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With the evolution of wireless technology, the mobility computing has been dramatically increased. WLAN has been adopted in very effective manner, due to the advantages that are noticed in the technology. For a network designer the challenging tasks have been raised at the same time, invoking the wireless technology. It is important to learn the key concepts that will influence the network performance by network engineer, before the practical network installation, some guiding steps and preliminary precautions should be taken. OPNET is the one of simulation software available in the market to test the anticipated network in the virtual world and analyse the network performance and limiting factors in the network as well.
In this paper, the studies and produced reports analyse the same on network designing and network performance analysis.
WLAN is the technology that has been widespread within short span. In this paper, the discussion of wlan technology has been produced initially to give a brief introduction on technology, following with the explanation of WLAN network design in 1st case scenario deployed in the Opnet simulation software and later exemplifying the 2nd case scenario, where the modification of the network that has been designed initially is noticed. The comparison section discusses critically the results and findings of 1st and 2nd case scenario networks performance. Conclusion section supports my opinions and findings of the assignment.
WLAN Network Design:
Computing technology is ever changing and challenging technology. The advances and rapid changes of technologies in computing world have attracted massive number of public towards the technology. Earlier it is just used and meant for research oriented and scientific computation, later on with the growth of IT and internet, the adoption of technology has been increased.
IEEE (Institute of Electrical and Electronics Engineers) adopted the WLAN technology and ensures the developments and future work of the technology. As of concerned with the technology innovation, and deployment in the world, the RFC (Request For Comments), plays an important role, which is maintained by the IETF (Internet Engineering Task Force). WLAN technology has been accepted by IEEE under the standards IEEE 802.11. There are multiple WLAN standards to jot down; 802.11, 802.11a, 802.11b, 802.11g, and 802.11n. [4, 6, 7]
For this campus network scenario, a WLAN network is needed to be deployed; Network that could afford the load and serve requests from students, staff and guests. For the chosen scenario, it is required to evaluate the geographical values and technical details that were essential to deploy the network in campus. For the concerned case; WLAN deployment, the network is needed to be designed in the OPNET Simulator and simulate the designed network for results, revealing the performance and other critical network's criteria. 
The below figure depicts the global designed network of the campus network. For this assignment it is chosen to deploy 4 Access points at 4 different locations, those are useful for wireless connectivity.
C:\Users\sreekanth's\Desktop\srikanth\scenario 1\1. main network.bmp
Image 1: Designed Campus Network
With the designed network; virtually in the OPNET Simulator, the software calculates the network performance, delay, throughput and load characteristics. It is essential to any network designer to deploy the environment first virtually, and later proceed with the real world installation. For the virtual installation, there are multiple simulators and software's available, which they go through in-detail of the network. Of those concerned simulators, Motorola's LAN Planner, Opnet Simulator, NS Simulator etc., were used for the wireless network design. Though the Opnet Simulator provides a brief and described performance of the network characteristics, Motorola's LAN planner goes beyond that and let you design the wireless network with obstructing physical obstacles, licensed and unlicensed wireless devices and coverage area as well. [2, 5]
The installation of 4 AP (Access Points) at different locations of the campus network will ensure the connectivity of the users uninterrupted across the campus. The set SSID will be sent over the AP as Beacons and let know the users about the availability of the network. For the WLAN network installation it is needed to deploy a server which manages the services, database etc., for the users connected to the network. Considered, the AP's installation, the AP's have been deployed at lrc, cis lab, library and coffee shop locations. With the availability of access points at different locations, the users can migrate from one location to another without losing the wireless connectivity. The same SSID and signal range properties will ensure the connectivity of user to the network. [6, 7]
The rest of the documentation has been followed under the guidelines and reference of Opnet modeller Tutorials .
How it Works:
With the installed server in cis lab, the permissions, database and internet access is made available to the users through access points. The router installed in the cis labs will let the staff and authorised users to get connected to the router either in wired or wireless connectivity: able to apply CAT5 connectivity to the router, whereas for the AP it is not possible. The router is the main hardware that is equipped in the WLAN for NAT, PAT, and DHCP operations. The said technologies involve complex working and usage purposes, which are not possible to jot down here, due to words constrain.
In the proposed campus network scenario, the different profiles and permissions are noticed; each user will be authenticated by the network by appropriate credentials provided. The network is tangible to security threats, so a WEP or WPA security should be applied, however in the Opnet it is not possible to apply security methods and of course the WLAN standards as well: wlan standards; a, b, g, n. The different located AP can serve large number of users, though the availability of AP are in large number's the Load, Delay and Throughput falls on Server only; which is deployed in the cis labs.
The below sections produce the installation, configuration and properties of WLAN network.
