Investment Philosophy Essays - Investment, Finance, Investor, Risk

Investment Philosophy The Care And Feeding Of Your Investment Philosophy If you are making a list of tasks you should accomplish in 1988, here's one to add to the list: Establish a well-balanced investment plan that suits your personal financial needs and goals. Every investor from the newest to the most experienced needs to develop or redefine an investment philosophy. The cornerstone of that philosophy should be a realistic attitude toward risk and return, especially in today's volatile financial markets. What is your personal comfort level with risk, emotionally and financially? The first step is to acknowledge your investment objective. Are you investing capital to earn income on which you will live? If so, you should probably choose the most conservative investments unless you are so well off that you can afford to take some risks. If you are investing capital to realize appreciation for a future purpose, such as retirement, you may want to be more aggressive than an investor for income would be, but how much more depends on a number of factors: Are you single or married with children and other dependents? Are you just beginning your career, heading into your peak earning years or ready for retirement? Will you need to tap your nest egg in the near future, or can you earmark a portion of your funds for long-term growth? Also important: your financial goals, your family's tax bracket and, above all, your earning power and investment temperament. Earning Power. Generally speaking, as your income rises so does your suitability for investments of above-average risk. If, on the other hand, your salary and savings are small but growing - keep risk taking to a bare minimum. Maintain only solid investments for your portfolio. U.S. Government Securities, insured certificates of deposit, high quality corporate or municipal bonds, and high quality common stocks offer you reasonable safety at a steady rate of return and they should form the base of almost every investment portfolio. If you can count on future income - or a sizable accumulation of assets - to cushion possible investment losses then perhaps you will want to consider opportunities that may carry greater risk, but also offer greater potential for profit. One way to do that is to invest in small companies with superior growth prospects or mutual funds that have a diversified portfolio in such stocks. In addition to income and net worth, measure your future cash needs, such as college tuition bills. Investment Temperament. Some people are more disposed than others to taking risks, and common sense suggests avoiding investments that leave you feeling uncomfortable. An investment of slightly above-average risk may set one investor's heart beating with anticipation - and another's beating even faster with apprehension. One helpful rule of thumb: Never invest in anything if you still feel nervous after investigating all of its pluses and minuses. Aggressive and timid investors alike can hedge risk by heeding the following five suggestions: Investigate before you invest. Careful research of potential investments often unearths the small but revealing details that, if nothing else, give you a clear idea of the kind of risk you will be taking. The greatest risk an investor can take is not knowing all the risks. Don't put all your eggs in one basket. In a word, diversity. Losses taken on one investment can be offset by gains in another. An experienced financial advisor can suggest ways to hedge risk through diversification. Set limits, and stick to them. Against their better instincts, investors often hang on to poor pertormers in the hopes they will bounce back given enough time. It takes discipline to set sell limits and stick to them, but in the long run you'll come out ahead if you do, because you'll know exactly how much you are risking before you buy. Monitor investments and the investment climate. Be prepared to adjust your holdings when research indicates it may be time to sell or when your own goals change. Similarly be alert to changes predicted for the general investment environment. If respected market analysts forecast rough weather, consider cutting your risk exposure. Conversely, consider increasing it - in line with your own risk boundaries - when the outlook turns favorable. Always Match Risk to Reward. This is possibly the most important rule

buy custom Ross Messingers Research essay

buy custom Ross Messinger's Research essay Structures increases effectiveness of virtual leaders. Similarly satisfaction and efficiency of virtual leaders also term to increase. However, such leaders are insignificant. One can not aspect one particular impact upon other. The main findings of the study were that virtual team can be made more successful then traditional teams by giving more attention to hierarchy and division of labor instead of work process. The biggest demerit of virtual team is that it restricts the information exchange only a limited quantity of information is used. There are many chances of the development of stereotypes and hierarchy in traditional teams. The limited information present with the virtual teams causes the division of labor and hierarchy the accepted characteristics that lead to the success of the task fulfillment. (Daphna, Niv and Dalia, 2005) Ross in his study found that leadership competencies that lead to quite effective global innovation teams in large multinational corporations. The concept of leadership has been complicated due to the attempt to encourage highly skilled, creative, multi-cultural and widely dispersed team members.