Stateless Auto Configuration Addressing With Ipv6 Computer Science Essay

Stateless Auto Configuration Addressing With Ipv6 Computer Science Essay Because of the ever increasing amount of devices that require IP addresses, IPv4 addressing will no longer be enough to provide these devices with an IP address. IPv6 was introduced to solve the problems of the exhaustion of IPv4 addresses by increasing the IP address size from 32b to 128b. This allows for more than enough IP addresses to be given out and is no chance of them ever running out. In this report you will see the different ways in which IPv6 addresses can be assigned to host machines on a network whether it be statically or dynamically. There are benefits and also drawbacks for each method which will be covered in this report. What is IPV6? IPv6 is an internet protocol which was developed to solve the problem of IPv4 address exhaustion. IPv4 uses 32b addressing so that means that it is 2^32 = 4,294,967,296 addresses. This may seem like more than enough IP addresses to provide everyone but in fact is not enough to keep up with the growing demand of IP addresses for the newer technology which requires IP addresses. IPv6 uses 128b addressing 2^128 = 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses. [1] As you can see there are a huge number of IPV6 addresses available which will almost never run out. Because of this it makes it harder for us humans to understand them in binary like in IPv4 so this is why with IPv6 they are changing to use hexadecimal instead of binary. By using hexadecimal it shortens the addresses to allot less than it would be if we kept on using binary but the drawback for this is that many people do not understand hexadecimal as most people havenà ¢Ã¢â€š ¬Ã¢â€ž ¢t seen it implemented before. Stateless auto configuration The stateless auto configuration is when host machines on a network have the ability to configure themselves with a routable IP address without the need of a DHCP server to assign it an address. The way this is done is that hosts generate a link local address for each interface connected to it but like MAC and IP addresses the link local address must be unique for each host. To make sure that all of the link local addresses are unique the host machines send a neighbour solicitation message containing its possible link local address that it wants to use. If there is a reply then it means that another host has the same address that it wants to use and so must change its possible address and send the neighbour solicitation message again until it gets a unique address it can use on its interface. Once the host has obtained a link local address its next aim is now to gain an IP address. To do this routers constantly send out router advertisements that hosts on the network listen out for and once the host receives an advertisement it then gains the network information to give its self an IP address to access the network. Advantages of stateless auto configuration are that there is almost no configuration for the client to do when it the computer tries to gain an IP address. All the client needs to do is wait on the machine getting an IP address from the information gained from the router and that is all that is required to get up and running. Another benefit of stateless auto configuration is that it does not need a DHCP server in order for hosts to gain IP addresses and even if it needs to get other information later on it can then contact a DHCP server to get other information such as DNS server addresses. A disadvantage of this method is that it doesnà ¢Ã¢â€š ¬Ã¢â€ž ¢t get the entire network configuration that it may need to be fully functional on the network. Instead it uses DHCPv6 when it has enough configuration to get reach the DHCPv6 server to get the rest of the configuration. This is not good as it would be more efficient to get all of the needed configuration by using stateless auto configuration. [2] Stateful auto configuration Stateful auto configuration is similar to DHCP in the way that IP addresses are given out to hosts on a network by using a server. Even though with IPv6 and its massive amounts of IP`s it is still a good idea to use a server to manage IP`s for companies to control and easily maintain what computers from each room or department are connected to the router. It also allows you to easily change the configuration of the network if needed from a central point in the network, this case being the DHCPv6 server and change settings such as the DNS server and the range of addresses to provide to hosts and this will also update to the clients when they