Computer networking device

A full list of Computer networking devices are units that mediate data in a computer network. Computer networking devices are also called network equipment, Intermediate Systems (IS) or InterWorking Unit (IWU). Units which are the last receiver or generate data are called hosts or data terminal equipment.

List of computer networking devices

Common basic networking devices:

Gateway: device sitting at a network node for interfacing with another network that uses different protocols. Works on OSI layers 4 to 7.

Router: a specialized network device that determines the next network point to which to forward a data packet toward its destination. Unlike a gateway, it cannot interface different protocols. Works on OSI layer 3.

Bridge: a device that connects multiple network segments along the data link layer. Works on OSI layer 2.

Switch: a device that allocates traffic from one network segment to certain lines (intended destination(s)) which connect the segment to another network segment. So unlike a hub a switch splits the network traffic and sends it to different destinations rather than to all systems on the network. Works on OSI layer 2.

Hub: connects multiple Ethernet segments together making them act as a single segment. When using a hub, every attached device shares the same broadcast domain and the same collision domain. Therefore, only one computer connected to the hub is able to transmit at a time. Depending on the network topology, the hub provides a basic level 1 OSI model connection among the network objects (workstations, servers, etc). It provides bandwidth which is shared among all the objects, compared to switches, which provide a dedicated connection between individual nodes. Works on OSI layer 1.

Repeater: device to amplify or regenerate digital signals received while setting them from one part of a network into another. Works on OSI layer 1.
Some hybrid network devices:

Multilayer Switch: a switch which, in addition to switching on OSI layer 2, provides functionality at higher protocol layers.

Protocol Converter: a hardware device that converts between two different types of transmissions, such as asynchronous and synchronous transmissions.
Bridge Router(Brouter): Combine router and bridge functionality and are therefore working on OSI layers 2 and 3.

Digital media receiver: Connects a computer network to a home theatre
Hardware or software components that typically sit on the connection point of different networks, e.g. between an internal network and an external network:

Proxy: computer network service which allows clients to make indirect network connections to other network services

Firewall: a piece of hardware or software put on the network to prevent some communications forbidden by the network policy

Network Address Translator: network service provide as hardware or software that converts internal to external network addresses and vice versa
Other hardware for establishing networks or dial-up connections:

Multiplexer: device that combines several electrical signals into a single signal

Network Card: a piece of computer hardware to allow the attached computer to communicate by network

Modem: device that modulates an analog "carrier" signal (such as sound), to encode digital information, and that also demodulates such a carrier signal to decode the transmitted information, as a computer communicating with another computer over the telephone network

ISDN terminal adapter (TA): a specialized gateway for ISDN

Line Driver: a device to increase transmission distance by amplifying the signal. Base-band networks only.

Network Device Connectivity

How to Increase Internet Connection Speed

Find out from your Internet Service Provider (ISP) what Internet connection speed your paying for. Make sure the speed your paying for is the speed programmed in their network.

Test your Internet connection speed. You can do this by going to one of these speed test websites: Speakeasy.net/speedtest or Speedtest.net. Record your results.

Compare the speeds from step one and step two. If your getting the speed your paying for go no further. If your not, go to the next step.

Disable web-browser Add-ons that can slow down your Internet connection speed. Check to see if you have multiple web browser Add-ons operating with your browser. For example, if your web browser is Internet explorer, go to Tools, select Manage Add-ons, and look at what Add-ons are enabled. Disable the ones you do not want to use.

Run anti-virus, adware, spyware, and malware scans. All of these, if found on your computer, could negatively affect your Internet connection speed.

Run Disk Cleanup and Disk Defragmenter from your System Tools menu.

Download TCP Optimizer software to optimize your computers MTU (Maximum Transmission Unit) values, RWIN (Receive Window) values, and broadband related registry keys. The most popular and FREE TCP Optimizer that I found is called "SG TCP Optimizer". You can download it at CNET: http://www.download.com/SG-TCP-Optimizer/3000-2155_4-10488572.html?tag=lst-1 or at PCWORLD: http://www.pcworld.com/downloads/file/fid,68524-order,1-page,1/description.html.

Retest your Internet connection speed by going to one of these speed test websites: Speakeasy.net/speedtest or Speedtest.net. Record and compare these results with the results obtained from steps one and two.

Disadvantages of Computer Networks

Following are some of the major disadvantages of computer networks.

Security Issues: One of the major drawbacks of computer networks is the security issues involved. If a computer is a standalone, physical access becomes necessary for any kind of data theft. However, if a computer is on a network, a computer hacker can get unauthorized access by using different tools. In case of big organizations, various network security softwares are used to prevent the theft of any confidential and classified data.

Rapid Spread of Computer Viruses: If any computer system in a network gets affected by computer virus, there is a possible threat of other systems getting affected too. Viruses get spread on a network easily because of the interconnectivity of workstations. Such spread can be dangerous if the computers have important database which can get corrupted by the virus.

Expensive Set Up: The initial set up cost of a computer network can be high depending on the number of computers to be connected. Costly devices like routers, switches, hubs, etc., can add up to the bills of a person trying to install a computer network. He will also have to buy NICs (Network Interface Cards) for each of the workstations, in case they are not inbuilt.

Dependency on the Main File Server: In case the main File Server of a computer network breaks down, the system becomes useless. In case of big networks, the File Server should be a powerful computer, which often makes it expensive.

Computer Networking Advantages

Following are some of the advantages of computer networks.

File Sharing: The major advantage of a computer network is that is allows file sharing and remote file access. A person sitting at one workstation of a network can easily see the files present on the other workstation, provided he is authorized to do so. It saves the time which is wasted in copying a file from one system to another, by using a storage device. In addition to that, many people can access or update the information stored in a database, making it up-to-date and accurate.

