Routers and routing algorithms

telecommunications networks. data - is. routers. (routers), called in English vellum and routers.

I think our readers understand how the general functioning routers, how to manage the network and allow traffikomi find the best route for data transmission (we 'll talk about the packets of information). In this paper we consider routing algorithms - how to find these optimal routes.

basics.

To find the shortest network path that is the way with a minimum of transportation between the routers to the time the inevitable delay in switching, routing algorithms use some.

Based on how routers gather information about the surrounding network, we can distinguish two major routing algorithms: centralized (global routing algorithms), and ( distributed ), decentralized (decentralized routing algorithms). As part of a distributed algorithm, each router has information on routers with which it is directly connected, he does not know about all routers in the network. This algorithm is also known as DV (distance vector). In a global, centralized routing, each device has information on all routers in the network and the state of the network data transfer. Another name for this algorithm - LS (link state).

LS- algorithm ( centralized routing).

By using this LS- algorithm, each router must sovresh sleduyuyuschie steps:.

a. Identify devices that are physically connected with it and get their IP- addresses. When the router is a network, it first sends a sort of 'Hello'- packet in the network and each router that receives such a message, sends a response containing the IP-address.

2. Measure the time delay (or average data rate ) for the neighboring devices. In order to do that, routers send echo- packets into the network, which receive the appropriate response. Dividing the time of the request on the road for 2, one can calculate the time delay, and at this time will be laid down as the period of delay in packet processing by routers.

3. Broadcast the information about the structure of its network segment and receive relevant information from. other routers. At this stage, routers determine the best routes for each node using a known algorithm for finding the shortest path Dijkstra (Dijkstra). Under this method, the router is based on information gathered builds a network graph showing the relative positions of routers and networks between. Each vertex of this graph is marked with numbers, called weights. It is an indicator that reflects the time delay, and sometimes the number of transitions between nodes. Thus, to establish a connection, the router uses the path with the lowest weight assigned to the nodes in the path.

Pros and cons.
ease of implementation.
- complexity of the topology change and load.
- there is no exchange of routing data between two routers.

DV- algorithm ( decentralized or distributed routing).

Algortitm distributed routing, also known as Bellman- Ford algorithm (Bellman-Ford) and Ford - Fulkerson (Ford-Fulkerson).

Also known as Distributed Bellman-Ford Routing or Ford Fulkerson Algorithm. It can be metaphorically described as: ... Each router maintains a routing table with one entry for each node in the subnet. The table is a vector containing two components: the selected line and the distance. A node estimates the distance ( number of hops between nodes, delay or queue length ) to each neighboring device and sends it to his neighbors, who repeat these steps. As a result of the information collected, each. router. again generates a routing table.

That is, the router performs the following actions:.

a. Assesses the weight of links directly related devices.

2. At certain times of sending this information to the neighboring router it gets relevant information from a neighboring router.

3. Based on this information builds or updates its routing table.

Pros and cons.
Self-Organization.
the relative ease of implementation.
low - convergence, or ...
- expansion of the network due to some difficulties.

The hierarchical (mixed ) routing.

The distributed and centralized routing is inevitably hampered the growth of network nodes. To solve this problem is designed hierarchical division of the network.

In hierarchical routing, the routers are divided into groups. Each router only contains information about the routers in the group and has no information about the routers and the other groups. Moreover, groups can be nested, allowing you to distribute routing information. Such a scheme can be used multiple routing protocols within the group and is widely distributed on the Internet.

Source:. http://computer. howstuffworks. com /.

Why do celebrities get dates

Drugs, alcohol, violence. In recent years, the classic formula of show business has undergone significant changes. Not that rock 'n ' roll and sex have ceased to arouse interest, just to pay for it became more. And for shooting in Hollywood, too. The extra millions often do not go for the future stars of show business and go for drugs, fast cars and. lawyers. A long list of celebrities who have trouble with the law, plunges into shock any lawyer, and fans can only marvel at the adventures given to his favorites.

This is an environment (in this case show business ) has a corrosive effect, or only people with such qualities, are able to achieve success? . In any case, some of the symptoms of the disease are a stellar criminal offenses. Luckily, a lot of celebrities and those who have never sat in the dock. But it is not about them.



