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| Technicalities from Geekdom | |
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| Tweet Topic Started: Feb 9 2005, 06:42 PM (325 Views) | |
| sourabh_soni2k2 | Feb 9 2005, 06:42 PM Post #1 |
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Sourabh Soni
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Freinds this is new topic to get knowledge from technical world . so whatever you come across from technical world please post it here so that it may help our juniors as well as other colleagues . What is Wi-Fi??? Short for wireless fidelity and is meant to be used generically when referring of any type of 802.11 network, whether 802.11b, 802.11a, 802.11g, dual-band, etc. The term is created by the Wi-Fi Alliance, an organization made up of leading wireless equipment and software providers with the missions of certifying all 802.11-based products for interoperability and promoting the term Wi-Fi as the global brand name across all markets for any 802.11-based wireless LAN products. While all 802.11a/b/g products are called Wi-Fi, only products that have passed the Wi-Fi Alliance testing are allowed to refer to their products as "Wi-Fi Certified" (a registered trademark). Products that pass are required to carry an identifying seal on their packaging that states "Wi-Fi Certified" and indicates the radio frequency band used (2.5GHz for 802.11b or 11g, 5GHz for 802.11a) This group was formerly known as the Wireless Ethernet Compatibility Alliance (WECA) but changed its name in October 2002 to better reflect the Wi-Fi brand it wants to build. ===================================== What is 802.11a/802.11b/802.11g?? 802.11a/b/g, or IEEE 802.11a/b/g, is a standard that has been developed by the IEEE (Institute of Electrical and Electronic Engineers), http://standards.ieee.org . The IEEE is an international organization that develops standards for hundreds of electronic and electrical technologies. The organization uses a series of numbers, like the Dewey Decimal system in libraries, to differentiate between the various technology families. The 802 committee develops standards for local and wide area networks (LANs and WANs). For example, the 802.3 committee develops standards for Ethernet-based wired networks, the 802.15 group develops standards for personal area networks, and the 802.11 committee develops standards for wireless local area networks (LAN). 802.11 is then further divided: 802.11b, or Wi-Fi, is a standard for wireless LANs operating in the 2.4 GHz spectrum with a bandwidth of 11 Mbps. 802.11a is a different standard for wireless LANs operating in the 5 GHz frequency range with a maximum data rate of 54 Mbps. Another draft standard, 802.11g, is for WLANs operating in the 2.4 GHz frequency but with a maximum data rate of 54 Mbps. Other task groups are working on enhanced security (802.11i), spectrum and power control management (802.11h), quality of service (802.11e), etc. ===================================== What is the difference between a Gateway and a WAP (Wireless Access Point)??? There are two types of Wi-Fi wireless base stations: a gateway and an access point. However, the distinctions between the two are not always clear, in part because the functions they perform can overlap. Even more confusing, many wired devices and other home Internet appliances also call themselves gateways. A wireless gateway is targeted toward a totally wireless home or small-office environment; an access point is targeted toward a more integrated combined Ethernet and wireless environment-usually - larger businesses, campuses, or corporations. Gateways and access points can also differ regarding their capacity to perform security functions, provide firewall protection, and manage network traffic and tasks. Gateways often include NAT (Network Address Translation) routing and DHCP (Dynamic Host Control Protocol) services. These create and provide the individual IP addresses all the wireless (and wired) clients need to function in a network and also enable a single Wi-Fi gateway to simultaneously provide Internet access to numerous users from a single shared Internet connection . Gateways may also include other applications and features such as encryption and security, VPN, firewall, and Voice over Internet Protocol (VoIP). An access point does not usually have NAT routing or DHCP; the wired routers in the system provide those network functions. Access points work as merely transparent bridges between wired networks and the various wireless users throughout a facility. Even though access points generally do not provide NAT or DHCP, they usually enable roaming (the ability to move from one access point to another without losing contact with your network), higher levels of security, and a high level of network control and management. Some gateways also provide these services. In fact, by toggling certain functions on and off, many wireless base stations can operate either as a gateway or as an access point. But a gateway is usually the only wireless base station in a small office or home, whereas in a large office or campus there might be hundreds or thousands of access points forming one or multiple overlapping wireless networks. ===================================== How do I use my Wi-Fi laptop when I am traveling? Just find a Wi-Fi network to which you can connect. These networks are becoming common in cities and towns worldwide — Internet cafes and coffee shops are popping up everywhere! — as well as in public areas like airports, hotels and convention centers or anywhere people gather. Some wireless HotSpot networks require you to manually configure your access connection; others work with your Wi-Fi radio to automatically log on. In addition, many large businesses and universities are providing wireless access to visitors and guests at their locations. |
