Unit 09 Computer Networkswiki.hct.ac.uk/_media/computing/btec/level3/network... · 2015. 3. 23. ·...
Transcript of Unit 09 Computer Networkswiki.hct.ac.uk/_media/computing/btec/level3/network... · 2015. 3. 23. ·...
Unit 09 Computer Networks
Gain a knowledge about network devices.
Discuss what network devices are required to create a basic network
Draw a bespoke network drawing using Visio
•Network Concepts & Devices •2
In order to setup a network a variety of devices are required.
The network devices differ according to what network you intend to setup.
A network segment is a portion of a computer network where every device communicates using the same physical layer.
•Network Concepts & Devices •3
A simple network can be created between two computers (peer to peer). In order to create this connection each computer
must have an NIC network interface card.
A Network card, Network Adapter, LAN Adapter or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network.
•Network Concepts & Devices •4
•Network Concepts & Devices •5
An NIC provides physical access to a networking medium and provides a low-level addressing system through the use of MAC (Media Access Control) addresses.
It allows users to connect to each other either by using cables or wirelessly.
•Network Concepts & Devices •6
Cross-Over cables are used to connect two computers directly through NICs
without the use of a Hub or Switch or routers.
A crossover cable is a cable that maps all output signals on one electrical
connector to the input signals on the other connector, allowing two electronic
devices to perform full-duplex communication.
Most commonly, the term refers to the Ethernet crossover cable, but other cables
follow the same principle. It also allows devices to communicate without a switch,
hub, or router.
The Pins of the RJ-45 Connectors at both ends of a cross-over cable are
connected as follows:
Pin 1 ----------- Pin 3 Pin 2 ----------- Pin 6
Only two pairs of wires in the eight-pin RJ-45 connector are used to carry Ethernet
signals. Both 10BASE-T and 100BASE-T use the same pins, a crossover cable
made for one will also work with the other.
•Network Concepts & Devices •7
Compare a crossover cable to a standard Cat 5e lead.
Discuss and make notes on the purpose of the crossover cable.
Find out more about MAC Addresses
Using the internet find out what a Modem is used for.
•Network Concepts & Devices •8
•HNC COMPUTING - Network
Concepts •9•Network Concepts & Devices •9
There are a variety
of different network devices that are
available, each of which has a
specific role within the network.
Switch
Hub
Router
Bridge
Gateway
Repeaters
•10•Network Concepts & Devices
A network switch connects network segments.
A switch is intelligent, it can recognise what cable has been inserted into it and adapt to allow the network to communicate.
It maintains a table of destination address and its port.
When the switch receives a packet:
It reads the destination address from the header information in the packet
Establishes a temporary connection between the source and destination ports
Sends the packet on its way, and then terminates the connection.
•Network Concepts & Devices •11
A network hub is a device
for connecting multiple
devices together, making
them act as a single network
segment.
When a hub receives a
packet at one of its ports
from a PC on the network, it
transmits (repeats) the
packet to ALL of its ports
•Network Concepts & Devices •12
What is the difference between a Hub and a Switch?
A hub receives a packet at one of its ports from a PC on the network, it transmits the packet to all of its ports (broadcast) thus, to all of the other PCs on the network.
A hub does not use any intelligence to determine the destination of a packet, whereas a switch does.
•13•Network Concepts & Devices
What problems could occur as a result of using a hub?
•Network Concepts & Devices •14
This is a device that forwards and routes data packets along networks.
A router is often included as part of a network switch.
A router is located where one network meets another.
It prevents the traffic on one from unnecessarily spilling over to the other. This process is known as routing.
•Network Concepts & Devices •15
A bridge is a device that connects two networks so that they
act as if they’re one network.
A key feature of a bridge is to enable a large network to be
partition into two smaller, more efficient networks.
A bridge directs frames according to hardware assigned MAC
addresses while a router makes its decisions according to
assigned IP Addresses.
Bridges work best in networks that are highly segregated.
A bridge directs frames based on hardware assigned MAC
addresses while a router uses IP Addresses. •Network Concepts & Devices •16
A gateway converts protocols between different communications networks.
A gateway can accept a packet formatted for one protocol (e.g. AppleTalk) and convert it to a packet formatted for another protocol (e.g. TCP/IP) before forwarding it.
A gateway can be implemented in hardware, software or both, but they are usually implemented by software installed within a router.
•Network Concepts & Devices •17
Watch the video – Switches, Routers & Hubs! Oh my!
Using the internet look into the various other available network devices/terms:
What is DSL and ADSL?
Also including repeaters, multiplexers, Analogue and digital frequencies.
Do you agree with the following descriptions of DSL and ADSL?
•Network Concepts & Devices •18
Asymmetric Digital Subscriber Line (ADSL) is a form of DSL.
A data communications technology that enables faster data transmission over copper telephone lines than a conventional voice band modem can provide.
Utilizing frequencies that are not used by a voice telephone call.
A splitter - or micro filter - allows a single telephone connection to be used for both ADSL service and voice calls at the same time.
•Network Concepts & Devices •19
DSL or xDSL, is a family of technologies that provide
digital data transmission over the wires of a local
telephone network.
DSL originally stood for digital subscriber loop, although
in recent years, the term digital subscriber line has been
widely adopted as a more marketing-friendly term for
ADSL.
DSL uses high frequency, while regular telephone uses
low frequency on the same telephone line.
DSL is the most popular version of consumer-ready DSL.
•Network Concepts & Devices •20
Bandwidth is the amount of data that can be transmitted within a fixed time period.
Bandwidth is measured in bits per second and is usually denoted by the following:
•bps - bits per second
•Kbps - kilobits per second
•Mbps - megabits per second
Latency is the amount of time it takes data to travel from source to destination.
Data is transmitted in one of three modes:
• Simplex (Unidirectional transmission) is a single, one-way transmission.
• Half-duplex allows data to flow in one direction at a time.
• Full-duplex allows data to flow in both directions at the same time.•Network Concepts & Devices •21
Gained knowledge about network devices
Discuss what network devices are required to setup a network
Create a bespoke network diagram in Visio
•Network Concepts & Devices •22