Network Topologies

Computers in a network can be connected in different ways, in different topologies. Topology is a geometric arrangement of the network. The three basic ways of connecting computers are: a bus, a ring, and a star topology.

A bus topology has all the computers connected to a common cable. The data travels in both directions along the cable. If a computer fails, or we remove one from the network, it won’t affect the other computers. But if the main cable (a backbone) fails, the entire network fails too.

In a ring topology each computer is connected to its neighbor in a circle. The data flows in one direction (clockwise or counterclockwise) round the ring. If a cable breaks or one of the computers fails, the whole network will be affected.

A star topology has a server computer and a separate cable connecting the server to each of the other computers in the network. This server is also called a hub. The central server controls the flow of data in the network. If any computer fails, it won’t affect the network. But if the central server fails, the whole network will fail.

A mesh topology includes the concept of routes. A message in the network can take any possible path from source to destination. It is the most reliable network topology, because if any computer or a cable fails, it won’t affect the entire network. But at the same time it’s the most expensive one.

Most networks are usually a combination of star, ring and bus topologies to overcome some of these problems.

Task 7. Which topologies do these statements refer to?

1. If one of the computers fails, the whole network will be affected.

2. If we remove a computer from the network, it won’t affect the other computers.

3. If the main cable fails, the whole network will fail.

4. If the central server fails, the whole network will fail.

5. If a cable breaks, the whole network will be affected.

6. If a computer fails, it won’t affect the other computers.

GRAMMAR: Revision (Indefinite Tenses (Active Voice))

Indefinite Tense (Active Voice)

Форма	The Present Indefinite Tense	The Past Indefinite Tense	The Future Indefinite Tense
Утвердительная	These keys move the cursor This key moves the cursor down.	These keys moved the cursor This key moved the cursor down.	These keys will move the cursor This key will move the cursor down.
Отрицательная	These keys don’t move the cursor. This key doesn’t move the cursor down.	These keys didn’t move the cursor. This key didn’t move the cursor down.	These keys will not=won’t move the cursor. This key will not=won’tmove the cursor down.
Вопросительная	Do these keys move the cursor? Doesthis keymove the cursor down?	Did these keys move the cursor? Didthis keymove the cursor down?	Will these keys move the cursor? Will this keymove the cursor down?

Task 8. Put the verbs in brackets into the correct tense.

1. Bill ________ (work) for the company for the last twenty-five years.

2. He ————————(graduate) in business studies and ________ (take) a job in London.

3. He ________ (train) as a systems analyst while he ________ (work) in London.

4. Now he ———————— (look after) all the systems used by the Technical Services Division.

5. At the moment he_______ ( develop) a system for handling repairs

6. When something _______(go) wrong in a service engineer ______ (send) to fix it.

7. Details of every repair __ (download) to the company’s mainframe each night.

8. No changes can ______ (make) until the system _________(test).

9. Bill thinks that communications_______( get) faster and faster in the future.

10. He thinks that a paper-free office_______ ( not happen)

Task 9. Make up questions beginning with the words in brackets

1. He will get up at 7 o’clock tomorrow. (when?)

2. I saw him in the library. (where?)

3. He plays computer games every day.(what?)

4. The students often come home late. (who?)

5. They studied English at school. (where?)

PROBLEM-SOLVING

Task 10. Tell about networks.

Task 11. Tell about network topologies.