- Data Comm & Networks Home
- DCN - Overview
- DCN - What is Computer Network
- DCN - Uses of Computer Network
- DCN - Computer Network Types
- DCN - Network LAN Technologies
- DCN - Computer Network Models
- DCN - Computer Network Security
- DCN - Components
- DCN - Connectors
- DCN - Switches
- DCN - Repeaters
- DCN - Gateways
- DCN - Bridges
- DCN - Socket
- DCN - Network Interface Card
- DCN - NIC: Pros and Cons
- DCN - Network Hardware
- DCN - Network Port
- Computer Network Topologies
- DCN - Computer Network Topologies
- DCN - Point-to-point Topology
- DCN - Bus Topology
- DCN - Star Topology
- DCN - Ring Topology
- DCN - Mesh Topology
- DCN - Tree Topology
- DCN - Hybrid Topology
- Physical Layer
- DCN - Physical Layer Introduction
- DCN - Digital Transmission
- DCN - Analog Transmission
- DCN - Transmission media
- DCN - Wireless Transmission
- DCN - Transmission Impairments
- DCN - Multiplexing
- DCN - Network Switching
- Data Link Layer
- DCN - Data Link Layer Introduction
- DCN - Data Link Control & Protocols
- DCN - RMON
- DCN - Token Ring Network
- DCN - Hamming Code
- DCN - Byte Stuffing
- DCN - Channel Allocation
- DCN - MAC Address
- DCN - Cyclic Redundancy Checks
- DCN - Error Control
- DCN - Flow Control
- DCN - Framing
- DCN - Error Detection & Correction
- DCN - Error Correcting Codes
- DCN - Parity Bits
- Network Layer
- DCN - Network Layer Introduction
- DCN - Network Addressing
- DCN - Routing
- DCN - Internetworking
- DCN - Network Layer Protocols
- DCN - Routing Information Protocol
- DCN - Border Gateway Protocol
- DCN - OSPF Protocol
- DCN - Network Address Translation
- DCN - Network Address Translation Types
- Transport Layer
- DCN - Transport Layer Introduction
- DCN - Transmission Control Protocol
- DCN - User Datagram Protocol
- DCN - Congestion Control
- DCN - TCP Service Model
- DCN - TLS Handshake
- DCN - TCP Vs. UDP
- Application Layer
- DCN - Application Layer Introduction
- DCN - Client-Server Model
- DCN - Application Protocols
- DCN - Network Services
- DCN - Virtual Private Network
- DCN - Load Shedding
- DCN - Optimality Principle
- DCN - Service Primitives
- DCN - Services of Network Security
- DCN - Hypertext Transfer Protocol
- DCN - File Transfer Protocol
- DCN - Secure Socket Layer
- Network Protocols
- DCN - ALOHA Protocol
- DCN - Pure ALOHA Protocol
- DCN - Sliding Window Protocol
- DCN - Stop and Wait Protocol
- DCN - Link State Routing
- DCN - Link State Routing Protocol
- Network Algorithms
- DCN - Shortest Path Algorithm
- DCN - Routing Algorithm
- DCN - Leaky Bucket Algorithm
- Wireless Networks
- DCN - Wireless Networks
- DCN - Wireless LANs
- DCN - Wireless LAN & IEEE 802.11
- DCN - IEEE 802.11 Wireless LAN Standards
- DCN - IEEE 802.11 Networks
- Multiplexing
- DCN - Multiplexing & Its Types
- DCN - Time Division Multiplexing
- DCN - Synchronous TDM
- DCN - Asynchronous TDM
- DCN - Synchronous Vs. Asynchronous TDM
- DCN - Frequency Division Multiplexing
- DCN - TDM Vs. FDM
- DCN - Code Division Multiplexing
- DCN - Wavelength Division Multiplexing
- Miscellaneous
- DCN - Shortest Path Routing
- DCN - B-ISDN Reference Model
- DCN - Design Issues For Layers
- DCN - Selective-repeat ARQ
- DCN - Flooding
- DCN - E-Mail Format
- DCN - Cryptography
- DCN - Unicast, Broadcast, & Multicast
- DCN - Network Virtualization
- DCN - Flow Vs. Congestion Control
- DCN - Asynchronous Transfer Mode
- DCN - ATM Networks
- DCN - Synchronous Vs. Asynchronous Transmission
- DCN - Network Attacks
- DCN - WiMax
- DCN - Buffering
- DCN - Authentication
- DCN Useful Resources
- DCN - Quick Guide
- DCN - Useful Resources
Cyclic Redundancy Checks (CRCs)
Cyclic Redundancy Checks (CRCs)
The Cyclic Redundancy Checks (CRCs) is the most powerful method for Error-Detection and Correction. It is given as a kbit message and the transmitter creates an (n k) bit sequence called frame check sequence. The out coming frame, including n bits, is precisely divisible by some fixed number. Modulo 2 Arithmetic is used in this binary addition with no carries, just like the XOR operation.
Redundancy means duplicacy. The redundancy bits used by CRC are changed by splitting the data unit by a fixed divisor. The remainder is CRC.
Qualities of CRC
-
It should have accurately one less bit than the divisor.
-
Joining it to the end of the data unit should create the resulting bit sequence precisely divisible by the divisor.
CRC Generator and Checker
Process
-
A string of n 0s is added to the data unit. The number n is one smaller than the number of bits in the fixed divisor.
-
The new data unit is divided by a divisor utilizing a procedure known as binary division; the remainder appearing from the division is CRC.
-
The CRC of n bits interpreted in phase 2 restores the added 0s at the end of the data unit.
Example
Message D = 1010001101 (10 bits)
Predetermined P = 110101 (6 bits)
FCS R = to be calculated 5 bits
Hence, n = 15 K = 10 and (n k) = 5
The message is generated through 25:accommodating 1010001101000
The product is divided by P.
The remainder is inserted to 25D to provide T = 101000110101110 that is sent.
Suppose that there are no errors, and the receiver gets T perfect. The received frame is divided by P.
Because of no remainder, there are no errors.