(purpose of the study is reflected here) The global innovation team leader is therefore, expected to possess certain competencies that are unique in nature and have never been underscored before. . About thirty six expertises were involved in the study. Delphi two round methodology and an internet-based data collection tool was use to analyze these leaders. (Ross Haynes Messinger, 2008) This study consisted of sixteen Asian, European and North American nationals. The outcomes of the study were derived on the basis of about twenty significant cultural, technical and social competencies. It was found that the cultural competencies were more significant than technical and social competencies. Participative style of leadership is important for the global innovation team leader. A participative leader possesses an entrepreneurial spirit and keeps an authenticity for others and also is self- managed. The global innovation team leader surpasses the cultural competencies. Ross developed a model that assists in the development of leadership in the corporate sector. (Ross Haynes Messinger, 2008) Ross presented a GIT leadership paradigm to initiate cultural, technical and social categories. The findings of the study showed that GIT leader resembles the generic manager in terms of teamwork and cooperation, several differences were found. Achievement orientation and impact and influence are the significant competencies for the generic manager and technical professional but are of only moderate importance for GIT leader. (Ross Haynes Messinger, 2008) A research was conducted to find out which causes the accomplishments virtual teams. A Norwegian tele-company sent four hundred emails for data collection. This study showed a prolix leadership approach. This tudy also identified the prolix devices that leader of agenda adopts to maintain trust and in-group solidarity. From the results of the study it was found that virtual leaders portray an egalitarian leader role, building personal and emotional ties and downplays her authority. (Karianne Skovolt, 2009) Virtual team is a group of people who collaborate across space, time and organizational boundaries and use electronic media as primary communication tool. The possibilities and challenges arise in the process of taking forward that are not present in all situations. These teams work in unison and are very close to each other despite having temporal, spatial and cultural differences. It is assumed that future organizations will require such leaders that will be capable to handle uncertainty and competition among a different working people. This will help leaders attain the viability and profitability of their organizations. This categorization also depends upon the principle of proximity to explicit whether employees are geographically close to each other or are scattered. (Karianne Skovolt, 2009) It was tried to find out how leadership carried out linguistically through email interaction. The communication style of the agenda leader was informal, personal and emotional with her team members. This showed that the author used prolix skills to communicate with the in-group and out-group members. Mostly she adopted an informal communication style and avoided categorizing leadership styles while communicating with in-group team members. Besides, in written messages a leader must adopt a formal style of communication. These entire activities of the leaders are based upon trust. In case of virtual teams the leaders have to take care of all the functions in an interrogative manner. The conditions are more challenging in virtual teams because here people do not have a face-to-face contact. (Karianne Skovolt, 2009) On of the component of virtual leaders and computer mediated networks is that boundaries are permeable, interactions are with divers others, connections switch between multiple networks, and hierarchies can be flatter and recursive. The community exists more in the informal networks than predefined work-groups. Rather than fitting into the same group as around them, each person has his own personal community. (Karianne Skovolt, 2009) Today, virtual teams are essential and indispensable constituent of several organizations. As the members of virtual team are not congregated at on particular place but are instead distributed and scattered at different places therefore such teams are dependent upon electronic devices to communicate and to complete their work. This distance among team member are challenging and have created a new field of leadership. It has become problematic for the leader to deliver appropriate structures due to cultural, geographic and time constraints. (Surinder, Jerry, Suling, Bruce, 2000) These variables also make restrict the leaders from evaluating the performance of their followers. Similarly the leaders have beeen limited from inspiring and developing their followers, and from making their followers capable of being identified with the organization. It is highly beneficial for the workers of the virtual leaders to understand its importance and the importance of technology to control and maintain the leader-follower interactions. (Surinder, Jerry, Suling, Bruce, 2000) Today, virtual leaders have emerged as a significant work structure. In fact, virtual teams are usually group of people arranged together to perform certain activities despite being physically apart. Only few researches conduct in field to about the virtual leadership show that effectiveness of virtual leaders can only be maintained by adopting an attempt to mentor the characteristics of both transformational and instrumental leadership. However, one but be little warned the outcomes of the field study of virtual leadership is not quite statistically valid because mostly the teams are students are used to collect data rather than organizational teams. (Surinder, Jerry, Suling, Bruce, 2000) Most of the work done on virtual leadership is done by using students virtual teams for data collection. The members of the virtual teams usually belong to divergent organizations and cultures. Admittedly, the virtual teams depend upon the electronic communication and informational technologies to fulfill their work. They provide a large number of advantages for the organizations. (Surinder, Jerry, Suling, Bruce, 2000) The work that cans me done in future upon the virtual leadership and virtual teams is focused upon the examining the effects of specific leadership behaviors. This behavior must be of the type to mould a unique and different style of leadership. It will provide a help to develop quit limited, in focus and important assistance to take forth virtual teams. The combination of transactional and transformational leaders should be done to maintain such behaviors. Individual and collective leadership should be examined in the virtual teams. It should be noticed the methods of examining the tasks, operating conditions, technology features, any interact with leadership pin virtual teams to influence group process and outcomes. (Surinder, Jerry, Suling, Bruce, 2000) The conclusion of the study suggests that competition, off shoring of work and the growth of internet and similar globally linking technologies are contributing to an increase in the use of virtual teams. The virtual teams are expected to become more noticeable in the coming world. However, today, more attention is given to the idea of developing strong virtual leader and enhancing their virtual leadership skills. Research done till now suggests that the leadership style of traditional leaders is different from those of virtual leaders. (Surinder, Jerry, Suling, Bruce, 2000) The context of the operation of the leaders also maintains certain leadership activities and opportunities are available in the market to avail. Virtual leaders possess certain behaviors which are more significant than others. It is leading a new leadership behaviors to change their effects. (Surinder, Jerry, Suling, Bruce, 2000) Buy custom Ross Messinger's Research essay