In the first case, the WLAN network for the campus has been deployed with the 4 access points at different locations. The designed, deployed network serves the users at different locations and with different profiles to get connected.
In the first case the installation includes minimal users connected to the network. The below produced figure illustrates the network design and work load on the network.
C:\Users\sreekanth's\Desktop\srikanth\scenario 1\2. cislabs network.bmp
Image 2: Scenario 1 network design
From the design it can be noticed that, installed router is serving 4 clients in the first case. As of configured in the first case, the first testing scenario server has been configured with few services made available to the users. Services like HTTP, EMAIL and FTP are allowed to be accessible by the users. The chosen situation is to test the server with the key network performance properties; Load, Throughput and Delay.
Concerned Services & Users
In the first case it vital to choose the minimum services, that server could afford; the same has been done by our group in designing the network for the first case. With the EMAIL, HTTP and FTP loads, the server serves the users with proclaimed services offering the minimum users to be accessing the network for initial case.
From the image 2, it is observed the configuration and designing of the network for the first case scenario. The router is being accessible by 4 nodes, serving the internet and intranet services to the users connected across the network. The below screenshots produced, defines the network performance in the first case. The network performance is analysed by studying the following properties:
For the concerned scenario, the network performance analysis is made globally and individually. Considering the whole network, the global statistics were calculated and individual nodes performance also calculated.
WLAN Delay: For the first case setup, the installed network has been offered to allow few users to access the network resources. With the usage of services and causing congestion to the network by users (node), the delay of communication and data transmission happens to the network. Delay is the property that often referred in the network terminology. From the initiation to destination arrival of data, the time took is referred to be as delay.
The below graphs produced depicts the Global properties of WLAN delay and WLAN MAC delay.
C:\Users\sreekanth's\Desktop\srikanth\scenario 1\global statistics\gs wlan delay media delay.bmp
Image 3: Global WLAN delay and WLAN MAC delay
From the above statistical report it is viewable that, the delay in network is noticeable. With the increased delay property, the network reacts and functions at worst case scenarios. Possibly in every built network (Wireless and Wired), the delay is counted and observed, but to an extent with the increased network congestion, the delay property also increases and causes the network performance weaker.
WLAN Load & Throughput: Load and throughput are the properties that refer to the networks performance. Load is the property that is best defined as, with the number of services and clients being increased in the network, the network load increases substantially. Load is the property that affects the performance of the overall network in negative way. Installed AP can serve large number of clients, but massive usage of particular AP, and heavily loaded services access through particular AP can cause network to diminish its performance. A highly loaded network cannot perform well in all situations, so the WLAN Network Interface Card re-associates with another nearby AP or temporarily suspend the services from concerned AP.
Similarly, the Throughput is the speed available to send data between end device and AP. The Throughput cannot be same at all locations, it varies with range between the AP and end device (client). As stated above regarding the different WLAN standards in the first section of this paper; said different technologies ranges and coverage area is different.
The below stats have been reported here, from the installed network.
C:\Users\sreekanth's\Desktop\srikanth\scenario 1\global statistics\gs wlan load throughput.bmp
Image 4: WLAN Load & Throughput
Global Ethernet Delay: Ethernet delay is the property noticed for data transmission times between deployed router and AP through constructed cables. The networks performance also relies on the Ethernet delay, due to the reason that overall communication between end devices and AP's are sent over to the router through cables and possible network congestion is possible, the Ethernet delay also plays a vital role in analysing the networks performance in the WLAN technology.
From the image produced above and below, the comparison between the WLAN delay and Ethernet delay, reveal that Ethernet delay is noticed in high figures than that of WLAN delay.
C:\Users\sreekanth's\Desktop\srikanth\scenario 1\global statistics\scenario1 ethernet delay.JPG
Image 5: Global Ethernet delay
Object statics have been produced here to depict the performance of the network at individual nodes. The global stats and individual stats vary due to the reason that multiple nodes (individual end users) usage of network impacts the performance. At one instance, a particular node may be using some services and other device might be using all the services causing high load impact due to the usage.
In this object statistic, the different locations of campus network has been taken and analysed for the network performance at concerned locations. However the complete statistical report of individual components has been produced here, a concise analysis of Email, data, delay and throughput performances are given.
LRC Location: Considering the lrc clients, those were being served by the lrc Access Point; the analysis reveals the following properties of individual clients.
Node 1 Email stats in lrc location: Deployed in the lrc location, the node 1 client's email access in the network has been reported here depicting the usage and working process of the WLAN technology by the client. Using the Email services, the node 1 client access the WLAN services and cause load, delay, throughput properties to the network. Highly accessing services like FTP, Database by the client could cause more congestion and impact on network performance.
