The Control Of Data Loss Computer Science Essay

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The main of the project is to control data loss. Many researches undertaken many steps to control data loss to provide standard network. Researches underwent testing with different routing protocol and given maximum output. In this project AODV and DSR routing protocol to implement virtual concept .Routing protocols are constructed using AODV and DSR protocols. Virtual ports are the virtual concepts, which is placed between two nodes or two networks .These nodes are sensor nodes with maximum of capability. When the node need to send the data packet to the destination, and when the node does not have sufficient sensing range to transmit the data packets, the node will guide with the virtual node. The virtual nodes have the higher transmission range and these are the mobile nodes and the will move around the network and it will act like the bridge for the source and destination. In the existing concept there so much of packet losses due to lack of transmission range. Here we avoid the problem of losing the data packets. And finally this project is going to compare the existing concept with the proposed virtual port concept and then result is evaluated.


Data transfer without data loss is ultimate aim of the project. But reliable transfer is difficult task to give expected output. While transferring the data following issue occurs like data loss congestion. Most of the researchers ended failure in giving out the expected output but researches' mange the output by reducing the data loss. New protocols and new algorithm has been introduced but there is no reliable data communication .In this way there are two type of routing protocols implemented in large and smaller network they are

* Pro-active (table-driven) routing

* On Reactive (demand routing) protocols.

This project started to find the better result in accordance with control data loss, so this can be achieved by different methods.

In this project entire section is divided into different parts .In the first chapter types of protocols used and their operations are discussed.

In second chapter technical description about DSR is discussed and then later chapter explanation about Network Simulator 2 and their various functions is discussed.

In other chapter what are the existing systems and proposed system is elaborated to demonstrated .Followed by that overall view of virtual node is discussed, why the virtual node is used and what are the steps involved in virtual nodes and the advantages of virtual node is discussed

Finally what are the possible ways to enhance the project is discussed



The main function of the PRO-ACTIVE protocol is to maintain information about one or more table. Each node maintains up to date information about the entire network topology. This node act as a log book, where information about node to node is recorded.

To maintain the up-to-date routing information, topology information needs to be exchanged betwe0en the nodes on a regular basis, leading to relatively high overhead on the network. One the other hand, routes will always be available on request.


The main function of the ON DEMAND ROUTING protocol is to reduce overhead in all active nodes this function applicable only for active node only .Active route is nothing but the node which send data from particular place to destination where reverse link take place in sending back the date to the sender it is done using LINK REVERSAL. This technique is called as piggy-backing .In Reactive (On Demanding Routing) there are two kinds of categories they are

* Source routing and

* Hop-by-hop routing


In source routing data packets carry complete source to destination .During the data packets data transmission all the information are present in the header side of the packet. This head information contains whole body information. This header information helps to route to intermediate node so need of maintaining all the information about neighbour connectivity through periodic beaconing messages


In source routing the strategy is described as dynamic. Each node send the information to fresher topology by selecting the better topology. It's based on request .This process is done by DSR protocol. This DSR (dynamic Source Routing) protocol requires each packet to carry the full address from source to destination


In large networks they do not perform. Well only in small network the performance is best. This is due to two main reasons

* There is more probability of route failure it's tough to identify.

* There is number of intermediate nodes.


In this projec0t the basic design of our secure on demand ad hoc network routing protocol, on the basic operation of the Dynamic Source Routing Protocol (DSR). [CITATION]. DSR is an entirely on-demand

ad hoc network routing protocol composed of two parts: Route Dis-

covery and Route Maintenance. In this section, we describe the

basic form of Route Discovery and Route Maintenance in DSR.

In DSR, when a node has a packet to send to some destination

and does not currently have a route to that destination in its Route

Cache, the node initiates Route Discovery to find a route; this node

is known as the initiator of the Route Discovery, and the destina-

tion of the packet is known as the Discovery's target. The initiator

transmits a ROUTE R EQUEST packet as a local broadcast, specify-

ing the target and a unique identifier from the initiator. Each node

receiving the ROUTE R EQUEST , if it has recently seen this request

identifier from the initiator, discards the R EQUEST . Otherwise, it

appends its own node address to a list in the R EQUEST and rebroad-

casts the R EQUEST . When the ROUTE R EQUEST reaches its target

node, the target sends a ROUTE R EPLY back to the initiator of the

R EQUEST , including a copy of the accumulated list of addresses

from the R EQUEST . When the R EPLY reaches the initiator of the

R EQUEST , it caches the new route in its Route Cache.

Route Maintenance is the mechanism by which a node sending

a packet along a specified route to some destination detects if that

route has broken, for example because two nodes in it have moved

too far apart. DSR is based on source routing: when sending a

packet, the originator lists in the header of the packet the complete

sequence of nodes through which the packet is to be forwarded.

