How American Sugar Buys Protection Essay Example for Free

How American Sugar Buys Protection Essay 1. The US General Accounting Office (2002) gauges that the sugar program cost local sugar clients about $1. 5 billion out of 1996 and about $1. 9 billion of every 1998. Would you be able to approve this announcement by utilizing Probit and Tobit examination. 2. What diagnostics are by and large (multicollinearity and typicality? ) run on Tobit and Probit? Do the diagnostics technique vary for binomial and multinomial (state trinomial) probit? 3. â€Å"Sugar considers the potential impact ( intensity) of a gathering in apportioning its contributions†-Explain the announcement. Likewise offer guides to demonstrate your clarification. 4. There exists a connection between crusade commitments and the express a Senator representsâ€Explain this announcement and use Probit and Tobit investigation to demonstrate your answer. Reference: US General Accounting Office (2002). Sugar Program: Supporting Sugar Prices Has Increased Users’ Costs While Benefiting Producers, GAO/RCED-00-126. http://staff. washington. edu/belas/543/GAOSugar. pdf. http://www.bbc.co.uk/pressoffice/pressreleases/stories/2005/12_december/08/todd_making.shtml

KIAI Marketing Plan Essay Sample free essay sample

* Executive aggregate upKiai Marketing Group ( Kiai ) . which is established by Roger Mills who are a student at the University of Western Ontario ( Western ) . London. Ontario. is a newly little house planned for providing propelled offering answers for London concern. With the advancement of the building. the college class currently has changed a clump than before. PC supplanted paper and compose as to go a typical apparatus for taking notes and looking for data during the college class. Plants has established that a greater part of Western’s 30. 000 students utilized PCs in the schoolroom and around grounds. In view of these conceivable ad media. our firm’s stock is to exploit the spotless reinforcement of PC palpebras which were new promotion vast by using a PC covering that is planned by Mills. Our firm’s end is making a net gain of $ 5. 000 for the main twelvemonth. permit 80 % understudies know Kiai and 50 % students seting advertisements in their PC palpe bras. * Current selling province of affairsMarket descriptionAs the tenth biggest city in Canada and the sixth biggest city in Ontario. the populace in London is more than 430. 000. Furthermore. for the ground of its area and is other than a significant center point for wellbeing consideration in Southwestern Ontario and spot to both the University of Western Ontario ( Western ) and Fanshawe College. it pulled in a major whole of understudies around the universe. As it were. the more understudies in London. the more workstations here. the greater ad we can set on the PC lips. Furthermore. the neighborhood little worry in London got the profoundly promising by the city and commonplace authoritiess. This will genuinely benefit for our gathering which is immediate focusing of understudies at Western. Truth be told. our product is an originative product that is exceptional. The market is ever pulled in by the new things. other than. our product can do total compensations both for the advertize r and the students. Item reappraisalOur stock is quite simple to deliver and got from our customers. We’ve as of now reached with a bit. exclusive activity in business locale. London to deliver an overlay stuff. it can simple be applied and expelled from PC palpebras by using a white cement reinforcement. Not only is it advantageous for understudies to set it on their PC palpebras. yet, help the advertizer to rescue the expenses. CompetitionThere are a bunch of notice media in London. some of them are outside of the college, for example, the London Free Press. It is the London’s significant everyday paper which pulled in around 226. 000 perusers every weekday. 250. 000 on Sabbatums and 140. 000 on Lords daies. In spite of the fact that it has army perusers and the estimating data of it is secret. the expense of posting ad on it is high to such an extent that is non appropriate for concern focusing on students. Since the intensity of college students’ ingestion is non truly elevated. the product that offered to them would non be so costly. so it is non cost-proficient for a house that pointing college understudies by commercial on London Free Press. A portion of the opponents are around the college, for example, Western insight. The Gazette. Direction Week Packages and Immobile Poster Campaigns. The closeness of these media is they are simpler to make out the understudies. In any case. the financial estimation of ad is non economical. The financial incentive in the Western News is gone from $ 31. 64 for a two-inch-wide advertizement to $ 497. 20 for a full half page. Advertisement in the Gazatte for one hebdomad ran from $ 120. 40 for one sixteenth of a page to $ 1. 430 for a full page. An expense for â€Å"Welcome to Western† and put business’s logo on the 5. 000 wash packs given to green bean understudies is $ 3. 000. The expense of stable posting runs in the Western is $ 110 every month because of the figure of casings and explicit areas. Contrasted with these conventional promotion media. non just does our product is originative. in any case, we other than spare expenses. All things considered. college students are attached to new things. this kind of ad would pull progressively significant sentiments contrasted with the basis. Moreover. Kiai is an organization which has a top of the line research of the Western students including seg ment of the Western. it will be a solid bit of leeway to those houses which experienced little toward the Western. DistributionThere are 5 unique methods of dispersion for our company’s stock. First. a public expo called Bridge to Better Business would be held in London for two yearss in August. It gives nearby little concern owner to show their stocks to around 500 to 1500 specialists. Factories would hold to fix our ain show. lighting and signage at an expected expense of $ 250. Second. the Small Business Center ( SBC ) in London. gives concern owners some worry exercises that we genuinely need. In any case, the expense of rank at the SBC is non modest and we need to distribute off instructive booklets and concern cards. So this could be the alternative. Nonetheless. the SBC other than hold workshops. organizing occasions. courses and meet-and-welcome occasions for neighborhood concern owners to talk. Plants will go to a lower cutoff of 20 Sessionss to â€Å"get his name and the worry out there† . furthermore, he would other than distribute off concern cards to planned customers. At that point. we utilize the most customary strategy which is immediate gross incomes. Factories would pass on at any rate 100 transcripts of enlightening booklet and 250 concern cards. fliping to neighborhood concern owners eye to eye or cold pitching them. Finally. we will build up an expert site for conceivable customer. on history of we are another organization proficient site would help us gain much-need validity for future turn of events. * Threat and chance analysisThe danger would be the expense of running a gathering. The entirety of the prophase cost will be bought ourselves. In add-on. the crew is non so huge that we don’t have sufficient work power to actualize all pieces of our anxiety. The conventional ad media, for example, paper. TV. communicate medium station would be an enormous test for us. For chance investigation. on the one manus. the administration we give is separated from everyone else. no 1 does previously. it is an originative things which could pull all the more going to in college students. On the different manus. we got a top notch research of the Western students segment. We could reach and see more than different organizations outside of the Western. * Aims and situating schemeIn the accompanying 1 twelvemonth after get bringing down the Kiai concern. making a net gain end of $ 5. 000 for the twelvemonth. be comfortable with at any rate 80 % Western students and permit them cognize Kiai’s administrations. at any rate 50 % students seting advertisements in their PC palpebras. Our administrations is separated from everyone else. the college students would simpler to acknowledge this kind of advertizement. It is regular and productive for both the understudies and the advertizer. * Marketing plan and tacticsAlthough it is difficult to mensurate the effectivity of another commercial run. we are certain that Kiai’s signifier of commercial would accomplish increasingly significant emotions contrasted with the basis. increasingly customary advertizements offered by the opposition. For the ground those organizations experienced difficulty making the college segment. which Kiai has. We intend to cover more than 50 % notoriety at the Western. more than 30 % in London. pull in excess of 100 advertizers. look into new designing that could utilize and take more advantageous than now. * Action plan†Find advertizer fitting to the conveyance of the selling program. †Advertise in the Western including seting up postings. passing out concern cards. promote on the facebook chirrup and university’s site. expressing companions and students at the Western. †Runing the worry with the advertizer and students. go about as a mediator man of issues. * BudgetsTrade shows $ 250Small Business Center Networking $ 360Websites $ 750Informational booklets $ 50Transcripts of posting ( 50 x 0. 5 + 50 ten 0. 25 ) $ 37. 5Business cards $ 50Hire representatives ( 4 x 500 ) $ 2. 000Others $ 1. 000Entire $ 4497. 5 * ControlsFollowing halting point to the line of the spending that recorded previously. don’t abundance the financial plan. expanding the advantages.