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--= Yes..I'm the man =-- -== who sold the world ==- [size=7]Sourabh Soni[/size] TATA CONSULTANCY SERVICES Chennai sourabh_soni@yahoo.com | |
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| sourabh_soni2k2 | Feb 9 2005, 06:47 PM Post #2 |
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Sourabh Soni
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Why do I need to know what NAT and DHCP are? NAT stands for Network Address Translation and enables your Wi-Fi gateway to share a single Internet connection among all the computers in your home or business. DHCP (Direct Host Configuration Protocol) is what enables your network to use TCP/IP to connect the different components. There are various networking protocols. Most Wi-Fi gateways for homes and small businesses provide both NAT and DHCP. In general, if you are setting up a stand-alone wireless network, you want NAT and DHCP. If you are adding a wireless gateway to an existing wired network, you probably want to turn off the NAT and DHCP functions built into your wireless gateway and have it function as a wireless access point. ===================================== What is the range of a wireless network? Range varies in a Wi-Fi network depending on the type of Wi-Fi radio you have, whether or not you use special antennas, and whether your network is in an open environment or in a building with lots of walls and furniture. The composition of your walls and floors can also have a major impact. Wi-Fi is a very low powered radio signal and does not penetrate metal, water or other dense materials. A Wi-Fi network generally provides a range of about 75 to 150 feet in a typical home or office. In an open environment like an empty warehouse or outdoors, a Wi-Fi network may provide a range of up to 1,000 feet or more. With the right antennas and optimal placement, a range of up to a mile is possible. With Wi-Fi technology, a "gradual degradation" in range occurs. This means that, instead of stopping all together, your data transmission rate just becomes slower as you move farther away from the access point. For example, with Wi-Fi 802.11b technology, within 100 feet of the access point, the Wi-Fi radio in your laptop computer will get about 11 Mbps data rate. As you move farther away, that rate will drop down to 5.5 Mbps, then to 2 Mbps and finally to 1 Mbps. Considering that many DSL and cable Internet connections are less than 1 Mbps, this connection speed is still very good. See What Range Can You Expect from Your Wi-Fi Network. ===================================== Will my microwave oven or cordless phone interfere with my Wi-Fi network? Microwave ovens and many cordless phones operate in the 2.4 GHz spectrum, the same radio spectrum used by 802.11b/g Wi-Fi wireless networks. That means they can cause interference — but in most instances this will just slow down the Wi-Fi connection; it won't stop transmission or break the connection. To reduce interference, you can move a 2.4 GHz cordless phone away from your Wi-Fi equipped computer or base station. Interference usually only happens with older microwave ovens. You can also try changing the channel on which your Wi-Fi network operates . In addition, some manufacturers have developed and implemented special technologies that can minimize interference from cordless phones and ovens. Check with the manufacturer for specific instructions for your equipment. __________________ |
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--= Yes..I'm the man =-- -== who sold the world ==- [size=7]Sourabh Soni[/size] TATA CONSULTANCY SERVICES Chennai sourabh_soni@yahoo.com | |
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| vinodbang_cse03 | Feb 10 2005, 11:44 AM Post #3 |
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BITALUMNI SITE FAN
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Good topic to start with. May be this link will help you all to know more....really a good one!!! www.howstuffworks.com |
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Regards, Vinod Bang, Satyam Computer Services, Hyderabad vinodbangmail@yahoo.com 098660 89654 | |
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| ADMIN_MANISHCSE03 | Feb 10 2005, 08:02 PM Post #4 |
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Administrator
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Buddy.. I never thought about our BIT site with the technical point of view.. The site can be a pool technical stuff too... Am really impressed by this post of yours... And I will talk with other administrators of the site to start a technical section seperately for the site too.. Gr8 going man, :blue: |
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| sourabh_soni2k2 | Feb 12 2005, 06:07 PM Post #5 |
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Sourabh Soni
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A must resd for DOS Attacks . final year students can make their project on DOS attacks . check it out . www.webopedia.com/TERM/D/DoS_attack.html www.denialinfo.com/ staff.washington.edu/dittrich/misc/ddos/ www.irchelp.org/irchelp/nuke whatis.techtarget.com/definition/ 0,289893,sid9_gci213591,00.html www.internetweek.com/newslead01/lead020501.htm www.pentics.net/denial-of-service/ |
