

– 9, 8, 7, 6, 5, 4, 3, 2, 1, 0– Binary:

• Base-2 has 2 digits– 1, 0

– Hexadecimal:• Base-16 has 16 digits

– F, E, D, C, B, A, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0

Binary to Decimal Conversion• Positional Notation (Decimal

Number System):– Means that a digit represents

different values depending on the position it occupies.

– The value that a digit represents is that value multiplied by the power of the base according to the position the digit occupies.

4312String

1101001,000Value

(2x103) + (1x102) + (3x101) + (4x100) = 2,134

0123Position

100101102103Base

Binary to Decimal Conversion

• Computers react only to electrical impulses.– They work with and store data

using electronic switches that are either on (1) or off (0).

– They can only understand and use data that is in this two state format.

– These 1's and 0's are called binary digits or bits.

Binary to Decimal Conversion• Positional Notation (Binary

Number System):– Means that a digit represents

different values depending on the position it occupies.

– The value that a digit represents is that value multiplied by the power of the base according to the position the digit occupies.

2021222324252627Base

01234567Position

1248163264128Value

00110110String

(1x26) + (1x25) + (1x23) + (1x22) 64 + 32 + 8 + 4 = 108

Binary to Decimal Conversion

2021222324252627Base

01234567Position

1248163264128Value00000000String10000000String01000000String

11111111String

Range: 0 to 255

Binary to Decimal Conversion

2021222324252627

1248163264128

10010011

IP Address: 11001001000100010001110100000100

11001001 00010001 0000010000011101

201

10001000

17

10111000

29 4

00100000

IP Address: 201.17.29.4

Binary to Decimal Conversion

27 26 25 24 23 22 21 20

Dec. 128 64 32 16 8 4 2 1

0 0 0 1 0 1 0 1

0 0 1 1 0 0 1 0

0 1 1 0 0 1 0 1

1 0 0 1 0 1 1 0

1 1 0 0 1 1 1 0

50

21

101

150

206

37

Managing Big Network

128.143.70.0/16

128.143.137.32/16subnetmask: 255.255.0.0

128.143.71.21/16subnetmask: 255.255.0.0

128.143.137.144/16subnetmask: 255.255.0.0

128.143.71.201/16subnetmask: 255.255.0.0

38

Managing Subnets

128.143.0.0/16

128.143.137.32/24subnetmask: 255.255.255.0

128.143.71.21/24subnetmask: 255.255.255.0

128.143.137.144/24subnetmask: 255.255.255.0

128.143.71.201/24subnetmask: 255.255.255.0

128.143.137.0/24Subnet

128.143.71.0/24Subnet

128.143.0.0/16

128.143.137.32/26subnetmask: 255.255.255.192

128.143.71.21/24subnetmask: 255.255.255.0

128.143.137.144/26subnetmask: 255.255.255.192

128.143.71.201/16subnetmask: 255.255.0.0

128.143.71.0/24Subnet128.143.137.128/26

Subnet128.143.137.0/26

Subnet

39

Different Network Size

Network Prefix # of Host Addresses Mask /30 4 255.255.255.252 /29 8 255.255.255.248

/28 16 255.255.255.240 /27 32 255.255.255.224

/26 64 255.255.255.192 /25 128255.255.255.128 /24 256255.255.255.0

40

Straight-Through, crossover, rollover

41

Straight Through- Switch to a router Ethernet port- Computer to switch- Computer to hub

42

Crossover Cables

•Switch to switch •Switch to hub •Hub to hub •Router to router Ethernet port•Computer to computer •Computer to a router Ethernet port

43

Console Cable

44

THANK YOU FOR YOUR ATTENTION

45

Reference• CCNA, St. Clair College in

Windsor, Ontario.

46

BACKUP

47

LAB#3: CREATING SUBNET

• Configure the 2 PCs to be in the same subnet– Try Pinging between the two PCs

• Configure the 2 PCs to be in different subnet– Try Pinging between the two PCs

48

IOS configuration Mode