Networking Experience
The common lament of job seekers, that "employers only hire people with experience, yet the only way to gain experience is to get hired" applies in the computer networking field as well. Despite optimistic statements that one hears frequently regarding the number of available jobs in IT, landing an entry-level position can still prove difficult and frustrating.
One way to gain networking experience is to pursue a full-time programming or help desk "internship" during the summer months, or a part-time "work study" job at school. An internship may not pay well initially, the work may turn out to be relatively uninteresting, and it is very likely one will not be able to finish any substantial project during the limited time there. However, the most important factor to consider is the training and hands-on experience such a job offers. The mere fact a person invests their time in this way, demonstrates the dedication and interest employers like to see.
The better the position, the more likely multiple candidates will apply for it, even if the job entails only part-time work. A good way to "stand out" from the competition is to demonstrate prior work and accomplishments, even if these involve projects done on one's own time. A person can start with a class project, for example, and extend it in some way. Or they can create their own personal projects, experimenting with networking administration tools and scripts, for example.
Explaining Experience
One of the most overlooked skills in computer networking is the ability to explain technical information. Whether verbally, through email, or in formal writing, networkers that communicate well gain a significant advantage in building their careers.
For the beginning networker, the most obvious benefit of good communications skills is realized in job interviews. Being able to talk with people about technical subjects can be hard to do, but as one gains skill in answering impromptu questions, one builds confidence and relaxes, making one that much better prepared for career advancement. It is a good idea to periodically engage in job interviews for this reason, even if the position involved does not seem particularly appealing. Likewise one should also consider visiting local job fairs occasionally.
Technologies
One of the most common questions asked by beginning networkers is "Which technology should I focus on first? Microsoft? UNIX? Cisco? Novell?" As with certifications, preferences vary from company to company and person to person.
One way for a person to answer this question is to start with the technology that appears most interesting to them personally. Researching a company that one plans to interview with, and choosing a technology that the company deems important, is another way. Ultimately it probably matters little which networking technology one learns first. More importantly, one should acknowledge that technology changes rapidly, and that the person who can enjoy a successful career by learning about only one technology is rare indeed.
Focus on the Basics
Computer networking involves a certain number of fundamental technologies. These technologies form the basis of many networking courses. Regardless of the form of education one chooses to invest in, one's career will always benefit from deeper study of technologies like IP and TCP/IP, the OSI model, Ethernet, internetworking, and others listed on this site, whether through formal coursework or through self-study.
Conclusion
Some people have asserted that networking (and IT generally) is a "young person's game," and that companies generally prefer to turn over their employee base periodically, to bring in younger, more affordable workers. This concept might sound appealing to some, but if it were true, it would make networking careers less inviting to most people.
Realistically, the field of computer networking presents so much complexity, and involves such a wide range of technologies, that most serious companies should value both experienced employees and ambitious new employees highly. In fact, an effective career strategy involves seeking out more experienced people in one's field, and learning new skills from these mentors.
Many firms view four-years degrees as a sign of commitment to the field. Network technology changes very fast, so employers care both about a person's current knowledge and also their ability to learn and adapt for the future. Certifications effectively prove current knowledge, but college degrees best demonstrate one's general learning ability.
Self-study in networking is always effective and underrated by many. By making contacts with those in networking careers, either people in one's local area, or individuals or sites on the Internet, one can quickly acquire a wealth of information ranging from technical details, to advice on writing a resume, to advice on specific hiring companies, schools, and so on.
Best wishes for a successful career in networking, or whatever other field you may choose!
Tuesday, April 28, 2009
Educational options abound for those interested in networking
Those interested in networking careers can benefit greatly from earning a college degree. Most university programs don't offer a degree in Computer Networking per se, and the precise name of the degree varies significantly from institution to institution. Four-year degree programs suitable for the computer networking field usually involve a variation on one of the following:
Computer Science
Electrical and Computer Engineering
Information Systems
Communications Science
Telecommunications, Telecommunications Management
Telecomputing
As an alternative to a general four-year degree (that covers a variety of technical subjects besides computer networking), some institutions offer shorter-term programs focused specifically on networking topics.
Until recently, computer networking courses were only found in post-secondary education. Nowadays, though, high school students have the opportunity to take networking courses too. These classes can be quite substantial, involving among other things configuring routers and switches, installing wire, network diagnostics, monitoring network activity, and working with various network protocols and operating systems.
Which Program Is Best?
Is a college degree worth the investment, or is a shorter, more focused curriculum the way to go? Opinions vary. A four-degree can demonstrate to prospective employers a level of dedication and long-term flexibility that a short program cannot. On the other hand, a more focused program can teach the basic networking skills quickly, and allow more time for on-the-job experience.
Certifications
Network adminstrators and managers in particular have grown fond of networking-based certifications like Microsoft MCSE and Cisco CCNA. In general, to gain and keep a certification one must pass a lengthy (usually multiple-choice question) paper exam, then pass recertification exams at periodic intervals (usually every two or three years). A person has the choice of preparing for the exam through self-study or by enrolling in a certification course or "program" run by a training organization (sometimes within high-tech companies themselves). Taking any certification exam involves paying a test "sitting" fee (usually in the range of $100 to $300 USD), and employers sometimes reimburse their employees for this cost.
Certifications are designed to accredit someone for a certain amount of industry experience that they've already gained. Some of the programs will even make recommendations to this effect, typically one to two years of prior background for the entry-level certifications. However, experience is not strictly required. Some have criticized the entry-level exams for being too "bookish" in this respect, too easy to pass without prior hands-on experience.
Which certification is best? MCSE? CCNA? Something else? Again, the answer depends on the individual's interests and also the preferences of hiring companies. Some ambitious students of networking avoid this problem by acquiring multiple certifications... sometimes as many as five or more! Be aware, though, that certifications are an incomplete substitute for formal education and industry experience. Ideally, one will acquire a few certifications as part of a balanced overall mix of education and career experience.
Many companies, particularly larger ones, offer their employees ongoing training opportunities. The employer will either build their own courses or will bring in an outside company to hold the training. These courses are typically focused on a specific product technology or tool, or on the specific technical information needed to pass a certification exam. One could argue it is preferable for the beginning networker to focus on general technologies at first rather than certifications, as companies in these case likely prefer to train employees "their own way" anyhow.
Computer Science
Electrical and Computer Engineering
Information Systems
Communications Science
Telecommunications, Telecommunications Management
Telecomputing
As an alternative to a general four-year degree (that covers a variety of technical subjects besides computer networking), some institutions offer shorter-term programs focused specifically on networking topics.
Until recently, computer networking courses were only found in post-secondary education. Nowadays, though, high school students have the opportunity to take networking courses too. These classes can be quite substantial, involving among other things configuring routers and switches, installing wire, network diagnostics, monitoring network activity, and working with various network protocols and operating systems.