EXAM Essay Example | Topics and Well Written Essays - 500 words - 1

EXAM - Essay Example Space geodesy is also known as satellite geodesy. Point positioning is a major application that accurately determines the coordinates of points in space, land and sea. The locations of points are determined by linking measurements of known points with terrestrial positions that are not known.It may include transformation between astronomical C.S and terrestrial C.S. Use of GPS satellites, triangulation and other satellite geodesy are used to for the known points positioning. The satellite geodesy is relevant in intersatellite tracking. Space geodesy determines the positions of points, both relatively and absolutely. Space geodesy, currently, has been formed to provide abundant and accurate geodetic data than the classical systems. Satellite geodesy helps in determination of precise local or regional geodetic control, earth’s gravitational pull determination and modelling and measurement of geodynamic phenomenon. Geodynamic phenomenon include polar motion,crustal deformation and the earth’s rotation. Space geodesy consists observation and computational techniques which allow for solutions above geodetic problems by precise measurements to or from artificial satellites. This is the geodesy aspect that strictly concerns geometrical relationships of the earth’s surface. The earth’s surface is measured in different ways, such as triangulation, electronic surveys and trilateration for the purpose of determining the shape, size of the earth and the precise location of points on the surface of the earth. Geometric geodesy is a science that considers the geoid by the use of astrogeodetic method. Most of the spatial data errors are processing errors: Numerical errors, cascading errors, topological errors, digitizing and geocoding errors. Processing errors are those errors that are introduced during digitizing and processing. For example, conversion of data from raster to

Great deprassion Research Paper Example | Topics and Well Written Essays - 1000 words

Great deprassion - Research Paper Example This saw most of the Americans loose their farms and homes which led to some of them deciding to escape from America using trains which crossed over their borders to the neighboring countries and other states within America which were not adversely affected by the depression. These people who migrated to other states and countries thought that they would find new jobs wherever they went but that was not to be as the depression had affected almost the whole of America and its neighbours.From the studies it was noted that America was the first country to recover from the Depression which started at around 1933 but the recovery was slowed down in the following two years but after the two years of slowing down the economy started to have a steady recovery in the year 1935.As the economy was recovering and doing well in the 1940 there came the World War 11 started and America was drawn into economic depression again which slowed down the process of recovery and that’s why it was ca me to be known as the Great Depression. In the history of U.S this depression which is said to have affected the whole world has come to be known as the ‘defining moment’. This depression made the federal government change the Way it was performing towards the economy. The government had to control all the business activities which the businessmen objected to in order to control the economy. Some of the drastic measures that the federal government took to recover the economy included laying down of the elderly citizens who were working thus giving them involuntary unemployment compensation. It as well changed the labor engagements between the employers and the employees through the Wagner Act which promoted the formation of unions to act as their arbitrator so that they could be fairly represented. But all this changes needed an increase in the federal government size. After the expansion of the federal government there were some economical changes which were experience d like in the case of paid citizens in the 1920s they increased in number as they approached the 1930s.The depression also changed the way people looked at the economy as many of them blamed lack of adequate demand which all the economists thought that the federal government should intervene and stabilize it through formulating good economic policies. Overtime many Economists have tried to demystify the cause of the depression and its reasons to affect other nations adversely than others but they have not come to a unanimous conclusion on what caused the depression. During this economic hardship America was very cautious with all the nations that it associated itself with economically. This was so because other European countries which had been hit by the depression had decided to operate within their borders this meant that there was less global trade which in turn would hurt the American economy due to its presence in most of these countries. The reason why some countries detached themselves from the global trade is that they blamed it for the emergence of the two world wars and they did not want to see the occurrence of such wars again. So as to resuscitate the global trade and promote the economy there was a dire need to form global monetary bodies so that they could assist in the supporting of the global trade. Due to this need then it led to the formation of two International Financial Institutions that would

There is a real danger of a house price bubble in London. Discuss Essay - 7

