Future Academy Networks 3rd year Computer Sciences Spring Semester 2009 Exercise (11) see lectures ----------------------------------------------------------------------------------------------------- Question (1) pp 3-15 You recommend an internet-in-a-box product for one of your friends. He found that the product includes; 1. web browser 2. e-mail software 3. modem 4. preselected ISP What is the function of each component? Web browser :- Is a software application which enables a user to display and interact with text, images, videos, music and other information typically located on a Web page at a website on the World Wide Web or a local area network. Text and images on a Web page can contain hyperlinks to other Web pages at the same or different website. Web browsers allow a user to quickly and easily access information provided on many Web pages at many websites by traversing these links. Web browsers format HTML information for display, so the appearance of a Web page may differ between browsers. Some of the Web browsers available for personal computers include Internet Explorer, Mozilla Firefox, Safari, Opera, and Flock, in order of descending popularity (in March 2008). Web browsers are the most commonly used type of HTTP user agent. Although browsers are typically used to access the World Wide Web, they can also be used to access information provided by Web servers in private networks or content in file systems. E-mail Software:- E-mail, short for electronic mail and often abbreviated to e-mail, email or simply mail, is a store and forward method of composing, sending, receiving and storing messages over electronic communication systems. The term "e-mail" (as a noun or verb) applies both to the Internet e-mail system based on the Simple Mail Transfer Protocol (SMTP) and to X.400 systems, and to intranet systems allowing users within one organization to e-mail each other. Intranets may use the Internet protocols or X.400 protocols for internal e-mail service supporting workgroup collaboration. E-mail is often used to deliver bulk unsolicited messages, or "spam", but filter programs exist which can automatically delete some or most of these, depending on the situation. Modem:- Modem (from modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used over any means of transmitting analog signals, from driven diodes to radio. Preselected ISP:- "ISP" redirects here. For other uses, see ISP (disambiguation). An Internet service provider (abbr. ISP, also called Internet access provider or IAP) is a company or business that provides access to the Internet and related services. In the past, most ISPs were run by the phone companies. Now, ISPs can be started by just about any individual or group with sufficient money and expertise. In addition to Internet access via various technologies such as dial-up and DSL, they may provide a combination of services including Internet transit, domain name registration and hosting, web hosting, and collocation. أً ين ناحيو تانيو نهَ عايز يكتب عن فيى بذل يا يشٌف انذش ده كهو , ىتتكهى عن يًيزات ً خصائص ً يا ريت يننساشISP يتصفح اننت , ً خصائص برايج انًيم ً خصائص انًٌدو اً انرًتر ً يًيزات ال ً احنا بنشرح اننا نتكهى عن كم حاجو ين حيث تٌفير انتطبيقات انًناسبو ً تٌفير حزو انبرًتٌكٌالت ًٍانًناسبو ً بانتانَ يذٍ سيٌنتيا باننسبو نًثيالتيا ين ادًات االستخذاو انيذ Question (2) pp 3-16 to 3-20 Make a comparison table for the items in figure, showing the cost, properties, construction, advantages, disadvantages, and favorable conditions for use. STP Stranded Wired Twisted cables pair UTP Solid Coax Transmission Thick Media net Thin net Wireless Fiber Single mode optics Multimode هتدوس على الكالم ده علشان يفتحلك الصفحه اللى فيها كل حاجه عن الكابالت , هتقراها و تفهن كل حاجه فى الكابالت و بعد كده تشىف هتكتب ايه و انت و دهاغكـ Question (3) pp 3-17 Explain with examples the meaning of; - 10baseT - Attenuation - The seven categories twisted pair - RJ-45 connector - Plenum - 10base2 10baseT:- Ethernet over twisted pair There are several standards for Ethernet over twisted pair or copper- based computer networking physical connectivity methods. The currently most widely used of these are 10BASE-T, 100BASE-TX, and 1000BASE-T (Gigabit Ethernet), running at 10 Mbit/s, 100 Mbit/s, and 1000 Mbit/s (1 Gbit/s) respectively. These three standards all use the same connectors. Higher speed implementations nearly always support the lower speeds as well, so that in most cases different generations of equipment can be freely mixed. They use 8 position modular connectors, usually (but incorrectly) called RJ45 in the context of Ethernet over twisted pair. The cables usually used are four-pair Category 5 or above twisted pair cable. Each of the three standards support both full-duplex and half-duplex communication. According to the standards, they all operate over distances of 'up to 100 meters'. The common names of the standards are derived from several aspects of the physical media. The number refers to the theoretical maximum transmission speed in megabits per second (Mbit/s). The BASE is short for baseband, meaning that there is no frequency-division multiplexing (FDM) or other frequency shifting modulation in use; each signal has full control of wire, on a single frequency. The T designates twisted pair cable, where the pairs of wires are twisted together for purposes of reducing crosstalk (FEXT and NEXT) when the pulsing direct current goes across the wires and creates electromagnetic induction effects. Where there are several standards for the same transmission speed, they are distinguished by a letter or digit following the T, such as TX. Some higher-speed standards use twin-axial cable, designated by CX. Attenuation:- Attenuation is the reduction in amplitude and