Local Area Networks Interconnection

Local Area Networks Interconnection This lab is designed to demonstrate the implementation of switched local area networks. The simulation in this lab will help you examine the performance of different implementations of local area networks connected by switches and hubs. A hub forwards the packet that arrives on any of its inputs on all the outputs regardless of the destination of the packet. Hub has only one collision domain. On the other hand, a switch forwards incoming packets to one or more outputs depending on the destination(s) of the packets. Switches has separate collision domains for each connection. Here we will study how the throughput and collision of packets in a switched network are affected by the configuration of the network and the types of switching devices that are used. Implementation of Network The implementation involves series of steps as follows: We select the network topology as star and edit all the attributes as per the lab manual. The next step is to configure the nodes of the network for setting the traffic generated by each station. The network consists of 16 nodes each of which is connected to a hub by a 10 Base-T Ethernet. The statistics are chosen for the simulation. We select the delay(sec), traffic sent ( packets/sec), traffic received ( packets/sec) and the collision count. The simulation is configured for the time duration of 2 minutes. The next step involves duplicating the scenario in order to have two hubs connected by one switch. Finally, the simulation is run and the results are compared for their performance based on the statistics chosen for simulation. Lab Results: We have experimented with two scenarios i.e. Scenario1: Only hub Scenario2: Two hubs and a switch. The statistics chosen for comparing the above mentioned scenarios are Ethernet Delay (sec) Traffic sent (packets/sec) Traffic received (packets/sec) Collision count. As per the implementation steps followed, we received the following results given below: The two figures given below compares the traffic sent/received(packets/sec) in the two scenarios. The Fig#1 indicates that the average time to send the data packets in a network with a hub or a hub switch is the same or almost identical. The Fig#2 indicates that the average time to receive data packets or the throughput in case of a hub switch network is more than that of a network with only hub. Fig1. Indicates the time average for traffic sent in packets/sec Fig2. Indicates the time average for traffic received in packets/sec The two figures given below compares the collision count and the time delay in the two scenarios. The Fig#3 indicates that the collision count in a hub and switch network is lesser than in an only hub network. The Fig#4 indicates that Ethernet delay in a hub and switch network is lesser than in an only hub network. Fig3. Indicates Ethernet collision count for the two scenarios Fig 4. Indicates Ethernet delay(sec) for the two scenarios. The Fig#5, compares the collision count in both the scenarios i.e. with only Hub and in HubSwitch networks. It shows that the collision count for only Hub is maximum as compared to the collision count for a HubSwitch network. The collision count for the Hub1 and Hub2 in the office network have almost the same collision rate. Thus, it proves that the collision rate reduces in a network with a switch compared to the network with a hub. Thus, the throughput of switched network is greater than only hub networks. Fig 5. Indicates the collision count of the Hub in the Only Hub network and the Hub1 and Hub used in the Hub and Switch network. Question and Answers Q-1 Explain why adding a switch makes the network perform better in terms of throughput and delay. Ans: As per the collision count identified for both the network with only Hub and other with a Hub Switch, the collision count for the Hub1 and Hub 2 in a switched network is much lesser than the Hub1 in the only Hub network. This happens because of the following reasons: As soon as the Hub receives the packets at its input ports, it forwards them to all outputs irrespective of the destination of the packet to be sent. This increases the chances of collision in hubs. Where as, in case of a switched network, the switch can receive the packets at its input ports in parallel, and forwards multiple packets to their destined addresses at the same time. In the lab experiment, there exists two hubs i.e. Hub1 and Hub2 with a switch connecting the two in the middle. Both the hubs receive the packets. The switch acts a a mediator between the two hubs and forwards the packets from one hub to the other with lesser collision. Thus, the switch helps to reduce the collision rate compared to that with a single hub. Hence, this improves the network performance in terms of throughput and delay. Q 2 We analyzed the collision counts of the hubs. Can you analyze the collision count of the à ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬Ãƒâ€¦Ã¢â‚¬Å"Switchà ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬Ã‚ ? Explain your answer. Ans: In the experiment, we have analyzed the collision counts of the hubs in both single and double hubs with a switch networks. From the results obtained from the experiment, it clears tha fact that the collision count using a switch reduces to a greater amount compared to that without a switch. This is due to the fact, that the switch can receive the packets in parallel and buffer the same in case of heavy incoming traffic and also forward the same in parallel to their destined address. Since, there is always a full duplex communication between the switch and the hub, thus the packets exchanged will never collide with each other. Thus, there are hardly any collisions in case of switch. Q 3 Create two new scenarios. The first one is the same as the OnlyHub scenario but replace the hub with a switch. The second new scenario is the same as the HubAndSwitch scenario but replace both hubs with two switches, remove the old switch, and connect the two switches you just added together with a 10BaseT link. Compare the performance of the four scenarios in terms of delay, throughput, and collision count. Analyze the results. Note: To replace a hub with a switch, right-click on the hub and assign ethernet16_switch to its model attribute. Ans: In the first scenario we have duplicated the scenario consisting of only a hub. Thus, the only hub shown in Fig3.1 has been replaced by a switch as shown in Fig3.2. In the second scenario, we have duplicated the network with Hub and a switch as shown in Fig#8. Thus, the two hubs in Fig3.3 have been replaced by two switches and have removed the older switch as shown in Fig3.4. Both the new switches have been connected using a 10 BaseT link. Fig 3.1 N/W configuration with only hub. Fig 3.2: N/W configuration with only switch. Fig 3.3 N/W configuration with two hubs and one switch Fig3.4 N/W configuration with two switches Comparing the Results: The four scenarios which have been compared include the following: (1) Network with only a hub (2) Network with a Switch and a Hub (3) Network with only a switch (4) Network with two switches. In the Fig3.5, the graph compares the Ethernet delay in seconds for all the four scenarios. It shows, that the time delay is maximum for a network with a single hub and least for networks with no hubs but switch(s). Thus, the graph shows that the time delay reduces with the number of switches added in the network The Fig3.6 compares the throughput i.e. the number of packets received per seconds for all the four scenarios. As per the graph, the throughput is almost the same and maximum for the networks consisting of one or two switches. Whereas, the throughput is less with only hub in the network. Thus, the no. of packets received is greater for the networks which are switched based. Fig 3.5 Compares the Ethernet delay in sec for four scenarios. Fig3.6 Compares the traffic received (Throughput) in packets/ sec for the four scenarios. We have not compared the collision count for the four scenarios because the collision count is very less in case of switched networks. Conclusion From this lab experiment we have concluded that the switched networks have better throughput, delay and collisions compared to the network with Hubs. The difficulty faced while performing the experiment was the reading of collision count for the switched network with two hubs and the switch in middle. We faced issues in collecting the combined results of collision for the first two scenarios. But towards the end of the lab experiment, we received good hands on experience on Opnet, and the advantages of having a switched network compared to hubs.

