U.S. Expatriates Benefits, Compensation, and Possible Risks

Fighting Music Piracy essays

Fighting Music Piracy essays Ah Internet, what a phenomenal invention! These days absolutely anything is possible to do and to get through the Internet. For instance, some of the most popular positive activities include the availability to instantly access the museums and libraries all across the world, as well as being able to learn about the latest news and events in a matter of seconds. Without doubt, Internet serves the major benefit by providing the immediate access to friends, family, and business associates through email, instant messaging, video conferencing, and other Internet mediums. Obviously, the whole concept of being able to shop from home without making a step out of the door, or even better, without getting up from the chair is always a great help. Also, Internet can provide a trivial knowledge, along with entertainment such as music, movies, books, radio and others. In other words, Internet these days simply became a speedy alternative to the U.S. Postal Service, a tool for enriching the minds of many and a worldwide shopping mall at the same time. Unfortunately, besides the vast amount of benefits that Internet brings to people, it also has become a home to the number of controversial, illegal and even criminal activities that were introduced to the society in the past couple of years. It is easy to see the significance of those unfavorable activities by just simply analyzing the fact that Internet provides an easy access to pornography, which for some reason children, sometimes, seem to be able to find even easier than the adults. Viru and malicious software that affects our home and business computers are extremely popular these days as well. Needless to say, just one big word SPAM, along with the deceptive marketing and scams, brings a lot of head ache to people. This could seem to be like a full list of disadvantages, but unfortunately it is not full just yet. Take a second and see if you can think of any other kind of a massive...

The Justification, Planning, and Preparation for the Attacks by Al-Qai Essay

The Justification, Planning, and Preparation for the Attacks by Al-Qaida in the United States on September 11, 2001 - Essay Example This paper will seek to reflect on the detailed planning, preparation and attempts at justification that bin Laden and his entire Al-Qaida organization did prior to the devastating September 11th attacks. In my opinion, the United States had not afforded the proper degree of attention to the threat that was posed by the bin Laden led Al-Qaida organization. This is evidenced by although bin Laden is quoted in a report issued by the United Kingdom government as having issued a number of proclamations against the United States, urging Muslims around the world to kill both American citizens and their military forces, the United States never took any direct action against this potential threat. In making the threat, Osama bin Laden had justified the attacks by claiming that the people of Islam had for long endured suffering from the wanton injustice, aggression and iniquity that was being forcibly imposed on them by the Zionist-Crusader alliance and their respective collaborators. He argued that it was now time that Muslims engaged in a Jihad targeted at cleansing the land from these Arabian peninsula crusader occupiers. Of concern also is that even after the devastating attacks conducted by the group in East Africa, against United States targets, relatively very little effort was put in place to try reign in and cripple the threat that was being posed by this organization. According to the same United Kingdom report, Bin Laden had justified attacks on American and Jewish targets by claiming that Muslims that happened to die in the course of them would be rewarded as they were carrying out God’s work (Murphy 239). The planning for the attacks on the United States was very extensive and took a number of years as is seen to be characteristic of all the attacks conducted by the Al-Qaida organization. In moving the attackers to the United States several years prior to the attacks, taking them through flight schools and using flight simulators to help them carefully study the controls of some of the larger aircraft; I believe that the al-Qaida organization displayed a great degree of detail in its planning.  Ã‚  

Principlies of finance Assignment Example | Topics and Well Written Essays - 2000 words

Principlies of finance - Assignment Example The paper outlines all the strong sides of such companies as Xtrata plc., Rio Tinto plc., HSBC pl., Tesco plc. and BT plc. HSBC has services from banking to financial products. Personal financial services under the HSBC group offer current account, personal account, loan, cards and payment services. Wealth management services take care of insurance, investment and financial products. It has existence in 87 countries for global banking, capital market and commercial banking facilities; it is headquartered in London, United Kingdom. Global financial crisis has affected a lot for global banking companies. This sector is not affected for in the emerging countries but considerably impacted on developed countries. HSBC has major revenue earning from developed countries hence most of the groups underlined have reflected bad performance in 2010. The major sector indicators are in still in bad condition. Rio Tinto plc is highly diversified company with operations in finding, mining and processing mineral resources. Rio Tinto produces aluminum, copper, gold, silver, diamond and other