There is a real danger of a house price bubble in London. Discuss - Essay Example ntly the property prices in London have gone up way too high; too high for investors to believe that there is a very high danger of a housing price bubble within London. This essay seeks to present a case for the high level of risk associated with housing prices in London, and it does so by backing up the case with substantial evidence. The property bubble in London is real, and investors need to exercise caution if they want to come out safe from this scenario. Looking at media reports makes one thing very clear – the property prices in London have touched their four year low by the end of 2014. This can be linked to the very basic principle of demand and supply like mentioned above. According to a survey of property agents and surveyors dealing in London based property, there a wide consensus amongst market makers that property value in London is likely to follow its downward trajectory as demand for housing falls has gone down, coupled with new projects being announced by builders, thus resulting in a very low volume of transactions (Edwards, 2014). The high probability of a housing price bubble in London also emanates from the fact that many property holders in London have all of a sudden found their property values going up multi folds. This has made them put their property out in the market for sale and realize profits, as they move to live in county areas. Also, there is a wide believe amongst these investors that the current prices in London are far too high, and the market can crash anytime and therefore it is best to realize profits rather than being a part of the loss themselves as the market witnesses a correction (Bracke, 2014). Besides the information mentioned above, a few other facts also prove the existence of a property bubble in London. The house price to earnings ratio computed by the famous mortgage lender, Halifax, shows how many times or what multiple of house prices are made up income of buyers. It is rather shocking to note that the

Fundamental Concepts Of Ethernet Technology Information Technology Essay

Fundamental Concepts Of Ethernet Technology Information Technology Essay In this module, we will discuss the fundamental concepts of networking, Ethernet technology, and data transmission in Ethernet networks. Module Objectives At the end of this module, you will be able to: Explain the seven network layers as defined by the Open Systems Interconnection (OSI) Reference model Describe, at a high level, the history of Ethernet List physical layer characteristics of Ethernet Explain the difference between half-duplex and full-duplex transmission in an Ethernet network Describe the structure of an Ethernet frame Explain how networks can be extended and segmented using various Ethernet devices, including hubs and switches Describe how frames are forwarded in an Ethernet network Explain, at a high level, how Virtual Local Area Networks (VLANs) function Network Fundamentals This section provides a brief overview of Local Area Network (LAN) technology. We will discuss LAN architecture from a functional perspective. A network is commonly divided into seven functional layers referred to as the OSI Reference model. In addition, we will briefly discuss the use of addressing in LANs. Instructor Note Point out that this section only touches briefly on LAN concepts, and students may want to explore LAN technology in more depth on their own. Network Layers A complete LAN implementation involves a number of functions that, in combination, enable devices to communicate over a network. To understand how Ethernet fits into this overall set of functions, we can use the OSI Reference model. The OSI Reference model was developed in 1984 by the International Organization for Standardization (ISO). Instructor Note You can introduce the discussion of the OSI Reference model by comparing analysis of the model to peeling an onion. Shown in Figure 1-1, the OSI Reference model defines seven functional layers that process data when data is transmitted over a network. When devices communicate over a network, data travels through some or all of the seven functional layers. The figure shows data being transmitted from Station A, the source, to Station B, the destination. The transmission begins at the Application layer. As data (referred to as the payload) is transmitted by Station A down through the layers, each layer adds its overhead information to the data from the layer above. (The process of packaging layer-specific overhead with the payload is referred to as encapsulation discussed later in this course.) Upon reaching the Physical layer, the data is placed on the physical media for transmission. The receiving device reverses the process, unpackaging the contents layer by layer, thus allowing each layer to effectively communicate with its peer layer. Ethernet operates at Layer 2, the Data Link layer. Using Figure 1-1 as a reference, we will briefly discuss what occurs at each layer. Figure 1-1: The OSI Reference Model Application Layer The Application layer, Layer 7 (L7), is responsible for interacting with the software applications that send data to another device. These interactions are governed by Application layer protocols, such as Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), and Simple Mail Transfer Protocol (SMTP). Presentation Layer The Presentation layer, Layer 6 (L6), performs data translation, compression, and encryption. Data translation is required when two different types of devices are connected to each other, and both use different ways to represent the data. Compression is required to increase the transmission flow of data. Encryption is required to secure data as it moves to the lower layers of the OSI Reference model. Session Layer The Session layer, Layer 5 (L5), is responsible for creating, maintaining, and terminating communication among devices. A session is a logical link created between two software application processes to enable them to transmit data to each other for a period of time. Logical links are discussed later in this course. Transport Layer The Transport layer, Layer 4 (L4), is responsible for reliable arrival of messages and provides error checking mechanisms and data flow controls. The Transport layer also performs multiplexing to ensure that the data from various applications is transported using the same transmission channel. Multiplexing enables data from several applications to be transmitted onto a single physical link, such as a fiber optic cable. The data flow through the Transport layer is governed by transmission protocols, such as Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), which are beyond the scope of this course. Network Layer The Network layer, Layer 3 (L3), is responsible for moving data across interconnected networks by comparing the L3 source address with the L3 destination address. The Network layer encapsulates the data received by higher layers to create packets. The word packet is commonly used when referring to data