The document presents a presentation by group members on cyclic redundancy check (CRC) and custom subnet mask calculation. It explains CRC as an error detection method that utilizes a polynomial for reliable data transmission, detailing the process of generating and checking CRC at sender and receiver sides. Additionally, it introduces subnet masks and provides examples for calculating custom subnet masks based on network and device requirements.

1. GROUP MEMBERS NAME :
RIYAN ALI (120)
SULEMANNAWAZ (097)
HASEEB ASIF (100)
ASHIR(79)

2. Welcome To My
Presentation
Topic : Cyclic Redundancy Check
Topic : Custom Subnet Mask Calculation

3. 03
01 02
04
Agenda
Error Detection
Method
Cyclic
Redundancy
Check
Performance
of CRC
Advantages of
CRC

4. What is Error Detection ?

Networks must be able to transfer data from one device
to another with complete accuracy.

Data can be corrupted during transmission.

For reliable communication, errors must be detected and
corrected.

6. Cyclic Redundancy Check
CRC or Cyclic Redundancy Check is a method of
detecting errors in the communication channel.
CRC uses Generator Polynomial which is available on
both sender and receiver side.

7. CRC Generation At Sender Side
1.Find the Length of Divisor ‘L’
2.Append 0 ‘L-1’bits to the original bits
3.Perform Binary Digit Operation
4.Remainder of the division=CRC

8. 1 Find the Length of Divisor ‘L’
2 Append 0 ‘L-1’bits to the original bits
3 Perform Binary Digit Operation
4 Remainder of the division=CRC

9. The sender performs a division operation
on the bits being sent and calculates the
remainder. Before sending the actual bits,
the sender adds the remainder at the end of
the actual bits.
(Data Bits+ Remainder)

10. Receiver Side:
Code word received at the receiver side
100100001
(data + CRC)

11. At The Receiver Side
 Receiver divides received data (data + CRC) with
generator.
 If remainder is zero, data is correctly received.
 Else, there is error.

12. Therefore, the remainder is all zeros.
Hence, the data received has no error.

13. Advantages of CRC
1. Cyclic codes have a very good performance in detecting
single-bit errors, double errors, an odd number of errors.
2. They can easily be implemented in hardware and
software.
3. They are especially fast when implemented in hardware.
4. This has made cyclic codes a good candidate for many
networks.

14. 01 CUSTOM SUBNET MASK CALCULATION:

15. CALCULATE CUSTOM SUBNET MASK:
What is a Subnet Mask?
A subnet mask is a 32-bit number that divides an IP address into two
parts:
Network ID: Identifies the specific network to which a device
belongs. Host ID: Uniquely identifies a particular device
within that network.
1. Classful IP Addressing:-
2. As we know 5 that classes: A, B, C, D, E.
3. Classes D & E: Reserved for special purposes-
4. Classes A, B, C: Used for IP addressing

16. CUSTOM SUBNET MASK:
Classes Ranges of The
Classes
Default Subnet Mask Network
/Host
Class : A 0 to 126 A: 255.0.0.0
N ,H,H,H
N=8, H=24
Class : B 128 to 191 B: 255.255.0.0
N, N,H,H
N=16, H=16
Class : C 192 to 223 C :255.255.255.0
N,N,N,H
N=24, H=8

 127 is the error detection, correction etc.
 “255” Represent the network and “0” Host.
8 8 8 8

17. PROBLEM 1 FOR CALCULATE CUSTOM SUBNET MASK:
Require:
 Host= 30
 Subnet= 6
 IP Address= 210.100.56.12

18. PROBLEM 2 FOR CALCULATE CUSTOM SUBNET MASK:
Require:
 Host= 2000
 Subnet= 30
 IP Address = 130.78.12.32

19. THANK YOU