Networks Flashcards
What does LAN stand for?
Local Area Networks
What do we call two or more computers connected together to share information and resources.
(this can involve physical or wireless connections, or both)
A computer network
What is a LAN (Local Area Networks)?
It is a connection of computers and devices.
Each device on a network is known as a node (e.g. computer, printer, etc.)
A LAN is confined to one site.
It’s therefore relatively small
All network infrastructure is the property of the organisation
What are the advantages of a LAN? (5 of them)
It enables digital communication between people
It enables the sharing of digital information
It enables the sharing of peripheral devices such as printers and scanners
It enables computers to be updated with the latest software from a central point
It enables distributed processing – the ability for a single program to be run simultaneously at various computers.
What are the two disadvantages of a LAN?
1) There requires a bit of ‘expertise’ to install and maintain a large network which can be costly.
2) There are a number of security issues from unauthorised access to data - measures to secure a network include:
• Passwords – strong passwords use a range of character types
• Not allowing users to install software
• With wireless access, use encryption
• Changing passwords frequently
What is needed to make a LAN?
At least two computers (Nodes)
Each having a NIC – network interface card (either wired or wireless)
The NICs convert the data signals from the nodes into data signals that can be transferred across the network.
For LAN you might need a Hub.
What is a Hub?
Hub
A device that connects
nodes together.
Makes all connected nodes
act as a single segment.
Not intelligent – data
packets are transmitted
across the whole of the
network.
Cheap devices – USB hubs
useful in home computer
installations.
For LAN you might need a Switch.
What is a Switch?
A device that connects nodes together.
An intelligent device that can create and connect to different segments of the network.
This reduces network traffic because data packets are sent to the nodes or segment where they are needed rather than being broadcast to the whole network.
Hardware needed for a LAN
If a LAN is to connect to the Internet then what is needed and what does it do?
If the LAN is to connect to the Internet, a Router is needed.
Routers manage the data packets enabling them to be sent between networks (e.g. over the internet)
Hardware needed for a LAN
A wireless access point has advantages and drawbacks.
What are they?
Wireless technology has many advantages over wired networks:
No need to do building work
Add new node with ease
General public can access network / internet if allowed.
But there are drawbacks:
There can be performance issues
…and security issues too!
What are the two types of Network in a LAN?
Peer - to - peer
Client - server
LAN Network - Peer - Peer
What are four key features of this type of network?
All computers have the same status.
Data transfer may be very slow because of
data collisions
shared processor power
Only really suitable for small and low traffic networks.
This is a very popular design for a home network
LAN Network - Client - Server
What are key features of this type of network?
At least one computer is designated as a server.
This usually needs to be high spec.
It offers services such as software and data to client PCs.
It manages the traffic on the network.
Records what people do.
Gives security.
Clients have to sign in and so their identification is known enabling certain rights to be given to certain people.
Large networks may have many servers to handle the increased network demand.
Different LANS can have different topologies. What are four topologies?
Bus
Ring
Mesh
Star
LAN - Bus topology
What are some pros and cons?
• It very cheap to set up due to little cabling
- Because data travels both ways along one cable, data collides which slows the network
- If the cable has a fault the whole network may suffer
- Only really useful over small areas
LAN - Ring topology
what is a pro and con?
• Only one cable -
data travels in only one direction which means no collisions
• If the cable breaks or a node breaks then the whole network may go down.
LAN - Mesh topology
what is a pro and a con?
• This is a fully connected network:
Every node is connected to all others, which means that if a cable breaks or if there is heavy traffic on one area, there are other routes for the data to take
•It can be a very expensive to set up due to the cabling required
LAN - Star topology
What is a pro and a con?
- All nodes connect to a hub or a switch and therefore data doesn’t share one cable this results in fewer data collisions and therefore a fast network
- It is an expensive topology as it requires a lot of cables