n analyze any multimedia file or application

n create your own multimedia project





SECTION 1 Introduction

questions to be asked and discussed

1) What do we use networks for?

2) Logical and physical setup.

3) What is the difference between ‘connection’ and ‘session’?

4) What can any network be characterized by?




Network Interface Cards



SECTION 2 Configuration

questions to be asked and discussed

1) What is a node?

2) What does a network consist of? What is its topology or general configuration?




Thin server and thin client


questions to be asked and discussed

1) What is a server?

2) What services does a server provide?

3) What is a client?


questions to be asked and discussed

1) What is a backbone?

2) What kinds of backbones do you know?



Exercise 1

In general, a hub is the central part of a wheel where the spokes come together. The term is familiar to frequent fliers who travel through airport «hubs» to make connecting flights from one point to another. In data communications, a hub is a place of convergence where data arrives from one or more directions and is forwarded out in one or more other directions. A hub usually includes a switch of some kind. (And a product that is called a «switch» could usually be considered a hub as well.) The distinction seems to be that the hub is the place where data comes together and the switch is what determines how and where data is forwarded from the place where data comes together. Regarded in its switching aspects, a hub can also include a router.

In describing network topologies, a hub topology consists of a backbone (main circuit) to which a number of outgoing lines can be attached («dropped»), each providing one or more connection port for device to attach to. For Internet users not connected to a local area network, this is the general topology used by your access provider. Other common network topologies are the bus network and the ring network. (Either of these could possibly feed into a hub network, using a bridge.)

As a network product, a hub may include a group of modem cards for dial-in users, a gateway card for connections to a local area network (for example, an Ethernet or a Token Ring), and a connection to a line (the main line in this example).

In telecommunication networks, a bridge is a product that connects a local area network (LAN) to another local area network that uses the same protocol (for example, Ethernet or Token Ring). You can envision a bridge as being a device that decides whether a message from you to someone else is going to the local area network in your building or to someone on the local area network in the building across the street. A bridge examines each message on a LAN, «passing» those known to be within the same LAN, and forwarding those known to be on the other interconnected LAN (or LANs).

In bridging networks, computer or node addresses have no specific relationship to location. For this reason, messages are sent out to every address on the network and accepted only by the intended destination node. Bridges learn which addresses are on which network and develop a learning table so that subsequent messages can be forwarded to the right network.

Bridging networks are generally always interconnected local area networks since broadcasting every message to all possible destinations would flood a larger network with unnecessary traffic. For this reason, router networks such as the Internet use a scheme that assigns addresses to nodes so that a message or packet can be forwarded only in one general direction rather than forwarded in all directions.

A bridge works at the data-link (physical network) level of a network, copying a data frame from one network to the next network along the communications path.

A bridge is sometimes combined with a router in a product called a brouter.

In packet-switched networks such as the Internet, a router is a device or, in some cases, software in a computer, that determines the next network point to which a packet should be forwarded toward its destination. The router is connected to at least two networks and decides which way to send each information packet based on its current understanding of the state of the networks it is connected to. A router is located at any gateway (where one network meets another), including each point-of-presence on the Internet. A router is often included as part of a network switch.

A router may create or maintain a table of the available routes and their conditions and use this information along with distance and cost algorithms to determine the best route for a given packet. Typically, a packet may travel through a number of network points with routers before arriving at its destination. Routing is a function associated with the Network layer (layer 3) in the standard model of network programming, the Open Systems Interconnection (OSI) model. A layer-3 switch is a switch that can perform routing functions.

An edge router is a router that interfaces with an asynchronous transfer mode (ATM) network. A brouter is a network bridge combined with a router.

For home and business computer users who have high-speed Internet connections such as cable, satellite, or DSL, a router can act as a hardware firewall. This is true even if the home or business has only one computer. Many engineers believe that the use of a router provides better protection against hacking than a software firewall, because no computer Internet Protocol address are directly exposed to the Internet. This makes port scans (a technique for exploring weaknesses) essentially impossible. In addition, a router does not consume computer resources as a software firewall does. Commercially manufactured routers are easy to install, reasonably priced, and available for hard-wired or wireless networks.

