Coining a new terminology in the technical field requires a strong impulse. The concept of DTN arrived primarily to combat the disruption which occurs in conventional TCP/IP (Transmission Control Protocol). Our communication network has many mediums that a data packet can take, like: wire, wireless, optical etc. These medium are subjective to various damages such as wire cut, power failure of a node and other human generated errors. As a consequence, the sender of data from one end of communication channel could not send the data. DTN, to some extent, eradicates this problem.
How TCP works?
TCP is the most widely used protocol in the history of computers, that's for sure. Lets just have a look on its basics in the figure below.
The main concept here is to confirm that a communication channel exists from sender to the receiver. That is exactly how TCP functions. The sender first sends a packet having SYN flag value high(1). The SYN high flag means a node wants to start a data transfer. The receiver who receives this SYN, if ready for data transfer, replies with a packet having its both ACK and SYN flags made high(1). The ACK high means that the receiver acknowledges the SYN flag from sender and the SYN means that the receiver also wants to start data transfer. The sender now replies with an ACKwhich now opens a two way channel for data transfer.
Thus our major protocol relies on the availability of connection from starting node to ending node. Only after the link from end to end is made, the communication takes place.Any disruption of the link between the two means that those SYN, ACK packets cannot flow which in turns means no data transfer.
DELAY/DISRUPTION TOLERANT NETWORKING(DTN)
As from its name, we can at-least imagine what DTN tends to achieve. It is designed to tolerate the disruption of conventional TCP protocol. The DTN functions in store and forward mechanism where each node itself stores the packets untill the adjacent node is available. This allows the sender at one end to continuously send the data even if there is link breakage somewhere between source and destination. Lets see the diagram below:
These are all the nodes that the data has to travel in order to reach from source (node A) to the destination (node E). These nodes are different from the conventional nodes in the way that they have storage capabilities. These storage are used to store packets whenever the next hop is not physically connected. For example, Consider the following diagram
Here, the communication channel between node C and D is broken. What happens now is, the node C now stores the packets originating from A. In this way, the sender node i.e A never feels as if the link is broken and it can continuously generate and send packets which was not possible in TCP/IP protocol.
The node C here also simultaneously keeps on checking for link availability between itself and node D. Once the link is restored, the transmission of packets from C to D continues. This property of DTN gives much more efficiency as the data doesnt need to be sent through A upon link restoration, rather the data now will be sent from C itself. This store and forward capability provides many benifits where the link between networking nodes is intermittent. In coming posts, we will discuss on the applications of DTN and will scrutinize the protocol itself for better understanding of the engineering aspects of DTN.
How TCP works?
TCP is the most widely used protocol in the history of computers, that's for sure. Lets just have a look on its basics in the figure below.
The main concept here is to confirm that a communication channel exists from sender to the receiver. That is exactly how TCP functions. The sender first sends a packet having SYN flag value high(1). The SYN high flag means a node wants to start a data transfer. The receiver who receives this SYN, if ready for data transfer, replies with a packet having its both ACK and SYN flags made high(1). The ACK high means that the receiver acknowledges the SYN flag from sender and the SYN means that the receiver also wants to start data transfer. The sender now replies with an ACKwhich now opens a two way channel for data transfer.
Thus our major protocol relies on the availability of connection from starting node to ending node. Only after the link from end to end is made, the communication takes place.Any disruption of the link between the two means that those SYN, ACK packets cannot flow which in turns means no data transfer.
DELAY/DISRUPTION TOLERANT NETWORKING(DTN)
As from its name, we can at-least imagine what DTN tends to achieve. It is designed to tolerate the disruption of conventional TCP protocol. The DTN functions in store and forward mechanism where each node itself stores the packets untill the adjacent node is available. This allows the sender at one end to continuously send the data even if there is link breakage somewhere between source and destination. Lets see the diagram below:
These are all the nodes that the data has to travel in order to reach from source (node A) to the destination (node E). These nodes are different from the conventional nodes in the way that they have storage capabilities. These storage are used to store packets whenever the next hop is not physically connected. For example, Consider the following diagram
Here, the communication channel between node C and D is broken. What happens now is, the node C now stores the packets originating from A. In this way, the sender node i.e A never feels as if the link is broken and it can continuously generate and send packets which was not possible in TCP/IP protocol.
The node C here also simultaneously keeps on checking for link availability between itself and node D. Once the link is restored, the transmission of packets from C to D continues. This property of DTN gives much more efficiency as the data doesnt need to be sent through A upon link restoration, rather the data now will be sent from C itself. This store and forward capability provides many benifits where the link between networking nodes is intermittent. In coming posts, we will discuss on the applications of DTN and will scrutinize the protocol itself for better understanding of the engineering aspects of DTN.
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