industrial minerals. Rio Tinto is engaged in all the continents; the head quarter is in London, United Kingdom. Rio Tinto’s business includes the mines, mills, refineries, refineries and research facilities. Company has 5 major product groups like aluminum, copper, diamonds, minerals, energy, iron ore, exploration and technology & innovation; and number of subsidiaries for availing facilities of economies of scale and cost structure. But iron ore is the main contributor to its earning with 73% dominance and copper has 18% contribution in the earning. Global financial crisis has affected Rio Tinto and created a challenge; but company is able to stabilize the situations with the proper strategic steps. This year company is able to manage a whopping increase in net earning from $4.9 billion to $14.3 b illion. Basic materials sector is also witnessing demand for above average GDP growth of China, India and other emerging nations. Global economic situation is also helpful for the increasing demand in ores. Investors and fund mangers also investing in diamonds and minerals, which is another positive force for short to medium term to the Rio Tinto’s growth. Through the SWOT analysis of the Rio Tinto, I found that the company has cash risk, market volatility threat and technological challenges in near future but the competitive advantages and growth in medium term is good opportunity for the inventors. Apart from this fundamental analysis, I found that the Rio Tinto’s return is combatively better and impressive than other competitors in the same sector for medium term and at this moment the share value is in uptrend but has major resistance in 4800. Hence selling the stock at this moment before

Ecological Agriculture for Sustainable Development

Ecological Agriculture for Sustainable Development Siddaraju V. G [*] Dr. M. Indira [**] Introduction Sustainable development is relevant issue of the present day. Sustainable development refers to development that meets the needs of the present without compromising the ability of future generation to meet their own needs. Sustainable development is achieved through sustainable agriculture. Food security for the common man is a basic right. Over 800 millions people in the world suffer from hunger which has to be reduced by half by the year 2015. Agriculture plays a crucial rule in addressing the needs of a growing global population, and is inextricably linked to poverty eradication, especially in developing countries. Sustainable agriculture and rural development is essential to the implementation of integrated approach to increasing food production and enhancing food security in an environmentally sustainable way. According to Pingali (2001) many countries across the world provide support for modern agriculture, mainly to increase the productivity for commercial purpose without considering the environment sustainability. Therefore, the concept of sustainability of agriculture is gaining momentum from last few years. The concept of ‘Sustainability’ has been discussed in Earth Summits of 1992 and 2002. The Earth summit offered an opportunity for the global community to address key action on agriculture with a view to sustainability and reducing poverty and hunger, protecting biodiversity and access to resources for small farmers everywhere. Sustainable development has three components i.e., economic sustainability, environmental sustainability and social sustainability. Ecological agriculture addresses the environment or ecological aspects of sustainability. Sustainable agriculture embraces several variants of non-conventional agriculture that are often called organic, alternative, regenerative, and ecological or low input. Ecological agriculture based on ecological principles aim at maintaining or enhancing the quality of the environment and conserve natural resources without using chemical inputs leading to sustainable development. The difference between sustainable agriculture and ecological agriculture is that sustainable agriculture is a broad concept compared to ecological agriculture. Ecological agriculture systems are one of the means of attaining sustainable agriculture. Sustainable agriculture aims continuous increase in yield and greater resilience. For a sound future, ecological agriculture offers a dynamic interaction between soil, animal, humans, ecosystem and environment. Ecological agriculture is economically viable because: Reduction in the use of external inputs and increase in farm organic inputs with the greatest potential to benefit the health of farmers and consumers. More productivity through the incorporation of natural process as nutrient cycles, nitrogen fixation, and pest predator relationships in to the agricultural production process. Greater productive use of the biological and genetic potential of plant and animal species. Improvement of the match between cropping patterns and the productive potential and physical limitations of agricultural lands to ensure long term sustainability of current production levels and Profitable and efficient production with emphasis on improved management and conservation of soil, water and energy and biological resources. The basic requirement in organic farming is to increase input use efficiency at each step of the farm operations. This is achieved partly through reducing losses and adoption of new technologies for enrichment of nutrient content in manure (Sravanan, 2006). The concept of organic farming lays emphasis on economic and ecological sustainability of agricultural system and hence avoids the dependence on chemical pesticides use (Dhawan and Deshmukh, 