Plato And Love -- :: essays research papers

Preservation of Biodiversity   Ã‚  Ã‚  Ã‚  Ã‚  Human beings have inhabited Earth for just a blink of an eye. Almost any ecosystem can provide resources valuable to humans. “However, recent reports show that approximately 40 percent of the earth’s land surface has been altered by humanity'; (Becher). These altered surfaces have provided communities for humans, but the process has destroyed many native species and ecosystems. Global biodiversity is currently in danger. Estimates vary in how fast a species becomes extinct, from “one species per day to one species per hour'; (Howes). In ancient times, geological activities and natural catastrophes would cause the extinction of species. But today, humans cause extinction through the manipulation of land use, pollution and etc. There are many reasons to preserve biodiversity such as medical advances, contributions to their ecosystem and much more. The primary arguments for preserving global biodiversity can be separated into two categories, human m otives and natural existence.   Ã‚  Ã‚  Ã‚  Ã‚  “Preserving a diversity of life on Earth has come to be an accepted goal for many people'; (Botkin/Keller). Four distinct categories why humans desire to preserve biodiversity are recreational, religious, aesthetic/emotive, and economic/intellectual reasons.   Ã‚  Ã‚  Ã‚  Ã‚  There are many reasons for preserving biodiversity because of recreation. Children love the sight of exotic animals and other species. The most accommodating site to view a wide variety of species is a zoo and other similar sites. These sites provide jobs and enjoyment for people of all ages. Recreation also means the poaching of animals whether or not they are rare.   Ã‚  Ã‚  Ã‚  Ã‚  The second reason to preserve biodiversity due to human motives is religion. Preserving a species for religious purposes can be taken two ways. An animal, insect or etc. can be worshipped (i.e. scarab beetles and cats in the days of ancient Egypt) or preserved because a higher being created its existence. Human beings are not all- knowing and all-powerful. Decimating a species should not be our choice, but our actions provide this result daily.   Ã‚  Ã‚  Ã‚  Ã‚  The next reasons are aesthetic and emotive. These can be described by the positive sensations humans see and feel when viewing a living organism. A dollar amount cannot be placed upon these sensations. Beauty of an organism is not always based upon the same standards. Some people may find trees beautiful to view while others may find them taking up needless space. Current generations of species must be preserved so the future generations of children may enjoy what we enjoy today.