Resource Sharing: Resource sharing is also an important benefit of a computer network. For example, if there are four people in a family, each having their own computer, they will require four modems (for the Internet connection) and four printers, if they want to use the resources at the same time. A computer network, on the other hand, provides a cheaper alternative by the provision of resource sharing. In this way, all the four computers can be interconnected, using a network, and just one modem and printer can efficiently provide the services to all four members. The facility of shared folders can also be availed by family members.

Increased Storage Capacity: As there is more than one computer on a network which can easily share files, the issue of storage capacity gets resolved to a great extent. A standalone computer might fall short of storage memory, but when many computers are on a network, memory of different computers can be used in such case. One can also design a storage server on the network in order to have a huge storage capacity.

Increased Cost Efficiency: There are many softwares available in the market which are costly and take time for installation. Computer networks resolve this issue as the software can be stored or installed on a system or a server and can be used by the different workstations.

Local Area Networks (LAN)

A single building or campus of few kilometers in size, LAN acts as privately-owned networks. LANs are limited to a single building or group of buildings. By using telephone lines and radio waves, one LAN can be attached to other LANs over any distance. A system of multiple connections of LANs is called a wide-area network (WAN).

Most LANs are used to connect workstations and personal computers. In a LAN, each host means individual computer has its own CPU with which it runs programs but it also able to access data and devices anywhere on the LAN. This means that many users can share data information and expensive devices like laser printers. By sending e-mail or engaging in chat session users can also make use of LAN to interact with each other.

In today's world, Local Area Networks become fundamental part of communication. LAN applications are used in hospitals, educational facilities businesses, stock exchanges and warehouses. Local area network provides reader-friendly, comprehensive coverage of LAN technologies to be used in real-world applications.

LANs are typically identified by the following properties
1)Multiple systems connected to shared medium
2)High total bandwidth
3)Low delay
4)Low error rate
5)Broadcast/Multicast capability
6)Limited geography 1-2 km
7)Limited number of stations
8)Peer relationship between stations
9)Confined to private property

LANs are distinguished from other network by three characteristics:
1)Their size
2)Their transmission technology and
3)Their topology.

LANs are limited in size which means that the worst case transmission time is restricted and known in advance. Knowing this limitation makes it possible to make use of certain kinds of designs that would not otherwise be possible. It also simplifies network management.

LANs often make use of a transmission technology including of a single cable to which all the machines are connected like the telephone company party lines used in rural areas. Traditionally LANs operates at speeds of 10 to 100 Mbps with low delay and make very few errors. Newer LANs are working at speed of up to 100 megabits/sec.

Various topologies of LANs are:
1) Bus Topology:
In a bus or linear cable network, at any instant one machine is allowed to transmit data or information. All other machines are needed to desist from sending. When two or more machines want to transmit simultaneously an arbitration mechanism is used to resolve conflicts. The arbitration mechanism used may be centralized or distributed. IEEE 802.3 known as Ethernet is a bus dependent broadcast network with decentralized control working at 10 or 100Mbps. Computers on an Ethernet can deliver data whenever they want to if two or more packets collide with each other then each computer just wait a random amount of time and tries again later.

2) Ring Topology:
A second type of topology used in broadcast system is the ring topology. In a ring topology, each bit circulates around on its own not waiting for the remaining packet to which it belongs. Each bit circulates the entire ring in the time. It uses to deliver a few bits usually before the complete packet has been delivered. Like all other broadcast system, some limitation is required for arbitrating simultaneously accesses to the ring. IEEE 802.5 known as token ring is a popular ring based LAN working at 4 and 16 Mbps.

3) Star topology:
In Star topology all devices are attached to a central hub. To install and manage Star networks are relatively easy but bottlenecks can occur because all data must pass through the hub.

4) Tree topology:
A tree topology is a combination of linear bus and star topologies. It includes groups of star-configured workstations attached to a linear bus backbone cable.

Design considerations :

1) Cabling medium :
The most costless cable is Category 5 twisted-pair cable. This cable operates with standard Ethernet at a speed of 10 Million bits per second or 10 Mbps and "fast" Ethernet works at a speed 100 Mbps and is able to speeds up to 150 Mbps with existing technology. This cable is used in most LAN designs. Fiber-optic cable delivers more data but its materials and installation are much more expensive. In building proper installation of fiber-optic cable is very difficult to achieve because the cable should not be bent during installation.

2) Wiring plan
In the building the location of wiring cabinets/closets is based on distances between computers. The maximum distance should be 10 meters between a computer and a network wiring cabinet/closet. In refrigerator-sized cabinet, cables come together. Network transmission equipments are collected can be enclosed with doors and stand in a large room or it can be located as an open rack in a small room or closet. Wiring cabinets/closets can be attached with twisted-pair cable but fiber-optic cable provides higher speed.

3) Number of network connections (plug-in points) :
Every computer requires a network connection and each connection is consists of
(1) A plug-in point in the wall of the room
(2) Wiring from this point to the wiring cabinet/closet.
While deciding for network connections short and long term technology aims need to be considered

LAN Hardware
Ethernet and Token Ring are common types of LAN hardware. Ethernet is easily designed and consists of data transfer devices which are less expensive than similar Token Ring devices. Ethernet and Token Ring’s performance are same in most situations. While it is possible to connect Ethernet and Token Ring networks in the same location, it adds to cost and complexity. It is best to maintain the data communication infrastructure’s configuration as simple as possible. Asynchronous Transfer Mode is another standard for data communication. It is more expensive than Ethernet or Token Ring but offers higher speeds and will eventually offer better integration of computer-data, digitized voice (telephone), and video.