How Do We Define a Computer Data Network?

A computer data network is comprised of a number of components, including the computers and other associated network attached devices. The computers and other peripherals are usually connected to each other through a network switch or hub and by means of copper electrical connections, fibre or by means of wireless.The hubs or switches normally provide local connectivity for the computer devices, in what is normally referred to as a LAN (Local Area Network). LANs are normally interconnected by means of routing devices, whether they are in a private network or indeed the Public Internet. The purpose of a computer data network is one of sharing and collaboration, where resources are made available by some of the devices on the network for use by other devices.In Peer-to-Peer networks, individual devices offer resources to other peers on the network, but there is no central control of these resources. Each peer can offer resources such as disk space, files, or even processing power.The Client Server network model clearly distinguishes between client devices and server devices. All clients, or selected clients can have access to resources hosted on specific network servers, for example, an email server, http server or file server. The client does not host any services, but merely requests a service from a particular server device. Some servers often host and offer multiple services to clients.Data networks are to be found in virtually every environment, not least of all our homes, as most of us now have a connection to the Internet and run a small local network ourselves. Almost all businesses also run data networks to provide employees with connections to the Internet and to other sites owned by the business. Components within a computer network fall into 4 main areas, and these are: the computers and servers (sometimes referred to as host devices), interconnections (comprising the cables or wireless medium), switches or hubs (which provide the local connectivity and routers that enable Local Area Networks to communicate with each other.The purpose of the computers is to host the private user information and also to provide a data interface to the network itself, in order to be able to communicate with other computers, or to connect to servers that provide information or provide some other service to the client computer devices. There are many different services or applications, with the most common coming under the headings of Email, File Transfer, Collaboration, Instant Messaging, Voice and Media over IP as well as the ability to access websites through the use of HTTP.The Servers allow the user to host a particular service such as a website with content for clients to download, email system, information service, such as a database or a storage system, where files can be made available for download.The interconnections predominantly fall into two main categories, Wired and Wireless. Modern day wired connections between end user devices and the network components are normally in the form of copper twisted pair cable, but coaxial cable or fibre optic cable can also be used. Fibre optic cable is becoming more popular, but at present it is normally used to provide higher bandwidth connections between switches and routers in the network. The communications fibre can provide extremely high bandwidth, when required and has the added benefit of being virtually immunie from electromagnetic interference.Most wireless interconnections are governed by the IEEE 802.11 standards, and users will normally access a wireless network by means of a wireless router or wireless access point. Wireless local area networks (WLANs) are becoming extremely popular, mainly due to the fact that the user is freed from the cumbersome cable connection, but wireless networks also have their drawbacks. Because most wireless networks use the unlicensed ISM (Industrial, Scientific and Medical) frequency bands, interference from other users can be a problem at times, even other adjacent wireless networks.Data switches forward the data traffic between end users and servers by using a unique identification feature known as the MAC Address, allocated to each user interface. A data switch builds up a table of all the connected user devices by reading the MAC Address in the Ethernet frames sent by each device. The table indicates to the switch the specific port of connection that each unique device is attached to. The switch can therefore ensure data is forwarded to the correctly addressed device. Some switches can provide a greater degree of sophistication by allowing the configuration of a variety of features, such as Quality of Service (QoS), port security, creation of Virtual Local Area Networks (VLANs), port forwarding and many more.Routers are designed to provide interconnectivity between different networks or sub-networks. This is achieved by addressing each device with a logical address, the most common of which is the IP (Internet Protocol) address. A router will build up a picture or map of all the available networks and router IP packets between different networks by reading the destination IP address within each data packet. In order to achieve this, local devices within a local area network must have addresses that are within the same unique range. In other words, they must have the same common network or sub-network identity. Routers can also provide a greater degree of security by filtering traffic between different local area networks or between different individual devices on the network. 7There are many other devices on modern computer data networks, such as Firewalls, Proxy Servers, Intrusion Detection Systems, Intrusion Prevention Systems to name just a few.We have come a long way since those early networks back in the early 1980s, and today’s networks are becoming more and more sophisticated as time goes by. Real time media and multimedia over data networks would be been near impossible 20 years ago, but nowadays voice and video are common media carried across our computer data networks.

