Network: Components and use
What is a network? What is used for it?
Network
Router
A router is a device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP's network. Routers are located at gateways, the places where two or more networks connect, and are the critical device that keeps data flowing between networks and keeps the networks connected to the Internet.
Hub
A hub is used in a wired network to connect Ethernet cables from a number of devices together. The hub allows each device to talk to the others. Hubs aren't used in networks with only wireless connections, since network devices such as routers and adapters communicate directly with one another
Switch
A switch is used in a wired network to connect Ethernet cables from a number of devices together. The switch allows each device to talk to the others. Switches aren't used in networks with only wireless connections, since network devices such as routers and adapters communicate directly with one another, with nothing in between.
Server
- Web Servers
- Proxy Servers
- FTP servers
- Online Game Servers
NIC
In computer networking, a Network Interface Card provides the hardware interface between a computer and a network. A NIC technically is network adapter hardware in the form factor of an add-in card such as a PCI or PCMCIA card.
Server
Print server: this is connected to the network printers and acts as the go-between for your computer and the printer when you send a document to print. The print server handles the task for you, leaving you free to get on with something else. If a job seems to be taking a long time, then you can normally click on your printer icon in the task bar to have a look at the 'print queue' to see what is holding it up.
Client
A client application, or client for short, is a program that submits requests (SQL queries) to the server and gets results back from the server.
A client program is separate from the server program. In many cases, the client is also running on a separate computer. Using shared memory access or linked library access, you can link the client's code directly to the server's code so that both run as a single process.
Ring Network
A ring network is a local area network (LAN) in which the nodes (workstations or other devices) are connected in a closed loop configuration. Adjacent pairs of nodes are directly connected. Other pairs of nodes are indirectly connected, the data passing through one or more intermediate nodes.
Star Network
A star network is a local area network (LAN) in which all nodes (workstations or other devices) are directly connected to a common central computer. Every workstation is indirectly connected to every other through the central computer. In some star networks, the central computer can also operate as a workstation.
Bus Network
A bus network is an arrangement in a local area network (LAN) in which each node (workstation or other device) is connected to a main cable or link called the bus.
Advantages of Networks
Bus
- Easy to implement and extend
- Well suited for temporary networks (quick setup)
- Initially less expensive than other topologies
- Cheap
Ring
- Data is quickly transferred without a ‘bottle neck’. (very fast, all data traffic is in the same direction)
- The transmission of data is relatively simple as packets travel in one direction only.
- Adding additional nodes has very little impact on bandwidth
- It prevents network collisions because of the media access method or architecture required.
Star
- Good performance
- easy to set up and to expand. Any non-centralised failure will have very little effect on the network, whereas on a ring network it would all fail with one fault
Disadvantages of Networks
- Difficult to administer/troubleshoot.
- Limited cable length and number of stations.
- If there is a problem with the cable, the entire network goes down.
- Maintenance costs may be higher in the long run.
- Performance degrades as additional computers are added or on heavy traffic.
- Low security (all computers on the bus can see all data transmissions).
- One virus in the network will affect all of them (but not as badly as a star or ring network).
- Proper termination is required.(loop must be in closed path).
- If one node fails, the whole network will shut down.
- If many computers are attached, the amount of data flowing causes the network to slow down.
Ring
- Data packets must pass through every computer between the sender and recipient therefore this makes it slower.
- If any of the nodes fail then the ring is broken and data cannot be transmitted successfully.
- It is difficult to troubleshoot the ring.
- Because all stations are wired together, to add a station you must shut down the network temporarily.
- In order for all computers to communicate with each other, all computers must be turned on.
- Total dependence upon the one cable
Star
- Expensive to install
- Extra hardware required
LAN
WAN
Advantages of Area Networks
- Easy to share devices (printers, scanners, external drives)
- Easy to share data (homework, pictures..)
- Build a complex enough one and you may get enough experience to get a new job.
- Cost of LAN Setup is low.
WAN
Disadvantages of Area Networks
- LAN
- Power - a good LAN is required to be on all the times.
- Security - each computer and device become another point of entry for undesirables.
- Upkeep - when things go wrong or the software gets updated.
- Frustration if having a problem setting up.
- A lot of times a network shares one Internet connection - if all computers running at once, can reduce speed for each.
- Area covered is limited.
- WAN
- Are expensive and generally slow
- Need a good firewall to restrict outsiders from entering and disrupting the network
- Setting up a network can be an expensive and complicated experience. The bigger the network the more expensive it is.
- Security is a real issue when many different people have the ability to use information from other computers. Protection against hackers and viruses adds more complexity and expense.
- Once set up, maintaining a network is a full-time job which requires network supervisors and technicians to be employed.
- Information may not meet local needs or interests
- Vulnerable to hackers or other outside threats