5 Comics to Watch for in January

5 Comics to Watch for in January Each month, we bring you 5 intriguing comicsâ€"whether destined to become bestsellers or under the radarâ€"that you should keep an eye out for. Bitch Planet #6, by Kelly Sue DeConnick,  Taki Soma, and  Valentine De Landro (Image Comics, January 6) Hey, remember Bitch Planet, one of Panels favorite series of 2015? Well, its back, after a three month hiatus. Since this is an issue divisible by three, we explore the background of Bitch Planeteer  Meiko Maki, drawn by guest penciller Taki Soma. Also, the single issues of  Bitch Planet  have had some utterly amazing essays on feminism, letters from readers, etc., in the back matter that, for whatever reason, are  not reprinted in the trades. This is one of the few series where if you arent reading the single issues (either digital or print), youre missing part of what makes it  so amazing. (Note: this issue came out last week, so you can actually buy it right now!) Rosalie Lightning: A Graphic Memoir, by Tom Hart (St Martins Press, January 12) After Eisner-nominated cartoonist Tom Harts daughter Rosalie died in 2011, shortly before her second birthday, he started work on a memoir about her life, death, and how he and his wife (fellow cartoonist  Leela Corman) dealt with their grief.  I have only read the first few preview pages, but that was enough to make me tear up.  Im not 100% sure I can make it through the book, but  Rosalie Lightning looks like it might be indispensable if you or someone you know has lost someone close to you. Poison Ivy: Cycle of Life and Death #1, by Amy Chu and Clay Mann (DC Comics, January 20) In her first-ever series, Dr. Pamela Isley a/k/a Poison Ivy, tries to go straight with a job at the Gotham Botanical Gardens, but comes under suspicion when a fellow scientist turns up dead. This is writer  Amy Chus first miniseries for a major publisher, but her work in  Sensation Comics and the Vertigo CMYK  and Strange Sports Stories anthologies  has been well-received and she was profiled as part of Comic Alliances Hire This Woman series a couple of years ago. Fingers crossed that this turns out to be her big break. I might even break my informal rule against buying DC floppies for this one. Captain Marvel #1, by  Michele Fazekas,  Tara Butters, and Kris Anka (Marvel Comics, January 20) Of course Im getting this. I mean, its Carol-freaking-Danvers. I mean, just last month I wrote a piece telling you what to read to get ready for this book. Im maybe slightly just a tad bit obsessed. But lets assume for a moment that you arent obsessed like me, that your response to the words Carol Corps is More like Carol BORE! Well, Ive got two words for you: Agent Carter. Remember that kickass series we were all obsessed with last January (and will be again this January) starring Hayley Atwell? Well, the showrunners from  Agent Carter, Michele Fazekas and Tara Butters, are taking over the writing on  Captain Marvel.  Did you just get a tingling sensation down your spine? Plus, check out that fantastic art by Kris Anka. Beverly, by  Nick Drnaso (Drawn and Quarterly, January 26) Im often  skeptical of books and movies about the sterile sameness of the suburbs (mostly because the theme has been explored  so many times that its hard to say something interesting), but Nick Drnasos  Beverly looks promising, with an art style evocative of Chris Ware (who praised the book over at DQs website) and a cast of disaffected teens that might have come out of the mind of Daniel Clowes. The graphic novel is written as a series of interconnected  short stories, promising additional insights on a reread. Sign up to The Stack to receive  Book Riot Comic's best posts, picked for you. Thank you for signing up! Keep an eye on your inbox.

Oedipus As A Tragic Hero - 1939 Words

Thesis Statement: Sophocles’ Oedipus is a perfect example of Aristotle’s definition of a tragic hero through the main characters prosperity to an emotional downfall caused by a tragic flaw. I. Oedipus is a Tragic Hero a. Definition of a tragic hero as defined by Aristotle i. Aristotelian tragic hero is defined (Aristotle 1961, p. 1453a). b. Oedipus falling into Aristotle’s tragic hero definition i. Aristotle directs us to Oedipus the King as a tragic hero (Bruening 1997, pp. 14-15). II. How Tragedy Affects the Audience a. Language of Tragedy i. Aristotle believes there is a present connection between tragedy and emotions (Konstan 1999, p. 1). b. Aristotle’s idea of a tragic plot i. Aristotle believes a tragic plot should be†¦show more content†¦Oedipus† (Aristotle 1961, p. 1453a). Aristotle’s definition of a tragic hero comprises the character Oedipus. Oedipus displays several qualities as a tragic hero to included the cause of his downfall. Even though Oedipus is not known as a wise scholar, he did have the ability to outwit the Sphinx and solve the riddle. This story of the Sphinx adds to his respect and sets up an emotional feel to like Oedipus’ character. Oedipus earns sanctification as a King by saving the natives of Thebes, which gains him more influence as he comes a consecrated King of the city. Even the Priest addresses Oedipus by saying, â€Å"Great Oedipus, O powerful King of Thebes† (Sophocles 425, p. 860). Oedipus’ character has sainthood like status. Even with his this status, Oedipus has a treacherous ethical wrongdoing. He is in an incest relationship with his mother, despite not knowing she was his mother. Using Aristotle’s definition, Oedipus’s downfall does not stem just from his evil. This downfall stems from his pride and a combination of different issues. One issue that contributes to Oedipus’ downfall is his anger. Oedipus becomes very angry when the blind prophet warns him by saying, â€Å"Am I to bear this from him? Damnation Take you! Out of this place! Out of myShow MoreRelatedOedipus As A Tragic Hero1506 Words   |  7 PagesA true hero does not merely wear a cape, but this individual possesses admirable characteristics. A hero inspires the people around him and he is honorable. Heroes influential individuals from fairytale stories and myths of a real-life hero. Yet, none of these influential people are perfect. The tragic hero is clearly defined by Aristotle as being a person of admirable character, yet completely human with noticeable flaws. Moreover, this individual is not exempt from suffering. In Sophocles’ tragicRead MoreOedipus-a Tragic Hero706 Words   |  3 PagesRunning head: Oedipus-A Tragic Hero Research Paper ENGL 102: Literature and Composition) Fall 2015 Melinda Meeds L26683811 APA Outline Thesis: In Sophocles’ â€Å"Oedipus†, Oedipus is exemplified as a tragic hero according to Aristotle’s definition because his story appeals to the reader’s humanity in the way he maintains his strengths after inadvertently causing his own downfall. I. Oedipus A. The noble birth. B. Describe Oedipus’ character. II. Tragedy A. DescribeRead MoreIs Oedipus A Tragic Hero?1167 Words   |  5 Pages2014 Is Oedipus a tragic hero? Aristotle, Ancient Greek philosopher whom did a lot of philosophizing, he believed in a logical reality. Aristotle’s objective was to come up with a universal process of reasoning that would allow man to learn every imaginable thing about reality. The initial process involved describing objects based on their characteristics, states of being and actions. Aristotle once said A man doesn t become a hero until he can see the root of his own downfall†. Oedipus was a mythicalRead MoreOedipus the Tragic Hero1390 Words   |  6 PagesOedipus; The Tragic Hero In the Fourth Century BC, a famous philosopher named Aristotle wrote about the qualities that a tragic hero must possess. Ever since that time, there have been many examples of tragic heroes in literature. None of those characters, however, display the tragic hero traits quite as well as Oedipus, the main character from the play Oedipus Rex by Sophocles. Oedipus is, without a doubt, the absolute quintessence of a tragic hero. His example shines as clear as a sunny summerRead MoreOedipus As A Tragic Hero1724 Words   |  7 Pagesstory of Oedipus, Oedipus is considered a â€Å"Tragic Hero† because of the tragic fate and effect that he had upon his life. My definition of a tragedy is a great loss that has a unhappy ending to which concluded me to state that Oedipus falls under that category. Throughout the book, Oedipus is leading himself to his own destruction when trying to find the killer of the late King Laios. So when a journal article I found published by The John Hopk ins University Press stated that a â€Å"tragic hero is a manRead MoreOedipus, A Tragic Hero1648 Words   |  7 Pages Oedipus, a Tragic Hero Bob Livingston Liberty University â€Æ' Sophocles presented the world with Oedipus around 2500 years ago. Never-the-less, the story remains among the most riveting of all time. He was, in fact, a man that was driven by a very high internal moral standard. It was that internal moral standard that ultimately entwined him in a sequence of events and circumstances that placed him in the spousal relationship with his mother. Oedipus, in fact, can truly be regarded as a tragic heroRead MoreOedipus a Tragic Hero1516 Words   |  7 PagesOedipus A Tragic Hero English 102 Literature and Composition Summer B 2011 Terry Garofolo 22816762 APA Sophocles presented the world with Oedipus around 2500 years ago. Never-the-less, the story remains among the most riveting of all time. Unfortunately, today when we hear the mention of the name Oedipus we place negative connotations around it. Oedipus, after all, had an unnatural sexual relationship with his own mother! In actuality, however, this relationship emerged entirely innocentlyRead MoreOedipus As A Tragic Hero1094 Words   |  5 PagesIn the play Oedipus the King, Oedipus struggles to accept the truth and lets his temper over power him. He can be displayed as a tragic hero. His refusal to accept the truth led to Oedipus’ down fall. A tragic hero, as defined by Aristotle, â€Å"is a literary character who makes a judgment error that inevitably leads to his/her own destruction.