Topic 3—Networks (9 hours)

3.1 Networks (9 hours)

--- Network fundamentals ---


Identify different types of networks.


Teaching Note:

Examples include local area network (LAN), virtual local area network (VLAN), wide area network (WAN), storage area network (SAN), wireless local area network (WLAN), internet, extranet, virtual private network (VPN), personal area network (PAN), peer-to-peer (P2P).

S/E, INT Globalization has been accelerated by the technical advances linked to network development.


Sample Question - FORMER CURRICULUM - Doesn't apply too well, but is worth looking at.:

A small company has a LAN connecting its various desk-top computers and
peripheral devices.

(a) Explain, with an example, how handshaking might be used during data
transmission over this LAN. [2 marks]

The company is going to provide Internet access to its LAN.

(b) State the name of an additional hardware device that would be required to permit
Internet access. [1 mark]

(c) Explain how a firewall would help to provide security for the LAN. [3 marks]

(d) Suggest, with reasons, two further measures that the company should take to
safeguard its data from unlawful access via the Internet. [4 marks]

JSR Notes:

Note that this assessment statement is not worth spending too much time with. It is simply an "identify" assessment statement. You do not need to know lots of details about each network; just enough to be able to identify the kind of network that either:
- would be appropriate for a given situation, or
- is used in a particular situation (based on its description)

But, in addition to the diagram below, here are some extra points:

local area network (LAN) - a wired network in a confined area such as a school. We have one at ISP with a few hundred computers connected via ethernet cables, which you for the most part can't see because they are hidden in walls and ceilings and under floors. Think of a "LAN" party too, where kids get together in one house and connect their comptuers together with a hub and ethernet cables to play CounterStrike, for example - they do so because the local wired connections are so fast.

virtual local area network (VLAN) - here, it seems as if there's a LAN when you look at the available computers on the network (as on a Mac by going Finder, Connect to Server), but there's actually no LAN and no hub; the VLAN is made viturally over another network, such as the Internet, and encrypts data over top of that network.

wide area network (WAN) - more than LAN connected together via dedicated wires (or even wirelessly) between locations (usually different buildings in a city, but it could be wider than that, spanning countries or even continents.) Banks, businesses, universities, and the military are four examples of groups that might have the money, resources, and reasons to set up WANs

storage area network (SAN) - one group of servers used for storage, which appears as one big storage device when you connect to it. In extremes, cloud storage warehouses are examples of this.

wireless local area network (WLAN) - this is what you are used to in your house, and at our school

internet - the one and only, though there are contries that have "their own" internet which filters out much of the outside world's internet. Take a look at Google images of the Internet, or check out Internet-map.net. And check out how the guys of Big Bang Theory use the Internet to control their lights!

extranet - any web services that are available outside of a local area via user login and password access - a good example is the "private" parts of school websites, such as schoolnet for us.

virtual private network (VPN) - any group of computers connected through encrypted lines, either within another LAN, or around the world, using the Internet.

For example, using Amazon web servers you could set up your own VPN to access it securely.

personal area network (PAN) - for example, in a house for sharing Internet access, or music and other media, or even sharing work files between two differnet computers.

peer-to-peer (P2P) - any time two computers directly share files, without needing a hub or server to direct and manage the traffic. "Bit Lord", "Deluge", "Limewire", and so on are torrenting examples of P2P services.

For example some games which don't have a company server, like Call of Duty; the host is a player and host to other players.

network types


In terms of the Former Curriculum, the new assessment statement says just to identify, so you only need to look at those notes if you don't understand what's in the diagram above.


---- From this point on, use the following legend for the FORMER CURRICULUM notes:

---- italics - the former curriculum assessment statements and teaching notes themselves
---- black, normal text - applies perfectly to this new assessment statement
---- green - pretty good fit; definitely look over and understand this
---- amber - applies, but not directly; will help your overall understanding of the assessment statement
---- gray - does not apply, but is left here to put the former curriculum notes into fuller context

JSR Notes - FORMER CURRICULUM - 6.4.1 Outline the role of the computers used in the separate type of networks: WAN, LAN and the Internet.
So this is way beyond "identify", but is useful to know.

So, it’s one thing to take a look at all of the very good stuff written in the text book, but this is one of those assessment statements wants you to be able to go beyond the facts, and draw connections.  The teaching note above is most salient in this regard.  In fact the three things mentioned in it are three different things.  So here are answers to each:

The roles of provider, servers and clients in:
Provider – the “main” server which enables the component LANs to connect, and gain access to some sort of common database.  So in a University system WAN, for example, a huge library database could be provided across the WAN.
Servers – in the example, the mainframes of each university, which pass on the services of the provider, along with their own services, like printing and Internet access.
Clients – the end-users, who connect to a local server, and in turn connect to the provider via a local server

Basically this is just a subset of what was written above.  The idea is that within a LAN you do not necessarily have access to “the outside world”, though usually now-a-days, all LANs will be at least connected to an Internet Service Provider, though not often to any other WAN provider.

The Internet
The first thing to point out here is that the Internet is indeed a WAN; it’s just that it’s a very big one.  And there is no one particular provider that provides all the other providers; they all work together.  Each client gains access to the Internet network either via a server on their LAN, which connects them to a provider, or they are directly connected to their ISP, like you are with your home computer, unless you have a LAN there.

In terms of what type of network is appropriate when and where, it’s pretty straight-forward, if you understand how each is structured.  To implement a Local Area Network, you generally need to be able to physically connect all of the devices on your network.  The Ethernet network is the most common structural set up, and for it, you run Cat-5 “Ethernet” cables from each computer/printer etc. to a switch.  So if it’s not a limited geographic area you won’t be able to do this.  Generally, therefore, you think of a LAN being in your house, or in any given building like a school, or perhaps multiple buildings, which are close to each other as in a hospital or university campus.

For all other “wider” physical setups, like a university campus that is spread all around a city, or a certain bank spread all around a country, you will need to take the structural and financial step up to a WAN.  In that case that equipment needed goes way beyond wires collected in a central switch, and so the costs go up as well.  Cost in fact may be a determining factor of whether or not a certain situation could accommodate a WAN.

The role of a gateway is to filter access to a LAN.  That’s basically it.  But what form that filtering takes is a little more complex.