План урока в 11 классе

"Компьютерные сети"

Тема: "Локальные сети (LANs)"

Дата проведения:  

План урока

Цели урока:

-Образовательная – практика применения специальных слов (терминов) и выражений в монологической и диалогической речи;

-Развивающая – развитие мышления, памяти, познавательного интереса;

-Воспитательная – повышение роли самостоятельной работы учащихся на уроке.

Задачи:

1.Практика восприятия и применения специальной терминологии в монологической и диалогической речи.

Материальное обеспечение урока:

1. Компьютер
2. Мультимедийный проектор
3. Раздаточные материалы (по усмотрению учителя)
4. Англо-русские словари

Ход урока

1. Начало урока 2 мин.

2. Рассказ учителя о классификации сетей (на английском языке) – 7 мин.

3. Типы компьютерных сетей, рассказ с показом – 15 мин.

4. Презентация, показ и краткое пояснение слайда "Вариант LAN" – 5 мин.

5. Выполнение упражнения "Вариант LAN", два прослушивания и заполнение таблицы с ответами – 10 мин.

6. Устное самостоятельное описание LAN учащимися (1 – 2 выступления) 5 мин.

7. Заключение, сдача выполненного задания, 1 мин.

ГБОУ школа № 639 с углублённым изучением иностранных языков

Санкт-Петербург

2013 год

Сценарий урока

1. Сначала учитель рассказывает о том, что такое компьютерная сеть, на английском языке, перемежая объяснения с вопросами для контроля понимания. Основная задача – чтобы учащиеся правильно воспринимали терминологию темы и могли пользоваться ею далее.

Основной вопрос – по каким основаниям классифицируются сети.

Computer networks.

A computer network is an interconnection of a group of computers. Networks may be classified by what is called the network layer at which they operate according to basic reference models considered as standards in the industry such as the four-layer Internet Protocol Suite model. While the seven-layer Open Systems Interconnection (OSI) reference model is better known in academia, the majority of networks use the Internet Protocol Suite (IP) as their network model.

Networks can be classified by:

By scale.

Computer networks may be classified according to the scale:

-Personal Area Network (PAN),

-Local Area Network (LAN),

-Campus Area Network (CAN),

-Metropolitan Area Network (MAN), or Wide Area Network (WAN).

As Ethernet increasingly is the standard interface to networks, these distinctions are more important to the network administrator than the end user. Network administrators may have to tune the network, based on delay that derives from distance, to achieve the desired Quality of Service (QoS). The primary difference in the networks is the size.

By connection method.

Computer networks may be classified according to the hardware technology that is used to connect the individual devices in the network such as Optical fiber, Ethernet, Wireless LAN, Home PNA (Home Phoneline Networking Alliance), or Power line communication.

Ethernets use physical wiring to connect devices. Often, they employ the use of hubs, switches, bridges, and routers.

Wireless LAN technology is built to connect devices without wiring. These devices use a radio frequency to connect.

By functional relationship (Network Architectures).

Computer networks may be classified according to the functional relationships which exist between the elements of the network, for example, Client-server and Peer-to-peer (workgroup) architectures.

By 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 (Token Ring) network, Mesh network, Star-bus network, Tree or Hierarchical topology network, etc.

Network Topology signifies the way in which intelligent 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.

By protocol.

Computer networks may be classified according to the communications protocol that is being used on the network. See the articles on “List of network protocols” for more information.

2. Типы сетей. Рассказ с показом. Учащиеся по ходу изложения материала делают зарисовки и записывают по-английски типы сетей. Как вариант, можно показать презентацию "Топология сетей".

3. Выполнение упражнения "Вариант LAN"

а) показ на экране типичной локальной сети, краткие пояснения учителя.

б) прослушивание записи "Вариант LAN" 2 раза. Перед этим рекомендуется создать звуковую запись текста (смотри ниже), попросив кого-нибудь из коллег. К сожалению, внести оригинальную звукозапись не позволяет формат сайта. У автора она есть.

в) заполнение таблицы с ответами:

4. Дополнительно, если остаётся время, предложить учащимся (добровольно) сделать описание LAN, пользуясь слайдом и прослушанной информацией

Ниже приводится текст описания варианта LAN.

Small networks are called local area networks, or LANs. These are groups of computers within a small physical area, like a home or an office building.

In this diagram we see a mixed wired and wireless LAN. It's a typical solution for small businesses that already have a wired LAN and decide to expand it with wireless technologies to accommodate new needs. In the existing fixed wired LAN the central computer is a file server with a large hard drive used to store common files and application programmes. The computers acting as clients are connected to the file server or to a printer via Ethernet cables.

In the wireless part of the network several devices including desktops, laptops, PDAs and a gaming console are connected to each other without cables. This part is controlled by the wireless access point, or so called a wireless router. This access point is like a base station that transmits and receives radio frequencies for wireless enabled devices.

Each device that operates over the network is equipped with a wireless card, or adaptor. Many wireless LANs use Wi-Fi, or wireless technology that uses radio waves to enable communication between devices in a limited area. This gives users flexibility and mobility. Another popular technology is Bluetooth used for short distances.

The whole network is linked to the Internet via broad band modem. This modem is plugged into a router or hub, which splits the Internet connection into parts, and allows all users to access e-mail and Web resources.

With appropriate networking software users on the wireless LAN can share files and the printer located on the wired LAN.

Vocabulary

Литература:

1. InfoTech. English for Computer Science.

1. Teacher’s book
2. Student’s book

Cambridge University Press, 2008 г.

2. Интернет - материалы (по усмотрению учителя).

NETWORK TOPOLOGIES.

Speaking about networks we usually mean two main types of them, according to their scale:

• local area networks, or LANs, (локальные сети),
• world-wide area networks, or WANs (глобальные сети, например Интернет).

An example of WAN:

Слайд Wide Area Network

Let's talk about LANs and their topologies. There are some commonly recognised topologies, such as bus, ring, star, and other types of networking (By Bradley Mitchell, About.com).

In computer networking, topology refers to the layout of connected devices. This article introduces the standard topologies of networking.

Network topologies are categorized into the following basic types:

• bus
• ring
• star
• tree
• mesh

More complex networks can be built as hybrids of two or more of the above basic topologies.

Bus Topology (Моноканал, Линейная Шина).

Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone, functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.

Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. 10Base-2 ("ThinNet" = Тонкий Эзернет) and 10Base-5 ("ThickNet" = Толстый Эзернет) both were popular Ethernet cabling options many years ago for bus topologies. However, bus networks work best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable.

Слайд a Bus network

A diagram of a Bus network

Ring Topology (Кольцо).

In a ring network, every device has exactly two neighbours for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counter clockwise"). A failure in any cable or device breaks the loop and can take down the entire network. Ring topologies are found in some office buildings or school campuses.

Слайд a Ring network

A diagram of a Ring network

Star Topology (Звезда).

Many home networks use the star topology. A star network features a central connection point called a "hub" that may be a hub, switch or router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.

Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)

Слайд a Star network

A diagram of a Star network

Tree Topology (Дерево).

Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.

Слайд a tree topology network

A diagram of a tree topology network

Mesh Topology (Ячеистая топология)

Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing.

A mesh network in which every device connects to every other is called a full mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.

Слайд Mesh Topology