What is CSMA/CD and CSMA/CA in Computer networking?

What is CSMA/CD in Computer networking?

CSMA/CD stands for carrier sense multiple access with collision detection.

CSMA/CD is a technology which is used to avoid collision even though there are thousands of computer connected through a network.

A technology was developed not only to help avoid collision, but also to respond correctly if a collision happens.

The CSMA/CD was early used in Ethernet networks to improve the performance of the communication. I.e. in half duplex networks that utilize coaxial cable and twisted pair cable.

How CSMA/CD works?

It basically works by each computer in the network first sense if the wire/channel is idle and if it is idle it sends its data

But if 2 computer sense the channel idle at the same time and send data at the same time, a collision will happen.

And if the collision happens they immediately stop sending data this reduce the time of collision because we do not want to waste time in sending the data packet completely when collision is already detected and computer will wait for random amount of time and this random time will now be double of what it was in previous collision which means the waiting time increase exponentially after every collision

And if in the next attempt it successfully send the data packet then the waiting time will again come back to normal that means it will not exponentially increase of the previous waiting time.

Note: CSMA/CD is only used in Half duplex communication network.In Full duplex communication network CSMA/CA is used.

What is CSMA/CA in Computer networking?

CSMA/CA stands for carrier sense multiple access with collision Avoidance.

CSMA/CA is a technology which is used to avoid collision even though there are thousands of computer connected through a wireless network.

A technology was developed not only to help avoid collision, but also to respond correctly if a collision happens.

The CSMA/CA is used in wireless networks to improve the performance of the communication. I.e. in full duplex networks.

How CSMA/CA works?

So, CSMA/CA (carrier sense multiple access with collision avoidance) is used in wire networks.

So when a computer wants to send a data on wireless network it can’t sense or hear If there are any collision on the network because there is no cable involved so instead it does its best to avoid collision altogether.

So in this method when a computer wants to send data it will first sense if there are any other transmission happening and if it detects any other transmissions, it will wait a short amount of time before checking the channel again.

And when it checks the channel again, and if it doesn’t sense any transmission it will again wait a short random amount of time and then it will go ahead and send its data then once the destination device receives the data it will acknowledgement the sender that it has received the data but if the sending computer does not receive an acknowledgement from the destination it will assume that it did not get the data and it will start the process all over again.

Now another method CSMA/CA use to avoid collision is the optional RTS (Ready to send), CTS (Clear to send) protocol. This is an optional protocol that’s used with CSMA/CA on wireless networks this protocol enables a computer to send out an RTS to the wireless access point requesting for an opportunity to send out its data and if the wireless access point grants this request the access point will temporarily stop all other communication on the network and then it will respond back to the computer with CTS which tells the computer to go ahead and send it’s data so, when this protocol the wireless access point is basically the traffic controller on the wireless network.

Comments

Topology-Mesh, Star, Bus, Ring and Hybrid

Computer Network Topology – Mesh, Star, Bus, Ring and Hybrid Geometric representation of how the computers are connected to each other is known as topology. There are five types of topology – Mesh, Star, Bus, Ring and Hybrid. Types of Topology There are five types of topology in computer networks: 1. Mesh Topology 2. Star Topology 3. Bus Topology 4. Ring Topology 5. Hybrid Topology Mesh Topology In mesh topology each device is connected to every other device on the network through a dedicated point-to-point link. When we say dedicated it means that the link only carries data for the two connected devices only. Lets say we have n devices in the network then each device must be connected with (n-1) devices of the network. Number of links in a mesh topology of n devices would be n(n-1)/2. Advantages of Mesh topology 1. No data traffic issues as there is a dedicated link between two devices which means the link is only available for those two devices. 2. Mesh topolog...

BIT ORIENTED PROTOCOLS : SDLC, HDLC, BISYNC, LAP & LAPB

BIT ORIENTED PROTOCOLS A bit-oriented protocol is a communications protocol that sees the transmitted data as an opaque stream of bits with no semantics, or meaning. Control codes are defined in terms of bit sequences instead of characters. Bit oriented protocol can transfer data frames regardless of frame contents. It can also be stated as "bit stuffing" this technique allows the data frames to contain an arbitrary number of bits and allows character codes with arbitrary number of bits per character. SDLC Synchronous Data Link Control (SDLC) supports a variety of link types and topologies. It can be used with point-to-point and multipoint links, bounded and unbounded media, half-duplex and full-duplex transmission facilities, and circuit-switched and packet-switched networks. SDLC identifies two types of network nodes: primary and secondary. Primary nodes control the operation of other stations, called secondary. The primary polls the secondary in a predeter...

What is a pulse oximeter? How does it help a COVID-19 patient?

OXIMETER

Computer Network : Layered Architecture

Layered Architecture Protocol Hierarchy To tackle with the design complexity most of the networks are organize as a set of layers or levels. The fundamental idea of layered architecture is to divide the design into small pieces. The layering provides modularity to the network design. The main duty of each layer is to provide offer services to higher layers, and provide abstraction. The main benefits of layered architecture are modularity and clear interfaces. Five Layered Network Design Issues: Layered architecture in computer network design Layered architectures have several advantages. Some of them are, Modularity and clear interface Provide flexibility to modify network services Ensure independence of layers Management of network architecture is easy Each layer can be ...

Can coronavirus spread through mosquitoes?

Can coronavirus spread through mosquitoes? Scientists have confirmed for the first time that the novel coronavirus behind the COVID-19 pandemic cannot be transmitted to people by mosquitoes , a finding that adds evidence to WHO claims that the disease is not mosquito-borne. The research, published in the journal Scientific Reports, provided the first experimental evidence on the capacity of SARS-CoV-2, the virus that causes COVID-19 disease, to infect and be transmitted by mosquitoes. "Here we provide the first experimental data to investigate the capacity of SARS-CoV-2 to infect and be transmitted by mosquitoes," the study noted. "While the World Health Organization (WHO) has definitively stated that mosquitoes cannot transmit the virus, our study is the first to provide conclusive data supporting the theory," said Stephen Higgs, a co-author of the research from Kansas State University in the US. According to the study, conducted at the university...

Computer Network and Types

Computer Network A network set up by connecting two or more computers and other supporting hardware devices through communication channels is called a computer network. It enables computers to communicate with each other and to share commands, data, etc., including the hardware and software resources. Uses of Computer Network: It allows you to share resources such as printers, scanners, etc. You can share expensive software and database among network users. It facilitates communications from one computer to another computer. It allows the exchange of data and information among users through a network. What Are the Important Types of Computer Networks? There are various types of computer networks available. We can categorize them according to their size as well as their purpose. The size of a network should be expressed by the geographic area and number of computers, which are a part of their networks. It includes devices housed in a single room to millions of devices sp...

Computer Network : ISO-OSI Reference Model

ISO-OSI Reference Model Principal of OSI Reference Model The OSI reference model has 7 layers. The principles that were applied to arrive at the seven layers can be briefly summarized as follows: A layer should be created where a different abstraction is needed. Each layer should perform a well-defined function. The function of each layer should be chosen with an eye toward defining internationally standardized protocols. The layer boundaries should be chosen to minimize the information flow across the interface The number of layers should be large enough that distinct functions need not be thrown together in the same layer out of necessity and small enough that architecture does not become unmanageble. Feature of OSI Model: Big picture of communication over network is understandable thr...

Sampoorntech

Search This Blog