Virtual Learning System: A Conceptual Framework of Network Optimization R. Soundhara Raja Pandian1, S. Thangalakshmi2 , S. Saravanan3 1
2
Project Officer, Webstudio, IC&SR, Indian Institute of Technology Madras, India Head and Associate Professor, Department of Electrical and Electronics Engineering,
GKM College of Engineering and Technology, Chennai, India 3
Assistant Professor, Department of Civil Engineering, National Institute of Techology, Trichy, India {
[email protected];
[email protected];
[email protected]}
Abstract. The demand for network communications is increasing every year, but the available resources are not increasing at the same rate. Bandwidth and network infrastructures are major issues in network related problems in remote areas for various applications. The current study uses Genetic Algorithm (GA) based optimization method to allocate the bandwidth related issues. In addition, it also considers the identification of optimal server location with minimal cost. In this regard, Geographical Information System (GIS) is used to identify the spatial location of network components (server setup) optimal location. The proposed methodology is demonstrated with a case study of National Programme on Technology Enhanced Learning (NPTEL) developed by Ministry of Human Resources Department (MHRD), Government of India, where the network optimization is of much importance. Keywords: Bandwidth, Infrastructure, Genetic Algorithm, Geographical Information System, Load balancer.
1 Introduction In recent years, there is a constructive growth in communication field over the world with dedicated network systems. Application of advanced networking systems opened up many possible implementations across various domains such as military, mobile communication, agriculture, education and medicine which are a few worth mentioning here. This study focuses on education field that uses net-
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R. Soundhara Raja Pandian, S. Thangalakshmi, and S. Saravanan
work applications effectively. Education is a key factor that improves countries economy through scientific development. Therefore, the educational system should be re-framed from the current traditional class room teaching into sophisticated computer based studies in order to transform the knowledge effectively. This is quite possible with advanced development in communication and multimedia technology. There are attempts that have been made by few on-line educational systems (i.e. NPTEL, Massachusetts Institute of Technology’s Open Course ware (MITOCW), Common wealth of learning, British Open University and Australian Open University are entities that provide similar services). These systems contain online teaching materials (e.g., web and video format courses) in favor of making fuller use of the country‘s top academic talent faculties in cost-effective ways [8]. However, the major drawback associated with these systems lacks in interaction between students and faculties and separated from traditional classroom teaching methodology. In addition, proper online enrollment, conducting examination are the major gaps that exist in providing the education. These problems could be solved through Virtual University (VU) concepts to some extent. The VU offers educational programs with communication and media technologies. The goal of virtual universities is framed to provide access to the student community who would not be able to get a chance in appearing for the physical campus education. The VU concept can aid in improving the quality of education with the help of reputed universities where there is limited number of direct admissions exist. In India, Indian Institutes of Technology (IITs) and IISC are the premier educational institutes offering quality-engineering studies. Hence, the VU concept is an alternative method of teaching where the students do not have exposure into IIT system. The NPTEL is an open access online educational system developed by IITs and IISc, which has received lot of attention among engineering students and industrialists. Therefore, these online courses can be directly included in VU without any additional efforts in newly creating online courses. However, the availability of bandwidth and network components is not able to effectively cater to the needs with current NPTEL system and its networking devices. Therefore network optimization is a necessary criterion that should be enhanced to improve the overall service [7]. Numerous researchers explored the possibility of applying the optimization algorithm in network bandwidth related issues (i.e. fixed point optimization algorithm [3], dual decomposition [5], game theory [2] and backbone topology [1]) In this study, the major focus has been attributed towards solving the network related issues with optimization algorithm to distribute the network slots based on the available bandwidth. It also considers the application of GIS in order to route the signal spatially where the server location is nearer.
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2 Methodology The main objective of the study focuses on developing an optimized solution to install server and network devices at the optimal location as well as allocation of slots based on the number of users and the distance between user and servers. Although this is associated with critical issues in design of communication channels and a network system, the dedicated networks are the key components in providing the services in a better way. As of now, Internet is one of main sources in providing access to the users. It is well known that the bandwidth of Internet connection is low. Still, there are options to provide this access via dedicated network lines such as NKN and VPN without bandwidth difficulties. The National Knowledge Network (NKN) is an e-infrastructure, which has high-speed network at 10 Gbps bandwidth. It is used to access the very large databases in a cost effective manner in order to connect more than 5000 nodes across the country. A virtual private network (VPN) is a computer network that uses a public telecommunication infrastructure to provide remote offices or individual users with secure access to their organization’s network. It encapsulates data transfers using cryptographic techniques between two or more network devices connected by a public network to ensure the security of information and data that is transferred. Cloud computing is a recently developed concept to connect remote server and users in order to access high speed computing and sophisticated software. Pandian and Kasiviswanathan [6] studies show that the possible implementation of Cloud Software as a Service (SaaS) to connect the local user (i.e. engineering students) with the high-speed server to make use of preferred application.