† Sophocles’ Oedipus exemplifies Aristotle’s definition of a tragic hero. In the play, Oedipus unknowingly has cursed the entire town of Thebes. He was cursedRead MoreOedipus, a Tragic Hero?2158 Words   |  9 PagesOedipus, a Tragic Hero? Elizabeth Howell English 102- B33 Professor Katie Robinson Liberty University October 12, 2012 Oedipus, a Tragic Hero? Thesis: Using Aristotle’s five different descriptions of a tragic hero, we will show that Oedipus in Oedipus the King is in fact a tragic hero and how his decisions led to his downfall. Outline: I. Introduction and Thesis Statement II. Is the character of noble birth? A. King of Thebes B. Real father was king III. Though the tragic heroRead MoreOedipus, A Tragic Hero1832 Words   |  8 Pagesmany others will likely fade away. Oedipus Rex is a tragic tale set in Ancient Greece. Greek thinker, Aristotle, said there were certain elements that would make a person qualified as a â€Å"tragic hero.† (Adade-Ywboah, Ahenkora Amankwah, 2012). We think of heroes being larger than life, possessing impeccable honor, integrity, strong leadership and having the higher moral ground. However, tragic heroes are different; they are imperfect and will inevitably face a tragic downfall. Per Aristotle, there are

The Norse tale of Ragnarok Essay - 1136 Words

The Norse tale of Ragnarok presents an interesting example of apocalyptic literature by providing both an end and a unique beginning. The world which rises from the cosmic rubble seems to be essentially equivalent to that which the apocalypse destroyed, possessing the same creatures, features and Gods of times past. This considered, and by incorporating themes of time and fate, Snorri challenges the concepts of the past, present and future of Norse lore by providing a framework which allows for the potential reiteration of history. By reviewing The Prose Edda’s telling of the events surrounding Ragnarok, the relationship between fate, time and history provide a unique alternative to the standard eschatological timeline. The Prose Edda†¦show more content†¦Instead the Gods are awarded most of the spotlight. Unlike John’s Revelation, The Poetic Edda offers no guidance to man on how to confront this issue, nor does it offer any means of escape. Therefor, it can be assumed that man has no effect on the end, except possibly by way of untrimmed nails and scrap leather (Snorri, 72). However, by presenting deities that possess more human characteristics, who have weaknesses and quarrels, they become the relatable entities within the text. Introductions established, The Edda continues by exhibiting the questioning of Odin, chief of the Gods, by Gylfi, a traveling king (Snorri, 10). Gylfi asks about the race of Gods, to which Odin tells the story of his wife Frigg and their favorite son Balder. The purity of whom foreshadows his future significance. Balder, Odin responds, suffered from a series of foreboding dreams which prompts Frigg’s to take maternal action. She traveled the world, requiring an oath from every substance and material that they will not harm her son. Thus protected, Balder could bear the abuse of swords, sticks and fire without sustaining injury (Snorri, 65). Here Odin introduces of Loki, the trickster God, who becomes jeal ous of Balder’s immunity. While disguised, Loki asks Frigg â€Å" ‘Have all things given their oath not to harm Balder?’ Frigg answers, ‘A shoot of wood grows to the west of Valhalla. It is called Mistletoe, and it seemed too young for me to demand itsShow MoreRelatedNorse Mythology : Norse Myth Essay1711 Words   |  7 PagesWhen you hear the words ‘Norse Mythology’, you typically begin to think about what you learned from the movies and comics produced by Marvel. The story you know revolves around Thor: The handsome and all-wise, powerful God of Thunder, who takes on his evil blood-brother Loki. You ve also probably heard of Thor’s magical flying hammer, and the rainbow bridge that allows the gods to cross over to different realms. However, Norse mythology goes way deeper than just tales of a superhero conquering allRead MoreHow To Train Your Dragon: A Film Created from Norse Mythology698 Words   |  3 Pagesvoice actors, and amazi ng animation, this film also includes something else I enjoy, Mythology! Norse Mythology, to be more precise. You can see the Viking characters looking very similar to that of Norse Gods very early in the film. They wear horned helmets, body armor and carry around round shields. Both men and women are fighting. Their weaponry are axes, swords, spears and hammers, are used by Norse gods. There hair is long and the men have grown long breads as well. Their form of transportationRead MoreThe End Of The World Essay1913 Words   |  8 Pagesrecord history there have been tales of creation and the end of the world. According to John Black in The Story of Ragnarok and the Armageddon, â€Å"it (the end days) is the ‘Judgment Day’ described in the Book of Revelations; in Judaism, it is the Achart hayamin; in Aztec mythology, it is the Legend of the Five Suns; and in Hindu mythology, it is the Story of Avatars and the Man on the House†. (Black) Some of the stories of how the world might end are happy, joyous tales where the world becomes a paradiseRead MoreMisconception of the God of Lighting Marvels Version1610 Words   |  7 Pagesspeaking? That would be the famous Norse God of Lighting, Thor, or at least in the Marvels version he is like that in the movie Thor. Marvels version of Norse Mythology is actually different from the actual mythology which results a misconception of the myth to the people who watch the movie Thor. People sometime believe that Marvels version of Norse Mythology is the actual myth of Norse Mythology itself, because they believe that Marvel is telling the true tales in their own way. They sometime haveRead MoreNorse Mythology And Norse Myths1210 Words   |  5 PagesWho are the Norse gods and goddesses? Where do they come form? The Norse myths are very complex and interesting. Many people study the myths. The Vikings actually started Norse mythology. Norse mythology also known as the Scandinavian mythology, is a kind of religion that was and is still practiced by some of the people in the Scandinavian countries (Vikings) and northern parts of Germany(Norse for Smart People, McCoy,Dan,2012-2016). In the last few decades, the stories and culture of the VikingsRead MoreSignificance And Significance Of Mythology1743 Words   |  7 Pagesrespected and influential figures. They served not only as priests but also as judges, teachers, and advisers. In addition, it was widely believed that the Druids had magical powers. The ancient Celts had a vibrant mythology made up of hundreds of tales. They did not, however, record their myths in writing but passed them on orally. Our knowledge of the gods, heroes, and villains of Celtic mythology comes from other sources—mainly Roman. Yet the Romans sometimes referred to Celtic gods by Roman namesRead MoreCharacter Analysis Of Loki1116 Words   |  5 Pageswithin Norse mythology. He is portrayed as a scheming, mischievous deity who has no real loyalties, his role is shrouded in mystery; what was his purpose in the ancient stories. Loki’s character arises questions about his role; was he a plot device, a foil for the Aesir, or maybe he was meant to be used as a warning to child? Within the pantheon of Norse gods, he was an anomaly; his fellow gods are mostly one dimensional and Loki is anything but. Loki is the antithesis to the culture the Norse godsRead MoreTrickster-God-Creator1433 Words   |  6 Pagesfirst lyre from its shell, but eventual ly transitions to a place amongst the Olympic pantheon as the messenger of the gods. In the Norse myths of the Scandinavian countries, Loki is a mischievous nuisance, nonetheless responsible for the creation of many of the other gods most identifiable possessions, but also the driving force behind the prophesied apocalypse, Ragnarok. Tricksters are more than thieves and mischief makers. As Lewis Hyde says in his introduction to the book Trickster Makes This WorldRead MoreHistory of Loki, The Trickster God Essay1025 Words   |  5 Pages Loki is known as the trickster god of Norse mythology and is even said to be one of the first anti-heroes. He is also probably one of the most well-known tricksters as well. In the Norse myths, he is often portrayed as being very mischievous and is always causing trouble for the gods. In fact, â€Å"he was so outrageously mischievous that he even sneaked his way into becoming a god† (Allen, and Saunders, par. 1). However, even though he a lmost always seems to be getting the gods into some kind ofRead MoreVikings1677 Words   |  7 Pagesmarriage ended in a divorce, the dowry was refundable. Also, women were allowed to own land and were very often left alone to manage it while their husbands went off to barter at markets or went overseas to trade or raid. Social structure among the Norse wasn’t what one could call equal for all. Though class distinctions were not absolute and fixed, they did separate the masses from those most likely to succeed. Slaves, or thralls, occupied the lowest rung of the social ladder, although prisoners