2005). According to Charjan and Hajare (2002) organic farming is only an alternative, which may not be acceptable on short-term basis, but may be viable on long-term basis, perhaps due to number of issues. An attempt is made in this paper to analyze the economic performance of ecological agriculture and modern agriculture system and to identify the reasons for the transition from modern agriculture to ecological agriculture. Methodology The present study is based on primary data collected from 50 ecological farmers and 50 modern farmers in the production of Paddy and Sugarcane in Mysore and Mandya districts of Karnataka. Economic performance of any system could be analyzed by analyzing the costs and returns. In the present study relative economic performance of ecological and modern agriculture is analyzed in terms of Farm Business Income (FBI). Location, distribution of sample farmers is presented in table 1. Table 1: Particulars of selected district and taluk District Taluk No. of Ecological farmers No. of Modern Farmers Mysore Mysore 16 16 Nanjanagud 9 9 Mandya Mandya 14 14 Maddur 11 11 The above table shows that Location, distribution of sample farmers. Ecological farmers are located in Mysore and Nanjanagud taluks in Mysore district and Mandya and Maddur taluks in Mandya district. Mysore taluk in Mysore district has the large number of ecological farmers and Mandya taluk in Mandya ditrict has more number of ecological farmers. Equal numbers of modern farmers were selected for comparative analysis. Analysis and Discussion Economic Performance Farm Business Income (FBI) is one of the indicators to measure the economic profitability of an agriculture farm. It has been chosen to understand the relative economic profitability of ecological farming and modern farming systems in the production of selected crops. FBI is the difference between the gross returns and Cost A1. Farm Business Income = Gross Income – Cost A1 Cost of Cultivation Average cost and returns under ecological and modern agriculture in the production of paddy and sugarcane are presented below. Paddy Average cost per acre in the production of paddy under ecological and modern farming systems, yield per acre, returns from main product and returns from by product, net returns per acre are presented in table 2. Table 2: Costs and Returns from Ecological and Modern Agriculture in the Production of Paddy Sl. No. Particulars Ecological Agriculture Modern Agriculture 1 Farm Power 6147 5539 2 Organic Nutrients 1957 655 3 Chemical Fertilizers 1030 4 Seed 367 352 5 Irrigation 379 389 6 Land Tax 29 24 7 Depreciation Charge on Farm implements 1018 449 8 Depreciation Charge on machinery 623 603 9 Repair of Machineries 449 233 10 Total Cost of Cultivation (1+2+3+4+5+6+7+8+9) 10968 9274 11 Yield (Quintal/acre) 23 22 12 Price Received (Rs/quintal) 639 612 13 Returns from main Product (Rs/acre) 14697 13464 14 Income from by-product (Rs/acre) 1067 786 15 Gross Returns/Rs (13+14) 15764 14250 16 Net returns/Rs (15-13) 4796 4975 Source: Survey Data Gross returns from paddy produced under ecological agriculture found to be marginally higher compared to the paddy produced under modern farming system. While gross returns from ecological agriculture was Rs. 15764 per acre, the same from modern agriculture was Rs. 14250 per acre, a difference of Rs 1514 per acre. But net return was relatively low from ecological agriculture (Rs. 4795 per acre) compared to modern agriculture (Rs. 4975/acre), because cost of cultivation was higher for ecological farms (Rs. 10969 per acre) compared to modern farms (Rs. 9274/acre). Cost of organic nutrients, farm power, farm depreciation charges are higher in ecological agriculture. Marginal differences could be seen in other costs. While organic nutrients were expensive, the transportation of FYM, its administration, transplantation, weeding require more labour, which is reflected in the farm power. Farm depreciation charge is higher in ecological agriculture due to more use of farm equipments. The yie ld from ecological agriculture was not found to be much higher than modern agriculture. While ecological farms produced 23 quintal/acre, 22 quintal/acre were produced from modern farms. Ecological farmers received Rs. 27 per quintal of paddy, which is slightly higher price than the modern farmers. The yield and price was not much difference under the two methods of cultivation. Therefore, net return also was not much different. Sugarcane Sugarcane is a commercial annual crop grown mainly in Mandya and Mysore districts of Karnataka. Average costs and returns in the production of sugarcane is presented in table 3. Table 3: Costs and Returns under Ecological and Modern Agriculture in the Production of Sugarcane Sl. No. Particulars Ecological Agriculture Modern Agriculture 1 Farm Power 22589 20441 2 Organic Nutrients 2414 861 3 Chemical Fertilizers 3502 4 Seed 1300 1300 5 Irrigation 424 443 6 Land Tax 27 26 7 Depreciation Charge on Farm Implements 1800 3403 8 Depreciation Charge on Machinery 1172 1499 9 Repair of Machineries 500 204 10 Total Cost of Cultivation (1+2+3+4+5+6+7+8+9) 30225 31679 11 Yield (Ton/acre) 52 49 12 Price Received (Tonn/Rs) 989 961 13 Gross Returns/Rs 51428 47089 14 Net Returns/Rs (13-10) 21203 15410 Source: Survey Data Net returns from sugarcane were found to be higher from ecological farms (Rs. 21202 per acre) compared to modern farms (Rs. 15410 per acre). Similarly the gross returns were Rs. 51428per acre from ecological agriculture and Rs. 47089 per acre from modern agriculture. Relatively higher cost of cultivation in modern agriculture is due to higher cost of