Life as a Parent

Growing up we all wish that one day we will have a family, with a partner and children. At least that’s what I’ve always known. That I believe should be everyone’s plan growing up. Unfortunately, there are some people not fortunate enough to have the opportunity to have children of their own, but like they say a parent is someone who raises them not someone who has just their blood. I met a young couple who got married at a very young age, and struggled much to have children. They tried and tried for many years. Their names were Phil Hansen and Candy Chang. They were a young couple who lived in a huge mansion. Phil was a great artist and Candy was an artist, designer, and urban planner. They had it all money, a big house, great jobs, but that wasn’t all they needed in life. They wanted to have children so bad but after so many treatments found out that neither of them had the capability of producing any children. Candy would always say to Phil â€Å"I want children so bad honey, I want to smell a newborn baby, their just so adorable†. This would upset Phil badly, he wanted to make Candy happy and give her everything she wanted. Until one day, he thought of a great idea. He thought maybe him and Candy could adopt two children. He thought it was a great idea but didn’t know how Candy would feel about it. One night he decided to take Candy out for dinner to her favorite restaurant. That night Candy got ready and said to Phil â€Å"What’s the reason is for this dinner? She said. Phil responded, No reason just felt like going out for dinner and having a serious conversation with you. That only left Candy wondering what was really going on. They arrived at a restaurant called â€Å"Ming Chinese Buffet†, it was a Chinese restaurant. After enjoying a wonderful tasty dinner, Phil asked Candy â€Å"Candy would you like to adopt some children and make hem our own†? Candy smiled, and replied of course that is a wonderful idea. She was so excited. The next morning they went to orphanage, where there were children left that had no parents, and were waiting for someone to want to be their parents. There were kids of all ages, from newborns to teenagers. Phil and Candy were undecided on wether to adopt newborns or teenagers, because they knew they wanted to adopt two children. They fell in love with many children there, they all were lovely. After giving it lots of though, they decided to go for thse two boys that were cousins. They were 5 & 6 years of age. Their names were Stephen Ritz and Ramsey Musallam. Their mothers were sisters; they both gave them up for their drug addiction. Phil and Candy completed the adoption process and took their boys home after a few weeks. These boys started changing their life’s since day one. Phil and Candy created rooms for both their boys, bought them clothes, toy, everything they wanted. They boys meant everything to them; they gave them the best education, the best of everything. They enjoyed every minute with them, they knew that time would fly, and they would be adult in no time. Years and years went by. Next thing you knew they were adults. Ramsey was 24 and Stephen was 25. They were two grown men. They were so thrilled, and happy that these two young men were all grown up, and were two young men. They both were very smart boys, that knew exactly what they wanted to be in life. Stephen knew he wanted to be a teacher, and he wanted to change the life of many children. Ramsey as well was interested in the education field; he wanted to be an educator. They knew exactly what they had to do, and with such great parents, they knew that they had all the support from them. Phil and Candy paid Stephen and Ramsey’s way through the best of the education there is out there. They successfully were able to accomplish everything they intended to. Stephen became a well-known teacher/administrator. He had a believe that students shouldn’t have to leave their community to live, learn and earn. He wanted to help children have something of their own, in their own community. That is why a successful group of his students features the first edible wall in New York City. This wall generates enough produce to feed about 450 students very healthy meals, and trains young children. His students traveled throughout New York and earned their own wage. He felt very successful for accomplishing one of his goals. Ramsey on the other hand was a successful educator. He believed that education was a slow and painful process. All this new technology, he believed was hard to consume. He was a great science teacher at Sacred Heart Cathedral Prep in San Francisco, CA. His goal from the start was to integrate multimedia into a hands on, inquiry-based learning cycle, and to empower other teachers to do the same. He became a successful advocate for flip teaching, tab casting, video casting, and screen casting in classrooms. They both succeeded in what they wanted to acknowledge. They became very well-known educators that made a change. They were able to accomplish all this with the help of Candy and Phil. They were such a great support system to them, and never failed to be there for them. Phil and Candy were very proud of their children and how successful they were. They knew that they had raised to very wonderful children. They were proud of all their accomplishments, and were very thankful for adopting such wonderful children, whom they loved as they were their own. The story of this wonderful couple really made me realize, there’s always an opportunity for everything. Phil and Candy were devastated of the thought of never having children, and at first didn’t acknowledge the opportunity of adoption. When they made that choice, they knew it wasn’t going to be easy, but decided to go for it anyways. Now they feel so grateful for the big opportunity life set for them, and for getting the opportunity to be such great parents. They felt like they succeeded as parents, and now plan for a wonderful future with their successful children.

How Ethernet Passive Optical Network Technology Is Utilized in Implementing Fiber to The Home/Curb/ Building Solutions for Last Mile Bandwidth Bottleneck Problems Free Essay Example, 3000 words

In order to increase transmission efficiency in an EPON system, the upstream and downstream transmission channels should ideally be separated. One simple solution is to utilize space division multiplexing, where two separate optical fibers and passive couplers are used for upstream and downstream transmissions. However, there is a more cost-effective solution. This is by using different wavelengths for upstream and downstream transmissions. Typically, a 1550 nm wavelength is used for downstream transmission and a 1310 nm wavelength is used for upstream transmission [2]. In the upstream direction of an EPON system, multiple ONUs transmit data packets to the OLT through a common passive combiner and share the same optical fiber from the combiner to the OLT. The passive combiner has a directional property so the data packets from an ONU can only reach the OLT but not the other ONUs. Conventional contention-based multiple access such as the carrier sense multiple access with collision d etection (CSMA/CD) protocol, is difficult to implement because the ONUs is unable to easily detect a collision that may occur at the OLT. Although the OLT is able to detect a collision and inform the ONUs by sending a collision message, the transmission efficiency is reduced because of considerable propagation delay between the OLT and the ONUs. We will write a custom essay sample on How Ethernet Passive Optical Network Technology Is Utilized in Implementing Fiber to The Home/Curb/ Building Solutions for Last Mile Bandwidth Bottleneck Problems or any topic specifically for you Only $17.96 $11.86/page