in the Network layer. The Network layer is also responsible for fragmentation and reassembly of packets. Data Link Layer The Data Link layer, Layer 2 (L2), responds to requests sent by the Network layer and sends service requests to the Physical layer. The Data Link layer is responsible for defining the physical addressing, establishing logical links among local devices, sequencing of frames, and error detection. The Ethernet frame is a digital data transmission unit on Layer 2. The word frame is commonly used when referring to data in the Data Link layer. The Data Link layer has been subdivided into two sub-layers: Logical Link Control (LLC) and Media Access Control (MAC). LLC, defined in the Institute of Electrical and Electronics Engineers (IEEE) 802.2 specification, manages communications among devices over a link. LLC supports both connection-oriented (physical, ex an Ethernet switch) and connectionless (wireless, ex a wireless router) services. The MAC sub-level manages Ethernet frame assembly and dissembly, failure recovery, as well as access to, and routing for, the physical media. This will be discussed in more detail in this module. Physical Layer The Physical layer, Layer 1 (L1), performs hardware-specific, electrical, and mechanical operations for activating, maintaining, and deactivating the link among communicating network systems. The Physical layer is responsible for transmitting the data as raw bits over the transmission media. Now that we have reviewed the OSI Reference model, lets discuss addressing of network devices. Stations Network devices that operate at the Data Link layer or higher are referred to as stations. Stations are classified as either end stations or intermediate stations. End stations run end-user applications and are the source or final destination of data transmitted over a network. Intermediate stations relay information across the network between end stations. A characteristic of stations is that they are addressable. In the next section, we discuss the specifics of addressing. Addressing Each device in an Ethernet network is assigned an address that is used to connect with other devices in the network. This address is referred to as the MAC address and is typically a permanent address assigned by the device manufacturer. Addressing is used in the network to identify the source station and the destination station or stations of transmitted data. As shown in Figure 1-2, the MAC address consists of 48 bits (6 bytes), typically expressed as colon-separated, hexadecimal pairs. Figure 1-2: MAC Address Structure The MAC address consists of the following: Individual / Group (I/G) Bit: For destination address, if the I/G bit = 0, the destination of the frame is a single station. This is referred to as a unicast address. If the I/G bit = 1, the destination is a group of stations. This is referred to as a multicast address. In source addresses, the I/G bit = 1. Universal / Local (U/L) Bit: The U/L bit identifies whether the MAC address is universally unique (U/L bit = 0) or only unique in the LAN in which it is located. Vendor-assigned MAC addresses are always universally unique. A locally unique MAC address is assigned by the network administrator. Organizationally Unique Identifier (OUI): This typically identifies the network equipment manufacturer. OUIs are assigned to organizations by the IEEE. To locate information on the OUI associated with a manufacturer go to the following website: http://standards.ieee.org/regauth/oui/index.shtml Vendor-Assigned Bits: These bits are assigned by the vendor to uniquely identify a specific device. Following is an example of a MAC address: 00:1B:38:7C:BE:66 Later in this module, we discuss how MAC addresses are used in Ethernet networks. Introduction to Ethernet Ethernet is an internationally-accepted, standardized LAN technology. It is one of the simplest and most cost-effective LAN networking technologies in use today. Ethernet has grown through the development of a set of standards that define how data is transferred among computer networking devices. Although several other networking methods are used to implement LANs, Ethernet remains the most common method in use today. While Ethernet has emerged as the most common LAN technology for a variety of reasons, the primary reasons include the following: Ethernet is less expensive than other networking options. Easy is easy to install and provision the various components. Ethernet is faster and more robust than the other LAN technologies. Ethernet allows for an efficient and flexible network implementation. History of Ethernet Ethernet was invented in 1973 by Bob Metcalfe and David Boggs at the Xerox Palo Alto Research Center (PARC). Ethernet was originally designed as a high-speed LAN technology for connecting Xerox Palo Alto graphical computing systems and high-speed laser printers. In 1979, Xerox ® began work with Digital Equipment Corporation (DEC) and Intel ® to develop a standardized, commercial version of Ethernet. This partnership of DEC, Intel, and Xerox (DIX) developed Ethernet Version 1.0, also known as DIX80. Further refinements resulted in Ethernet Version 2, or DIX82, which is still in use today. Project 802 In 1980, the Institute of Electrical and Electronics Engineers (IEEE) formed Project 802 to create an international standard for LANs. Due to the complexity of the technology and the emergence of competing LAN technologies and physical media, five working groups were initially formed. Each working group developed standards for a particular area of LAN technology. The initial working groups consisted of the following: IEEE 802.1: Overview, Architecture, Internetworking, and Management IEEE 802.2: Logical Link Control IEEE 802.3: Carrier Sense Multiple Access / Collision Detection (CSMA/CD) Media Access Control (MAC) IEEE 802.4: Token Bus MAC and Physical (PHY) IEEE 802.5: Token Ring MAC and PHY Additional working groups have since been added to address other areas of LAN technology. The standards developed by these working groups are discussed as we move through this course. However, lets look at IEEE 802.3, which addresses standards specific to Ethernet. IEEE 802.3 IEEE 802.3 was published in 1985 and is now supported with a series of supplements covering new features and capabilities. Like all IEEE standards, the contents of supplements are added to the standard when it is revised. Now adopted by almost all computer vendors, IEEE 802.3 consists of standards for three basic elements: The physical media (fiber or copper) used to transport Ethernet signals over a