chemical fertilizers and farm depreciation charges. Chemical fertilizers like Urea, Potash, Complex and Salt were expensive. Farm depreciation charge is higher in ecological agriculture due to more use of farm equipments. Marginal differences could be seen in other costs except farm power. Because the cost of the transportation of FYM, weeding, harvesting and its administration require more labour, which is reflected in the farm power. The cost of cultivation of sugarcane with modern agriculture is costing Rs. 1454 more per acre. Yield per acre under ecological farming is nearly three ton more than that from modern cultivation and ecolog ical farmers received Rs. 28 higher for one ton of sugarcane than the modern farmers. Higher yield and returns have contributed to higher returns from ecological farming than the modern farming. Net returns from sugarcane under ecological farming are Rs. 5792 more than that from modern agriculture. Farm Business Income Farm business income under ecological and modern agriculture in the production of annual crops (paddy and sugarcane) is presented in table 4. Table 4: Farm Business Income of Annual Crops under ecological and modern farming system Paddy Sugarcane Variables Ecological Agriculture Modern Agriculture Ecological Agriculture Modern Agriculture Gross Returns 15,764 14,250 51,428 47,089 Cost A1 10,968 9,274 30,225 31,679 Farm Business Income (FBI) 4,796 4,976 21,203 15,410 Source: Survey Data The above table shows that larger variation in the FBI could be observed in the production of Sugarcane, which is a commercial crop. In the production of Paddy, FBI under ecological farming is marginally lower i.e., by Rs.180. Cost A1 under ecological agriculture is higher by Rs.1694 per acre. However gross returns is higher by Rs.1514 per acre. But in the case of sugarcane, FBI from ecological cultivation is higher by Rs.5, 793 per acre. In the case of sugarcane, cost of cultivation under ecological cultivation is relatively low. It is lower by Rs.1, 454 per acre. Gross returns are higher under ecological agriculture. The above analysis clearly shows that ecological agriculture is economically profitable. It has double advantage to the grower; it provides greater returns to the growers at present and ensures the sustainability of these returns in future by protecting the fertility of the soil. Transition Transition is the process of conversion from modern agriculture to ecological agriculture. After introduction of all necessary changes needed also, it might take some time before the transition is completed. Modern farming system depends on external inputs and is market oriented. On the other hand ecological farming is based on ecological principles of nature and depends more on inputs produced on farm. The production under ecological agriculture need not necessarily for subsistence. The growers may have several objectives in shifting from modern system of cultivation to ecological system. By understanding the motivation behind the shifting, it is possible to encourage more conversions. Reasons for Transition Process Information on what made the selected farmers to switch over to organic farming system from modern farming system was gathered. In many cases majority of the farmers reported that transition from modern agriculture to ecological agriculture was due to the possibility of producing healthy food, environmental protection and soil fertility management under organic farming system. A detailed analysis of Paddy and Sugarcane is presented in table 5. Table 5: Crop wise Reasons for transition from modern agriculture system to ecological agriculture system Sl. No Reasons for transition Frequency and Percentage Paddy Sugarcane 1 Cost of cultivation is low 8 (28.6) 10 (35.7) 2 Health 28 (100.0) 23 (82.1) 3 Employment 14 (50.0) 15 (53.6) 4 Soil Fertility Management 20 (71.4) 22 (78.6) 5 Environmental Protection 16 (57.1) 19 (67.9) 6 Yield 18 (64.8) 12 (42.9) Source: Survey Data, Note: Values within brackets represent percentage to total growers (Percentage don’t add to 100 due to multiple response) In recent years paddy farmers are practicing ecological agriculture due to different reasons. According to selected farmers, more than 70 per cent of the total farmers have shifted from modern agriculture to ecological agriculture, in order to maintain soil fertility. According to them, by using cowdung, ash, farm yard manure soil fertility can be maintained for many years. Health is one of the important factors influencing the paddy farmers to shift from modern agriculture to ecological agriculture. According to these farmers ecological food has positive impact on health and to be sure of the supply of organic food, they shifted to ecological agriculture. Paddy farmers also said that ecological agriculture creates more employment compared to modern agriculture. Survey results have shown that employment in ecological agriculture is more by 9 mandays/acre compared to modern agriculture. More than 50 per cent of the total farmers have shifted from modern agriculture to ecological agric ulture due to employment. Cost of cultivation is high in ecological agriculture compared to modern agriculture, because initially more investment is required in ecological agriculture. After completion of transition (5 years) gradually cost is decreased in ecological agriculture. Nearly 65 per cent of the ecological paddy farmers said that they shifted due to higher and stable yield that they are expected under ecological agriculture. The results support this and yield under ecological farm is more by 1 quintal per acre. In the case of sugarcane, 82.1 