The Purpose of Education Free Essays

The purpose of education is to spread knowledge to the younger generation. Without education, tradition is lost, as well as the potential of youth. For centuries, the old have taught the young. We will write a custom essay sample on The Purpose of Education or any similar topic only for you Order Now They have passed the torch of knowledge from one hand to another. Whether it was a master teaching an apprentice, or a teacher teaching a class, the tradition of teaching has been in practice since the beginning of man. Without a mentor for a child to learn from, the child will never find the truth behind the mysteries of life. The child needs to be trained to succeed and even better, reach self-fulfillment. That is why the teacher must be of the highest quality. The student will take after the teacher, not only in knowledge, but also in style and example. If the teacher has a flaw, the child will accept that flaw as his or her own. There is a special bond between the teacher and the student. The teacher must be prepared to take on the student as more than a student, but as a friend. Those, whose intelligence surpasses other’s, should be given a challenge in every circumstance available. Harder work should be provided, but not demanded. Although, those with the skills to complete such work, should not let their minds go to waste. They should harness their brain’s power to be as successful as possible. A person with college education and gained analyzing skills and deep knowledge field of studies, not only the person will be qualified and prepared for the job advertised from that company; but will also have potential to excel faster and have high salaries. College education is a very important central in everyday life. It plants the fundamentals for confronting problems and obstacles found in part of life, and being able to solve them with ease and accuracy. It gives a wide opportunity and potential in apply for higher profile jobs with good pay. It gives a person confidence in understanding life and the environment. A person with a college education will be successful in life because he understands it and knows it. An ideal system of education requires distinct characteristics. Our education system today is not quite perfect. All education institutions share a common goal. The goal is for all the students to gain knowledge that they didn’t have before in order to compete in the real world. The majority of people believe that getting knowledge is â€Å"obtaining education. † There is more to the concept that â€Å"students are depositories† and the â€Å"teachers are the depositor. Paule Friere ) The success of the students is directly connected to the environment he is surrounded. A perfect education system has to start with a comfortable environment. The teacher also has to be knowledgeable and not believe in the myth that â€Å"teachers justifies their own existence through their students ignorance absolute. â€Å"(Paule Friere) A perfect institution of education should be able to accommodate cultural change, diversity, have a strict curriculum with alternative teaching strategies, and promotes interaction among their peers. In a perfect educational system, interaction among students will greatly be encouraged. And there are many elements that need drastic change so that this educational system may be more refined and more productive. Teachers are a very important element in successfully transferring knowledge from the teacher to the pupil. In this institution, teachers are not allowed to believe that they are superior to the students. When this occurs, and the inequality sets in, the student will be hesitant to ask questions about subjects they don’t understand. When a student does this, he is unintentionally hurting himself. He will not have gain and understand the true meaning of what is being taught by the teacher because he is more focused on the educational gap between the student and teacher. The student needs to able to question everything that is being taught. By using the Socratic method, students will understand topics rather than believing what other people are saying. There needs to be a respectful relationship between the student and teacher. The student respects the teacher and the teacher respects the student equally. This relationship between student and teacher is very important journey of obtaining knowledge. There should be no other kinds of relationship. The only acceptable form is through the connection that they both share as being teacher and being student. Next, the teacher need to responsible for the materials they are covering. They need to be fluent or else the student will have doubts about the material and ultimately the teacher. The more secure the teacher is with his material the more the student will trust the material and the teacher. If a teacher is not confident and prepared, there will be doubts that will be raised in the minds of the student. More importantly, the teacher will need to care about the student and guide them towards their goal. All teachers need to know when to step aside so that the student can make progress and help the student up when he fails. The most beneficial qualities of an excellent teacher are the ability to care for the student and the encouragement teachers provide for the students. Teachers are just an extension of parents; caring and encouragement are two characteristics of parents. The next important element in a perfect educational institution, is the curriculum. There needs to be a flexible curriculum that accommodates all the different intellectual abilities of all the students. Not all the students will have the same learning capabilities. Some students may have a learning disability and others may be genuinely intelligent. The curriculum is strict but still is flexible enough to accommodate each individual student. The actual courses need to be comprehensive. The subjects being studied needs to be updated constantly by the teachers. A perfect institution will have all area of studies accessible to the students. Any particular major or subject will be left to the students to decide. When they do decide what they want to study, there will be the necessary courses to cover that major. In order for a student to pass a course, he needs to be able to teach the information he learned in that course. This teaching method is very important. If a student is able to teach something then that student truly understands it. This method of testing the knowledge of the student should be the final examination for every course. This method is more valid than the constant â€Å"question and answer† method being used today, which promotes temporarily memorization. The next ingredient in a perfect institution is the actual environment itself. Their surrounding influences many people. An intellectual community needs to look like an intellectual community. It will be located in an area, which is safe. The students need to feel comfortable. A comfortable learning environment leads to the success of the students. There should be no distractions that will keep the student from learning. With all of these characteristics, the student’s should be able to concentrate on obtaining their education. Though the task of creating and maintaining a perfect institution is a difficult task, it can be created. People need to come together with this structure and guideline in mind. The educated ones need to continue to educate others. This realization is extremely important to future students. Educated people need to think of the future and society as a whole. They need to help educate others, just as others, educated them. If all of these characteristics are met in an institution, then that institution can be labeled, â€Å"perfect How to cite The Purpose of Education, Papers