network MAC rules that enable devices connected to the same transmission media to share the transmission channel Format of the Ethernet frame, which consists of a standardized set of frame fields We will discuss the transmission media used in Ethernet networks, the MAC rules, and the Ethernet frame later in this module. Instructor Note Tell the class that we will discuss the transmission media used in Ethernet networks, the MAC rules, and the Ethernet frame later in this module. You can briefly explain the differences among LANs, WANs, and MANs to the students. Ethernet Transmission Fundamentals This section covers basic fundamentals of data transmission on Ethernet networks. Specifically, we will cover the following topics: Physical layer characteristics Communication modes Ethernet frames Repeaters and hubs Ethernet bridges and switches Multilayer switches and routers Ethernet Virtual LANs (VLANs) Ethernet beyond the LAN Physical Layer Characteristics Our discussion of physical layer characteristics covers both the physical media over which network communications flow and the rate at which communications occur. In fact, the nomenclature for the various types of Ethernet is based on both of these characteristics. The Ethernet type is referred to in the following format: n-BASE-phy, such as 10BASE-T where: n is the data rate in megabits per second (Mbps). BASE indicates that the media is dedicated to only Ethernet services. phy is a code assigned to a specific type of media. A variety of media and transmission rates are available for Ethernet networks. The major media types used today are: Unshielded Twisted Pair (UTP) copper cable Shielded Twisted Pair (STP) copper cable Fiber optic cables The IEEE 802.3 standard identifies the following types of media for an Ethernet connection: 10BASE2: Defined in IEEE 802.3a, 10BASE2 Ethernet uses thin wire coaxial cable. It allows cable runs of up to 185 meters (607 feet). A maximum of 30 workstations can be supported on a single segment. This Ethernet type is no longer in use for new installations. 10BASE-T: Defined in IEEE 802.3i, 10BASE-T uses UTP copper cable and RJ-45 connectors to connect devices to an Ethernet LAN. The RJ-45 is a very common 8-pin connector. Fast Ethernet: Defined in IEEE 802.3u, Fast Ethernet is used for transmission at a rate of 100 Mbps. It includes 100BASE-TX, which uses UTP copper cable. With this type of cable, each segment can run up to 100 meters (328 feet). Another media option specified in this standard is 100BASE-FX, which uses optical fiber supporting data rates of up to 100 Mbps. Gigabit Ethernet (GbE): Defined in IEEE 802.3z, GbE uses fiber for transmitting Ethernet frames at a rate of 1000 Mbps or 1 Gbps. GbE includes 1000BASE-SX for transmission over Multi-Mode Fiber (MMF), and 1000BASE-LX for transmission over Single-Mode Fiber (SMF). The differences between Multi-Mode and Single-Mode are the physical makeup of the fiber itself and the light source that is normally used multi-mode normally uses an LED while single-mode uses a laser. Multi-mode has limited distance capability when compared to single-mode. 1000BASE-T: Defined in IEEE 802.3ab, 1000BASE-T provides GbE service over twisted pair copper cable. 10 GbE: Defined in IEEE 802.3ae, 10 GbE transmits Ethernet frames at data rates up to 10 Gbps. Communication Modes Ethernet can operate in either of two communication modes, half-duplex or full-duplex. Ethernet MAC establishes procedures that all devices sharing a communication channel must follow. Half-duplex mode is used when devices on a network share a communication channel. Full-duplex mode is used when devices have no contention from other devices on a network connection. Lets discuss each of these modes in more detail. Half-Duplex Mode As shown in Figure 1-3, a device operating in half-duplex mode can send or receive data but cannot do both at the same time. Originally, as specified in the DIX80 standard, Ethernet only supported half-duplex operation. Figure 1-3: Half-Duplex Transmission Half-duplex Ethernet uses the CSMA/CD protocol to control media access in shared media LANs. With CSMA/CD, devices can share media in an orderly way. Devices that contend for shared media on a LAN are members of the same collision domain. In a collision domain, a data collision occurs when two devices on the LAN transmit data at the same time. The CSMA/CD protocol enables recovery from data collisions. With CSMA/CD, a device that has data to transmit performs carrier sense. Carrier sense is the ability of a device to monitor the transmission media for the presence of any data transmission. If the device detects that another device is using the transmission media, the device waits for the transmission to end. When the device detects that the transmission media is not being used, the device starts transmitting data. Figure 1-4 shows how CSMA/CD handles a data collision. When a collision occurs, the transmitting device stops the transmission and sends a jamming signal to all other devices to indicate the collision. After sending the jamming signal, each device waits for a random period of time, with each device generating its own time to wait, and then begins transmitting again. Figure 1-4: CSMA/CD Operation Full-Duplex Mode In the full-duplex communication mode, a device can send and receive data at the same time as shown in Figure 1-5. In this mode, the device must be connected directly to another device using a Point-to-Point (P2P) link that supports independent transmit and receive paths. (P2P is discussed later in this course.) Figure 1-5: Full-Duplex Transmission Full-duplex operation is restricted to links meeting the following criteria: The transmission media must support the simultaneous sending and receiving of data. Twisted pair and fiber cables are capable of supporting full-duplex transmission mode. These include Fast Ethernet, GbE, and 10 GbE transmission media. The connection can be a P2P link connecting only two devices, or multiple devices can be connected to each other through an Ethernet switch. The link between both devices needs to be capable of, and configured for, full-duplex operation. CSMA/CD is not used for full-duplex communications because there is no possibility of a data collision. And, since each device can both send and receive data at the same time, the aggregate throughput of the link is doubled. (Throughput is the amount of data that can be transmitted over a certain period of time.) Ethernet Frames Lets discuss another fundamental aspect of Ethernet transmission the Ethernet frame. The Ethernet