per cent of the total farmers have shifted from modern agriculture to ecological agriculture because they believe that it leads to healthy life. More than 65 per cent of the total farmers have transformed from modern agriculture to ecological agriculture due to soil fertility maintenance and environmental factors like pollution control, sustainability, water management etc. Sugarcane farmers also opined that ecological agriculture creates more employment compared to modern agriculture. Only 36 per cent of the farmers shifted because they think that cost of cultivation is low under ecological agriculture. In the case of paddy more shifts took place due to ecological factors than economic factors. The main reasons for transition can be found in environmental sustainability as well as health and soil fertility management. Paddy and sugarcane farmers mainly reported that cost of inputs like chemical fertilizers and pesticides are highly expensive. The results clearly show that the awareness about environmental impact of modern agriculture is the main reason for the farmers to shift to ecological agriculture. Conclusion The over all analysis of the study highlights that ecological agriculture is economically profitable compared to modern agriculture. It provides greater returns to the growers at present and ensures the sustainability of these returns in future by protecting the fertility of the soil and enhancing the quality of environment and conserve natural resources. Farm Business Income from ecological agriculture is more due to higher yield and price. It is mainly due to the purchase of organic manure by the growers. Efforts should be made to encourage farmers to keep livestock to produce on farm organic inputs in order to reduce the cost of organic manures. The main reason for transition from modern agriculture to ecological agriculture was the awareness about environment and health. This awareness is limited only to those who are educated. Efforts should be made to create awareness about two aspects of ecological farming i.e., awareness about environmental consequences of ecological farming and economics of ecological agriculture. References: CharjanY.D and T.N Hajare (2002), Ecological Agriculture Solves the Problems of Indian Agriculture, Kisan World, l29 (7), pp. 43-4. Dhawan AS and MS. Deshmukh 92005), Organic Farming in Relation to Environment Pollution, Kisan World, 32(2) February 2005, Pp: 27-28. Saravanane M et al (2007) â€Å"Organic Production System† Kisan World, 34 (03), Pp. 45 – 47, March 2007 Thakur and Sharma KD (2005), Organic Farming for Sustainable Agriculture and Meeting the Challenges of Food Security in 21st Century: An Economic Analysis, Indian Journal of Agriculture Economics, 60 (2), April-June 2005, Pp: 205-219. 1 [*] Senior Research Scholar, Department of Studies in Economics and Cooperation, University of Mysore, Mysore, Email: [emailprotected] [**] Reader, Department of Studies in Economics and Cooperation, University of Mysore, Mysore, Email: [emailprotected].

Teaching Morals and Character at State University :: Teaching Education Essays

Teaching Morals and Character at State University Introduction Several weeks ago, there was a slight uproar on State U.’s campus when a threatening homophobic message was found scrawled on a student’s personal belongings. The controversy revolved around the intentions of this message and, once it was discovered who had written the message, how that individual should be punished. Most of the dialogue on campus, both amongst the administration and the student body, focused on the individual’s motives, the individual’s actions, and the individual’s punishment. Yet, I argue that such actions can not simply be attributed to the character of the individual, but also reflect the character of the institution. A somewhat humorous, yet appalling parallel can be drawn between this situation and one presented by constructionist Rheta DeVries during her discussion of teaching morality in a classroom of three-year-olds where a teacher found urine on the floor of the bathroom for several consecutive days. DeVries wrote, "[The teacher] did not know who was responsible, but suspected that more than one child was involved. She figured that they were not being malicious but thought it was funny" (2). In this same manner, the State U. individual who wrote a threatening, homophobic message probably did not do so out of sheer hate, or with harmful intentions. Nevertheless, the message offended the State U. community in the same way that the urine on the bathroom floor interrupted the three-year-olds’ classroom. In both situations, we must ask ourselves: what encouraged such actions? Why did the three-year-olds think it was okay to urinate on the floor? Why does a State U. student think it is per missible to write such a negative message? Neither the children nor the college student would have committed such acts had they believed that it would not have been accepted — if not by everyone, at least by the majority. This State U. student faced a semester of suspension for his actions, but was permitted to return to school the following year. However, short-lived suspension is not the only necessary action. By temporarily ridding the institution of this individual, State U. alleviated the symptoms of immorality but avoided directly treating the problem at hand: State U.’s moral atmosphere. Such a negative action, even if committed merely by one student, is a summons to the institution to re-examine its ethical environment in order to prevent inconsiderate actions before they occur, not treat them after the fact.