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--= Yes..I'm the man =-- -== who sold the world ==- [size=7]Sourabh Soni[/size] TATA CONSULTANCY SERVICES Chennai sourabh_soni@yahoo.com | |
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| sourabh_soni2k2 | Feb 22 2005, 05:14 PM Post #6 |
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Sourabh Soni
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4 all those environmentally conscious people here's some good news:the kyoto protocol has finally born into existence.so whats it all abt. hers's an insight KYOTO PROTOCOL The Kyoto Protocol, negotiated by more than 160 nations in December 1997, aims to reduce net emissions of certain greenhouse gases (primarily carbon dioxide (CO2)). Each of the participating developed countries must decide how to meet its respective reduction goal during a five-year period (2008-2012); but specific ground rules remain to be worked out. "Carbon Price" For a Range of Deviations From 1990 Carbon Emission Levels ------------------------------------------------------------ ----------- To reduce carbon emissions, EIA assumes that a "carbon price" is added to the price of delivered energy fuels based on their carbon content. For example, coal prices rise more than petroleum and natural gas prices; and the cost of generating electricity from non-carbon-emitting nuclear and renewable fuels is not increased due to the carbon price. Although electricity does not have the carbon price directly added to it, its price is increased due to the higher cost of fossil fuels used for generation. The price increases encourage a reduction in the use of energy services (heating, lighting, and travel, for example), the adoption of more energy-efficient equipment, and a shift to less carbon-intensive fuels. The carbon price reflects the amount fossil fuel prices in the U.S., adjusted for the carbon content of the fuel, must rise to achieve the removal of the last ton of carbon emissions that meets the carbon reduction target in each case. All Sectors Need to Adjust; Motor Vehicles Face Main Non-Electric Impact ------------------------------------------------------------ ----------- EIA assumes that carbon prices would be imposed at the point of consumption--raising the "delivered" prices of both primary fuels and electricity across the board. Because various fuels face different price increases (based on their different carbon contents), all end-use sectors will not be affected identically. History has shown that residential, commercial, industrial, and transportation users of energy react differently to price changes. As energy costs rise, all consumers tend to use less. In the broadest terms, the required carbon reductions could prompt the nation to lower "energy intensity" (the quantity of energy consumed per dollar of Gross Domestic Product) as much as three times faster between 2005 and 2010 than in the Reference Case. The rate of decline slows after 2010 reaching a decline rate from 1.4 to 1.7 percent for the 2005 to 2020 period. In the Reference Case, energy intensity declines at 0.9 percent per year. MORE ON.. -------------------- The greenhouse gases included in the targets are carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.12 For the latter three gases, individual nations have the option of using 1995 as the base year from which to achieve reductions, instead of 1990. The aggregate target is established using the carbon dioxide equivalent of each of the greenhouse gases. Other greenhouse gases are not limited by the Protocol, although CFCs and HCFCs are controlled by the Montreal Protocol. This analysis focuses on carbon emissions from the combustion of energy fuels, which constituted 83 percent of all U.S. greenhouse gas emissions in 1990. Carbon dioxide emissions from sources other than energy use are not included in the analysis, nor are emissions of the five other gases covered by the Kyoto Protocol; however, reductions in those gases may lessen the required reductions in energy-related carbon emissions, as discussed below. The established targets must be achieved over the period 2008 to 2012, the first commitment period. Essentially, each country can average its emissions over that 5-year period to establish compliance, smoothing out short-term fluctuations that might result from economic cycles or extreme weather patterns. Each country must have made demonstrable progress by 2005. No targets are established for the period after 2012, although lower targets may be set by future Conferences of the Parties. Sources of emissions include fuel combustion, fugitive emissions from fuels, industrial processes, solvents, agriculture, and waste management and disposal. The Protocol does not prescribe specific actions to be taken but lists a number of potential actions, including energy efficiency improvements, enhancement of carbon-absorbing sinks, such as forests and other vegetation, research and development of sequestration technologies, phasing out of fiscal incentives and subsidies that may inhibit the goal of emissions reductions, and reduction of methane emissions in waste management and in energy production, distribution, and transportation. Several provisions of the Protocol allow for some flexibility in meeting the emissions targets. Net changes in emissions by direct anthropogenic land-use