Transcript Networks - dolinski.co.uk

Chapter 3
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Help you understand what hardware is required to
allow networks to work including:
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Repeaters
Hub
Switch
Bridge
Gateway (not needed for exam)
Router
Network Interface Cards
Wireless Access Points
Wireless Network Interface Cards
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Used to boost signals if they become weak.
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Weak signals can be caused by a drop in voltage. This
is usually the cause of distances being too big between
networks.
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As distances increase voltages drop.
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Room 1
Repeater
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Server
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Room 2
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Quicky  What type of hardware could go where the question mark is?
Discuss.
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Used to connect many computers to one place.
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A star network is a typical example of this.
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All computers connect to a hub.
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The hub then connects to the server.
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Data packets are broadcast to all connected devices.
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Hub
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The hub is used to allow 4
computers to physically connect to
the network. The hub is then
connected to the server.
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The following diagram shows two hubs segmented using a bridge (see bridge). Four
computers have direct access to the network, although only one hub has direct access to the
server.
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Hub
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Bridge
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More ‘intelligent’ than a hub.
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Can set up communication paths between different
clients and servers.
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This can all be done at the same time (unlike the hub –
which can only deal with one thing at a time).
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This is particularly good when network traffic is high.
Print Server
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Printer
Web Server
Switch
Server
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File Server
Mail Server
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Four web designers share both large and small files. Sometimes they send and receive emails with
videos attached, download animations, upload large web pages, save and retrieve large files and
print various files.
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A star topology was used because of its speed and security.
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A switch was used as it can direct files efficiently by choosing the connections needed to make.
This is especially useful when all four designers are accessing the network at the same time.
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As the switch can make simultaneous connections.
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Used to connect two similar LANs together.
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Users think it is logically one LAN even though it is
physically two.
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Allows clients of one network to access resources on
another network.
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Used to split large networks into segments.
Segment 2
Segment 1
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Port A
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Bridge
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Port B
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Segments are simple parts of a whole network.
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Networks often split into smaller segments to maximise network efficiency.
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◦ Computers that usually talk to each other are kept in the same network. This minimises the risk of
packet collisions.
◦ This is common place when businesses are split into departments. Computers in the sales department
will be on one segment, where as the finance department will have computers in a different segment.
But, they are still part of the same network.
◦ The bridge will have ports so that it can forward any traffic to another segment if needed. The bridge
also blocks communications. It will know which computers are in which segment. If a packet is sent to
a computer in the same segment as its originator, it will be blocked from going to the other segments
on the network.
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More ‘intelligent’ than a bridge.
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Allows different network types to communicate.
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Will convert one network protocol into another network
protocol so that it may be understood across the network.
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This allows each network type to send and receive data across
different network types.
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This is especially useful when networks are in different places
and require the use of the telephone network to transmit
data e.g. when using a WAN.
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This can be both hardware and software.
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It takes a packet of data, looks at its intended address,
and then forwards it to the correct location on the
network.
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This network might be a LAN or WAN, such as the
internet.
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It is mainly used to connect LANs to WANs.
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Every computer wishing to connect to a network will need
a network card.
◦ Or Network Interface Card (NIC)
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It can be a stand-alone card or built into a
motherboard…regardless of which…you still need one.
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Each card has its own physical address known as a MAC
address – (Media Access Control).
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The MAC address is a unique address that no other device
will have in the world.
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Effectively a hub but communicates wirelessly.
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Usually connected via a single cable to a switch.
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Because they broadcast signals, data packets are easy to
intercept.
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For this reason, WAP provides encryption methods...but
this can slow down data transfer speeds as more data
needs to be sent!
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The better the encryption the slower the transfer speed.
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WAP
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Switch
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WAP
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WAP
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Switch
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WAP
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WAP
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WAP
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WAP
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Baddy
Client!
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WAP
Switch
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Baddy
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WAP
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Baddy
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Baddy
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WAP
Switch
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Baddy
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There are different methods that can be used to
connect to a network wirelessly.
◦ The wireless NIC may form part of the internal circuitry of the
device.
◦ A USB wireless dongle could be used.
◦ An adapter card that fits in to a PCMCIA slot on a laptop or an
expansion slot in a desktop computer.
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It too will have a MAC address and will need to use the
802.11g communication standard.
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Clearly explain the difference between a hub and a switch.
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Explain why WAPs provide encryption methods.
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Describe the use of a repeater.
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What does a network card do?
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Clearly describe the purpose of a router.
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A company wants to set up an intranet. What is an intranet
and why might they want one?
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Compare the advantages and disadvantages of a Hub, Switch and
Router. You may use a table to help you but your final answer
should be in continuous prose.
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What is a MAC address?
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Identify the device that extends the range of cables.
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Draw a diagram which describes the following situation:
◦ Two rooms are far apart but in the same building. They form the same
logical network but don’t share the same physical network. Some of the
computers need to connect wirelessly in only one of the rooms. Because a
lot of computers are connected to this network traffic is a problem so a
device is required to minimise the ‘noise’ on the network by only
forwarding data packets to the correct address.