frame is used to exchange data between two Data Link layer points via a direct physical or logical link in an Ethernet LAN. The minimum size of an Ethernet frame is 64 bytes. Originally, the maximum size for a standard Ethernet frame was 1518 bytes; however, it is now possible that an Ethernet frame can be as large as 10,000 bytes (referred to as a jumbo frame). As shown in Figure 1-6, an Ethernet frame consists of the following fields: (NOTE: The first two fields are added/stripped at Layer 1 and are not counted as part of the 1518 byte standard frame.) Preamble: This 7-byte field establishes bit synchronization with the sequence of 10101010 in each byte. Start Frame Delimiter: This 1-byte field indicates the start of the frame at the next byte using a bit sequence of 10101011. Destination MAC Address: This field contains the MAC hardware address of the Ethernet frames destination. Source MAC Address: This field contains the MAC hardware address of the device sending the frame. Type / Length: The specific use of this field depends on how the frame was encapsulated. When type-encapsulation is used, the field identifies the nature of the client protocol running above the Ethernet. When using length-encapsulation, this field indicated the number of bytes in the Data field. The IEEE maintains a list of accepted values for this field, the list may be viewed at: http://standards.ieee.org/regauth/ethertype/ Data: This field contains the data or payload that has been sent down from Layer 3 for packaging to Layer 2. Frame Check Sequence (FCS): This 32-bit field is used for checking the Ethernet frame for errors in bit transmission. FCS is also known as Cyclical Redundancy Check (CRC). Figure 1-6: Ethernet Frame Now that we have defined the basic structure of an Ethernet frame, lets see how we can use the destination MAC address to create three different types of Ethernet frames. Unicast Frames An Ethernet frame intended for a single device on the network is a unicast frame. An example is shown in Figure 1-7. In this example, Station A is transmitting an FTP request to a specific FTP server on the network. The destination MAC address in the frames being sent for this request is the MAC address assigned to the FTP server by its manufacturer. Therefore, these frames are unicast frames, only intended specifically for one device on the network, the FTP server. Figure 1-7: Unicast Frame Transmission Multicast Frames Multicast is a mechanism that provides the ability to send frames to a specific group of devices on a network one sender to all who are set to receive. This is done by setting a frames destination MAC address to a multicast address assigned by a higher level protocol or application. However, devices must be enabled to receive frames with this multicast address. An example of multicast frames is shown in Figure 1-8. In this example, the video server is transmitting the same video channel, via an Ethernet switch, to a group of video display devices on the network. The destination MAC address is the multicast address assigned by the video application. The receiving stations are configured to accept Ethernet frames with this multicast address. Figure 1-8: Multicast Frame Transmission Broadcast Frames Broadcasting is a mechanism for sending data in broadcast frames to all the devices in a broadcast domain. A broadcast domain is defined as a set of devices that can communicate with each other at the Data Link layer. Therefore, in a network that does not include higher layer devices, all of the network devices are in the same broadcast domain. In broadcast frames, the hexadecimal destination MAC address is always ff:ff:ff:ff:ff:ff which, in binary notation, is a series of 48 bits, each set to a value of 1. All devices in the broadcast domain recognize and accept frames with this destination MAC address. Instructor Note Be sure that students understand hexadecimal vs. binary notation, but do not take this topic beyond the scope of this course. Since broadcasting reaches all devices within a broadcast domain, Ethernet can use this capability to perform various device setup and control functions. This is a very useful feature, allowing implementation and growth of a LAN with little intervention from a network administrator. Figure 1-9 shows a broadcast transmission in which Station A is transmitting frames with this broadcast destination MAC address. All devices in the same broadcast domain as Station A receive and process the broadcast frames. Figure 1-9: Broadcast Frame Now that we have covered some basic concepts for LANs and Ethernet transmission, lets continue by discussing how devices on Ethernet LANs are connected. Instructor Note Check the existing knowledge of students on the differences among switches, hubs, routers, and gateways. Initiate a discussion around the differences among these devices and their suitability to different applications. Repeaters and Hubs A very simple LAN topology consists of network devices that are all connected directly to a shared medium as shown in Figure 1-10. If we need to connect more devices to the LAN, we are limited by the characteristics of the shared media. Devices such as repeaters and hubs can be used to overcome distance limitations of the media, allowing the reach of the network to be extended. Figure 1-10: Simple LAN Topology Repeaters are Physical layer devices that regenerate a signal, which effectively allows the network segment to extend a greater distance. As shown in Figure 1-11, we can use the additional segment length to add more devices to the LAN. Keep in mind that devices added through implementation of repeaters are still in the same collision domain as the original devices. This results in more contention for access to the shared transmission media. Such devices are in little use today. Figure 1-11: LAN Extended with a Repeater As shown in Figure 1-12, hubs can also be used to extend the distance of a LAN segment. Hubs are Layer 1 (physical) devices. The advantage of a hub versus a repeater is that hubs provide more ports. Increased contention for media access still exists since the additional devices connected to the hub(s) are still in the same collision domain. Figure 1-12: LAN Extended with a Hub Ethernet Bridges and Switches Ethernet bridges and switches are Layer 2 (Data Link) devices that provide another option for extending the distance and broadcast domain of a network. Unlike repeaters and hubs, bridges and switches keep the collision domains of connected LAN segments isolated from each other as shown in Figure 1-13. Therefore, the