C:\Users\sreekanth's\Desktop\srikanth\scenario 1\object statistics\lrc\client email sent rcvd.bmp
Image 6: Individual Object statistics; Node1 LRC location Email Stats
Data Traffic stats of Node1 in lrc location: The data traffic that is observed in the client analysis at lrc location reveals the data being sent over and across the network by Node 1 device. The more data being sent and accessing by any particular device or group of devices in the network, it will drastically cause the network to pay much attention on collisions and load on the network.
The below image illustrates the data traffic being accessed by the Node 1 client.
C:\Users\sreekanth's\Desktop\srikanth\scenario 1\object statistics\lrc\wlan data traffic sent rcvd.bmp
Image 7: Node 1 Data traffic sent/received stats at lrc location
Node 1 Throughput and Load: In this section, the node 1 throughput and load has been analysed and reported to understand the variation between the global load and individual load the is being observed in the network. The below produced image gives the understanding between the global network load and concerned; particular client load being caused on the network.
C:\Users\sreekanth's\Desktop\srikanth\scenario 1\object statistics\lrc\wlan load throughput.bmp
Image 8: Node 1 Load and Throughput stats at lrc location
The above image reveals the essential information on networks performance characters and understanding of the whole network infrastructure. The individual stats reported here has the lowest affecting factors on load and throughput, whereas considering the global stats, the increased load and throughput on network is noticed.
Library Location: Deployed Access Point at Library location has been utilised by clients for the internet and intranet purposes. The analysis of clients at Library location helps in understanding the variation between the individual as well at different locations.
The below produced report analyses the client Database sent and received stats. This image depicts the database service being offered to the client by the server.
C:\Users\sreekanth's\Desktop\srikanth\scenario 1\object statistics\library\client db traffic sent rcvd.bmp
Image 9: Client DB Traffic Sent/Received at Library location
The above stats report the client database access and stats of traffic being received and sent across the network.
In the second scenario, the designed network has been modified to analyse the impacts on network due to the modification. The networks performance will be affecting due to the additional clients deployment and services accessibility to the clients.
The below produced image has been abstracted from the designed second scenario network. The image shoes the additional client's usage at lrc location, where the needed analysis on network with the additional usage of services and added clients were noticed.
C:\Users\sreekanth's\Desktop\srikanth\scenario 2\scenario 2 model network.bmp
Image 10: Second Scenario Network
In this picture it is vital to know the fact that, additional deployment of clients on network would cause the network to perform weak. Load, Throughput and Delay properties will be affected with the additional client invoke.
Analysing the Global Statistics
In the second scenario, it is important to look at key properties of the network that were responsible for the performance of the network. In the first case it is taken into consideration of Load, Throughput and Delay; the same were considered here in the second case to reveal the affects and influences ion the network performance.
In the second case, with the increased load and clients on network, the global delay stats will be increased dramatically. As of in earlier discussion, regarding the delay property, it is the time factor considered for the data transmission between client and access point. A large delay factor would impact on service quality.
The below image illustrates the variation between first and second case scenarios: Less clients in the first case and increased clients in the second case.
C:\Users\sreekanth's\Desktop\srikanth\scenario 2\global statistics\wlan delay.bmp
Image 11: Comparing scenario 1 & Scenario 2 global WLAN delay
In the second case (see above Image 11), the increased WLAN delay is noticed. The reason for it is simple and straight forward: with the increased clients and services usage on the network, the performance of the network would mitigate substantially. The same is observed from the above image 11.
The red colored lines were stats for the second case scenario, whereas the blue lines were for the first case scenario. It clearly demonstrates that, with the increased clients and load on network the delay is also increased.
The property of throughput is, the maximum availability of speed to send pr received data from client to access point is said to be the throughput and is measured in the same basis. In the second case scenario, the Throughput has also been increased in the second cases, the increased throughput is recommended but, the load factor by such clients should not be relied on network due to the negative performance factors.
The below produced figure illustrates the throughput property of network and variation between the first and second case scenarios.
C:\Users\sreekanth's\Desktop\srikanth\scenario 2\global statistics\wlan wlan throughput.bmp
Image 12: Comparing WLAN Throughput in 1st and 2nd case network design
The substantial growth of throughput has been noticed in the above figure. With the effective usage of clients and services across the network the performance of the network can be increase. The factors like hidden node problem and re transmission in wireless technology is in high accountancy and are negative impacting features as well.
Individual object statistics
Node 1 Email activity: In the second case scenario, the node 1 email activity has been seen altered. In the below image produced, the comparison between the first case and second case of node 1 has been attempted to figure out the variation and impacts ion network.
The drastic changes in data being sent and received have been noticed in the second case scenario. For the illustration purposes, the first email stats have been compared with the second case, the comparison reveals the changes and affects on network.