Which Program Is Best?
Is a college degree worth the investment, or is a shorter, more focused curriculum the way to go? Opinions vary. A four-degree can demonstrate to prospective employers a level of dedication and long-term flexibility that a short program cannot. On the other hand, a more focused program can teach the basic networking skills quickly, and allow more time for on-the-job experience.
Certifications
Network adminstrators and managers in particular have grown fond of networking-based certifications like Microsoft MCSE and Cisco CCNA. In general, to gain and keep a certification one must pass a lengthy (usually multiple-choice question) paper exam, then pass recertification exams at periodic intervals (usually every two or three years). A person has the choice of preparing for the exam through self-study or by enrolling in a certification course or "program" run by a training organization (sometimes within high-tech companies themselves). Taking any certification exam involves paying a test "sitting" fee (usually in the range of $100 to $300 USD), and employers sometimes reimburse their employees for this cost.
Certifications are designed to accredit someone for a certain amount of industry experience that they've already gained. Some of the programs will even make recommendations to this effect, typically one to two years of prior background for the entry-level certifications. However, experience is not strictly required. Some have criticized the entry-level exams for being too "bookish" in this respect, too easy to pass without prior hands-on experience.
Which certification is best? MCSE? CCNA? Something else? Again, the answer depends on the individual's interests and also the preferences of hiring companies. Some ambitious students of networking avoid this problem by acquiring multiple certifications... sometimes as many as five or more! Be aware, though, that certifications are an incomplete substitute for formal education and industry experience. Ideally, one will acquire a few certifications as part of a balanced overall mix of education and career experience.
Many companies, particularly larger ones, offer their employees ongoing training opportunities. The employer will either build their own courses or will bring in an outside company to hold the training. These courses are typically focused on a specific product technology or tool, or on the specific technical information needed to pass a certification exam. One could argue it is preferable for the beginning networker to focus on general technologies at first rather than certifications, as companies in these case likely prefer to train employees "their own way" anyhow.
How to Become a Networker
Job Titles
Several types of positions exist in networking, each with different average salaries and long-term potential, and one should possess a clear understanding of these. Unfortunately, job titles in networking, and in Information Technology (IT) generally, often lead to confusion among beginners and experienced folks alike. Bland, vague or overly bombastic titles often fail to describe the actual work assignments of a person in this field.
The basic job titles one sees for computer networking and networking-related positions include
Network Administrator
Network (Systems) Engineer
Network (Service) Technician
Network Programmer/Analyst
Network/Information Systems Manager
The Network Administrator
In general, network administrators configure and manage LANs and sometimes WANs. The job descriptions for administrators can be detailed and sometimes downright intimidating! Consider the following description that, although fictitious, represents a fairly typical posting:
NETWORK ADMINISTRATOR - HOBO COMPUTING
"Candidate will be responsible for analysis, installation and configuration of company networks. Daily activities include monitoring network performance, troubleshooting problems and maintaining network security. Other activities include assisting customers with operating systems and network adapters, configuring routers, switches, and firewalls, and evaluating third-party tools."
Needless to say, a person early in their career often lacks experience in a majority of these categories. Most employers do not expect candidates to possess in-depth knowledge of all areas listed in the job posting, though, so a person should remain undeterred by the long, sweeping job descriptions they will inevitably encounter.
Comparing Roles and Responsibilities
The job function of a Network Engineer differs little from that of a Network Administrator. Company A may use one title while Company B uses the other to refer to essentially the same position. Some companies even use the two titles interchangeably. Firms making a distinction between the two often stipulate that administrators focus on the day-to-day management of networks, whereas network engineers focus primarily on system upgrades, evaluating vendor products, security testing, and so on.
A Network Technician tends to focus more on the setup, troubleshooting, and repair of specific hardware and software products. Service Technicians in particular often must travel to remote customer sites to perform "field" upgrades and support. Again, though, some firms blur the line between technicians and engineers or administrators.
Network Programmer/Analysts generally write software programs or scripts that aid in network analysis, such as diagnostics or monitoring utilities. They also specialize in evaluating third-party products and integrating new software technologies into an existing network environment or to build a new environment.
Managers supervise the work of adminstrators, engineers, technicians, and/or programmers. Network / Information Systems Managers also focus on longer-range planning and strategy considerations.
Salaries for networking positions depend on many factors such as the hiring organization, local market conditions, a person's experience and skill level, and so on. (Links to more in-depth information on networking salaries appear in the box at the top of each page.)
Several types of positions exist in networking, each with different average salaries and long-term potential, and one should possess a clear understanding of these. Unfortunately, job titles in networking, and in Information Technology (IT) generally, often lead to confusion among beginners and experienced folks alike. Bland, vague or overly bombastic titles often fail to describe the actual work assignments of a person in this field.
The basic job titles one sees for computer networking and networking-related positions include
Network Administrator
Network (Systems) Engineer
Network (Service) Technician
Network Programmer/Analyst
Network/Information Systems Manager
The Network Administrator
In general, network administrators configure and manage LANs and sometimes WANs. The job descriptions for administrators can be detailed and sometimes downright intimidating! Consider the following description that, although fictitious, represents a fairly typical posting:
NETWORK ADMINISTRATOR - HOBO COMPUTING
"Candidate will be responsible for analysis, installation and configuration of company networks. Daily activities include monitoring network performance, troubleshooting problems and maintaining network security. Other activities include assisting customers with operating systems and network adapters, configuring routers, switches, and firewalls, and evaluating third-party tools."
Needless to say, a person early in their career often lacks experience in a majority of these categories. Most employers do not expect candidates to possess in-depth knowledge of all areas listed in the job posting, though, so a person should remain undeterred by the long, sweeping job descriptions they will inevitably encounter.
Comparing Roles and Responsibilities
The job function of a Network Engineer differs little from that of a Network Administrator. Company A may use one title while Company B uses the other to refer to essentially the same position. Some companies even use the two titles interchangeably. Firms making a distinction between the two often stipulate that administrators focus on the day-to-day management of networks, whereas network engineers focus primarily on system upgrades, evaluating vendor products, security testing, and so on.
A Network Technician tends to focus more on the setup, troubleshooting, and repair of specific hardware and software products. Service Technicians in particular often must travel to remote customer sites to perform "field" upgrades and support. Again, though, some firms blur the line between technicians and engineers or administrators.
Network Programmer/Analysts generally write software programs or scripts that aid in network analysis, such as diagnostics or monitoring utilities. They also specialize in evaluating third-party products and integrating new software technologies into an existing network environment or to build a new environment.