Each node along the route forwards the packet to the next hop indi-

cated in the packet's header, and attempts to confirm that the packet

was received by that next node; a node may confirm this by means

of a link-layer acknowledgment, passive acknowledgment [29], or

network-layer acknowledgment. If, after a limited number of local

retransmissions of the packet, a node in the route is unable to make

this confirmation, it returns a ROUTE E RROR to the original source

of the packet, identifying the link from itself to the next node as

broken. The sender then removes this broken link from its Route

Cache; for subsequent packets to this destination, the sender may

use any other route to that destination in its Cache, or it may attempt

a new Route Discovery for that target if necessary.

The DSR protocol also defines a number of optimizations to

these mechanisms (e.g., [18, 19, 26, 27, 28, 32]). Some of these op-

timizations are relatively easy to secure; for example, flow state [19]

requires only broadcast authentication of control messages, whereas

link-state caching [18] requires some mechanism to authenticate

links, whereas Ariadne only attempts to authenticate nodes. In this

paper, we secure only a basic version of DSR, (with a limited path

cache), without these optimizations, and the use of these optimiza-

tions is beyond the scope of this paper.


This system was developed with IBM compatible personal computer with Pentium IV processor.

Main processor : Pentium IV processor 1.13 GHz or higher

HDD Capacity : 20GB

Cache memory : 512 MB

Monitor : Digital Color Monitor

Keyboard : QWERTY

Mouse : Standard


Operating system : Fedora 8 (Linux)

Scripting language : Network Simulator 2.33

Protocol developed : C++

Scripting : Tool Command Language


The main aim of NS2 is to support networking in various stage. It is open source can be modify or make changes in NS2 same as LINUX and UNIX .For this reason most of the universities this is available at free of cost .Mostly it support networking education and research this helps NS2 to maintain and do development process.The main advantage is use to design new protocols and developing new protocols

Network Simulator (NS2) is a part of the VINT project and a discrete event driven simulator developed at UC Berkeley[ CITATION]. NS2 is developed as a collaborative environment and the major aim of NS2 is supporting networking education and research. It's a freeware and available as an open source in many institutes where people indulging in development and research make good use of it and thereby maintain and develop NS2. It mainly helps in development and design of new protocol .NS2 has many version it is most compatible in almost all operating system like Linux, Windows and Solaris, Mac OS X,


NS2 is built using object oriented methods in C++ and OTcl (object oriented variant of Tcl.


Fig 3.1 Simplified User's View of Ns

As shown in Fig 3.1, the simulation scripts written in OTcl are interpreted by NS2. The simulation environment mainly consists of three components, namely setup module libraries, network components libraries and event scheduler objects.

The simulation is coded as an OTcl script and the network components are compiled together to setup and complete the simulation. When there arises a necessity for new network components, they can be implemented free of cost and brought to the viewers' simulation also. The other major component besides network components is the event scheduler, which is responsible for triggering events of the simulation like sending packets, starting and stopping tracing process. Few parts of NS2 are coded in C++ as its proven to be efficient. The control path which is in OTcl is treated separate from the data path which is in C++. The compiled Data path object is then sent to the OTcl interpreter through an OTcl linkage (tclcl) which maps methods and member variables of the C++ object to methods and variables of the linked OTcl object. OTcl objects controls the C++ objects. Hence it has been made possible to add methods and member variables to a C++ linked OTcl object.


There is various functionalities in NS2 .It can be specified in both wires and wireless network


This wired network includes

* Routing DV, LS, and PIM-SM

* Transport protocols: TCP and UDP for unicast and SRM for multicast

* Traffic sources: web, ftp, telnet, cbr (constant bit rate), stochastic, real audio.

* Different types of Queues: drop-tail, RED, FQ, SFQ, DRR.

* Quality of Service: Integrated Services and Differentiated Services.

* Emulation.


The wireless support the following methods

Ad hoc routing with different protocols, e.g. AODV, DSR, DSDV, TORA

* Wired-cum-wireless networks

* Mobile IP

* Directed diffusion

* Satellite

* Senso-MAC

* Multiple propagation models (Free space, two-ray ground, shadowing)

* Energy models

* Tracing

* Visualization

* Network Animator (NAM)

* Trace Graph

* Utilities


In an existing system we have a collection of nodes which spread over a large network.

These all also a sensor nodes that will act upon the routing protocol like AODV, DSR and DSDV. In this there are so many disadvantages in these protocols and will work accordingly with their instructions. This will never knows what to do with the situation that when the node not be able to send the datagram to the destination. And also it does not know that it will not have knowledge about how far the destination node avails. In these cases the node will prompt to lose the packets. So this may cause the information leaking. When the node loses the data packets it will never gain back that. But it will only have the copy of that message and it will send again the same data to the destination. In order to overcome this we are going to implement the Virtual node concept


In this proposed systems we are going to implement the virtual nodes in a normal sensor networks. In this concept we will have 5 nodes as virtual nodes that will have some special attributes. These are all the nodes will automatically move around the networks will receive the packets via their sensing range. After sensing this packets the routing table which stores in their memory, will refer the path and the destination of the packets to be sent. After getting the information about the destination node, the virtual node will try to send this data packet to the other virtual node or the normal node. If there is chance to that virtual node to send the packet to the other node it will send the packets by mobile (moving) and it will assure for reaching the destination. When the node will node will get the data another virtual node or normal node, it will move towards the destination using the Random way point model. When the destination is reachable it will sense the destination node through the his sensing signals , and it will deliver to the destination to the destination using its transmission range. By this way we can avoid maximum of the packet loss

NOTE: Arun here i told about the Random way point model . This already exists in NS2 . So feel free about that .