C:\Users\sreekanth's\Desktop\srikanth\scenario 2\object statistics\lrc\client email traffic sent rcvd.bmp
Image 13: Email activity of node 1 in 2nd scenario
Node 1 Throughput stats: The below image depicts the altering information of throughput of node 1 in lrc location in the second scenario. The throughput change is noticed. As of concerned with the throughput in first scenario, a drastic change is noticed.
C:\Users\sreekanth's\Desktop\srikanth\scenario 2\object statistics\lrc\wlan throughput.bmp
Image 14: Throughput stats in 2nd case scenario for node1
Delay stats: From the analysed reports, the delay of WLAN for individual object has been studied for the purposes of network performance. In the below produced image, the stats reports that tremendous increase in delay has been noticed due to invoke of new clients and services usage by them.
C:\Users\sreekanth's\Desktop\srikanth\scenario 2\object statistics\lrc\wlan delay.bmp
Image 15: WLAN delay in 2nd scenario
The above image: stats reports that, with the increased clients on network, the delay property would be tremendously increasing, causing the network performance mitigated. The results reveal the information on network created and modified in the second case, the network has been facing negative impacts with the new client's deployment.
Library node stats:
In the first scenario, the library located node has been analysed with its properties on database usage and traffic received, sent across the network. Now consider the same node with the same properties affecting the network performance. In the second case, the client database traffic has been impacted, results the variation between the first and second case stats.
C:\Users\sreekanth's\Desktop\srikanth\scenario 2\object statistics\library\client db traffic sent rvcd.bmp
Image 16: Database traffic load comparison in library location
Comparison between 1st and 2nd case scenarios:
Until now, the stats and illustration has revealed the different network design concepts and impacts of load, delay and throughput conceits on network performance. This section compares the results noticed in the 1st and 2nd section network scenarios.
Comparing global network Delay property:
The below image has been abstracted from the 1st and 2nd case scenarios of designed WLAN network. The change of delay property on the global network design has been considered for the change in networks performance.
C:\Users\sreekanth's\Desktop\srikanth\scenario 2\global statistics\wlan delay.bmp
Image 17: Comparing Global Delay property in 1st and 2nd case scenarios
The above image clearly demonstrates the change of delay property on the network. The more clients being added in the second scenario has affected the network delay property, a substantial growth of delay would congest the network and mitigate the network performance.
Comparing Global Throughput:
In this section, the throughput property has been analysed, where the variation between 1st and 2nd case scenario have noticed.
C:\Users\sreekanth's\Desktop\srikanth\scenario 2\global statistics\wlan wlan throughput.bmp
Image 18: Comparing global throughput in 1st and 2nd case scenarios
In the above produced image, the variation is noticed extremely. Similarly in the rest cases for load the variation has been noticed. The study shows that a highly influencing factor for the network is relied clients on the network. The more number of users are accessing the network resources, the more affects on network is noticed, and inevitably the performance would be decreased.
Comparing the CIS lab Router:
In this case, the router's performance has been analysed. Router's throughput and load at different scenarios has been analysed for the comparison purposes. The below produced image reports the variation of router stats in concerned two different situations:
C:\Users\sreekanth's\Desktop\srikanth\scenario 2\object statistics\cislabs\wlan throughput load.bmp
Image 19: Comparing router's Load and Throughput statistics at different scenarios
Router's WLAN and MAC delay:
The below image depicts the router's wlan delay and mac delay at different situations. At two scenarios, the performance of router should be noticed due to the factor of network performance calculation.
C:\Users\sreekanth's\Desktop\srikanth\scenario 2\object statistics\cislabs\wlan delay media access delay.bmp
Image 20: Comparing router's WLAN and Mac delay
Analysing the results:
The analysis of the results, obtained from the deployed network design, the results reveals the influencing and impacting factors of the network by additional load and services usage. In the first case, it is seen that network has been deployed with 4 AP, and minimum clients in the Opnet simulation software, the simulation results in the first case has been analysed to understand the situation of network and its health. In the second case, the increased clients and services in the network has been done to increase the network activity, the results has been produced doing so. Comparing the 1st and 2nd case situations, the results proclaims the variation between the either cases with the additional resources.
To analyse the network, it is essential to understand the key concepts; Load, Throughput and Delay by any network designer and installation engineer.
Studies and work conducted in the Opnet environment has shown extreme properties of the WLAN and its components. The results showed the variations and impacts on the network due to the additional client's usage. It is essential to increase the network activity and capability with the focused study on network performance. The increased activity and load in the network should not be supported if the performance was being mitigated of the network. I would recommend using the Motorola's LAN planner for enhanced network designing and conceptual learning's.