Cs ch2

what is data transmission

data broken down into packet to be transmitted

Decribe header payload trailer

Header

• IP address of source device ( sender)

IP address of destivation device (receiver)

Size of packet (in byte)

Sequence number of pachet

Payload

• The actual data in packet (64 kib)

Trailer

Error checking method

• Method of ending packet

What is packet switching

• Method of Decoding it will arrange packet in order

Advantage of packet switching

• No need for single tie communication

• allow multiple transmission over same network resources

Disadvantage of packet switching

Data can be lost e need to re-sent

Step of packet swiching

1. router will determine which pachet should be sent to

2. Bouter decide which part the packet should take

3. The shortest part alway be selected

Type of data transmission

Series

Parallel

Type of transmission mode

• Simplex

• Half-duplex

• Full- duplex

Decribe serial

1 bit at a time

Single wire

Eg 3d printer

Decribe parallel

Multiple bit

Multiple wire

Eg printer

Different between serial and parallel

Serial

• Long distance

• Slower

Parallel

• Short distance

• Faster

Decribe simplex

Simplex - 1 direction

Advantage

requires less bandwidth

Disadvantage

Cannot send data back to the sender

Decribe half duplex

Half duplex both direction not sametime

Advantage

Enable 2 way transmission using full band width.

Disadvantage

-Deay in communication

Decribe USB (universal serial bus)

• from serial data transmission

• allow half duplex and full duplex

Decribe usb cable

USD cable consists 4 wire

• reds black for power

• whiter grun for data transmition

Decribe USB C

• is 24 pin symmetrical connector

• it smallery thinne than old UsB

• it ofter 100 watt

Advantage of USB

• No damage to the computer

• Easy to use

• casy to maintain

Disadvantage of USB

limited power supply

Decribe METHODS OF ERROR DETECTION

Need to check for error after data transmition

• because error can occur during data tranmission due to intenterence Eg: data loss, data change

Parity check

• based on the number of 1

• it can be add or Even

Parity block

Count horizontal line 1 to 9

Count vertical 1 to 8

Describe check sum

• When block of data about to transnitten the checksun calculated from block of data, calculation done by agreed algorithm how check sum can be check

• If 2 checksun sane, no transmittion error

Calculate check sum

put x given valul

1. divide x by 256 and round neareat integer = y

2. Multiply y by 256 = z

3. Chick sun: x - z

Describe eco check

• check if data transffed corruct Data sunt to receiver$ immediately back to sender

Disadvantage of eco check

• Require a lot of extra data to tramitted

Decribe ARQ (Automatic repeat request)

Use positive negative achnowledgement, timeout

How it ensure data integrity during transmission?? In ARQ

• If data is correct receiver will sund back data

• If data is wrong recciver will send negative acknowledgment

• Sender will wait limited tine to get acknowledgment from receiver

• If none receive sender resent the data

Decribe check digit

Contain ISBN 13 methods and MEDOLO 11 METHOD

help to sport error during data transmission

Eg detect error

• Omited or Extra digit eg instead 507 if it 5301

• Phonetic error eg 13 instead of 30

Decribe ISBN 13 METHODS

• Add odd num

• Add even num y multiply 3

• Add odds even a divide 10

• 10 Subtract Remainder

Decribe MEDOLO 11 METHOD

use when number less than is digit

• has weight eg: 8 digit (8, 7, 6,.)

• Each digit multiply the weight

• Add a divide by 11

• Subtact remainder by 11

• If value is 10 mention a x

• check will correct when remainder is o

Purpose of encryption

• to scrambing data

• protect data fron being stolen

Decribe WIRELESS DATA ENCRYPTION

• identiftied by SSID Sevice Set identifier along with password to create master key

• When device connect sare wireless network they given copy of master key

• Master key encrypts data into cipher text betor transmitting

• Receiver uses same master key to turn sy cipher text back Ho plain text

• To kup data sate it never sent over network

• Wireless network use special rules a called protocols like WRAz to protect wifi connection

Decribe WIRED DATA ENCRYPTION

• using master key to encrypty decrypt data

• Each application orten decides how to use encryption

Eg : HTTPS

Plaintext - Blinare before data encrypted

Ciphertext - name after data encrypted

Decribe SYMMETIC ENCRYPTION

• use to encrpts decrpt a message

• , Method is called Caesar Cipher

Eg: Original message: I have covid → plain text

Key : 4578

i have covid

467 84 57 8 45

n nh use to encrpts decrpt a message

• , Method is called Caesar Cipher

Eg: Original message: I have cavid → plain text

Key : 4578

i have covid

4678457845

mmhdihdmi → cipher text

Decribe ASYMMETRIC ENCRYPTION

when 2 key are used, public and private

Public Key - Know to everyone

Private Key - know ohly to the receiver

Different between Symmetric Encryption Asymmetric encryption

Symmetric Encryption

Faster

Less secure

Asymmetric Encryption

• Slower

• More secure