Managers supervise the work of adminstrators, engineers, technicians, and/or programmers. Network / Information Systems Managers also focus on longer-range planning and strategy considerations.
Salaries for networking positions depend on many factors such as the hiring organization, local market conditions, a person's experience and skill level, and so on. (Links to more in-depth information on networking salaries appear in the box at the top of each page.)
Thursday, April 23, 2009
Technology
Technology is a broad concept that deals with an animal species' usage and knowledge of tools and crafts, and how it affects an animal species' ability to control and adapt to its environment. Technology is a term with origins in the Greek "technologia", "τεχνολογία" — "techne", "τέχνη" ("craft") and "logia", "λογία" ("saying").[1] However, a strict definition is elusive; "technology" can refer to material objects of use to humanity, such as machines, hardware or utensils, but can also encompass broader themes, including systems, methods of organization, and techniques. The term can either be applied generally or to specific areas: examples include "construction technology", "medical technology", or "state-of-the-art technology".
The human race's use of technology began with the conversion of natural resources into simple tools. The prehistorical discovery of the ability to control fire increased the available sources of food and the invention of the wheel helped humans in travelling in and controlling their environment. Recent technological developments, including the printing press, the telephone, and the Internet, have lessened physical barriers to communication and allowed humans to interact on a global scale. However, not all technology has been used for peaceful purposes; the development of weapons of ever-increasing destructive power has progressed throughout history, from clubs to nuclear weapons.
Technology has affected society and its surroundings in a number of ways. In many societies, technology has helped develop more advanced economies (including today's global economy) and has allowed the rise of a leisure class. Many technological processes produce unwanted by-products, known as pollution, and deplete natural resources, to the detriment of the Earth and its environment. Various implementations of technology influence the values of a society and new technology often raises new ethical questions. Examples include the rise of the notion of efficiency in terms of human productivity, a term originally applied only to machines, and the challenge of traditional norms.
Philosophical debates have arisen over the present and future use of technology in society, with disagreements over whether technology improves the human condition or worsens it. Neo-Luddism, anarcho-primitivism, and similar movements criticise the pervasiveness of technology in the modern world, claiming that it harms the environment and alienates people; proponents of ideologies such as transhumanism and techno-progressivism view continued technological progress as beneficial to society and the human condition. Indeed, until recently, it was believed that the development of technology was restricted only to human beings, but recent scientific studies indicate that other primates and certain dolphin communities have developed simple tools and learned to pass their knowledge to other generations.
DEFINATION & USAGE
In general technology is the relationship that society has with its tools and crafts, and to what extent society can control its environment. The Merriam-Webster dictionary offers a definition of the term: "the practical application of knowledge especially in a particular area" and "a capability given by the practical application of knowledge".[1] Ursula Franklin, in her 1989 "Real World of Technology" lecture, gave another definition of the concept; it is "practice, the way we do things around here".[2] The term is often used to imply a specific field of technology, or to refer to high technology or just consumer electronics, rather than technology as a whole.[3] Bernard Stiegler, in Technics and Time, 1, defines technology in two ways: as "the pursuit of life by means other than life", and as "organized inorganic matter."[4]
Technology can be most broadly defined as the entities, both material and immaterial, created by the application of mental and physical effort in order to achieve some value. In this usage, technology refers to tools and machines that may be used to solve real-world problems. It is a far-reaching term that may include simple tools, such as a crowbar or wooden spoon, or more complex machines, such as a space station or particle accelerator. Tools and machines need not be material; virtual technology, such as computer software and business methods, fall under this definition of technology.[5]
The word "technology" can also be used to refer to a collection of techniques. In this context, it is the current state of humanity's knowledge of how to combine resources to produce desired products, to solve problems, fulfill needs, or satisfy wants; it includes technical methods, skills, processes, techniques, tools and raw materials. When combined with another term, such as "medical technology" or "space technology", it refers to the state of the respective field's knowledge and tools. "State-of-the-art technology" refers to the high technology available to humanity in any field.
Technology can be viewed as an activity that forms or changes culture.[6] Additionally, technology is the application of math, science, and the arts for the benefit of life as it is known. A modern example is the rise of communication technology, which has lessened barriers to human interaction and, as a result, has helped spawn new subcultures; the rise of cyberculture has, at its basis, the development of the Internet and the computer.[7] Not all technology enhances culture in a creative way; technology can also help facilitate political oppression and war via tools such as guns. As a cultural activity, technology predates both science and engineering, each of which formalize some aspects of technological endeavor.
Science, engineering and technology
The distinction between science, engineering and technology is not always clear. Science is the reasoned investigation or study of phenomena, aimed at discovering enduring principles among elements of the phenomenal world by employing formal techniques such as the scientific method.[8] Technologies are not usually exclusively products of science, because they have to satisfy requirements such as utility, usability and safety.
Engineering is the goal-oriented process of designing and making tools and systems to exploit natural phenomena for practical human means, often (but not always) using results and techniques from science. The development of technology may draw upon many fields of knowledge, including scientific, engineering, mathematical, linguistic, and historical knowledge, to achieve some practical result.
Technology is often a consequence of science and engineering — although technology as a human activity precedes the two fields. For example, science might study the flow of electrons in electrical conductors, by using already-existing tools and knowledge. This new-found knowledge may then be used by engineers to create new tools and machines, such as semiconductors, computers, and other forms of advanced technology. In this sense, scientists and engineers may both be considered technologists; the three fields are often considered as one for the purposes of research and reference.[9]
The exact relations between science and technology in particular have been debated by scientists, historians, and policymakers in the late 20th century, in part because the debate can inform the funding of basic and applied science. In immediate wake of World War II, for example, in the United States it was widely considered that technology was simply "applied science" and that to fund basic science was to reap technological results in due time. An articulation of this philosophy could be found explicitly in Vannevar Bush's treatise on postwar science policy, Science—The Endless Frontier: "New products, new industries, and more jobs require continuous additions to knowledge of the laws of nature... This essential new knowledge can be obtained only through basic scientific research." In the late-1960s, however, this view came under direct attack, leading towards initiatives to fund science for specific tasks (initiatives resisted by the scientific community). The issue remains contentious—though most analysts resist the model that technology simply is a result of scientific research.
The human race's use of technology began with the conversion of natural resources into simple tools. The prehistorical discovery of the ability to control fire increased the available sources of food and the invention of the wheel helped humans in travelling in and controlling their environment. Recent technological developments, including the printing press, the telephone, and the Internet, have lessened physical barriers to communication and allowed humans to interact on a global scale. However, not all technology has been used for peaceful purposes; the development of weapons of ever-increasing destructive power has progressed throughout history, from clubs to nuclear weapons.