A gateway is a network point that acts as an entrance to another network. On the Internet, a node or stopping point can be either a gateway node or a host (end-point) node. Both the computers of Internet users and the computers that serve pages to users are host nodes. The computers that control traffic within your company's network or at your local Internet service provider (ISP) are gateway nodes.

In the network for an enterprise, a computer server acting as a gateway node is often also acting as a proxy server and a firewall server. A gateway is often associated with both a router, which knows where to direct a given packet of data that arrives at the gateway, and a switch, which furnishes the actual path in and out of the gateway for a given packet.

questions to be asked and discussed

1) What are a bridge, hub, router, gateway used for?

2) What is the difference between them?


SECTION 3 Data transmission


twisted pair cabling

coaxial cabling

fiber-optic cabling

infrared connection

narrowband radio transmission


questions to be asked and discussed

1) What can data be transmitted via according to the type of connection? (via cables and wirelessly)

2) What cable connections do you know? (twisted-pair, coaxial, fibre-optic)

3) What are advantages and disadvantages of the three cable categories?

4) What networks can use wireless connection?

5) What are the two common techniques for wireless transmission? (infrared and narrowband radio



group work


study the table and make a dialogue about the use of the three categories of network cables

Cable categories Use if Do not use if
Twisted-pair You want a relatively easy installation in which computer connections are simple. Your LAN requires a high level of signal shielding to protect it from electromagnetic waves that may interfere with the electrical signal carried in the cable. You must transmit data over long distances at high speeds.
Coaxial You need to transmit data for greater distances that is possible with less expensive cabling. You need to change the network cables frequently due to relocations.
Fiber-optic You need to transmit secure data at very high speeds over long distances. You have a small budget. You do not have the expertise to properly install it and connect devices to it.


questions to be asked and discussed

1) What is bandwidth? What is data transfer rate?

2) What is bandwidth measured in? And data transfer rate?

3) What is full-duplex data transmission? Half-duplex one?

4) What is the difference between synchronous and asynchronous transmission?

5) What is a packet?



Exercise 3

Read the text and do exercises


SECTION 4 Topology

questions to be asked and discussed

1) What is topology?

2) What is the difference between the physical topology and the logical topology?

3) What layouts of physical topology can you imagine?

4) What are the advantages and disadvantages of each configuration?


Exercise 4


label each picture with the type of the network it depicts. Write a report on advantages and disadvantages of each topology





token ring topology


group work

Exercise 5


arrange the steps how Token Ring works in the logic order


A Token Ring network is a local area network (LAN) in which all computers are connected in a ring or star topology and a bit- or token-passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time. The Token Ring protocol is the second most widely-used protocol on local area networks after Ethernet. The IBM Token Ring protocol led to a standard version, specified as IEEE 802.5. Both protocols are used and are very similar. The IEEE 802.5 Token Ring technology provides for data transfer rates of either 4 or 16 megabits per second. Very briefly, here is how it works:

  1. The frame is examined by each successive workstation. If the workstation sees that it is the destination for the message, it copies the message from the frame and changes the token back to 0.
  2. When the frame gets back to the originator, it sees that the token has been changed to 0 and that the message has been copied and received. It removes the message from the frame.
  3. When a computer has a message to send, it inserts a token in an empty frame (this may consist of simply changing a 0 to a 1 in the token bit part of the frame) and inserts a message and a destination identifier in the frame.
  4. The frame continues to circulate as an «empty» frame, ready to be taken by a workstation when it has a message to send.
  5. Empty information frames are continuously circulated on the ring.


questions to be asked and discussed

What relationship can there be among different workstations within a network?



relationship of nodes (master/slave, client/server, peer-to-peer network)



SECTION 5 networks


questions to be asked and discussed

1) What is PAN?

2) What is control network? Give examples.










Exercise 6


Read the text and summarize it.