are due to renew their lease. Stateful auto configuration is used when there is no router on the link that is advertising router advertisements to provide the information to give its self an IP address. Instead it goes to a DHCP server that issues the host with all of the required configuration to get access to the network. A disadvantage of stateful auto configuration is that it needs a DHCPv6 server in order to get an IP address and if the DHCPv6 server goes down then there is no way for hosts to get network configurations unless there is a router on the link that is advertising router advertisements. But in the worst case scenario when their being no router available then there is no way for hosts to get assigned an IP address. DHCPv6 DHCPv6 is the protocol that has been developed to work with IPv6. It allows for hosts on a network to gain an IP address and other settings like DNS and default gateway from the DHCPv6 server by using statefull DHCP. The hosts make contact to the DHCP server by using multicasts and also using the UDP protocol. Below is information on the different messages that are exchanged between the host and the DHCP server in order for the host to gain a valid IPv6 address and get access to network resources with the address given to the host. Solicit This is when the client first makes contact with the DHCP server. Advertise This is when the DHCP server sends an advertise message saying that it is available to assign IP addresses to the client. Request The client machine now sends a request message to the server requesting an IP address and other information such as DNS, Default gateway. Confirm The client now sends a confirm message asking if the information is still valid since the IP address was given out. Renew This is when the clients DHCP lease time is running out and needs to be extended or given out a new IP address. With DHCP is it most likely during a renew process that the IP address will be extended to the client. Rebind This is similar to the renew message but with the rebind message the client contacts the server to increase its lease time but is also able to update any changes to other network configuration such as the DNS servers without changing its IP address Reply This is when the server sends a reply message with network configuration information in response to a solicit, request, renew and rebind messages received from the client before. The server then sends another reply message to confirm that the configuration that the client has received is appropriate for that network the client is connected to. Release The release message is used to indicate to the DHCP server that the client will no longer use the IP address and that the IP address the client had can go back into the address pool for another client to use. Decline The decline message is sent from the client to tell the DHCP server that the IP address given out from the server has already been assigned to another host on the network. Reconfigure This message is sent from the DHCP server to inform the client that there is new configuration on the network and the client must then send a renew and reply message in order to receive the updated information. [3] Conclusion IPv6 is a vast improvement on the previous IPv4 protocol with the ability to provide almost unlimited IP addresses to hosts. The two ways in which hosts can gain an IP address are both adequate ways to distribute IP addresses but there are disadvantages with both stateful and stateless auto configuration. Because stateless requires that there must be a router that is advertising router adverts then it means that if there is no router then of course also means it cannot gain its IP address by using stateless configuration. Another disadvantage of this is that the router advertisements do not provide the hosts with all of the network configuration that it may need and then the host has to go to a DHCPv6 server using stateful configuration to get the rest of the configuration. There are also disadvantages for stateful addressing too in that if there is no DHCP server available then it cannot issue IP addresses to hosts. But out of the two auto configurations I would choose stateful to be the best method of issuing IP addresses because it allows for a remote server to distribute address and you can easily change the network settings on the DHCP server and it will also update the clients on the network. It also allows for more control on who gets what range of IP addresses and lets you easily manage IP`s to be issued to certain departments or rooms in a company so you can monitor the machines more easily.