The most star- spot on the planet - Hollywood. That there is something going on, and most of all violations of law by the heroes of gloss and big screen. However, for drunk driving anywhere on the head did not pat. But Hollywood's laws regarding alcohol are extremely harsh. The loudest event - the sad story of Paris Hilton. She was detained in September 2006 for driving while intoxicated. Then the Paris court sentenced to a fine and three years probation and ordered to attend a course about the dangers of alcohol. It seems that windy little blonde, this case has taught, because in February 2007 she again seriously violated the rules of the road. Paris riding at night without lights. According to police, her car was raced at high speed. For violation of probation in May 2007, California Court sentenced a secular lioness to 45 days in jail. But the most severe punishment awaited her in front of. After this scandal Paris grandfather, Barron Hilton, deprived of its multimillion-dollar inheritance.

Not so disastrous were the consequences of drunk driving for Mel Gibson. In August 2006 he was sentenced to three years probation. ' Peppercorn ' this case has given the fact that the director of the movie ' The Passion of the Christ ', not only was drunk and was driving with a large excess of the speed - when he allowed himself to arrest a number of very stringent anti-Semitic remarks. Most likely, this is what the court found an aggravating circumstance. But it appears that Gibson is so severe sentence has gone to benefit: for the last 2 years the actor has never been detained by police.

However, the star alcoholics - is the lesser of evils of Hollywood. In the life of celebrity parties happen almost every day. But only some get-togethers it does not end with tequila. You're rich and famous? . And the drug - even a star - in most countries are not particularly zhaluyut. Prohibited substances ' helped ' to create many writers, musicians and actors from time immemorial. But now a celebrity, apparently relying on the talented lawyers, began to appear more and more drugs. Even Whitney Houston, I remember, in 2000, was arrested at Honolulu Airport for possession of marijuana. On smoking ' weed ' in 2004 and got the movie star of ' Home Alone ' actor, Macaulay Culkin. Later, the court sentenced him to one year of probation.

But in most cases, in criminal cases of celebrities appear harder drugs marijuana. Most cocaine. Indicative of the recent Lindsay Lohan, actress verdict. In August 2007 she was sentenced to one day in prison after being admitted to driving while intoxicated and possession of cocaine. She was also prescribed 10 days of work on a voluntary basis and the rate of drug release. In addition, the next three years it will be under special control of police.

And just this past February was caught with cocaine -known French writer Frederic Beigbeder. Police arrested the Franks '99 's ' and his friend at a time when they sniffed the powder with the writer's car hood. Later released Beigbeder. But now for some time, he will be under police surveillance.

But the loudest cocaine scandal last year did not take place in France and even in Hollywood, and in the UK. Lawyers for the well-known singer Pete Doherty, leader of the group Babyshambles, worthy of applause. As a result of their masterly work of Doherty twice in 2006 was able to avoid prison. Both times, the singer was accused of possession of cocaine, but he escaped with only a fine.

However, even before the arrests in 2006 Doherty has repeatedly caught with banned substances: in his ' honor list', except for cocaine and heroin appear, marijuana and crack. And in 2005 he was involved in an unpleasant history with his then girlfriend, model Kate Moss. Then in the leaked photos, which Kate Moss sniffing cocaine in Babyshambles studio. The scandal nearly cost model career. However, the wave of condemnation and the contracts terminated subsided after Moss issued a public apology and has been treated for drug addiction. But the resonance that made ​​the case, was much more noticeable than first thought. Doherty and Moss came to the pages of the annual report of the UN agencies. drug trafficking. Now, if Doherty will fall once again on drugs, fine it just does not get rid of. As, however, and singer Amy Winehouse, who also was recently arrested for Cocaine.

Obviously, the star of addicts in London, no less than Hollywood. In October 2006, in the northwest of the capital of the British formed a traffic jam. The culprit turned out to be its well-known musician George Michael. He just fell into a drug stupor while driving. Arriving on the scene, law enforcement officers arrested the singer, and later released on bail. Later, the court sentenced George Michael to 100 hours of community service, and deprived of his right to drive a car for 2 years.