Technology has affected society and its surroundings in a number of ways. In many societies, technology has helped develop more advanced economies (including today's global economy) and has allowed the rise of a leisure class. Many technological processes produce unwanted by-products, known as pollution, and deplete natural resources, to the detriment of the Earth and its environment. Various implementations of technology influence the values of a society and new technology often raises new ethical questions. Examples include the rise of the notion of efficiency in terms of human productivity, a term originally applied only to machines, and the challenge of traditional norms.
Philosophical debates have arisen over the present and future use of technology in society, with disagreements over whether technology improves the human condition or worsens it. Neo-Luddism, anarcho-primitivism, and similar movements criticise the pervasiveness of technology in the modern world, claiming that it harms the environment and alienates people; proponents of ideologies such as transhumanism and techno-progressivism view continued technological progress as beneficial to society and the human condition. Indeed, until recently, it was believed that the development of technology was restricted only to human beings, but recent scientific studies indicate that other primates and certain dolphin communities have developed simple tools and learned to pass their knowledge to other generations.
DEFINATION & USAGE
In general technology is the relationship that society has with its tools and crafts, and to what extent society can control its environment. The Merriam-Webster dictionary offers a definition of the term: "the practical application of knowledge especially in a particular area" and "a capability given by the practical application of knowledge".[1] Ursula Franklin, in her 1989 "Real World of Technology" lecture, gave another definition of the concept; it is "practice, the way we do things around here".[2] The term is often used to imply a specific field of technology, or to refer to high technology or just consumer electronics, rather than technology as a whole.[3] Bernard Stiegler, in Technics and Time, 1, defines technology in two ways: as "the pursuit of life by means other than life", and as "organized inorganic matter."[4]
Technology can be most broadly defined as the entities, both material and immaterial, created by the application of mental and physical effort in order to achieve some value. In this usage, technology refers to tools and machines that may be used to solve real-world problems. It is a far-reaching term that may include simple tools, such as a crowbar or wooden spoon, or more complex machines, such as a space station or particle accelerator. Tools and machines need not be material; virtual technology, such as computer software and business methods, fall under this definition of technology.[5]
The word "technology" can also be used to refer to a collection of techniques. In this context, it is the current state of humanity's knowledge of how to combine resources to produce desired products, to solve problems, fulfill needs, or satisfy wants; it includes technical methods, skills, processes, techniques, tools and raw materials. When combined with another term, such as "medical technology" or "space technology", it refers to the state of the respective field's knowledge and tools. "State-of-the-art technology" refers to the high technology available to humanity in any field.
Technology can be viewed as an activity that forms or changes culture.[6] Additionally, technology is the application of math, science, and the arts for the benefit of life as it is known. A modern example is the rise of communication technology, which has lessened barriers to human interaction and, as a result, has helped spawn new subcultures; the rise of cyberculture has, at its basis, the development of the Internet and the computer.[7] Not all technology enhances culture in a creative way; technology can also help facilitate political oppression and war via tools such as guns. As a cultural activity, technology predates both science and engineering, each of which formalize some aspects of technological endeavor.
Science, engineering and technology
The distinction between science, engineering and technology is not always clear. Science is the reasoned investigation or study of phenomena, aimed at discovering enduring principles among elements of the phenomenal world by employing formal techniques such as the scientific method.[8] Technologies are not usually exclusively products of science, because they have to satisfy requirements such as utility, usability and safety.
Engineering is the goal-oriented process of designing and making tools and systems to exploit natural phenomena for practical human means, often (but not always) using results and techniques from science. The development of technology may draw upon many fields of knowledge, including scientific, engineering, mathematical, linguistic, and historical knowledge, to achieve some practical result.
Technology is often a consequence of science and engineering — although technology as a human activity precedes the two fields. For example, science might study the flow of electrons in electrical conductors, by using already-existing tools and knowledge. This new-found knowledge may then be used by engineers to create new tools and machines, such as semiconductors, computers, and other forms of advanced technology. In this sense, scientists and engineers may both be considered technologists; the three fields are often considered as one for the purposes of research and reference.[9]
The exact relations between science and technology in particular have been debated by scientists, historians, and policymakers in the late 20th century, in part because the debate can inform the funding of basic and applied science. In immediate wake of World War II, for example, in the United States it was widely considered that technology was simply "applied science" and that to fund basic science was to reap technological results in due time. An articulation of this philosophy could be found explicitly in Vannevar Bush's treatise on postwar science policy, Science—The Endless Frontier: "New products, new industries, and more jobs require continuous additions to knowledge of the laws of nature... This essential new knowledge can be obtained only through basic scientific research." In the late-1960s, however, this view came under direct attack, leading towards initiatives to fund science for specific tasks (initiatives resisted by the scientific community). The issue remains contentious—though most analysts resist the model that technology simply is a result of scientific research.
Monday, April 20, 2009
Networking part 1
A computer network is a collection of computers and devices connected to each other. The network allows computers to communicate with each other and share resources and information. The Advanced Research Projects Agency (ARPA) designed "Advanced Research Projects Agency Network" (ARPANET) for the United States Department of Defense. It was the first computer network in the world in late 1960s and early 1970s.
Connection method
Computer networks can also be classified according to the hardware and software technology that is used to interconnect the individual devices in the network, such as Optical fiber, Ethernet, Wireless LAN, HomePNA, Power line communication or G.hn.
Ethernet uses physical wiring to connect devices. Frequently deployed devices include hubs, switches, bridges and/or routers.
Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium.
ITU-T G.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/s) local area network
CLASSIFICATION
Networks are often classified as Local Area Network (LAN), Wide Area Network (WAN), Metropolitan Area Network (MAN), Personal Area Network (PAN), Virtual Private Network (VPN), Campus Area Network (CAN), Storage Area Network (SAN), etc. depending on their scale, scope and purpose. Usage, trust levels and access rights often differ between these types of network - for example, LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical locations (such as a building), while WANs may connect physically separate parts of an organization to each other and may include connections to third parties.
Computer networks may be classified according to the functional relationships which exist among the elements of the network, e.g., Active Networking, Client-server and Peer-to-peer (workgroup) architecture.
Network topology
Computer networks may be classified according to the network topology upon which the network is based, such as bus network, star network, ring network, mesh network, star-bus network, tree or hierarchical topology network. Network topology signifies the way in which devices in the network see their logical relations to one another. The use of the term "logical" here is significant. That is, network topology is independent of the "physical" layout of the network. Even if networked computers are physically placed in a linear arrangement, if they are connected via a hub, the network has a Star topology, rather than a bus topology. In this regard the visual and operational characteristics of a network are distinct; the logical network topology is not necessarily the same as the physical layout. Networks may be classified based on the method of data used to convey the data, these include digital and analog networks.