changes and forestry activities will also be used in meeting the commitment; however, these are limited to afforestation, reforestation, and deforestation since 1990. Emissions trading among the Annex I countries is permitted. No rules for trading are established, however, and the Conference of the Parties is required to establish principles, rules, and guidelines for trading at a future date. Joint implementation projects are also allowed among the Annex I countries, whereby a nation could take emissions credits for projects that reduce emissions or enhance sinks in other countries. It is specifically indicated that trading and joint implementation are supplemental to domestic actions. The Protocol also establishes a Clean Development Mechanism (CDM), under which Annex I countries can take emissions credits for projects that reduce emissions in non-Annex I countries, provided that the projects lead to measurable, long-term benefits. Reductions from such projects undertaken from 2000 until the first commitment period can be used to assist compliance in the commitment period. This provision calls for the establishment of an executive board to oversee the projects. In addition, an unspecified share of the proceeds from the project activities must be used to cover administrative expenses and to assist with adaptation those countries that are particularly vulnerable to climate change. Banking—the carrying over of unused allowances from one commitment period to the next—is allowed; however, the borrowing of emissions allowances from a future commitment period is not permitted. Under the Protocol, Annex I countries, such as the nations of the European Union (EU), may create a bubble or umbrella to meet the total commitment of all the member nations. In a bubble, countries agree to meet the total commitment jointly by allocating a share to each member. In an umbrella arrangement, the total reduction of all member nations is met collectively through the trading of emissions rights. There is potential interest in the United States in entering into an umbrella trading arrangement. Non-Annex I countries have no targets under the Protocol, although it reaffirms the commitments of the Framework Convention by all parties to formulate and implement climate change mitigation and adaptation programs and to promote the development and diffusion of environmentally sound technologies and processes. Developing countries can voluntarily enter into the Protocol by full amendment of the Protocol. The Protocol became open for signature on March 16, 1998, for a 1-year period. Under its provisions, it enters into force 90 days following acceptance of at least 55 Parties, including Annex I countries accounting for at least 55 percent of the total 1990 carbon dioxide emissions from Annex I nations. Signature by the United States would need to be followed by Senate advise and consent to ratification. There are a number of uncertainties and issues to be resolved at future Conferences of the Parties. As indicated in the Protocol, rules and guidelines for the accounting of emissions and sinks from activities related to agriculture, land use, and forestry activities must be developed. The specific guidelines may have a significant impact on the level of reductions from other sources that a country must undertake. This issue was directed to the IPCC by subsequent climate change talks in Bonn in June 1998. In addition, rules and guidelines must be established for emissions trading, joint implementation projects, and the CDM. Other issues covered in the Protocol but deferred to subsequent sessions include flexibility for Annex I countries undergoing transition to market economies, commitments for subsequent periods, climate change adaptation actions, sanctions for failure to meet commitments, guidelines for the reporting and review of emissions and sinks, and international cooperation in education, research and development, and technology transfer. Emissions Trading Even before the Kyoto Protocol, many analyses of the impacts of greenhouse gas emissions reductions have favored emissions trading programs, including joint implementation programs, as a means of achieving emissions reductions. In the United States, the Clean Air Act Amendments of 1990 (CAAA90) established a trading program for emissions of sulfur dioxide (SO2) by electricity generators in order to reduce emissions to fixed specified levels. Permits issued to electricity generators allow them to emit up to a specified level of SO2, with the total number of issued permits equal to the national limit on emissions. Generators may reduce emissions by using lower-sulfur coals, installing scrubbers, or increasing the utilization of cleaner-generating plants. Generators that reduce emissions below their allowed levels can sell excess emissions permits, which can be purchased by other generators for whom it is more cost-effective to purchase permits at the prevailing market price than to reduce emissions. Emissions permits can also be banked for future use. Compared with traditional control programs that mandate specific compliance options or require uniform reductions, this SO2 trading program is credited with reducing the overall cost of compliance by allowing reductions to be made in the most cost-effective manner. Unlike SO2, carbon emissions are primarily an international, rather than domestic, issue. In theory, a similar trading scheme for carbon emissions could be formulated either internationally or within individual