Address Resolution Protocol

————————————————- Address Resolution Protocol The  Address Resolution Protocol  (ARP) is a  computer networking  protocol for determining a network host's link layer or hardware address when only its  Internet Layer  (IP) or  Network Layer  address is known. This function is critical in local area networking as well as for routing internetworking traffic across gateways (routers) based on  IP addresses  when the next-hop router must be determined. ARP was defined by  RFC 826  in 1982. [1]  It is  Internet Standard  STD 37. ARP has been implemented in many types of networks, such as  Internet Protocol  (IP) network,  CHAOS,  DECNET, Xerox  PARC Universal Packet,  Token Ring,  FDDI,  IEEE 802. 11  and other  LAN  technologies, as well as the modern high capacity networks, such as  Asynchronous Transfer Mode  (ATM). Due to the overwhelming prevalence of  IPv4  and Ethernet in general networking, ARP is most frequently used to translate  IPv4 addresses  into Ethernet  MAC addresses. In the next generation Internet Protocol,  IPv6, ARP's functionality is provided by the  Neighbor Discovery Protocol  (NDP). ———————————————— Overview and IPv4-plus-Ethernet example Consider a LAN where machines using IPv4 over Ethernet wish to communicate. A sender wishes to send a message to some other machine on the LAN and knows a destination IPv4 address. The destination IPv4 address is hopefully associated with some appropriate network interface belonging to the recipient machine, and is present on the LAN. But in order for communication to succeed, the sending machine  first needs to discover the ethernet MAC address of the intended recipient network interface. This requirement comes about because Ethernet hardware does not (necessarily) understand IPv4 protocols or IPv4 addresses in the sense that Ethernet hardware ‘listens out for' relevant Ethernet MAC addresses but does not ‘listen out for' IPv4 addresses. (An impractical alternative would be to have all units listen to every Ethernet packet and inspect the contents for relevant IPv4 addresses, discarding the packets that are intended for other devices, but this would be very inefficient. ) So before sending an IPv4 packet, the sender sends a roadcast message onto the LAN using ARP in order to discover the Ethernet MAC address of some interface that is listening for that desired target IPv4 address. Some appropriate unit replies that it has a network interface with a certain MAC address that is associated with the IPv4 address in question. The original would-be sender now has the information needed and can go ahead and send its IPv4 packet to the destination inserting it int o an Ethernet frame with the correct destination MAC address for the appropriate recipient. The sender's operating system also stores the newly discovered MAC address in a table (‘caches' the result). This table of mappings from IPv4 addresses to MAC addresses is retained and consulted again and again, so the ARP discovery procedure only has to be performed one time, when a packet is sent to a ‘new' destination IPv4 address. ————————————————- Operating scope The Address Resolution Protocol is a low level request and answer protocol that is communicated on the media access level of the underlying network. For  Ethernet  systems, an ARP message is the payload of Ethernet packets. ARP therefore operates only across the local link that a host is connected to. Within the framework of the  Internet Protocol Suite, this characteristic makes ARP a  Link Layer  protocol. [2] ARP is also very often discussed in terms of the  Open Systems Interconnect  (OSI)  networking model, because that model addresses hardware-to-software interfaces more explicitly and is preferred by some equipment manufacturers. However, ARP was not developed based on the design principles and strict encapsulation hierarchy of this model and, therefore, such discussions create a number of conflicts as to the exact operating layer within this model. Most often ARP is placed into the  Data Link Layer  (Layer 2), but since it requires the definitions of network addresses of the  Network Layer, it is not unusual to find it referenced at that layer. An example of use in OSI networking, is ATMARP, used to resolve  Asynchronous Transfer Mode  (ATM)  NSAP  addresses in IP over ATM deployments. ————————————————- Packet structure The  Address Resolution Protocol  uses a simple message format that contains one address resolution request or response. The size of the ARP message depends on the upper layer and lower layer address sizes, which are given by the type of networking protocol (usually  IPv4) in use and the type of hardware or virtual link layer that the upper layer protocol is running on. The message header specifies these types, as well as the size of addresses of each. The message header is completed with the operation code for request (1) and reply (2). The payload of the packet consists of four addresses, the hardware and protocol address of the sender and receiver hosts. The principal packet structure of ARP packets is shown in the following table which illustrates the case of IPv4 networks running on Ethernet. In this scenario, the packet has 48-bit fields for the sender hardware address (SHA) and target hardware