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

Network layer is the third layer in the OSI model of computer networking. Packet forwarding including routing through routers and quality of service management are done by the network layer.Nature of the serviceThe transport layer at the host side receives the service provided by the network layer. But the transport layer resides in the hosts while the network layer resides in the subnet.We know the subnet is a collection of routers which consists of only the bottom three layers. Hence, we can say that the service provided by the network layer to the transport layer is more effective, than the ... Read More

Sliding window protocol is a transmission control protocol. To hold the outgoing and incoming packets both the sender and receiver maintains a finite buffer. Every packet sent from the sender side must be acknowledged by the receiver.The sender is maintaining a timer for every packet sent, and any unacknowledged packet in a certain time is resent. The sender will send a complete window of packets before receiving an acknowledgement for the first packet in the window. This leads to a higher transfer rate, as the sender may send multiple packets without waiting for each packet's acknowledgement.The Receiver advertises a window ... Read More

In the Link - State Routing Protocol, the router attempts to construct its own internal map of the network topology. It provides the information about whether the link to reach the router is active or not.Every router will create something called Link state packets.In the first round every node creates link state packets with the help of “Hello packets”.Step 1 − Prepare the link state packet at every router.DSeqTTLC11B7A1CSeqTTLD11B3ASeqTTLB2D1BSeqTTLA2D7C3Step 2 − Every router flood the link state packets to every offer routerAt A −Link state packet B, C, DFrom BA2C3D7From CB3D11From DA1B7C11Now A can construct the entire graph using the ... Read More

Network delay is defined as how much time will take a bit of data to travel from one node to another node.Network delay can be divided into following ways −Transmission delayPropagation delayLet us learn about both of them in detail.Transmission delayIt is the time required to put a packet’s bit (or data bits) on the transmission medium that can be wired or wireless. Transmission delay depends on the length of the packet and bandwidth of the network.Transmission delay can be calculated as follows −Transmission delay = Packet size / bandwidth          packet           ... Read More

Traffic throttling is one of the approaches for congestion control. In the internet and other computer networks, senders trying to adjust the transmission need to send as much traffic as the network can readily deliver. In this setting the network aim is to operate just before the onset of congestion.There are some approaches to throttling traffic that can be used in both datagram and virtual-circuit networks.Each approach has to solve two problems −FirsRouters have to determine when congestion is approaching ideally before it has arrived. Each router can continuously monitor the resources it is using.There are three possibilities, which are ... Read More