Types of networks
Personal area network
A personal area network (PAN) is a computer network used for communication among computer devices close to one person. Some examples of devices that are used in a PAN are printers, fax machines, telephones, PDAs and scanners. The reach of a PAN is typically about 20-30 feet (approximately 6-9 meters), but this is expected to increase with technology improvements.
Local area network
A local area network (LAN) is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines)[2].
For example, a library may have a wired or wireless LAN for users to interconnect local devices (e.g., printers and servers) and to connect to the internet. On a wired LAN, PCs in the library are typically connected by category 5 (Cat5) cable, running the IEEE 802.3 protocol through a system of interconnected devices and eventually connect to the Internet. The cables to the servers are typically on Cat 5e enhanced cable, which will support IEEE 802.3 at 1 Gbit/s. A wireless LAN may exist using a different IEEE protocol, 802.11b, 802.11g or possibly 802.11n. The staff computers (bright green in the figure) can get to the color printer, checkout records, and the academic network and the Internet. All user computers can get to the Internet and the card catalog. Each workgroup can get to its local printer. Note that the printers are not accessible from outside their workgroup.
Typical library network, in a branching tree topology and controlled access to resourcesAll interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router that connects to the Internet and academic networks' customer access routers.
The defining characteristics of LANs, in contrast to WANs (wide area networks), include their higher data transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 100 Gbit/s, and possibly 400 Gbit/s.
Campus area network
A campus area network (CAN) is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area. It can be considered one form of a metropolitan area network, specific to an academic setting.
In the case of a university campus-based campus area network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls. A campus area network is larger than a local area network but smaller than a wide area network (WAN) (in some cases).
The main aim of a campus area network is to facilitate students accessing internet and university resources. This is a network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, office building, or a military base. A CAN may be considered a type of MAN (metropolitan area network), but is generally limited to a smaller area than a typical MAN. This term is most often used to discuss the implementation of networks for a contiguous area. This should not be confused with a Controller Area Network. A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings. In TCP/IP networking, a LAN is often but not always implemented as a single IP subnet.
[edit] Metropolitan area network
Main article: Metropolitan area network
A metropolitan area network (MAN) is a network that connects two or more local area networks or campus area networks together but does not extend beyond the boundaries of the immediate town/city. Routers, switches and hubs are connected to create a metropolitan area network.
Wide Area Network
A wide area network (WAN) is a computer network that covers a broad area (i.e. any network whose communications links cross metropolitan, regional, or national boundaries [1]). Less formally, a WAN is a network that uses routers and public communications links [1]. Contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs), which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively. The largest and most well-known example of a WAN is the Internet. A WAN is a data communications network that covers a relatively broad geographic area (i.e. one city to another and one country to another country) and that often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.
Global area network
IEEE 802.20
A global area networks (GAN) specification is in development by several groups, and there is no common definition. In general, however, a GAN is a model for supporting mobile communications across an arbitrary number of wireless LANs, satellite coverage areas, etc. The key challenge in mobile communications is "handing off" the user communications from one local coverage area to the next. In IEEE Project 802, this involves a succession of terrestrial WIRELESS local area networks (WLAN).[3]
Virtual Private Network
A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires. The link-layer protocols of the virtual network are said to be tunneled through the larger network when this is the case. One common application is secure communications through the public Internet, but a VPN need not have explicit security features, such as authentication or content encryption. VPNs, for example, can be used to separate the traffic of different user communities over an underlying network with strong security features.
A VPN may have best-effort performance, or may have a defined service level agreement (SLA) between the VPN customer and the VPN service provider. Generally, a VPN has a topology more complex than point-to-point.
A VPN allows computer users to appear to be editing from an IP address location other than the one which connects the actual computer to the Internet.
Internetwork
Internetworking involves connecting two or more distinct computer networks or network segments via a common routing technology. The result is called an internetwork (often shortened to internet). Two or more networks or network segments connected using devices that operate at layer 3 (the 'network' layer) of the OSI Basic Reference Model, such as a router. Any interconnection among or between public, private, commercial, industrial, or governmental networks may also be defined as an internetwork.
In modern practice, the interconnected networks use the Internet Protocol. There are at least three variants of internetwork, depending on who administers and who participates in them:
Intranet
Extranet
Internet
Intranets and extranets may or may not have connections to the Internet. If connected to the Internet, the intranet or extranet is normally protected from being accessed from the Internet without proper authorization. The Internet is not considered to be a part of the intranet or extranet, although it may serve as a portal for access to portions of an extranet.
Intranet
An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that is under the control of a single administrative entity. That administrative entity closes the intranet to all but specific, authorized users. Most commonly, an intranet is the internal network of an organization. A large intranet will typically have at least one web server to provide users with organizational information.
Extranet
An extranet is a network or internetwork that is limited in scope to a single organization or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities (e.g., a company's customers may be given access to some part of its intranet creating in this way an extranet, while at the same time the customers may not be considered 'trusted' from a security standpoint). Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although, by definition, an extranet cannot consist of a single LAN; it must have at least one connection with an external network.
Internet
The Internet is a specific internetwork. It consists of a worldwide interconnection of governmental, academic, public, and private networks based upon the networking technologies of the Internet Protocol Suite. It is the successor of the Advanced Research Projects Agency Network (ARPANET) developed by DARPA of the U.S. Department of Defense. The Internet is also the communications backbone underlying the World Wide Web (WWW). The 'Internet' is most commonly spelled with a capital 'I' as a proper noun, for historical reasons and to distinguish it from other generic internetworks.
Participants in the Internet use a diverse array of methods of several hundred documented, and often standardized, protocols compatible with the Internet Protocol Suite and an addressing system (IP Addresses) administered by the Internet Assigned Numbers Authority and address registries. Service providers and large enterprises exchange information about the reachability of their address spaces through the Border Gateway Protocol (BGP), forming a redundant worldwide mesh of transmission paths.
Basic hardware components
All networks are made up of basic hardware building blocks to interconnect network nodes, such as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers. In addition, some method of connecting these building blocks is required, usually in the form of galvanic cable (most commonly Category 5 cable). Less common are microwave links (as in IEEE 802.12) or optical cable ("optical fiber"). An ethernet card may also be required.
Network interface cards
A network card, network adapter or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network. It provides physical access to a networking medium and often provides a low-level addressing system through the use of MAC addresses.
Repeaters
A repeater is an electronic device that receives a signal and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable which runs longer than 100 meters.
Hubs
A hub contains multiple ports. When a packet arrives at one port, it is copied unmodified to all ports of the hub for transmission. The destination address in the frame is not changed to a broadcast address.[4]
Bridges
A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. Bridges do not promiscuously copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address only to that port. Bridges do send broadcasts to all ports except the one on which the broadcast was received.