Open Flow Essay Example

Open Flow Essay Load Balancing Surya Prateek Surampalli Information Technology Department, Southern Polytechnic State University [emailprotected] edu Abstract—in high-traffic Internet today, it is often desirable to have multiple servers that represent a single logical destination server to share the load. A typical configuration comprises multiple servers behind a load balancer that would determine which server would serve the request of a client. Such equipment is expensive, has a rigid set of rules, and is a single point of failure. In this paper, I propose an idea and design for an alternative load-balancing architecture with the help of an OpenFlow switch connected to a NOX controller that gains political flexibility, less expensive, and has the potential to be more robust to failure with future generations of switches I. Introduction In today’s increasingly internet-based cloud services, a client sends a request to URL or a logical server and receives a response from a potentially multiple servers acts as a logical address server. Google server is said to be the best example, the request is sent to server farm as soon as the client resolves the IP address from the URL [1]. Load balancers are expensive that acts as a reverse proxy and distributes network or application traffic across a number of servers. Load balancers are used to increase capacity (concurrent users) and reliability of applications. They improve the overall performance of applications by decreasing the burden on servers associated with managing and maintaining application and network sessions, as well as by performing application-specific tasks [1]. We will write a custom essay sample on Open Flow specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Open Flow specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Open Flow specifically for you FOR ONLY $16.38 $13.9/page Hire Writer Since load balancers are not basic equipment and run custom software, policies are rigid in their choices. Specific administrators are required and also the arbitrary policies are not possible to implement. Since running policy and the switch are connected it is reduced to a single point of failure [2]. The order of magnitude will cost less than a commercial load-balancer if architecture with an OpenFlow switch is implemented which is controlled by the commodity server and also provides flexibility for writing patterns which allow the controller to be applied arbitrary political [1]. If the next generation of OpenFlow switches has the capability of connecting to multiple controllers, there is a chance of making the system much robust to abortion by keeping the any server behind the which that acts as the controller [1]. II. Background A. Load Balancing Load balancing helps make networks more efficient. It distributes the processing and traffic evenly across a network, making sure no single device is overwhelmed [1]. Web servers, as in the example above, often use load balancing to evenly split the traffic load among several different servers. This allows them to use the available bandwidth more effectively, and therefore provides faster access to the websites they host [3]. Whether load balancing is done on a local network or a large Web server, it requires hardware or software that divides incoming traffic among the available servers. Networks that receive high amounts of traffic may even have one or more servers dedicated to balancing the load among the other servers and devices in the network. These servers are often called (not surprisingly) load balancers [1]. Load balancing can be performed using dedicated hardware devices such as load balancers or having intelligent DNS servers. A DNS server can redirect traffic data centre with a heavy load or redirect requests made by customers for a data centre that is less network stretches from clients. Many data centres use of expensive hardware load balancing equipment that makes in distributing the network traffic across multiple machines to avoid congestion on a server. A DNS server resolves a hostname to a single IP address where the client sends the request. To the outside world there is a logical address that resolves a host name [3]. This IP address is not associated with a single machine, but is the type of service a client request. DNS can resolve a host name to a load balancer within a data centre. But this could be avoided for safety reasons and to avoid attacks on the device. When a client request comes to the load balancer, the request is redirected according to the policy. B. OpenFlow Switch An OpenFlow switch is a software program or hardware device that forwards packets in a software-defined networking (SDN) environment. OpenFlow switches are either based on the OpenFlow protocol or compatible with it [1]. In a conventional switch, packet forwarding (the data plane) and high-level routing (the control plane) occur on the same device. In software-defined networking, the data plane is decoupled from the control plane. The data plane is still implemented in the switch itself but the control plane is implemented in software and a separate SDN controller makes high-level routing decisions. The switch and controller communicate by means of the OpenFlow protocol. The OpenFlow switch on the other hand uses an external controller called NOX to add rules into its flow table. C. NOX Controller NOX is a network control platform, that provides a high-level programmatic interface upon which network management and control applications can be built. In brevity, NOX is an OpenFlow controller [3]. Therefore, NOX applications mainly assert flow-level control of the network meaning that they determine how each flow is routed or not routed in the network. The OpenFlow switch is connected to the NOX controller and communicates over a secure channel using the OpenFlow protocol. The current design of OpenFlow only allows one NOX controller per switch. The NOX controller decides how packets of a new flow should be handled by the switch. When new flows arrive at the switch, the packet gets redirected to the NOX controller which then decides whether the switch should drop the packet or forward it to a machine connected to the switch. The NOX controller can also delete or modify existing flow entries in the switch. The NOX controller can execute modules that describe how a new flow should be handled. This provides us an interface to write C++ modules that dynamically add or delete routing rules into the switch and can use different policies for handling flows. D. Flow Table A flow table entry of an OpenFlow switch consists of a header fields, counters and actions. Each flow table entry stores Ethernet, IP and TCP/UDP header information. This information includes destination/source MAC and IP address and source/destination TCP/UDP port numbers. Each flow table entry also maintains a counter of number of packets, and bytes arrived per flow. A flow table entry can also have one or more action fields that describe how the switch will handle packets that match the flow entry. Some of the actions include sending the packet on all output ports, forwarding the packet on an output port of a particular machine and modifying packet headers (Ethernet, IP and TCP/UDP header). If a flow entry does not have any actions, then the switch drops all packets for the particular flow. Each Flow entry also has an expiration time after which the flow entry is deleted from the flow table. This expiration time is based on the number of seconds a flow was idle and the total amount the time (in seconds) the flow entry has been in the flow table. The NOX controller can chose a flow entry to exist permanently in the flow table or can set timers which delete the flow entry when the timer expires. III. Load-Balancer Design Load balancing architecture comprises an OpenFlow switch with a control device of NOX and server machines connected to output ports of the switch server. The OpenFlow switch uses an interface to connect to the Internet. Each server has a static IP address and NOX controller maintains a list of currently connected to the OpenFlow switch servers. Each server is running web server emulation on a well known port. [pic] Figure1. Load-balancer architecture using OpenFlow switch and NOX controller The hostname of server to IP address is resolved by each client and a request is sent to that IP address on the known port number. If you consider the above diagram, when a packet is reached to the switch from the client, the header information of the packet is compared with the entries of the flow table. If the header information of the packet corresponds to an inlet of the flow, the counter for the number of packets, the byte count is incremented, and the actions associated with the input of the flow are performed on the packet. If no match is found, the switch forwards the packet to NOX. NOX decides how the packet for this flow should be handled by the