countries to achieve fixed emissions levels. Indeed, the Kyoto Protocol provides for international emissions trading but defers the determination of specific guidelines and rules for establishing an open trading market and managing the international flow of funds for the purchase of permits. Additional complexities may arise in establishing baseline projections against which to monitor and verify net emissions reductions, particularly with regard to the CDM. Even within the United States, carbon emissions trading may be more complicated than the current SO2 trading plan for several reasons. The largest sources of SO2 are a small number of large coal-burning generation plants. This makes it relatively easy to monitor their fuel use and emissions and to build and maintain an allowance trading system to ensure compliance. In contrast, there are a large number of entities that emit carbon, including households, commercial establishments, industrial facilities, automobiles, trucks, airplanes, ships, and fossil-fired generating stations. The development and operation of a monitoring and trading system for carbon emissions would thus be much more complicated. In addition, there were technologies available to reduce SO2 emissions at generation plants at the time the allowance trading program was initiated, and switching to low-sulfur coal was an option. Although research is ongoing, there are no readily available pre- or post-combustion technologies for removing carbon from fossil fuels (although the high technology sensitivity case included in this analysis assumes that carbon sequestration technologies will become available for electricity generators). Therefore, the options for carbon reduction are limited to fuel switching to lower-carbon or carbon-free fuels, efficiency improvements, and reductions in energy demand. Methodology of the Analysis In March 1998, the U.S. House of Representatives Committee on Science requested that the EIA perform an analysis of the Kyoto Protocol, focusing on the impacts of the Protocol on U.S. energy prices, energy use, and the economy in the 2008 to 2012 time frame for a number of emissions targets. (See letters of request in Appendix D.) The request specified that the analysis use the same reference case assumptions as in AEO98 unless changes in the assumptions could be justified on the basis of the Protocol—that is, there should be no changes in assumptions regarding policy, regulatory actions, or funding of energy or environmental programs, including the energy-related provisions of the Administration's revenue proposals of February 1998. Each target in the analysis was to be achieved on average between 2008 and 2012, phasing in beginning in 2005 and stabilizing at the target level after 2012, although targets beyond 2012 have not yet been established and may in fact be more stringent. The Committee indicated that no new nuclear plants should be allowed, although economical life extensions of nuclear plants should be permitted. Construction of new nuclear plants, variations in economic growth, and different assumptions concerning technology characteristics were all to be analyzed as sensitivities to the target cases. Numerous studies have been conducted on the topic of reducing greenhouse gas emissions. They can be clustered into several broad categories. One group of studies are cost-benefit analyses, which seek to establish an optimal level of either emissions reductions or emissions prices with a goal of balancing the costs and benefits of emissions reductions, explicitly accounting for the mitigation of damage as a result of emissions controls. A second category of studies address the cost-effectiveness of alternative paths for emissions reductions. Assuming a level of global concentrations of greenhouse gases, these analyses derive an optimal timing strategy for the imposition of emissions controls. Other studies are more narrowly focused on the costs of achieving specific emissions reductions or on the impacts of policies and technology on emissions levels. Before the Conference of the Parties in Kyoto, analyses examined the costs of emissions targets under a variety of assumptions about the possible level and timing of the targets. Since the Conference, analyses have focused on the levels and timing specified in the Kyoto Protocol and studied the costs of achieving those levels under a range of assumptions about the international provisions and other flexibility measures in the Protocol. Some of those analyses are included in the comparison of results in Chapter 7. This EIA analysis is among this final category of studies, with more detail on U.S. energy markets and the economy than other analyses but not addressing the potential benefits of emissions reductions, optimal timing, or international trade. The Protocol includes a number of international provisions—including international emissions trading, joint implementation projects, and the CDM—that may reduce the cost of compliance. Because EIA cannot fully address these aspects of the Protocol at this time, the analysis focuses on domestic impacts and includes a range of cases with different levels of energy-related carbon emissions. Although any impact on the global climate will likely be caused by atmospheric concentrations of greenhouse gases, the targets in the Kyoto Protocol are in terms of annual emissions. This analysis addresses the annual emissions targets as specified in the Protocol. |
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