2006 was rich in the harsh sentences and trials. In October the Court in Manhattan sentenced another famous singer and show- Names Boy George to five days of community service and fined one thousand dollars and $ 160 court costs. In addition, the singer was obliged to undergo treatment for drug dependence. All of this was the consequence of a paranoid call to the police. Apparently, in a fit of panic drug Boy George called police and said that his apartment was robbed. Arriving at the place of the ministers of law and order found in luxury apartments singer traces of cocaine, and the singer in a deranged state of.

Not a Boy George have problems with the nervous system due to drug use. Everyone knows the story of Britney Spears, which for some two years into a hysterical aggressive. Even before the singer denied the right to motherhood, the court ordered her to pass weekly tests for drugs, the reason - the testimony of the former bodyguard of Britney. In court, he said that after the passage of drug treatment in the clinic, Spears took banned substances, appeared naked in the presence of children, and are not paid enough attention to their safety.

But inappropriate, aggressive behavior of stars is not always due to drug use ( but who knows ). In any case, the investigation has not revealed in the blood of Naomi Campbell banned substances, although earlier top-model have repeatedly figured in scandals related to drugs. At this time, Campbell distinguished by the fact that the maid has launched its mobile phone. The maid Ana Skolavino sued. As a result, Naomi Campbell was sentenced to five days of community service.

The behavior of Russell Crowe is very similar to the wrath of Naomi Campbell. Winner of Oscar threw the phone in the clerk a New York hotel, for which shlopotal fine $ 160.

We should also say about the fights with the paparazzi celebrities. Although judges and realize that photographers ubiquitous in many cases are well-deserved, but some celebrities aggressive resistance to intrusive paparazzi turns into a criminal record. In these scandals were lit by stars such as Jude Law and Cameron Diaz, even.

But the lead in the degree of inadequacy of behavior - who would have thought! . Both have extensive criminal behind the experience. Tyson was a child caught stealing in the pocket. Since then, the Court of Tyson began to appear a little less than in the ring. In 1992, the boxer who has been 6 years for rape. But out in 3 years for good behavior. We will not be considered a criminal offense that, in 1997 Tyson bit off part of the ear to his opponent around the ring. That business is not engaged in court and sports authorities. But the story of 2001 is even more revealing. Boxer received a year in jail for having attacked a motorist during a road accident. True, he spent only 3 months and then released for good behavior.

Well, aggression Tyson is quite clear: the profession of a. A systematic violence by themselves Naseri anything other than stellar disease can not be explained. Nongray received time ( no more than 10 months ) for fighting, assault on a fashion designer, racist remarks against a police officer. Perhaps accustomed to the image of a tough cabbie.

However, there are just too inexplicable actions. Where, for example, lie causes a daring robbery, which made ​​Winona Ryder? . In December 2001 she brought out of the store Saks Fifth Avenue for more than 20 items totaling $ 5000 $ 600. Los Angeles court sentenced Ryder to three years probation, community service and fined 10,000 dollars.

Individual attention from the criminal history of the world rappers. Those belonging to the counter-culture requires at least once to light up in a criminal case. Therefore, it makes no sense to list all - too long a list will. Suffice it to say that 50 Cent haggling ' junk ', and Snoop Dogg accused of arms trafficking. It is honorable for the present article ' gangsta rappers '. Until recently known in the rap coterie jeweler Jacob Arabo was arrested for money laundering at his store in Manhattan. According to prosecutors, they were able to prove that Jacob was leading a double entry bookkeeping, in parallel with the jewelry business to launder money to drug dealers in Detroit, referred to as the Black Mafia Family. In the current case, the investigation which was carried out about 7 years old, were arrested another 41 people: the group were charged with distributing more than 476 kilograms of cocaine and laundering profits in the amount of $ 270 million. Now the Arab threatens about 36 years in prison - an unprecedented period for this level of celebrity.

As can be seen, with few exceptions, the stars, even for serious crimes get off relatively mild punishments. They get away with a lot. And the cost of lawyers kept in the strictest confidence. But this does not mean that crimes of celebrities are role models.




Discuss.

I want to Kirov!

Kirov librarians to their professional holiday will receive 10 thousand. rubles.

This March 4, said regional governor Nikita Belykh at a meeting on the development of culture.

... - And today I want to say that we have not forgotten about the library staff. By the All-Russian Day of libraries as they will be paid bonuses of $ 10 thousand rubles ... Recall libraries otmchaetsya day May 27.

Source - News of the Kirov region.