switch. NOX and then inserts a new article in the cash flow of the switch using the OpenFlow protocol. To achieve load-balancing features, the modules should be written in C++ that is executed by NOX controller. NOX should perform the function of handle () when a new flow arrives at the switch. This function sets the load balancing policy and adds new rules in the flow table of the switch. All client requests should be destined for the same IP address, then whatever the module is executed by NOX, should add rules for each flow which can modify the destination MAC and IP address of the packet with a server’s MAC and IP address. The switch will forward the packet to the server output port after modifying the packet header. When servers return a packet to the client, the module adds an entry flow that changes the source IP address with the IP address of the host that the client sends its request. So the client should always receive packets from the same IP address. If the client connection / server connection is closed or remains idle for 10 seconds, then the inactivity timer expires causing the input stream to be deleted from the cash flow of the switch. This allows input stream recycling Servers wait for a NOX to register and then report their current load on some schedule similar to the Listener Pattern. NOX in a separate thread listening on a UDP socket for heartbeats with reported by server loads and maintains a table with the current loads of all servers. When applying for a new stream is received, it chooses the server with the lowest and the load current increases to the low current server. This prevents flow of all flows routed to the same server as the server reports a new load. It also breaks ties by turning it into a round robin until the servers report their actual load heartbeat. Flow Algorithm Require: Flow, path 1: sourceHost = LocateSource(flow); 2: destinationHost = LocateDestination(flow); : layer = setToplayer(); 4: currentSwitch = LocateCurrentSwitch(); 5: direction = 1; //upward 6: path = null; //list of switches 7: return search (); This algorithm works as follows. When the OpenFlow controller receives a packet from a switch, it switches the control to the load balancer. Line 1 to 6 introduces the initialization for necessary variables. The load balancer ? rstly a nalyses the packet’s match information including the input port on the switch that receives the packet as well as the packet’s source address and destination address. Then it looks up those addresses using its knowledge about the network topology. Once the source and destination hosts are located, the load balancer calculates the top layer that the ? ow needs to access. We use the search direction ? ag. The ? ag has two values: 1 for upward and 0 for downward. It is initialized to 1. A path is created for saving a route grouped by a list of switches later. Line 7 calls search () that performs the search for paths recursively. In the method search (), It ? rstly adds current switch into path. It returns the path if current search reaches the bottom layer. It reverses the search direction if current search reaches the top layer. Then it calls a method 1: search () { 2: path. add(curSwitch); 4: if isBottomLayer(curSwitch) then 5: return path; 6: end if 7: if curSwitch. getLayer ( ) == layer then 8: direction = 0; //reverse 9: end if 10: links = findLinks(curSwitch, direction); 11: link = findWorstFitLink(links); 12: curSwitch = findNextSwitch(link); 13: return search (); 14:} that returns all links on current switch that are towards current search direction. Only one link is chosen by picking up the worst-? t link with maximum available bandwidth. And then the current switch object is updated. The method search () is called recursively layer by layer from the source to destination. At last the path will be return to the load balancer. The path information will be used for updating ? ow tables of those switches in the path. Flow Scheduling The Flow scheduling functionality works as follows. Each OpenFlow switch maintains its own ? ow table. Whenever any packet comes in, the switch checks the packet’s match information with the entries in its ? ow table. The packet’s match information includes ingressPort, etherType, srcMac, dstMac, vlanID, srcIP, dstIP, IP protocol, T CP/UDP srcPort, TCP/UDP dstPort. If it ? nds a match, it will send out the packet to the corresponding port. Otherwise it will encapsulate the packet in a PACKET IN message and send the message to the controller. As a module of the OpenFlow controller, the load balancer will handle the PACKET IN message. It ? nds a proper path by executing a search with the DLB algorithm described in Algorithm 1. The path is a list of switches from source to destination of the packet. Then the load balancer creates one FLOW MOD message for each switch in the path and sends it to the switch. This message will have the packet’s match information as well as a output port number on that switch. The output port number is directly calculated by the path and network topology. If one switch receives a FLOW MOD message, it will use it to update its ? ow table accordingly. Those packets buffered on ports of that switch may ? nd their matches in the updated ? ow table and be sent out. Otherwise the switch will repeat this process. IV. Future Work The OpenFlow specification includes an optional feature that would allow multiple NOXs to make active connections to the switch. In the case then of the NOX failing, another machine could assume the role of the NOX and continue routing traffic. Naturally the system would need to detect the failure, have a mechanism to remember any state associated with the current policy, and all servers would have to agree on who the new NOX was. These requirements naturally lend themselves to the Paxos consensus algorithm in which policy and leader elections can be held and preserved with provable progress [3]. We have implemented Paxos in another research project and could add it to our server implementation at the controller/signaler layer. As long as at least half of the nodes in the cluster stay up, state will be preserved and traffic should continue to flow. V. Conclusion It is possible to achieve similar functionality to a commercial load balancer switches using only physical commodities. The OpenFlow switch provides the flexibility to implement the arbitrary policy in software and politics separate the switch itself. Since the policy is decoupled from the switch, we can avoid the machine implementation of the policy of a single point of failure and the creation of a more robust system. References [1] OpenFlow Switch Specification. Version 0. 8. 9 (Wire Protocol 0x97). Current maintainer: Brandon Heller ([emailprotected] edu). December 2, 2008. [2] Web caching and Zipf-like distributions: evidence and implications. Breslau, L. Pei Cao Li Fan Phillips, G. Shenker, S. Xerox Palo Alto Res. Center, CA. INFOCOM 1999. [3] Paxos Made Simple. Leslie Lamport [4] M. Al-Fares, A. Loukissas, and A. Vahdat. A Scalable, Commodity Data Center Network Architecture. ACM SIGCOMM, 2008. [5] C. E. Leiserson. Fat-trees: Universal networks for hardware-ef? cient supercomputing. IEEE Transactions on Computers, 1985. [6] T. Benson, A. Anand, A. Akella, and M. Zhang. Understanding Datacenter Traf? c Characteristics. SIGCOMM WREN workshop, 2009. [7] HOPPS, C. Analysis of an Equal-Cost Multi-Path Algorithm. RFC 2992, IETF, 2000. [8] W. J. Dally and B. Towles. Principles and Practices of Interconnection Networks. Morgan Kaufmann Publisher, 2004. [9] S. Kandula, S. Sengupta, A. Greenberg, P. Patel and R. Chaiken. The Nature of Data Center Traf? c: Measurements Analysis. ACM IMC 2009. [10] N. McKeown, T. Anderson, H. Balakrishnan, G. Parulkar, L. Peterson, J. Rexford, S. Shenker, and J. Turner. OpenFlow: Enabling Innovation in Campus Networks. ACM SIGCOMM CCR, 2008. [11] R. N. Mysore, A. Pamporis, N. Farrington, N. Huang, P. Miri, S. Radhakrishnan, V. Subramanya, and A. Vahdat. PortLand: A Scalable, Fault-Tolerant Layer 2 Data Center Network Fabric. ACM SIGCOMM, 2009. [12] Beacon OpenFlow Controller https://OpenFlow. stanford. edu/display/Beacon/Home. [13] B. Lantz, B. Heller, and N. McKeown. A Network in a Laptop: Rapid Prototyping for Software-De? nded Networks. ACM SIGCOMM, 2010. [14] Y. Zhang, H. Kameda, S. L. Hung. Comparison of dynamic and static load-balancing strategies in heterogeneous distributed systems. Computers and Digital Techniques, IEE, 1997. [15] OpenFlow Switch Speci? cation, Version 1. 0. 0. http://www. OpenFlow. org/documents/OpenFlow-spec-v1. 0. 