devices in one segment do not contend with devices in another segment for media access. Figure 1-13: LAN Extended with an Ethernet Switch Frame Forwarding with Ethernet Switches As Layer 2 devices, Ethernet switches make frame-forwarding decisions based on source and destination MAC addresses. One of the processes used in making these decisions is MAC learning. To make efficient use of the data pathways that are dynamically cross connected within an Ethernet switch, the switch keeps track of the location of as many active devices as its design allows. When an Ethernet frame ingresses (enters) a switch, the switch inspects the frames source address to learn the location of the sender and inspects the destination address to learn the location of the recipient. This knowledge is kept in a MAC address table. Figure 1-14 shows an example of a MAC address table. As long as the sender remains connected to the same physical port that their MAC address was learned on, the switch will know which port to forward frames to that are destined for that particular senders address. Figure 1-14: MAC Address Table MAC address information stored in a MAC address table is not retained indefinitely. Each entry is time stamped; and if no activity is sensed for a period of time, referred to as an aging period, the inactive entry is removed. This is done so that only active devices occupy space in the table. This keeps the MAC address table from overloading and facilitates address lookup. The default aging period is typically five minutes. Figure 1-15 shows how an Ethernet switch forwards frames based on entries in the MAC address table. The forwarding process consists of the following steps: Inspect the incoming frames MAC destination address: If the MAC destination address is a broadcast address, flood it out all ports within the broadcast domain. If the MAC destination address is a unicast address, look for it in the MAC address table. If the address is found, forward the frame on the egress (exit) port where the NE knows the device can be reached. If not, flood it. Flooding allows communication even when MAC destination addresses are unknown. Along with multicast, which is actually a large set of special-purpose MAC addresses, network traffic can be directed to any number of devices on a network. Inspect the incoming frames MAC source address: If the MAC source address is already in the MAC address table, update the aging timer. This is an active device on the port through which it is connected. If the MAC source address is not currently in the MAC address table, add it in the list and set the aging timer. This is also an active device. Periodically check for MAC address table entries that have expired. These are no longer active devices on the port on which they were learned, and these table entries are removed. If a device is moved from one port to another, the device becomes active on the new ports MAC table. This is referred to as MAC motion. An Ethernet switch will purposely filter (drop) certain frames. Whether a frame is dropped or forwarded can depend on the switch configuration, but normal switch behavior drops any frame containing a destination address that the switch knows can be reached through the same port where the frame was received. This is done to prevent a device from receiving duplicate frames. Figure 1-15: Frame-Forwarding Process A MAC Learning and Broadcast Domain Analogy Mail Delivery Consider this following analogy to understand the concept of MAC learning and broadcast domain: Consider a situation where your friend wants to send you a birthday party invitation (the invitation represents an Ethernet frame). You and your friend live on the same street (the street represents a broadcast domain). However, there is a problem. Your friend does not know your house address so she writes her return (source) address on the birthday party invitation card and writes the street name as your (destination) address. Your friend drops the envelope in her mail box (your friends mail box represents a LAN) as shown in Figure 1-16. Figure 1-16: Broadcast Analogy, Part 1 When the mail carrier picks up the mail, he notices that the destination address is unknown. The postman goes to a copier and makes enough copies so that he can deliver one copy to each possible destination address on the street. This would mean every house on the street, except for your friends house, will get a copy of the invitation. After the postman has delivered the envelopes to all the houses (this process is analogous to a broadcast transmission), you receive the birthday party invitation and recognize your name on the envelope. So, you open the envelope and read the invitation. Figure 1-17: Broadcast Analogy, Part 2 All of your neighbors receive copies of the same envelope, but they see that the name is not theirs so they simply discard it. After reading the invitation, you send a thank you card back to your friend with your friends address; and you include a return (source) address. The postman sees that this envelope has a specific destination address so it can be delivered without broadcasting. It also has a source address, so the postman now knows your address. It is now possible to exchange mail directly with your friend without broadcasting letters to your neighbors. In other words, you can communicate using unicast transmission. If you and your friend were on different streets (broadcast domains), you would have never received your invitation card; and communication could have never occurred. Multilayer Switches and Routers In this course, our discussion of switching focuses on switching at the Data Link level since Ethernet is a Layer 2 technology. However, switching can also be

Justice in the Book of Job Essay -- essays research papers

Does the Book of Job strengthen your faith in God’s justice? Why does God allow Satan to cause such tragedy in Job’s life, a man whom God has already acknowledged as â€Å"my servant Job, that there is none like on the earth, a blameless and upright man, who fears God and turns away from evil?†(1.8) From the beginning, it is known that Job is in no way deserving of his injustices, so a reason must be given. God gives Job an opportunity to prove that under any circumstances Job will still have faith. This simply a test for Job. The whole Book is a â€Å"double† journey for Job -- he shows God his faith and realizes the faith God has that Job will not stray from his path. Job knows deep down that God has not forsaken him. God deserves to be praised simply on the basis of who he is, apart from the b...