intensity of a signal. Signals may be attenuated exponentially by transmission through a medium, in which case attenuation is usually reported in dB with respect to distance traveled through the medium. Attenuation can also be understood to be the opposite of amplification. Attenuation is an important property in telecommunications and ultrasound applications because of its importance in determining signal strength as a function of distance. Attenuation is usually measured in units of decibels per unit length of medium (dB/cm, dB/km, etc) and is represented by the attenuation coefficient of the medium in question. Rj-45 connector:- The 8 Position 8 Contact (8P8C) modular plugs and jacks are communications connectors. Under the same naming scheme, an 8P6C connector has eight positions, with six positions containing conductors, and a 6P6C connector has six positions, all containing conductors. 8P8C connectors are typically used to terminate twisted pair cable. These connectors are often referred to as RJ45 plugs and jacks. This is technically incorrect because the RJ45 standard specifies both the mechanical interface and a different wiring scheme than T568A/B, which is often used for Ethernet and telephones. 8P8C consists of two paired components: the male plug and the female jack or socket. Each has eight equally-spaced conductors. On the plug, these conductors are flat contacts positioned parallel with the connector body. Inside the jack or socket, the conductors are suspended diagonally toward the insertion interface. When an 8P8C plug is mated with an 8P8C jack, the conductors meet and create an electrical connection. Spring tension in the jack's conductors ensure a good interface with the plug and allow for slight travel during insertion and removal. The 8P8C connector is probably best known for its use in Ethernet. Since about 2000, it is nearly universal as the type of connector used on a cable that carries a single Ethernet network, and has replaced many older connector types. Older connectors have also been phased out as modern cables no longer have the high current and voltage requirements for which the bulkier connectors were designed. Plenum:- Plenum may refer to: • the antithesis of a vacuum; in other words, completely-filled, positive-pressure space (see Plenism). • the pressures slightly above atmospheric, usually inside air or gas systems as the result of the action of fans or blowers. The plenum is measured in small units of pressure such as pascals (Pa) or ounces- force per square inch or millimeters of mercury. • a legislative meeting in which all members of the body are present and voting. Frequently this is used to refer to a full meeting of a Communist Party central committee. Compare to quorum. • a second set of bellows in devices such as hand or foot pumped organs with a weight on the top which acts as an air reservoir. • Plenums in buildings are enclosed spaces that are not for human occupancy, but are often used for heating, ventilating, and/or air- conditioning equipment and airflow, and for other equipment such as cables, piping, and luminaires. 'Plenum boxes' or sections are portions of HVAC air handlers or terminal units. • Plenum cable refers to structured cabling permitted under building codes for plenum spaces. Plenum rated cable has slow- burning, fire-resistant casing that emits little smoke • Plenum filtration, a method of aquarium filtration using a deep sand bed with a gap below it. 10base2 :- 10BASE2 (also known as cheapernet, thin Ethernet, thinnet or thinwire) is a variant of Ethernet that uses thin coaxial cable (RG-58 or similar, as opposed to the thicker RG-8 cable used in 10BASE5 networks), terminated with BNC connectors. For many years this was the dominant 10 Mbit/s Ethernet standard, but due to the immense demand for high speed networking, the low cost of Category 5 Ethernet cable, and the popularity of 802.11 wireless networks, both 10BASE2 and 10BASE5 have become almost obsolete. Question (4) pp 3-16 to 3-19 State some networking situations where you may come across the following terminology Abbreviation Details Circumstances STP Shielded twisted pair UTP Unshielded twisted pair BNC British naval connector BNC Bayonet Neill- Concelman Abbreviation Details Circumstances STP Shielded twisted pair STP cabling includes metal shielding over each individual pair of copper wires. This type of shielding protects cable from external EMI (electromagnetic interferences). e.g. the 150 ohm shielded twisted pair cables defined by the IBM Cabling System specifications and used with token ring networks. UTP Unshielded twisted UTP cables are found in pair many Ethernet networks and telephone systems. For indoor telephone applications, UTP is often grouped into sets of 25 pairs according to a standard 25-pair color code originally developed by AT&T. A typical subset of these colors (white/blue, blue/white, white/orange, orange/white) shows up in most UTP cables. UTP cable is also the most common cable used in computer networking. UTP cables are often called ethernet cables after Ethernet, the most common data networking standard that utilizes UTP cables. Twisted pair cabling is often used in data networks for short and medium length connections because of its relatively lower costs compared to optical fiber and coaxial cable. BNC British naval The older version of connector Bayonet Neill- Concelman BNC Bayonet Neill- The BNC connector is Concelman used for RF signal connections, both for analog and Serial Digital Interface video signals, amateur radio antenna connections, aviation electronics (avionics) and on nearly every piece of electronic test equipment manufactured in the last 35 years.
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