Bridges learn the association of ports and addresses by examining the source address of frames that it sees on various ports. Once a frame arrives through a port, its source address is stored and the bridge assumes that MAC address is associated with that port. The first time that a previously unknown destination address is seen, the bridge will forward the frame to all ports other than the one on which the frame arrived.
Bridges come in three basic types:
Local bridges: Directly connect local area networks (LANs)
Remote bridges: Can be used to create a wide area network (WAN) link between LANs. Remote bridges, where the connecting link is slower than the end networks, largely have been replaced by routers.
Wireless bridges: Can be used to join LANs or connect remote stations to LANs.
Switches
A switch is a device that forwards and filters OSI layer 2 datagrams (chunk of data communication) between ports (connected cables) based on the MAC addresses in the packets.[5] This is distinct from a hub in that it only forwards the packets to the ports involved in the communications rather than all ports connected. Strictly speaking, a switch is not capable of routing traffic based on IP address (OSI Layer 3) which is necessary for communicating between network segments or within a large or complex LAN. Some switches are capable of routing based on IP addresses but are still called switches as a marketing term. A switch normally has numerous ports, with the intention being that most or all of the network is connected directly to the switch, or another switch that is in turn connected to a switch.[6]
Switch is a marketing term that encompasses routers and bridges, as well as devices that may distribute traffic on load or by application content (e.g., a Web URL identifier). Switches may operate at one or more OSI model layers, including physical, data link, network, or transport (i.e., end-to-end). A device that operates simultaneously at more than one of these layers is called a multilayer switch.
Overemphasizing the ill-defined term "switch" often leads to confusion when first trying to understand networking. Many experienced network designers and operators recommend starting with the logic of devices dealing with only one protocol level, not all of which are covered by OSI. Multilayer device selection is an advanced topic that may lead to selecting particular implementations, but multilayer switching is simply not a real-world design concept.
Routers
Routers are networking devices that forward data packets between networks using headers and forwarding tables to determine the best path to forward the packets. Routers work at the network layer.
Connection method
Computer networks can also be classified according to the hardware and software technology that is used to interconnect the individual devices in the network, such as Optical fiber, Ethernet, Wireless LAN, HomePNA, Power line communication or G.hn.
Ethernet uses physical wiring to connect devices. Frequently deployed devices include hubs, switches, bridges and/or routers.
Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium.
ITU-T G.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/s) local area network
CLASSIFICATION
Networks are often classified as Local Area Network (LAN), Wide Area Network (WAN), Metropolitan Area Network (MAN), Personal Area Network (PAN), Virtual Private Network (VPN), Campus Area Network (CAN), Storage Area Network (SAN), etc. depending on their scale, scope and purpose. Usage, trust levels and access rights often differ between these types of network - for example, LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical locations (such as a building), while WANs may connect physically separate parts of an organization to each other and may include connections to third parties.
Computer networks may be classified according to the functional relationships which exist among the elements of the network, e.g., Active Networking, Client-server and Peer-to-peer (workgroup) architecture.
Network topology
Computer networks may be classified according to the network topology upon which the network is based, such as bus network, star network, ring network, mesh network, star-bus network, tree or hierarchical topology network. Network topology signifies the way in which devices in the network see their logical relations to one another. The use of the term "logical" here is significant. That is, network topology is independent of the "physical" layout of the network. Even if networked computers are physically placed in a linear arrangement, if they are connected via a hub, the network has a Star topology, rather than a bus topology. In this regard the visual and operational characteristics of a network are distinct; the logical network topology is not necessarily the same as the physical layout. Networks may be classified based on the method of data used to convey the data, these include digital and analog networks.
Types of networks
Personal area network
A personal area network (PAN) is a computer network used for communication among computer devices close to one person. Some examples of devices that are used in a PAN are printers, fax machines, telephones, PDAs and scanners. The reach of a PAN is typically about 20-30 feet (approximately 6-9 meters), but this is expected to increase with technology improvements.
Local area network
A local area network (LAN) is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines)[2].
For example, a library may have a wired or wireless LAN for users to interconnect local devices (e.g., printers and servers) and to connect to the internet. On a wired LAN, PCs in the library are typically connected by category 5 (Cat5) cable, running the IEEE 802.3 protocol through a system of interconnected devices and eventually connect to the Internet. The cables to the servers are typically on Cat 5e enhanced cable, which will support IEEE 802.3 at 1 Gbit/s. A wireless LAN may exist using a different IEEE protocol, 802.11b, 802.11g or possibly 802.11n. The staff computers (bright green in the figure) can get to the color printer, checkout records, and the academic network and the Internet. All user computers can get to the Internet and the card catalog. Each workgroup can get to its local printer. Note that the printers are not accessible from outside their workgroup.
Typical library network, in a branching tree topology and controlled access to resourcesAll interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router that connects to the Internet and academic networks' customer access routers.
The defining characteristics of LANs, in contrast to WANs (wide area networks), include their higher data transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 100 Gbit/s, and possibly 400 Gbit/s.
Campus area network
A campus area network (CAN) is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area. It can be considered one form of a metropolitan area network, specific to an academic setting.
In the case of a university campus-based campus area network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls. A campus area network is larger than a local area network but smaller than a wide area network (WAN) (in some cases).
The main aim of a campus area network is to facilitate students accessing internet and university resources. This is a network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, office building, or a military base. A CAN may be considered a type of MAN (metropolitan area network), but is generally limited to a smaller area than a typical MAN. This term is most often used to discuss the implementation of networks for a contiguous area. This should not be confused with a Controller Area Network. A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings. In TCP/IP networking, a LAN is often but not always implemented as a single IP subnet.
[edit] Metropolitan area network
Main article: Metropolitan area network
A metropolitan area network (MAN) is a network that connects two or more local area networks or campus area networks together but does not extend beyond the boundaries of the immediate town/city. Routers, switches and hubs are connected to create a metropolitan area network.
Wide Area Network
A wide area network (WAN) is a computer network that covers a broad area (i.e. any network whose communications links cross metropolitan, regional, or national boundaries [1]). Less formally, a WAN is a network that uses routers and public communications links [1]. Contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs), which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively. The largest and most well-known example of a WAN is the Internet. A WAN is a data communications network that covers a relatively broad geographic area (i.e. one city to another and one country to another country) and that often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.
Global area network
IEEE 802.20
A global area networks (GAN) specification is in development by several groups, and there is no common definition. In general, however, a GAN is a model for supporting mobile communications across an arbitrary number of wireless LANs, satellite coverage areas, etc. The key challenge in mobile communications is "handing off" the user communications from one local coverage area to the next. In IEEE Project 802, this involves a succession of terrestrial WIRELESS local area networks (WLAN).[3]
Virtual Private Network
A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires. The link-layer protocols of the virtual network are said to be tunneled through the larger network when this is the case. One common application is secure communications through the public Internet, but a VPN need not have explicit security features, such as authentication or content encryption. VPNs, for example, can be used to separate the traffic of different user communities over an underlying network with strong security features.