address (THA), and 32-bit fields for the corresponding sender and target protocol addresses (SPA and TPA). Thus, the ARP packet size in this case is 28 bytes. Hardware type (HTYPE) This field specifies the Link Layer protocol type. Example: Ethernet is 1. Protocol type (PTYPE) This field specifies the upper layer protocol for which the ARP request is intended. For example, Internet Protocol (IPv4) is encoded as 0x0800. Hardware length (HLEN) Length (in  octets) of a hardware address. Ethernet addresses size is 6. Protocol length (PLEN) Length (in octets) of a  logical address  of the specified protocol (cf. PTYPE). IPv4 address size is 4. Operation Specifies the operation that the sender is performing: 1 for request, 2 for reply. Sender hardware address (SHA) Hardware (MAC) address of the sender. Sender protocol address (SPA) Upper layer protocol address of the sender. Target hardware address (THA) Hardware address of the intended receiver. This field is ignored in requests. Target protocol address (TPA) Upper layer protocol address of the intended receiver. ARP protocol parameter values have been standardized and are maintained by  IANA Internet Protocol (IPv4) over Ethernet ARP packet| bit offset| 0 – 7| 8 – 15| 0| Hardware type (HTYPE)| 16| Protocol type (PTYPE)| 32| Hardware address length (HLEN)| Protocol address length (PLEN)| 48| Operation (OPER)| 64| Sender hardware address (SHA) (first 16 bits)| 80| (next 16 bits)| 96| (last 16 bits)| 112| Sender protocol address (SPA) (first 16 bits)| 128| (last 16 bits)| 144| Target hardware address (THA) (first 16 bits)| 160| (next 16 bits)| 76| (last 16 bits)| 192| Target protocol address (TPA) (first 16 bits)| 208| (last 16 bits)| ————————————————- ARP probe An  ARP probe  is an ARP request constructed with an all-zero  sender IP address. The term is used in the  IPv4 Addre ss Conflict Detection  specification (RFC 5227). Before beginning to use an IPv4 address (whether received from manual configuration, DHCP, or some other means), a host implementing this specification must test to see if the address is already in use, by broadcasting ARP probe packets. ————————————————- ARP announcements ARP may also be used as a simple announcement protocol. This is useful for updating other host's mapping of a hardware address when the sender's IP address or MAC address has changed. Such an announcement, also called a  gratuitous ARP  message, is usually broadcast as an ARP request containing the sender's protocol address (SPA) in the target field (TPA=SPA), with the target hardware address (THA) set to zero. An alternative is to broadcast an ARP reply with the sender's hardware and protocol addresses (SHA and SPA) duplicated in the target fields (TPA=SPA, THA=SHA). An ARP announcement is not intended to solicit a reply; instead it updates any cached entries in the ARP tables of other hosts that receive the packet. The operation code may indicate a request or a reply because the ARP standard specifies that the opcode is only processed after the ARP table has been updated from the address fields. [4][5][6] Many operating systems perform gratuitous ARP during startup. That helps to resolve problems which would otherwise occur if, for example, a network card was recently changed (changing the IP-address-to-MAC-address mapping) and other hosts still have the old mapping in their ARP caches. Gratuitous ARP is also used by some interface drivers to effect load balancing for incoming traffic. In a team of network cards, it is used to announce a different MAC address within the team that should receive incoming packets. ARP announcements can be used to defend  link-local  IP addresses in the  Zeroconf  protocol (RFC 3927), and for IP address takeover within  high-availability clusters. ————————————————- ARP mediation ARP mediation  refers to the process of resolving Layer 2 addresses when different resolution protocols are used on multiple connected circuits, e. . , ATM on one end and Ethernet on the others. ————————————————- Inverse ARP and Reverse ARP The  Inverse Address Resolution Protocol  (Inverse ARP or InARP), is a protocol used f or obtaining  Network Layer  addresses (e. g. ,  IP addresses) of other nodes from  Data Link Layer(Layer 2) addresses. It is primarily used in  Frame Relay  (DLCI) and ATM networks, in which Layer 2 addresses of  virtual circuits  are sometimes obtained from Layer 2 signaling, and the corresponding Layer 3 addresses must be available before these virtual circuits can be used. As ARP translates Layer 3 addresses to Layer 2 addresses, InARP may be described as its inverse. In addition, InARP is actually implemented as a protocol extension to ARP. It uses the same packet format from ARP; but has different operation codes. Reverse Address Resolution Protocol  (Reverse ARP or RARP), like InARP, also translates Layer 2 addresses to Layer 3 addresses. However, while in InARP the requesting station is querying the Layer 3 address of another node, RARP is used to obtain the Layer 3 address of the requesting station itself for address configuration purposes. RARP is now obsolete. It was replaced by  BOOTP, which was later superseded by the  Dynamic Host Configuration Protocol  (DHCP). ————————————————- Proxy ARP Proxy ARP  (Address Resolution Protocol) is a