Carrier Sense Multiple Access (CSMA) is a random-access protocol (multiple access protocol) that is used to minimise the chance of collision and increase performance. The main principle used is 'sense before transmit'. CSMA is using a shared medium which means any data passed with a common interconnection network.The Carrier Sense Multiple Access (CSMA) Protocol is diagrammatically represented as follows −Suppose the sender places a frame without sensing the status of the channel it will lead a collision with other nodes, if the other node also sends frames to the shared memory. So we sense before transmitting.There are mainly two conditions ... Read More

Carrier Sense Multiple Access (CSMA) is a random-access protocol (multiple access protocol) that is used to minimise the chance of collision and increase performance. The main principle used is 'sense before transmit'. CSMA is using a shared medium which means any data passed with a common interconnection network.The Carrier Sense Multiple Access (CSMA) Protocol is diagrammatically represented as follows −Suppose the sender places a frame without sensing the status of the channel it will lead a collision with other nodes, if the other node also sends frames to the shared memory. So we sense before transmitting.There are mainly two conditions ... Read More

Protocols in which stations listen for a carrier and act accordingly are called Carrier Sense Protocols. Multiple Access tells the fact that multiple nodes send and receive on the medium.Transmissions of one node are received by all other nodes using the medium. Carrier Sense Multiple Access (CSMA) is a probabilistic Media Access Control (MAC) protocol in which a node verifies the absence of other traffic before transmitting on a shared physical medium, such as an electrical bus, or a band of electromagnetic spectrum.Carrier Sense Multiple Access (CSMA) ProtocolsThe three protocols that discuss the various implementations are as follows −1-persistent CSMANon- ... Read More

Aloha is a packet switching system. The time interval required to transmit one packet is called a slot. Aloha is a random access technique.There are two ALOHA protocols as follows −Pure ALOHASlotted ALOHANow let us see what Slotted ALOHA is −Slotted ALOHAThe slotted ALOHA is explained below in stepwise manner −Step 1 − Slotted ALOHA was introduced to improve the efficiency of pure ALOHA, because in pure ALOHA there is a high chance of collision.Step 2 − In this protocol, the time of the shared channel is divided into discrete intervals called as slots.Step 3 − The stations can send ... Read More

Aloha is a packet switching system. The time interval required to transmit one packet is called a slot. Aloha is a random access technique.There are two ALOHA protocols as follows −Pure ALOHASlotted ALOHANow let us see what Pure ALOHA is.Pure ALOHAThe mode of random access in which users can transmit at any time is called pure Aloha. This technique is explained below in a stepwise manner.Step 1 − In pure ALOHA, the nodes transmit frames whenever there is data to send.Step 2 − When two or more nodes transmit data simultaneously, then there is a chance of collision and the ... Read More

Multiple access protocols are generally used to coordinate access to link, here nodes can regulate their transmission onto the shared broadcast channels by using multiple access protocol, It is used on both wired and wireless LAN and satellite network.Multiple nodes can transmit frames at the same time, if so the transmitted frame collides at the entire receiver. When there is a collision, there is no acknowledgement to the receiver that the frame is transmitted or not.Thus, all frames involved in the collision are lost, and the broadcast channel is wasted during the collision interval. To rectify this problem Multiple Access ... Read More

In wireless networks, a channel can be allocated between source and destination, and in between source and destination each router is connected to its neighbour router in peer to peer manner, the whole channel consists of a number of routers.So some of the channels are used for static routing and some of them are for dynamic routing schemes.Types of Channel AllocationThe different types of channel allocation schemes are as follows −Static channel allocationDynamic channel allocationHybrid channel allocationNow let us discuss dynamic channel allocation.Dynamic channel allocationIn this channel an interface can switch from one channel to another channel frequently. The dynamic ... Read More

In wireless networks, a channel can be allocated between source and destination, and in between source and destination each router is connected to its neighbour router in peer to peer manner, the whole channel consists of a number of routers.So some of the channels are used for static routing and some of them are for dynamic routing schemes.Types of Channel AllocationThe different types of channel allocation schemes are as follows −Static channel allocationDynamic channel allocationHybrid channel allocationNow let us discuss about static channel allocation −Static channel allocationThe process of static channel allocation scheme is explained below in a stepwise manner ... Read More

Selective-repeat Automatic Repeat Request (ARQ) is one of the techniques where a data link layer may deploy to control errors.Techniques to control ARQGenerally, there are three types of techniques which control the errors by Automatic Repeat Request (ARQ) they are −Stop-and-wait ARQGo-Back-N ARQSelective Repeat ARQRequirements for Error ControlThere are some requirements for error control mechanisms and they are as follows −Error detection − The sender and receiver, or any must ascertain that there is some error in the transit.Positive ACK − Whenever a receiver receives a correct frame, it should acknowledge it.Negative ACK − Whenever the receiver receives a damaged ... Read More

Let us understand what error control in the computer networks is.Error ControlError control is concerned with ensuring that all frames are delivered to destination possibly in an order.To ensure the delivery it requires three items, which are explained below −AcknowledgementTypically, reliable delivery is achieved using the “acknowledgement with retransmission” paradigm, whereas the receiver returns a special ACK frame to the sender indicating the correct receipt of a frame.In some systems the receiver also returns a negative ACK (NACK) for incorrectly received frames. So, it tells the sender to retransmit a frame without waiting for a timer to expire.TimersOne problem that ... Read More