0. pdf. [16] N. Handigol, S. Seetharaman, M. Flajslik, N. McKeown, and R. Johari. Plug-n-Serve: Load-balancing web traf? c using OpenFlow. ACM SIGCOMM Demo, 2009. [17] R. Wang, D. Butnariu, J. Rexford. OpenFlow-Based Server Load Balancing Gone Wild. Hot ICE, 2011. [18] M. Koerner, O. Kao. Multiple service load-balancing with OpenFlow. IEEE HPSR, 2012. Figure 2: Load-Balancer block diagram architecture using OpenFlow switch and NOX controller. Open Flow Essay Example Open Flow Essay Load Balancing Surya Prateek Surampalli Information Technology Department, Southern Polytechnic State University [emailprotected] edu Abstract—in high-traffic Internet today, it is often desirable to have multiple servers that represent a single logical destination server to share the load. A typical configuration comprises multiple servers behind a load balancer that would determine which server would serve the request of a client. Such equipment is expensive, has a rigid set of rules, and is a single point of failure. In this paper, I propose an idea and design for an alternative load-balancing architecture with the help of an OpenFlow switch connected to a NOX controller that gains political flexibility, less expensive, and has the potential to be more robust to failure with future generations of switches I. Introduction In today’s increasingly internet-based cloud services, a client sends a request to URL or a logical server and receives a response from a potentially multiple servers acts as a logical address server. Google server is said to be the best example, the request is sent to server farm as soon as the client resolves the IP address from the URL [1]. Load balancers are expensive that acts as a reverse proxy and distributes network or application traffic across a number of servers. Load balancers are used to increase capacity (concurrent users) and reliability of applications. They improve the overall performance of applications by decreasing the burden on servers associated with managing and maintaining application and network sessions, as well as by performing application-specific tasks [1]. We will write a custom essay sample on Open Flow specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Open Flow specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Open Flow specifically for you FOR ONLY $16.38 $13.9/page Hire Writer Since load balancers are not basic equipment and run custom software, policies are rigid in their choices. Specific administrators are required and also the arbitrary policies are not possible to implement. Since running policy and the switch are connected it is reduced to a single point of failure [2]. The order of magnitude will cost less than a commercial load-balancer if architecture with an OpenFlow switch is implemented which is controlled by the commodity server and also provides flexibility for writing patterns which allow the controller to be applied arbitrary political [1]. If the next generation of OpenFlow switches has the capability of connecting to multiple controllers, there is a chance of making the system much robust to abortion by keeping the any server behind the which that acts as the controller [1]. II. Background A. Load Balancing Load balancing helps make networks more efficient. It distributes the processing and traffic evenly across a network, making sure no single device is overwhelmed [1]. Web servers, as in the example above, often use load balancing to evenly split the traffic load among several different servers. This allows them to use the available bandwidth more effectively, and therefore provides faster access to the websites they host [3]. Whether load balancing is done on a local network or a large Web server, it requires hardware or software that divides incoming traffic among the available servers. Networks that receive high amounts of traffic may even have one or more servers dedicated to balancing the load among the other servers and devices in the network. These servers are often called (not surprisingly) load balancers [1]. Load balancing can be performed using dedicated hardware devices such as load balancers or having intelligent DNS servers. A DNS server can redirect traffic data centre with a heavy load or redirect requests made by customers for a data centre that is less network stretches from clients. Many data centres use of expensive hardware load balancing equipment that makes in distributing the network traffic across multiple machines to avoid congestion on a server. A DNS server resolves a hostname to a single IP address where the client sends the request. To the outside world there is a logical address that resolves a host name [3]. This IP address is not associated with a single machine, but is the type of service a client request. DNS can resolve a host name to a load balancer within a data centre. But this could be avoided for safety reasons and to avoid attacks on the device. When a client request comes to the load balancer, the request is redirected according to the policy. B. OpenFlow Switch An OpenFlow switch is a software program or hardware device that forwards packets in a software-defined networking (SDN) environment. OpenFlow switches are either based on the OpenFlow protocol or compatible with it [1]. In a conventional switch, packet forwarding (the data plane) and high-level routing (the control plane) occur on the same device. In software-defined networking, the data plane is decoupled from the control plane. The data plane is still implemented in the switch itself but the control plane is implemented in software and a separate SDN controller makes high-level routing decisions. The switch and controller communicate by means of the OpenFlow protocol. The OpenFlow switch on the other hand uses an external controller called NOX to add rules into its flow table. C. NOX Controller NOX is a network control platform, that provides a high-level programmatic interface upon which network management and control applications can be built. In brevity, NOX is an OpenFlow controller [3]. Therefore, NOX applications mainly assert flow-level control of the network meaning that they determine how each flow is routed or not routed in the network. The OpenFlow switch is connected to the NOX controller and communicates over a secure channel using the OpenFlow protocol. The current design of OpenFlow only allows one NOX controller per switch. The NOX controller decides how packets of a new flow should be handled by the switch. When new flows arrive at the switch, the packet gets redirected to the NOX controller which then decides whether the switch should drop the packet or forward it to a machine connected to the switch. The NOX controller can also delete or modify existing flow entries in the switch. The NOX controller can execute modules that describe how a new flow should be handled. This provides us an interface to write C++ modules that dynamically add or delete routing rules into the switch and can use different policies for handling flows. D. Flow Table A flow table entry of an OpenFlow switch consists of a header fields, counters and actions. Each flow table entry stores Ethernet, IP and TCP/UDP header information. This information includes destination/source MAC and IP address and source/destination TCP/UDP port numbers. Each flow table entry also maintains a counter of number of packets, and bytes arrived per flow. A flow table entry can also have one or more action fields that describe how the switch will handle packets that match the flow entry. Some of the actions include sending the packet on all output ports, forwarding the packet on an output port of a particular machine and modifying packet headers (Ethernet, IP and TCP/UDP header). If a flow entry does not have any actions, then the switch drops all packets for the particular flow. Each Flow entry also has an expiration time after which the flow entry is deleted from the flow table. This expiration time is based on the number of seconds a flow was idle and the total amount the time (in seconds) the flow entry has been in the flow table. The NOX controller can chose a flow entry to exist permanently in the flow table or can set timers which delete the flow entry when the timer expires. III. Load-Balancer Design Load balancing architecture comprises an OpenFlow switch with a control device of NOX and server machines connected to output ports of the switch server. The OpenFlow switch uses an interface to connect to the Internet. Each server has a static IP address and NOX controller maintains a list of currently connected to the OpenFlow switch servers. Each server is running web server emulation on a well known port. [pic] Figure1. Load-balancer architecture using OpenFlow switch and NOX controller The hostname of server to IP address is resolved by each client and a request is sent to that IP address on the known port number. If you consider the above diagram, when a packet is reached to the switch from the client, the header information of the packet is compared with the entries of the flow table. If the header information of the packet corresponds to an inlet of the flow, the counter for the number of packets, the byte count is incremented, and the actions associated with the input of the flow are performed on the packet. If no match is found, the switch forwards the packet to NOX. NOX decides how the packet for this flow should be handled by the switch. NOX and then inserts