I Am the Grass Essay Essay

Am the Grass is a short story written by Daly Walker, who has also written other short stories for The Sewanee Review and The Sycamore Review. Born in Winchester, Indiana in 1924, Daly Walker is a surgeon by trade and started to write after he was forty. Daly also served in the Vietnam War from 1967-1968, it serves as an inspiration for I Am the Grass. The story details a mans struggle of life after the war in Vietnam, and returning to Vietnam. This includes painful psychological trauma, the feeling of guilt for his actions, and finally his attempt to redeem himself in his own eyes. At the start of the story we read about assorted atrocities committed during the Vietnam War by a nameless man, who is the main character. They include raping a thirteen-year old girl, decapitating a man with a machete, and throwing defenseless prisoners off of a helicopter. Along with the atrocities, the reader sees a battered past and something that haunts the main character . The story also goes on to explain how after the war, the main character goes on to medical school where he becomes a successful plastic surgeon. The main character also describes the fear that comes back to him when anti-war protestors blow up a classroom while he’s asleep. It takes him back to the attacks done on his base while he was in Vietnam, he goes on to explain that even though the he has left the war, â€Å"the war has followed him home† (316). The main character shows how he tries to redeem himself for the bad he has done. This includes going to impoverished countries to repair deformities on people who can’t afford plastic surgery. He explains â€Å"how it makes me feel like a decent man, a healer† (317). This shows how it feels good for him to heal people as opposed to feeling good killing them when he was younger. After the minor back-story and introduction to his past and inner-demons, the main character is on a plane headed to Vietnam. Ironically, this time to help the people he once did horrible things to. He is taken around the countryside, where he recognizes many of the nicknames of the roads soldiers gave. Then he is introduced to another surgeon, one who he would have originally called an enemy, to take him to those in need of the surgery. In nother twist of irony, the Vietnamese â€Å"surgeon† is missing his thumbs. This prevents him from performing surgery unlike the main character. They both talk about fighting each other in the war and then go forth to perform the surgeries on the people who needed them. As the story continues, the narrator, has been successful in 18 surgeries and feels good. Until he has to â€Å"make a difficult decision†(320) when the thumbless Vietnamese surgeon asks him to perform a â€Å"difficult surgery†(321) on him. A surgery where the big toe of the foot is transplanted to where the thumb once was. Despite the risk and lack of any more advanced medical tools, the narrator decides to go forward with it. This shows that the narrator is willing to do an extremely difficult surgery without the proper tools, so that perhaps he may find some peace in himself. Yet the dreams of the man he decapitated still haunt him, even on the eve of the big surgery. While he prepares himself, the narrator explains the feeling as â€Å"a sense of power that has been in no other place but surgery, except when my finger was on the trigger of an M60† (324). He starts and is meticulous in using the primitive medical instruments provided to him. He feels as if he has done a good job and even forms a steady friendship with the Vietnamese surgeon. However, the day he has to leave, it goes south. The main character goes to unwrap the bandages and finds that the transplant has failed, as the implanted big toe has rotted. Furious at himself, he removes it before he leaves. In an attempt to make himself feel better, it is shown how the main character hopes to see the thumbless surgeon at the airport. Perhaps saying bye to him and thanking him for his efforts. However there is no one there, on the flight home though, he realizes that the risk involved with Vietnam made him feel like a part of the country. He comes to see that he embraces the risk and everything that comes with it. I Am the Grass is presented as a story that is simple to understand, but also has an emotional effect. Walker gives us a character with a detailed past, a very good storyline, and the setting and theme of redemption which is present throughout the whole story. The theme of redemption is supported throughout the story. The main character tries to redeem himself in his own yes by doing surgeries for free in impoverished nations. Also, when he takes on the risky task of the toe transplant. It leaves the reader wondering, what if it would have worked? Would he have calmed his conscience of reminding him about the past atrocities he committed? The story, which begins by describing very graphic atrocities, turns into a story of more peace than war. One where the narrator has lost himself in the scourge of war, but is trying to find himself by using his talents for good. Trying to find inner-peace from his personal demons. It comes together near the end of the story. When he finds out the transplant didn’t work and he wants to leave immediately. But contrary to his expected reaction, the Vietnamese surgeon calmly tells him to remove it, which the main character does. In a way he faced his own inner demons despite the disappointment. Walker’s decision to make the setting a run down dirty hospital isn’t one that a lot of people can relate to. However, the message of redemption is one that a lot of people can. The conflict he delivers is one that is present in others, just not in the form of war crimes and surgeries. That’s something that a lot can relate to. In this story, Walker has shown a veteran who is haunted by his past and tries to redeem himself. It delivers a powerful message on how the road to the inner-peace of a person is faced with many challenges and setbacks. Ironically, amidst the moment of disappointment, the character realizes that he has come to accept the risks he took in life, along with the consequences. There he finds at that moment of redemption that he had long been looking for.