technique by which a device on a given network answers the  ARP  queries for a  network address  that is not on that network. The ARP Proxy is aware of the location of the traffic's destination, and offers its own MAC address in reply, effectively saying, â€Å"send it to me, and I'll get it to where it needs to go. Serving as an ARP Proxy for another host effectively directs LAN traffic to the Proxy. The â€Å"captured† traffic is then typically routed by the Proxy to the intended destination via another interface or via a  tunnel. The process which results in the node responding with its own MAC address to an ARP request for a different IP address for proxying purposes is sometimes referred to as ‘publishing'. ————————————————- Uses Below are some typical uses for proxy ARP: Joining a broadcast LAN with  serial  links (e. g. ,  dialup  or  VPN  connections). Assume an Ethernet broadcast domain (e. g. , a group of stations connected to the same hub) using a certain IPv4 address range (e. g. , 192. 168. 0. 0/24, where 192. 168. 0. 1 – 192. 168. 0. 127 are assigned to wired nodes). One or more of the nodes is an  access router  accepting dialup or VPN connections. The access router gives the dial-up nodes IP addressses in the range 192. 168. 0. 128 – 192. 168. 0. 254; for this example, assume a dial-up node gets IP address 192. 168. 0. 254. The access router uses Proxy ARP to make the dial-up node present in the subnet without being wired into the Ethernet: he access server ‘publishes' its own MAC address for 192. 168. 0. 254. Now, when another node wired into the Ethernet wants to talk to the dial-up node, it will ask on the network for the MAC address of 192. 168. 0. 254 and find the access server's MAC address. It will therefore send its IP packets to the access server, and the access server will know to pass them on to the particular dial-up node. All dial-up nodes therefore appear to the wired Ethernet nodes as if they are wired into the same Ethernet subnet. Taking multiple addresses from a LAN Assume a station (e. g. , a server) with an interface (10. 0. 0. 2) connected to a network (10. 0. 0. 0/24). Certain applications may require multiple IP addresses on the server. Provided the addresses have to be from the 10. 0. 0. 0/24 range, the way the problem is solved is through Proxy ARP. Additional addresses (say, 10. 0. 0. 230-10. 0. 0. 240) are  aliased  to the  loopbackinterface of the server (or assigned to special interfaces, the latter typically being the case with  VMware/UML/jails/vservers/other virtual server environments) and ‘published' on the 10. . 0. 2 interface (although many operating systems allow direct allocation of multiple addresses to one interface, thus eliminating the need for such tricks). On a firewall In this scenario a firewall can be configured with a single IP address. One simple example of a use for this would be placing a firewall in front of a single host or group of hosts on a subnet. Example- A network (10. 0. 0. 0/8) has a serve r which should be protected (10. 0. 0. 20) a proxy-arp firewall can be placed in front of the server. In this way the server is put behind a firewall without making any changes to the network at all. Mobile-IP In case of  Mobile-IP  the Home Agent uses Proxy ARP in order to receive messages on behalf of the Mobile Node, so that it can forward the appropriate message to the actual mobile node's address (Care Of Address). Transparent subnet gatewaying A setup that involves two physical segments sharing the same IP subnet and connected together via a  router. This use is documented in  RFC 1027 ————————————————- Advantages The advantage of Proxy ARP over other networking schemes is simplicity. A network can be extended using this technique without the knowledge of the upstream router. For example, suppose a host, say A, wants to contact another host B, where B is on a different subnet/broadcast domain than A. For this, host A will send an  ARP  request with a Destination IP address of B in its ARP packet. The multi-homed router which is connected to both the subnets, responds to host A's request with its MAC address instead of host B's actual  MAC  address, thus proxying for host B. In the due course of time, when host A sends a packet to the router which is actually destined to host B, the router just forwards the packet to host B. The communication between host A and B is totally unaware of the router proxying for each other. ————————————————- Disadvantages Disadvantage of Proxy ARP include scalability (ARP resolution is required for every device routed in this manner) and reliability (no fallback mechanism is present, and masquerading can be confusing in some environments). It should be noted that ARP manipulation techniques, however, are the basis for protocols providing  redundancy  on broadcast networks (e. g. ,Ethernet), most notably  CARP  and  Virtual Router Redundancy Protocol. Proxy ARP can create DoS attacks on networks if misconfigured. For example a misconfigured router with proxy ARP has the ability to receive packets destined for other hosts (as it gives its own MAC address in response to ARP requests for other hosts/routers), but may not have the ability to correctly forward these packets on to their final destination, thus blackholing the traffic.