A hub in an ethernet network is a multiport repeater. Hubs are most often used on networks usin UTP (unshielded twisted pair) cabling as the limit for this type of cable is 100 metres.

A hub will also divide the network up into a series of different sgments, thus reducing the likelyhood that a cable fault wil bring the whole network down. Hubs are commonly supplied with 12 or 24 ports, and are suitable for distributing a UTP cable to a room ot office full of network sections.

A hub also functions at the lowerst level of the OSI networking model, the physical layer.

A hub in an ethernet network is a multiport repeater. Hubs are most often used on networks usin UTP (unshielded twisted pair) cabling as the limit for this type of cable is 100 metres.

A hub will also divide the network up into a series of different sgments, thus reducing the likelyhood that a cable fault wil bring the whole network down. Hubs are commonly supplied with 12 or 24 ports, and are suitable for distributing a UTP cable to a room ot office full of network sections.

A hub also functions at the lowerst level of the OSI networking model, the physical layer.

Firstly we discussed that you could make your own blog in glow but this would not be any use due to the fact that only you can see it and this rules out others commenting or saying that you may have misunderstood something. We went over the Using networks unit in computer systems and were told that a sheet on topics to revise for the prelim will be posted on to the blog (See last entry from Mr Stratton). This will be uploaded as a PDF file so you can save it and/or print it.
We looked at Using Networks 6.2.1 Network Hardware – the HUB found on slide 116 on Power point on higher computing found on glow website which we discussed yesterday and continued with at the start of the period. This power point can be copied from glow.

We were told that other subjects we may be studying this year have been add to glow and that we are reminded that glow is not just for higher computing.

We continued on networks and discovered that a network can still operate even if the server stops. We discussed ‘the Ping of Death’, a malformed PACKET that courses your computer to crash when it is downloading a file. We discussed the router which we started new on today on page 130 of Using Network notes. The class were reminded to look over the glossary of computer terms as they will come up often and you must know the meaning of them e.g. ISTN or ADSL – download speed is greater than upload speed. We started discussing the performance affecting the machines.

One way of improving performance is installing a better network card which can help into improving the streaming data to and from your machine.

We discussed the factors affecting performance of networks page 131. We were once again reminded to look over glossary noted as we did not know what RAID was. It actually means a Redundant Array Inexpensive Disks.

We finished off by talking about network operating systems and on topic 6.4 and finally a little about bandwidth and compressing files to fit to smaller bandwidths.

Next week we will be looking at Broadcasting.

IMPORTANT

The NAB for Software Development has been rescheduled and will take place on Wednesday of next week, the 19.1.11, during period 3.

In the past, network operating systems were confusing and very difficult to set up but with today’s technology, networking operating systems have improved dramatically and made it much easier to connect computers together, with new operating systems coming with networking built in enabling such easy access to setting up a network.

The main function of a network operating system is to allow users to view resources hosted somewhere else, but access them as if they were stored in their own computer’s harddrive.  These resources may include important documents such as text files, media files such as images and video, or even software to be used to create new documents for work reasons.

A network operating system works like this image explains, it is simply one computer – normally a mainframe – hosting all resources needed, sending them out via the network.  The mainframe sending this network out hosts the operating system also, so limited use is given in most cases so malicious acts are found seldom when needed within business uses a network operating system.

Client-server

Large Local Area Networks (LANs) use one or more file servers to host resources for other machines on the network.  A file server will be one of the more powerful machines on the network, and it won’t need to be replaced as often as it will be ready for prolonged use with a lot of memory, high capacity and high speed.  These file servers are likely to be fitted with multiple backup facilities like tape drives and RAID hard disks.  File servers will have prevention from failing, using hardware such as extra power supplies & un-interruptable power supplies (UPS) to be prepared for power failures.

Advantages of a client-server system are that the file server can provide access to resources being used by many machines without taking away from the performance of any of the machines.  Large networks may use more than one high performance computer as a file server, so each one may provide different services to users meaning the network manager can set which machine will host which content and how much users can access it at a time to prevent the one machine from being overloaded.

The services provided by a client-server network include…

• Security: Only people with the correct username and password may enter a client-server network so they are secure in the way that private files will be kept private.
• Networked Storage means you may log in to the server on any computer on the network so work can be done at different machines if neccessary.
• Communications: Local networks will tend to provide a means of communication between the network users through the use of email and will give access to the internet under monitored conditions along with an intranet which will make use of the internet by storing some of the information in the browser.
• Applications: If applications are installed on the file server the user is connected to then the user may access that application.

• Support Services: Network managers will keep the network’s machines safe with anti-virus software and if anything bad were to happen, although unlikely with restricted access, they could undo it with their remote monitoring and control authority.  The network will regularly backup files also.

Peer-to-Peer

While larger networks put client-server networks to use, smaller networks are more likely to utilise peer-to-peer as it is the common choice when setting up up to five machines because large amounts of data are not usually transferred between such a small number.  It also makes sense to use a peer-to-peer with a small number as it is not set up using an expensive dedicated server.  Machines are connected together to make a small LAN which, like a client-server, allows users of the network to share peripherals and internet connections but unlike the client-server a peer-to-peer network has no network manager and all machines are equal.

This kind of system is mostly used in homes or small offices due to it’s suitability for smaller requirements, but this is not all good because due to the network not needing to have as much hard disk capacity and sometimes only one copy of some files the network can crash due to many users trying to access the one file at a time.  If not crash, then it will certainly decrease performance.

Network Servers

There are many different servers available for everyone, everywhere, and they can broadcast almost anything to users.  Here are only some of the possible servers you may encounter:

• A file server manages logins to a network and gives the allowed users access to files it is hosting, it is composed of a powerful machine and many high capacity disks.
• A print server allows users granted access to use the printer attached to it.
• A news server can store messages posted on online bulletin boards by users and sends them out via WAN normally, but also used by LAN users to keep up to date about others on the network.