A VPN may have best-effort performance, or may have a defined service level agreement (SLA) between the VPN customer and the VPN service provider. Generally, a VPN has a topology more complex than point-to-point.
A VPN allows computer users to appear to be editing from an IP address location other than the one which connects the actual computer to the Internet.
Internetwork
Internetworking involves connecting two or more distinct computer networks or network segments via a common routing technology. The result is called an internetwork (often shortened to internet). Two or more networks or network segments connected using devices that operate at layer 3 (the 'network' layer) of the OSI Basic Reference Model, such as a router. Any interconnection among or between public, private, commercial, industrial, or governmental networks may also be defined as an internetwork.
In modern practice, the interconnected networks use the Internet Protocol. There are at least three variants of internetwork, depending on who administers and who participates in them:
Intranet
Extranet
Internet
Intranets and extranets may or may not have connections to the Internet. If connected to the Internet, the intranet or extranet is normally protected from being accessed from the Internet without proper authorization. The Internet is not considered to be a part of the intranet or extranet, although it may serve as a portal for access to portions of an extranet.
Intranet
An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that is under the control of a single administrative entity. That administrative entity closes the intranet to all but specific, authorized users. Most commonly, an intranet is the internal network of an organization. A large intranet will typically have at least one web server to provide users with organizational information.
Extranet
An extranet is a network or internetwork that is limited in scope to a single organization or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities (e.g., a company's customers may be given access to some part of its intranet creating in this way an extranet, while at the same time the customers may not be considered 'trusted' from a security standpoint). Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although, by definition, an extranet cannot consist of a single LAN; it must have at least one connection with an external network.
Internet
The Internet is a specific internetwork. It consists of a worldwide interconnection of governmental, academic, public, and private networks based upon the networking technologies of the Internet Protocol Suite. It is the successor of the Advanced Research Projects Agency Network (ARPANET) developed by DARPA of the U.S. Department of Defense. The Internet is also the communications backbone underlying the World Wide Web (WWW). The 'Internet' is most commonly spelled with a capital 'I' as a proper noun, for historical reasons and to distinguish it from other generic internetworks.
Participants in the Internet use a diverse array of methods of several hundred documented, and often standardized, protocols compatible with the Internet Protocol Suite and an addressing system (IP Addresses) administered by the Internet Assigned Numbers Authority and address registries. Service providers and large enterprises exchange information about the reachability of their address spaces through the Border Gateway Protocol (BGP), forming a redundant worldwide mesh of transmission paths.
Basic hardware components
All networks are made up of basic hardware building blocks to interconnect network nodes, such as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers. In addition, some method of connecting these building blocks is required, usually in the form of galvanic cable (most commonly Category 5 cable). Less common are microwave links (as in IEEE 802.12) or optical cable ("optical fiber"). An ethernet card may also be required.
Network interface cards
A network card, network adapter or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network. It provides physical access to a networking medium and often provides a low-level addressing system through the use of MAC addresses.
Repeaters
A repeater is an electronic device that receives a signal and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable which runs longer than 100 meters.
Hubs
A hub contains multiple ports. When a packet arrives at one port, it is copied unmodified to all ports of the hub for transmission. The destination address in the frame is not changed to a broadcast address.[4]
Bridges
A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. Bridges do not promiscuously copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address only to that port. Bridges do send broadcasts to all ports except the one on which the broadcast was received.
Bridges learn the association of ports and addresses by examining the source address of frames that it sees on various ports. Once a frame arrives through a port, its source address is stored and the bridge assumes that MAC address is associated with that port. The first time that a previously unknown destination address is seen, the bridge will forward the frame to all ports other than the one on which the frame arrived.
Bridges come in three basic types:
Local bridges: Directly connect local area networks (LANs)
Remote bridges: Can be used to create a wide area network (WAN) link between LANs. Remote bridges, where the connecting link is slower than the end networks, largely have been replaced by routers.
Wireless bridges: Can be used to join LANs or connect remote stations to LANs.
Switches
A switch is a device that forwards and filters OSI layer 2 datagrams (chunk of data communication) between ports (connected cables) based on the MAC addresses in the packets.[5] This is distinct from a hub in that it only forwards the packets to the ports involved in the communications rather than all ports connected. Strictly speaking, a switch is not capable of routing traffic based on IP address (OSI Layer 3) which is necessary for communicating between network segments or within a large or complex LAN. Some switches are capable of routing based on IP addresses but are still called switches as a marketing term. A switch normally has numerous ports, with the intention being that most or all of the network is connected directly to the switch, or another switch that is in turn connected to a switch.[6]
Switch is a marketing term that encompasses routers and bridges, as well as devices that may distribute traffic on load or by application content (e.g., a Web URL identifier). Switches may operate at one or more OSI model layers, including physical, data link, network, or transport (i.e., end-to-end). A device that operates simultaneously at more than one of these layers is called a multilayer switch.
Overemphasizing the ill-defined term "switch" often leads to confusion when first trying to understand networking. Many experienced network designers and operators recommend starting with the logic of devices dealing with only one protocol level, not all of which are covered by OSI. Multilayer device selection is an advanced topic that may lead to selecting particular implementations, but multilayer switching is simply not a real-world design concept.
Routers
Routers are networking devices that forward data packets between networks using headers and forwarding tables to determine the best path to forward the packets. Routers work at the network layer.
Information Technology
Information technology (IT), as defined by the Information Technology Association of America (ITAA), is "the study, design, development, implementation, support or management of computer-based information systems, particularly software applications and computer hardware."[1] IT deals with the use of electronic computers and computer software to convert, store, protect, process, transmit, and securely retrieve information.
Today, the term information technology has ballooned to encompass many aspects of computing and technology, and the term has become very recognizable. The information technology umbrella can be quite large, covering many fields. IT professionals perform a variety of duties that range from installing applications to designing complex computer networks and information databases. A few of the duties that IT professionals perform may include data management, networking, engineering computer hardware, database and software design, as well as the management and administration of entire systems.
When computer and communications technologies are combined, the result is information technology, or "infotech". Information Technology (IT) is a general term that describes any technology that helps to produce, manipulate, store, communicate, and/or disseminate information. Presumably, when speaking of Information Technology (IT) as a whole, it is noted that the use of computers and information are associated.