3 Case Study In this study, it was found that the current NPTEL system could connect 1500 users effectively at the given specified time. Figure 1 shows the number of users visited NPTEL website from 2008 to 2011 and it is very clear that the curve moves in a linearly increasing trend and it is confirmed with the study [4]. Therefore, it is a prior requirement that the bandwidth and network issues should be designed by considering the future increasing demand. The NKN covers spectrum of application ranges from education and research, agriculture, climate change, military, heath care and industry.
R. Soundhara Raja Pandian, S. Thangalakshmi, and S. Saravanan
10000 No of users per day
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8000 6628
6000 4000 2000
4040 1738
0 2008
2009
2010
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Year Fig. 1. Visitors history of NPTEL website (Source: Google Analytics).
User from any node
Dedicated Network Load balancer Online courses loaded in main server
M1
M2
M3
Mn Mirror
Load evenly distributed for effective usage
Optimization of slot distribution using GA Fig. 2. Proposed methodology
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The NPTEL is one among the applications proposed using this network. This involves various steps to be followed for effective implementation. Therefore the current study would be an attempt in addressing the various levels of complex issues that are involved in this process and possible solutions can be met. The proposed methodology is given in the flowchart (Fig. 2). The optimal location of server is an important step and this could be solved using GIS based educational topography that contains the nodes of colleges and university location and number of visitors who use NPTEL website. According to the flowchart given in fig.2, the user from any node of India will initially contact main server which includes load balancer and other networking devices such as router and switches that calculates the load based on bandwidth availability and distance from the user to nearest mirror. In this stage, the optimization helps in selecting the mirror, which has the slot as well as location-wise near. The GA based optimization algorithm routes the user in different servers based on nearer server location and the available bandwidth. Server
1
2
n
Bnm
B11 B2m B21 B1m
Bn1 1
2
3
m
City Fig. 3. Network connecting server and users.
The available network connection that is being adopted so far connects the server and user based on Internet Protocol (IP) using GIS. The major limitation pertains to this type of connection is that connects the server locally and fails to connect the server which is located other than local server. Therefore, the present study is focused on connecting the user and server even if the server is located far
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R. Soundhara Raja Pandian, S. Thangalakshmi, and S. Saravanan
from the user. The primary objective is to distribute the available bandwidth based on distance. In this way, connecting the next nearest server ensures the optimum bandwidth allocation. Figure 3 shows the typical servers that are connected with different cities. Each city has a specified number of users subsequently the bandwidth used by different users will vary based on the application (i.e. web course or video course). The following equations describe the objective functions and constraints of the proposed method. Objective function: m n Minimize : Z Bnm *Dnm 1 1
(1)
Constraints: City m j k
B1m B2 m ...Bnm ( bk ) m
(2)
Server n Bn1 Bn 2 ...Bnm Sn
(3)
j 1
Where, B is the total bandwidth in Gbps, S indicates the total server capacity, b refers to the bandwidth that is used by single user and the total number of user is k. The n, m are total number of servers and cities respectively. It is to be noted that all the variables in the equations are non-negative quantities. The objective function is formulated in such a way that based on the distance (D in Km/Gbps) the bandwidth is allocated between the server and user with relevant constraints as mentioned earlier. The distance is calculated using GIS and it is coupled with optimization algorithm such as GA. Here it is worth mentioning that the proposed methodology is associated with some of the challenges, which need to be taken care (i.e. Cyber security, Data access and ownership, Encryption needs, High performance servers and effective networking devices and Very high implementation cost).
4 Conclusion Virtual University (VU) concepts can certainly help in getting good quality of education where the students are not having the physical access. This requires dedicated network devices and servers to access services that are in general costlier. Therefore, network optimization is a major concern. Network optimization reduces the cost involved in hardware selection and its maintenance. This study aimed in addressing the optimization involved spatially where the
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server to be located and temporally where slot distribution to be allocated based on the available bandwidth. In this regard, GIS has been suggested in finding the optimal location of mirror based servers, and GA based optimization algorithm could be the better choice for optimal allocation of bandwidth as these techniques are powerful tools and applied in various fields due to their promising results.
Acknowledgment We would like to thank Prof. Mangala Sunder Krishnan, Professor and NPTEL Coordinator, IIT Madras for his support and encouragement as well as three anonymous reviewers for the excellent comments to improve the quality of the manuscript. We would also like to extend our thanks to Mr. K.S. Kasiviswanathan, IIT Madras for his support and technical inputs.
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