A Guide to Network Equipment

To the home user there is a multitude of networking equipment on sale. The naming and specifications of these devices can be confusing to the novice. The following guide is designed to cut through all the jargon and explain the terms, names and specifications making it easier to make the correct decisions when setting up a home or small office network.What is a Network?
A network usually consists of multiple computer devices which can communicate with each other enabling the sharing of information or data between them. With today’s technical advances networks are not limited to computers and laptops as they have extended to televisions, stereo equipment and even mobile devices such as phones and tablet PCs.Wired Networks
Before the advances in wireless technology networks would mainly be “wired”. This would involve various devices between computers that would allow cables to be plugged into the machines enabling communication. These cables would limit the movement of the devices and on home networks would be impractical as it would usually require the drilling of holes.Wireless Networks
In the last few years wireless networking has improved and now operates at speeds that allow networking of equipment reliably and more easily than ever before.Network Speed
Network speeds are important when deciding which way to go when building a network for the home or office. Wired networks currently run at three speeds. These are measured in Megabits Per Second, the current speeds are 10Mbps, 100Mbps and Gigabit which runs at 1000Mbps. 10Mbps is very outdated in today’s networks as it cannot really cope with the transfer of data required by today’s applications and file sizes. 100Mbps can still be acceptable as long as there is not too much multimedia requirements as these files are large and usually take up a lot of network bandwidth.There are currently four wireless standards for use around the home or office, 802.11a, 802.11b, 802.11g, or 802.11n. The first two standards 802.11a and 802.11b are very slow and also very insecure to the point where they should not be used on networks at all. 802.11g operates at 54Mbps and is still useable on networks. It will work adequately when surfing the internet and handles the transfer of data at home or in the office. 802.11n is the latest standard to be introduced and can operate at speeds up to 100mbps. This is the standard that should be implemented if using wireless networks.Network EquipmentCables
Wired networks require special cables or network cables to function. The computer, laptop or network equipment has to have a network port to enable these cables to be connected to them. The port is called a RJ45 port. There are a couple of types of network cable that can connect network enabled devices to a wired network, these are CAT5, CAT5e and CAT6 cables. For the majority of uses the CAT5e should be used as this can handle all network speeds including Gigabit 1000Mbps speeds. Note that CAT5 does not support Gigabit networking.Network Switches
A network switch is used to connect multiple computer devices using network cables. They usually have a number of RJ45 ports used to connect the devices to the switch. They can come in various sizes and have a differing amount of ports built-in. A network switch can have as little as four ports for home or small office use but they also can come with 8, 16, 32 and 48 ports, obviously the larger switches are usually found on larger business networks.Some switches come with a management interface which can be accessed via a web browser allowing certain settings to be manipulated in the switch such as enabling and disabling ports. It will also allow segmenting of the network but this is not usually a requirement for home and small office networks.Network Routers
As the name suggests, the role of the network router is to route traffic around a network. They take the data being transmitted around the network and analyse it and then send it to the required destination.Typically a home router will interface with the various network equipment around the home and manage the passing of information between these devices and even the internet via the modem. Before the common application of modern routers, internet connection sharing between multiple devices was long winded and very unreliable. These days many ISPs (Internet Service Providers) supply a router as part of their installation or package.A router may also have wireless technology built-in allowing the connection of wireless devices to the network. These wireless devices then have the ability to access and share resources on the network via the same router.A typical home router will have four RJ45 ports, a port for connecting it to the internet and wireless capabilities allowing it to become the central networking device around the home.Network Attached Storage
NAS or network attached storage was once only used for business to store data shared amongst devices on the network. There are now devices designed to do this for home use. The network attached storage is basically one or more hard disk drives contained in a box which interfaces with the home network using a cable. These can be connected to the router or switch. They have an interface that can be accessed by a web / internet browser allowing simple configuration and backing up etc. These devices are accessed by computers, laptops etc using built-in networking allowing browsing, copying of files to and from the network attached storage directly.Media Players
These are some of the latest network devices that can be installed around the home. They can interface with the home television and even stereo equipment allowing movies and audio files to be played. Media players are put to good use in conjunction with network attached storage accessing media files and playing them around the home.Network Cards and Adapters
These devices are used to connect a device to the network. They can be wireless or wired. A modern PC should come with these fitted by default. If a computer / laptop does not have network capabilities or does not have the required capabilities for the network to which it is connecting then an adapter can be purchased to enable the connection to be added.Summary
There is a lot of varied network equipment that can be used around the home or office and hopefully this article has cleared up some of the confusion about the technologies available. If you are unsure of your requirements then a simple search will bring millions of results enabling research and advice from other users who have created their own network.