The virtual nodes are specially developed to overcome the packet loss in any of the sensor networks. The virtual nodes are works with some basic additional attributes. The main thing we consider here is here is the Propagations Range, Carrier sensing range and the transmission range.


Radio propagation is the behaviour of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere.[1] Like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization and scattering.[2]


Carrier sensing range is the range at which signal can be correctly sensed

that is the received signal strength is greater than receiving sensitivity. The

signal may not be correctly received. For PHY abstract this is the range at

witch received signal strength is greater or equal to "PHY-ABSTRACT-RX-

SENSITIVITY". For 802.11 this is the range at which received signal strength is greater or equal to sensitivity of lowest data rate.


Transmission range mainly depends on the configuration parameter "PROPAGATION-LIMIT" whose default value is set as "-111.0". Signal from the node can be transmitted up to the point where its strength lowers down to this limit i.e. "-111.0" dB and can be received at distant nodes as interference. Carrier sensing range is the range at which signal can be correctly sensed that is the received signal strength is greater than receiving sensitivity. The signal may not be correctly received. For 802.11 Carrier sensing range is the range at which received signal strength is greater than or equal to sensitivity of lowest data rate.

So in our project we have given the maximum of attentions to these attributes. We have given the maximum of ranges to the virtual nodes. Bu this we make it easy to have the virtual nodes to move around the network. And also we need to consider is routing table. This plays a very viral role.


In computer networking a routing table, or Routing Information Base (RIB), is a data structure in the form of a table-like object stored in a router or a networked computer that lists the routes to particular network destinations, and in some cases, metrics associated with those routes. The routing table contains information about the topology of the network immediately around it. The construction of routing tables is the primary goal of routing protocols. Static routes are entries made in a routing table by non-automatic means and which are fixed rather than being the result of some network topology 'discovery' procedure.

Routing tables are generally not used directly for packet forwarding in modern router architectures; instead, they are used to generate the information for a smaller forwarding table which contains only the routes which are chosen by the routing algorithm as preferred routes for packet forwarding, often in a compressed or pre-compiled format that is optimized for hardware storage and lookup. The remainder of this article will ignore this implementation detail, and refer to the entire routing/forwarding information subsystem as the "routing table"

Note: arun Please reedit the above 4 aragraphs. I have got it from net.


The virtual nodes are plays a important role in sending the data packets to the destination without having the packet loss. The main idea is make a reliable communication with the most efficient data transmission. By this way we have a more contribution of these virtual nodes with any of the sensor nodes. Here the main thing we need to consider is the frequency of the virtual nodes. Because in a normal wireless networks we consider the frequency of the particular node merely equal to the reliability of date transmission of the node. So here we have virtual nodes with the maximum of the frequency range and we will have the effective data transmission. And also in any of the IEEE 802.11 networks the nodes will node act independently. This will act according to the routing protocols. But here we have given the virtual node with the outstanding attributes. And it will work perfectly with any of the sensor networks to achieve the maximum of performance. These are all the reasons we introduce a virtual node concept in our project.


There are some steps involved in making the virtual nodes there are

1. node formation

2. giving the random moment

3. setting the attributes

4. make a different than a normal node in his physical appearance

5. evaluation


In this we have making the node with the NS2. We have are some codlings to implement with ith

Note: Arun please add some codings from Ns2 for node formation steps. I hope i have teache u how to add a new node . Just give these steps thats enough.

giveing the random moment :

here we are going to make the node to move around the notwork.

Note: Arun please add some coding from Ns2 for random moment. This will have like

$ns at 1.0 setdest 1002 2001 3000

please add this and give the explanation for this as X axis y axis and the 3000 is the speed.


Here we are going to set the some more additional steps to make the node better way

Note: we need to add the some attributes like

/////Tx_range 1.232 i think there are some attributes which i made u add in your codlings. Do u remember that. Just add that and give a brief explanation about that. That enough

Make a different than a normal node in his physical appearance

Here we need the make the changes done in your codlings which used for colouring and the Hexagon outline generation. Just add that codlings and give a brief explanation.///


This is the implementation of the node in a network. When the start up a network the NS2 will read all the values and perform the execution operation. Initially it will placed over a common place and when the run starts the nodes move around the network.

Pls add some more ur own lines


* Will reduce the packet loss.

* To Give a reliable communication

* reliable in sensor and also normal networks

* energy consumption

* mobile

* have a large sensing propagation sensing and transmission ranges.

* Will work effectively with the difficult situations