A home network is two or more computers interconnected to form a local area network (LAN) within the home. In the United States, for example, it is estimated that 15 million homes have more than one computer. A home network allows computer owners to interconnect multiple computers so that each can share files, programs, printers, other peripheral devices, and Internet access with other computers, reducing the need for redundant equipment and, in general, making everything easier to use. For example, if you have an older computer without a CD-ROM, you can access your newer computer's CD-ROM instead of purchasing one for your older computer. Sharing files across a home network is also easier than copying a file to a floppy and running to the other computer to use the file. A new trend, sometimes referred to as an intelligent network, extends the home network to include controls for the home ambient environment, security systems, and kitchen devices. In general, a home network is distinguished from a small office-home office (SOHO) network only by its more general purpose and possibly by the kinds of devices that are interconnected.

Before deciding what kind of home network you want, you must ask yourself if it bothers you to drill holes and run wire throughout your house? Do you mind opening your computer and installing network cards? Are your computers in the same room? What is your budget for a home network? Do you mind paying someone to come in and do the setup for you?

There are five types of home networks, two that use wire connections and three that use wireless connections:

  • Direct cable connection: This allows you to connect both computers with a $10 null modem that plugs into both computers' serial, parallel, or Universal Serial Bus port. You simply configure the Windows 9x/NT Direct Cable Connection feature and you're ready to go. You lose your printer's parallel port if you use a parallel port connection. USB is faster than both serial and parallel, but you must make sure you are using Windows 95B or Windows 98 when using a USB network. This is a possible choice when two computers are in the same room.
  • Traditional Ethernet: A peer-to-peer Ethernet network requires installing network interface cards (NIC) inside each computer and interconnecting them with a coaxial cable or a twisted pair cable. You have to install driver and configure Windows 9x/NT. The drawback to an Ethernet network is the difficulty of hardware installation. Will your computers recognize the new cards? If your computers have several cards installed already, you might run into hardware conflicts. This type of network is suitable for use with two to twelve computers. You can have your computers scattered throughout your house, but you will have to wire each room that has a computer. Beginning cost of an Ethernet network is $100.
  • AC network: An AC (alternating current) network is a possibility when computers are in different locations in your house. You don't need to drill any holes or wire any rooms. You simply plug one end of an adapter into the parallel port of your computer and plug the other end into an outlet. You do the same for each computer. Your data is transmitted through the power lines. You can have a ready-made network anywhere in the house at any time. When purchasing the equipment and software for your AC network, make sure it includes extra outlet strips and an adapter for your printer. The software setup can be difficult for AC networks. The cost of an AC network is $200 for two computers.
  • Phoneline network This type of wireless network was developed by the Home Phoneline Networking Alliance (HomePNA) to offer an easy and inexpensive (starting at $150 for two computers) solution that uses existing phone lines. For example, Action Tec's ActionLink Home Networking Kit provides PCI card that share a single registered jack with your modem and telephone. The HomePNA technology is designed to not interfere with your voice and data transmissions. This means that you can talk on the phone and use your Internet connection at the same time without any noticeable decrease in modem speed. A phoneline network does require you to install PCI cards and software drivers. The data transfer rate of a phoneline network is 10 Mbps.
  • Radio Free (RF) network: This type of wireless network uses radio frequency (RF) waves to transmit through walls and floors up to 800 feet. The only hardware is a special card inserted into each computer or a transceiver plugged into each computer's parallel port. If you purchase an RF network that uses transceivers, make sure equipment is included for connecting your printer. The problem with an RF network is interference from other wireless communication devices. Some RF network packages promise no interference from other wireless devices. RF networks start at $100.

A number of companies offer approaches to an intelligent network in the home. For example, IBM is partnering with home developers to equip new houses with Home Director Model 200, which includes the distribution of video and satellite connections throughout your house, using your DVD player in the living room to watch a movie in your bedroom, automatically turning on and off your lights, and lowering your thermostat at night.




Exercise 7


Read the text and match the diagram key to the components of the network




questions to be asked and discussed

1) LANs, WANs, CANs, MANs, VANs


SECTION 6 Revision


Exercise 8


With the help of the diagram, try to describe the function of these components of a typical network system.



group work


Exercise 9


Work in groups. One group lists advantages of networks. The other group lists disadvantages of networks.

Then together decide how the disadvantages can be minimized.




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