The term Information Technology (IT) is sometimes said to have been coined by Jim Domsic of Michigan in November 1981.[citation needed] Domsic, who worked as a computer manager for an automotive related industry, is supposed to have created the term to modernize the outdated phrase "data processing". The Oxford English Dictionary, however, in defining information technology as "the branch of technology concerned with the dissemination, processing, and storage of information, esp. by means of computers" provides an illustrative quote from the year 1958 (Leavitt & Whisler in Harvard Business Rev. XXXVI. 41/1 "The new technology does not yet have a single established name. We shall call it information technology.") that predates the so-far unsubstantiated Domsic coinage.
In recent years ABET and the ACM have collaborated to form accreditation and curriculum standards for degrees in Information Technology as a distinct field of study separate from both Computer Science and Information Systems. SIGITE is the ACM working group for defining these standards.
Today, the term information technology has ballooned to encompass many aspects of computing and technology, and the term has become very recognizable. The information technology umbrella can be quite large, covering many fields. IT professionals perform a variety of duties that range from installing applications to designing complex computer networks and information databases. A few of the duties that IT professionals perform may include data management, networking, engineering computer hardware, database and software design, as well as the management and administration of entire systems.
When computer and communications technologies are combined, the result is information technology, or "infotech". Information Technology (IT) is a general term that describes any technology that helps to produce, manipulate, store, communicate, and/or disseminate information. Presumably, when speaking of Information Technology (IT) as a whole, it is noted that the use of computers and information are associated.
The term Information Technology (IT) is sometimes said to have been coined by Jim Domsic of Michigan in November 1981.[citation needed] Domsic, who worked as a computer manager for an automotive related industry, is supposed to have created the term to modernize the outdated phrase "data processing". The Oxford English Dictionary, however, in defining information technology as "the branch of technology concerned with the dissemination, processing, and storage of information, esp. by means of computers" provides an illustrative quote from the year 1958 (Leavitt & Whisler in Harvard Business Rev. XXXVI. 41/1 "The new technology does not yet have a single established name. We shall call it information technology.") that predates the so-far unsubstantiated Domsic coinage.
In recent years ABET and the ACM have collaborated to form accreditation and curriculum standards for degrees in Information Technology as a distinct field of study separate from both Computer Science and Information Systems. SIGITE is the ACM working group for defining these standards.
Saturday, April 18, 2009
Cisco Opens Green Technology R&D Lab
"Cisco's innovation initiative and its establishment of a green technology lab are clear examples of our commitment to China, and our focus on the long-term growth potential," said John Chambers, chairman and chief executive officer, Cisco. "Today's announcement further demonstrates our strategic approach to capturing local innovation, win-win partnerships and leadership development through collaboration."
Underscoring the strategic importance of China to its global operations and the company's determination to deliver on its $16 billion multi-year investment, Cisco has introduced a cultivated innovation model aimed at boosting local innovation through capital, technology, process expertise, incubation resources and leadership investments. The model is expected to accelerate time to market for Cisco and its partners and customers as they pursue new local and global market opportunities together.
Cisco intends to allocate $1 billion of its $16 billion investment commitment, announced in November 2007 to support this new innovation model. This initiative will underpin Cisco's collaboration with top universities and entrepreneurs to support programmes to develop technologies for intelligent urbanisation, promote growth enterprises and foster next-generation Internet development.
Cisco said the new model in China will spur even greater innovation through cultivation and collaboration. It is said to be designed to expand the capabilities of Cisco and its partners to pursue new local market opportunities with greater speed, agility and market relevance.
The cultivated innovation model initially focusses on three major areas -- intelligent urbanisation, new business model initiatives for growth enterprises and next-generation Internet, including video and mobility.
As part of intelligent urbanisation, Cisco intends to collaborate with Tongfang to jointly explore and create new markets and business models for intelligent urbanisation in China.
As part of its investment in video development, Shanghai DigiVision in early March announced an investment from Cisco that includes access to select Cisco video technologies. DigiVision is focussing on the design of an open, interactive, HD digital cable TV platform that will support new value-added business models to facilitate Shanghai's plan for cable TV digitisation.
Cisco is working with Ambow, a provider of e-learning technologies and education services in China, to explore business models for connected cities and connected schools. These initiatives are aligned with China's priorities of preparing college graduates for job readiness, developing replicable business process outsourcing skills and instigating 21st-century education in earthquake-stricken areas of Sichuan.
In addition, as part of Cisco's prior commitment, the company today announced it would establish a Supply Chain Institute with Fudan University to support China's ongoing development through a jointly designed and delivered educational programme. The first of its kind for Cisco in China, the Supply Chain Institute will offer learning and development for leaders of Chinese companies, driving thought leadership in supply chain management and accelerating participants' ability to lead on a global scale, Cisco said.
Underscoring the strategic importance of China to its global operations and the company's determination to deliver on its $16 billion multi-year investment, Cisco has introduced a cultivated innovation model aimed at boosting local innovation through capital, technology, process expertise, incubation resources and leadership investments. The model is expected to accelerate time to market for Cisco and its partners and customers as they pursue new local and global market opportunities together.
Cisco intends to allocate $1 billion of its $16 billion investment commitment, announced in November 2007 to support this new innovation model. This initiative will underpin Cisco's collaboration with top universities and entrepreneurs to support programmes to develop technologies for intelligent urbanisation, promote growth enterprises and foster next-generation Internet development.
Cisco said the new model in China will spur even greater innovation through cultivation and collaboration. It is said to be designed to expand the capabilities of Cisco and its partners to pursue new local market opportunities with greater speed, agility and market relevance.
The cultivated innovation model initially focusses on three major areas -- intelligent urbanisation, new business model initiatives for growth enterprises and next-generation Internet, including video and mobility.
As part of intelligent urbanisation, Cisco intends to collaborate with Tongfang to jointly explore and create new markets and business models for intelligent urbanisation in China.
As part of its investment in video development, Shanghai DigiVision in early March announced an investment from Cisco that includes access to select Cisco video technologies. DigiVision is focussing on the design of an open, interactive, HD digital cable TV platform that will support new value-added business models to facilitate Shanghai's plan for cable TV digitisation.
Cisco is working with Ambow, a provider of e-learning technologies and education services in China, to explore business models for connected cities and connected schools. These initiatives are aligned with China's priorities of preparing college graduates for job readiness, developing replicable business process outsourcing skills and instigating 21st-century education in earthquake-stricken areas of Sichuan.
In addition, as part of Cisco's prior commitment, the company today announced it would establish a Supply Chain Institute with Fudan University to support China's ongoing development through a jointly designed and delivered educational programme. The first of its kind for Cisco in China, the Supply Chain Institute will offer learning and development for leaders of Chinese companies, driving thought leadership in supply chain management and accelerating participants' ability to lead on a global scale, Cisco said.
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