a new article in the cash flow of the switch using the OpenFlow protocol. To achieve load-balancing features, the modules should be written in C++ that is executed by NOX controller. NOX should perform the function of handle () when a new flow arrives at the switch. This function sets the load balancing policy and adds new rules in the flow table of the switch. All client requests should be destined for the same IP address, then whatever the module is executed by NOX, should add rules for each flow which can modify the destination MAC and IP address of the packet with a server’s MAC and IP address. The switch will forward the packet to the server output port after modifying the packet header. When servers return a packet to the client, the module adds an entry flow that changes the source IP address with the IP address of the host that the client sends its request. So the client should always receive packets from the same IP address. If the client connection / server connection is closed or remains idle for 10 seconds, then the inactivity timer expires causing the input stream to be deleted from the cash flow of the switch. This allows input stream recycling Servers wait for a NOX to register and then report their current load on some schedule similar to the Listener Pattern. NOX in a separate thread listening on a UDP socket for heartbeats with reported by server loads and maintains a table with the current loads of all servers. When applying for a new stream is received, it chooses the server with the lowest and the load current increases to the low current server. This prevents flow of all flows routed to the same server as the server reports a new load. It also breaks ties by turning it into a round robin until the servers report their actual load heartbeat. Flow Algorithm Require: Flow, path 1: sourceHost = LocateSource(flow); 2: destinationHost = LocateDestination(flow); : layer = setToplayer(); 4: currentSwitch = LocateCurrentSwitch(); 5: direction = 1; //upward 6: path = null; //list of switches 7: return search (); This algorithm works as follows. When the OpenFlow controller receives a packet from a switch, it switches the control to the load balancer. Line 1 to 6 introduces the initialization for necessary variables. The load balancer ? rstly a nalyses the packet’s match information including the input port on the switch that receives the packet as well as the packet’s source address and destination address. Then it looks up those addresses using its knowledge about the network topology. Once the source and destination hosts are located, the load balancer calculates the top layer that the ? ow needs to access. We use the search direction ? ag. The ? ag has two values: 1 for upward and 0 for downward. It is initialized to 1. A path is created for saving a route grouped by a list of switches later. Line 7 calls search () that performs the search for paths recursively. In the method search (), It ? rstly adds current switch into path. It returns the path if current search reaches the bottom layer. It reverses the search direction if current search reaches the top layer. Then it calls a method 1: search () { 2: path. add(curSwitch); 4: if isBottomLayer(curSwitch) then 5: return path; 6: end if 7: if curSwitch. getLayer ( ) == layer then 8: direction = 0; //reverse 9: end if 10: links = findLinks(curSwitch, direction); 11: link = findWorstFitLink(links); 12: curSwitch = findNextSwitch(link); 13: return search (); 14:} that returns all links on current switch that are towards current search direction. Only one link is chosen by picking up the worst-? t link with maximum available bandwidth. And then the current switch object is updated. The method search () is called recursively layer by layer from the source to destination. At last the path will be return to the load balancer. The path information will be used for updating ? ow tables of those switches in the path. Flow Scheduling The Flow scheduling functionality works as follows. Each OpenFlow switch maintains its own ? ow table. Whenever any packet comes in, the switch checks the packet’s match information with the entries in its ? ow table. The packet’s match information includes ingressPort, etherType, srcMac, dstMac, vlanID, srcIP, dstIP, IP protocol, T CP/UDP srcPort, TCP/UDP dstPort. If it ? nds a match, it will send out the packet to the corresponding port. Otherwise it will encapsulate the packet in a PACKET IN message and send the message to the controller. As a module of the OpenFlow controller, the load balancer will handle the PACKET IN message. It ? nds a proper path by executing a search with the DLB algorithm described in Algorithm 1. The path is a list of switches from source to destination of the packet. Then the load balancer creates one FLOW MOD message for each switch in the path and sends it to the switch. This message will have the packet’s match information as well as a output port number on that switch. The output port number is directly calculated by the path and network topology. If one switch receives a FLOW MOD message, it will use it to update its ? ow table accordingly. Those packets buffered on ports of that switch may ? nd their matches in the updated ? ow table and be sent out. Otherwise the switch will repeat this process. IV. Future Work The OpenFlow specification includes an optional feature that would allow multiple NOXs to make active connections to the switch. In the case then of the NOX failing, another machine could assume the role of the NOX and continue routing traffic. Naturally the system would need to detect the failure, have a mechanism to remember any state associated with the current policy, and all servers would have to agree on who the new NOX was. These requirements naturally lend themselves to the Paxos consensus algorithm in which policy and leader elections can be held and preserved with provable progress [3]. We have implemented Paxos in another research project and could add it to our server implementation at the controller/signaler layer. As long as at least half of the nodes in the cluster stay up, state will be preserved and traffic should continue to flow. V. Conclusion It is possible to achieve similar functionality to a commercial load balancer switches using only physical commodities. The OpenFlow switch provides the flexibility to implement the arbitrary policy in software and politics separate the switch itself. Since the policy is decoupled from the switch, we can avoid the machine implementation of the policy of a single point of failure and the creation of a more robust system. References [1] OpenFlow Switch Specification. Version 0. 8. 9 (Wire Protocol 0x97). Current maintainer: Brandon Heller ([emailprotected] edu). December 2, 2008. [2] Web caching and Zipf-like distributions: evidence and implications. Breslau, L. Pei Cao Li Fan Phillips, G. Shenker, S. Xerox Palo Alto Res. Center, CA. INFOCOM 1999. [3] Paxos Made Simple. Leslie Lamport [4] M. Al-Fares, A. Loukissas, and A. Vahdat. A Scalable, Commodity Data Center Network Architecture. ACM SIGCOMM, 2008. [5] C. E. Leiserson. Fat-trees: Universal networks for hardware-ef? cient supercomputing. IEEE Transactions on Computers, 1985. [6] T. Benson, A. Anand, A. Akella, and M. Zhang. Understanding Datacenter Traf? c Characteristics. SIGCOMM WREN workshop, 2009. [7] HOPPS, C. Analysis of an Equal-Cost Multi-Path Algorithm. RFC 2992, IETF, 2000. [8] W. J. Dally and B. Towles. Principles and Practices of Interconnection Networks. Morgan Kaufmann Publisher, 2004. [9] S. Kandula, S. Sengupta, A. Greenberg, P. Patel and R. Chaiken. The Nature of Data Center Traf? c: Measurements Analysis. ACM IMC 2009. [10] N. McKeown, T. Anderson, H. Balakrishnan, G. Parulkar, L. Peterson, J. Rexford, S. Shenker, and J. Turner. OpenFlow: Enabling Innovation in Campus Networks. ACM SIGCOMM CCR, 2008. [11] R. N. Mysore, A. Pamporis, N. Farrington, N. Huang, P. Miri, S. Radhakrishnan, V. Subramanya, and A. Vahdat. PortLand: A Scalable, Fault-Tolerant Layer 2 Data Center Network Fabric. ACM SIGCOMM, 2009. [12] Beacon OpenFlow Controller https://OpenFlow. stanford. edu/display/Beacon/Home. [13] B. Lantz, B. Heller, and N. McKeown. A Network in a Laptop: Rapid Prototyping for Software-De? nded Networks. ACM SIGCOMM, 2010. [14] Y. Zhang, H. Kameda, S. L. Hung. Comparison of dynamic and static load-balancing strategies in heterogeneous distributed systems. Computers and Digital Techniques, IEE, 1997. [15] OpenFlow Switch Speci? cation, Version 1. 0. 0. http://www. OpenFlow. org/documents/OpenFlow-spec-v1. 0. 0. pdf. [16] N. Handigol, S. Seetharaman, M. Flajslik, N. McKeown, and R. Johari. Plug-n-Serve: Load-balancing web traf? c using OpenFlow. ACM SIGCOMM Demo, 2009. [17] R. Wang, D. Butnariu, J. Rexford. OpenFlow-Based Server Load Balancing Gone Wild. Hot ICE, 2011. [18] M. Koerner, O. Kao. Multiple service load-balancing with OpenFlow. IEEE HPSR, 2012. Figure 2: Load-Balancer block diagram architecture using OpenFlow switch and NOX controller.