Background of Daoism and Confucianism in China and its Influences

Confucianism has been very essential in the preservation of the Chinese civilization. It is embodied by the teachings of Confucius and Mencius, supported by the followers until the modern ages. The Neo-Confucianists of the Sung and the Ming periods instilled some teachings of Daoism’s naturalism (Wen-shun, p. 123) Confucianism shaped the national character of what we know as the China of today. It has also permeated the aspect of the society which involves family, arts and literature, and all the virtues of human relationship.All that embraces the Confucian teachings worked in two ways. It affected the ideologies and way of thinking of the writers who still follow the tradition, and even those who are not into it. Daoism took over the disordered state of the country, where there is man’s disappointments in his personal life, which can be associated to worldliness. On the other hand, Confucianism came victorious in times of tranquility and success (Wu-Chi, 1990, p. 4) Th e western beliefs contribute to the deviation of the anti-Confucian literary artists who influence a lot the people of China.Even the normal people of the modern times instill to them the reasons of not inclining themselves anymore on the Confucian dogma. Because of these western influences, the influence exerted by Confucianism in modern China has gone lower dramatically. The promotion of science in modernization, together with the growth of democratic thoughts made Confucianism unsuitable to modern China (Wen-Shun, 1992, p. 200). Still, many political thinkers agree, like for example, Ch’en, that dealing with modernization does not require involvement of the western or any foreign ideas.China’s modern world has increasing debates whether the influence of Confucianism has a negative impact on the country’s economic development. Confucianism teaches that the profit orientation of a government or a society negates virtue, which is emphasized by capitalism. Confuc ius continues in his articulation against the capitalistic China that he would not engage himself on such wrongdoings even if it is for the betterment of the society (Killion, 2006, p. 32). Daoism thrives on achievement of perfection against the politics of imperial administration (Woodhead, 2001, p.93).Perfection is equated to immortality; the ‘dao’ or ‘The Way’ being the force of the universe where people are inclined to be one to it. Dao is a metaphysical, at the same time, philosophical conception, which is synonymous to the ‘nature’ being used by the Greeks. The meaning creates thinking about generation and regeneration which controls the existence of things in the moral influence. In Confucianism, the principle of the ‘heavenly order’ is emphasized, while in Daoism, it is only ‘The Way’ itself.Daoism created a number of hermetic traditions. In addition to it, the traditions of the lay liturgy have also been influ enced. The highlight of their teachings is on the exorcism and healing. Under the emperors, these teachings were approved, and have turned from a heart of texts to a canon law. The presence of Daoism in the China today does not articulate optimistic speculation that the age-old Daoism has come back in the modern China. They have no doubt that it is still the Daoism in the past that revolves around China in the modern times.There is a struggle against the anti-religious policies and government officials who create misinterpretations of the Daoism dogma. The Chinese local culture has been influenced by Daoism, that it lives in every home. The negative aspect is that the local policies and the openness of controlling these local policies control the balance regarding the religion’s existence. Even so, Daoism influence the school systems and the medical systems in China that leads them to the road of modernization (Pui-tak, 2006, p. 47). It still lives in the rural areas of China , although many Daoists are being oppressed by the government.

Lightening vs. Lightning How to Choose the Right Word

The words lightening and lightning look and sound similar, but their meanings are very different. The former is a verb, while the latter can be either a noun or an adjective. How to Use Lightening The word lightening is the present participle form of the verb lighten, which means to make lighter or brighter. Lighten can also mean to make happier or less serious (as in lighten the mood). As a present participle, lightening is often used in the continuous tense to indicate simultaneous actions: The painter mixed some white into the blue, lightening the color. In this sentence, the blue is lightened as the painter adds the color white; both actions—the mixing and the lightening—occur at the same time. How to Use Lightning The noun lightning refers to the flash of light that precedes thunder, the result of electrical activity in the atmosphere. As an adjective, lightning describes things that happen—like a flash of lightning—very suddenly or quickly. For example, a runner who outpaces her competitors might be described as moving at a lightning pace. Examples Lightening always refers to a change in condition that results in something becoming brighter, less heavy, or less serious than it was before: The sky was lightening as the sun rose over the hill.Her son helped carry some of the groceries home, lightening her heavy load.Putting on a funny movie is one way of lightening the mood. As a noun, lightning refers to the atmospheric phenomenon that produces a bolt of light in the sky: He saw lightning in the dark clouds; a few seconds later he heard thunder. Lightning can also be used as an adjective to describe lightning-related nouns: A narrow lightning rod was positioned at the top of the church steeple.The meteorologist reported that a lightning storm was headed their way. As an adjective, lightning can also modify nouns that relate to pacing: When he got the call for help, he rushed away at lightning speed.The conductor raced through the final movement, waving his arms and giving the music a lightning tempo. How to Remember the Difference The only difference between lightning and lightening is a single syllable, but that wasnt always the case. For several centuries, writes scholar Roy Blount, Jr., the job of representing aerial bolts of electricity was up in the air, flickering back and forth between lightning and lightening. The spellings eventually settled, and the two-syllable lightning became the word for the electrical phenomenon. To keep the terms straight, remember that lightning appears in the sky for a short moment, and lightning has fewer syllables than lightening. You can remember the definition of lightening by thinking of the rhyming words brightening and whitening. All three of these words refer to a change in state or condition: to make something lighter, brighter, or whiter. If the context calls for a verb, you should use lightening. Sources Blount, Roy Jr.  Alphabet Juice: The Energies, Gists, and Spirits of Letters, Words, and Combinations Thereof. Farrar, Straus and Giroux, 2008, p. 172.