Guide to network cards

This guide is aimed at an audience with some experience in computer science because it contains enough specific terminologies. The network card is a piece of hardware needed to connect the ” machine ” that is installed (PC, Printer, Switch, Router, etc. ..) with a network, whether local or global.

This board, which then acts as an interface between the device and the computer network, has the function of sending, check and receive data. Another work of the board is to prepare the data to be sent and rework those incoming working, then, as a translator between the network and our apparatus.

This operation is performed by the transceiver, a member of the board, which is responsible for transforming the output data from parallel to serial and those entering from parallel to serial. This process is necessary because the data cables can only travel to 1bit (electrical signal when it comes to metal cables, light signal when using the optical fiber) while the computer apparatus to carry data using the bus can be 8 ( older), 16, 32 and 64 bit (the latest).

A further task of the board is to communicate to the network its own IP address, released by the providers, in order to be reached by other machines on the network. But, because the card’s mountain all the same components, as does the provider make out a card to another? This is made possible thanks to the MAC addresses, defined by the IEEE (Institute of Electrical and Electronic Engineer) that assigns to various builder’s certain range of addresses, making each chip unique and unmistakable.

From a physical point of view, the network adapter is a printed circuit on which are welded a number of electronic components, or that presents a ” port ” for connection of the cable or an antenna (in the case of technology radio waves) and the metal contacts, called pin to be inserted in the PCI slot of the device information. Some models also feature LEDs that indicate the status of the card and the possible transmission of data. The network adapter, also known by the names NIC (Network Interface Controller / Card) and LAN (Local Area Network), can be built according to different technologies. The best known are Ethernet, Wi-Fi and Bluetooth but there are others such as token ring or token bus. While the Ethernet card using the cable as a transmission medium for data, the other two using a radio wave technology, then wireless.

1.) The card uses Ethernet as a communication cable (with 4 twisted pair, shielded and enclosed by a protective rubber) with RJ45 jacks. The three most common standards correspond to the three most common data flows: 10Base-T, which allows a data stream of 10 Mbit/s and uses only 4 of the 8-wire cable; 100Base-T, with a maximum data rate of 100 Mbit/s and even that only uses 4 wires; 1000Base-T, with which you can reach speeds of 1000 Mbit/s but uses all 8 wires. There is also a standard that uses the optical fiber as a communication medium.

2.) The board Wi-Fi (Wireless – Fidelity), also known as IEEE 802.11b, is a wireless technology (wireless) that uses radio waves as a medium to transmit data. Thanks to this system it is possible to connect different computing devices to each other without the need to realize networks physically wired. The adapter serves as a terminal for access to the Internet you need an access point (AP), a device that provides local coverage with a radius of up to 100m depending on the power. IEEE 802.11b operates in a range from 2,400 to 2,483.5 MHz but there is another standard, IEEE 802.11a, who works on two bands that fall in the neighborhood of 5 GHz, and so called Wi-Fi5.

The two ranges are: 5,150 – 5,350 GHz and 5,725 – 5,825 GHz. As for the Wi-Fi standard, there are 13 channels available to send the signal Wi-Fi but, in the same area, you can use only three channels 1, 6 and 13. So if we are in area several AP, these have to work on different channels. This is explained by the interference of electromagnetic waves, to which the radio waves belong.

We can simplify the concept by saying that each channel causes interference with adjacent channels 4 thus forcing us to use only the three above-mentioned channels. This does not mean that the other channels are not feasible, we can use them freely if there is no other nearby APs. There are several classes of Wi-Fi cards and the most common are the class ” b ” to 11 Mbit/s, the ” g ” to 54 Mbit/s and the ” n ” at 450 Mbit/s.

3.) The Bluetooth adapter is also based on a technology to radio waves but is not compatible with the Wi-Fi. The latter is designed to provide high transmission speed and a larger radius while the Bluetooth system is designed to operate at low power, short-range. This standard allows the connection of many devices provided that, as already mentioned, are located nearby. The Bluetooth system works around the 2.4 GHz frequency band and to reduce the interference band has been divided into 79 channels and provides to switch the various channels 1,600 times per second (frequency hopping). Using the Bluetooth system can create local networks that are called piconet. Each device is able to simultaneously manage communication with other devices through a communication 7 of type ” master-slave ” limiting, the communication with the server to a device at a time.

The Bluetooth communication can only occur if the two devices are synchronized and this is possible thanks to the clock (CLK). Each device defines 3 clock values: a ” native clock ” (CLKN) that controls the timing; the ” clock piconet ” that is the clock network and coincides with the CLKN the master device; the ” clock estimated ” (CLKE) that is used by the master when it comes into contact with a new slave, before the two devices are synchronized.

There are several versions of Bluetooth. The versions 1.1 and 1.2 work at a speed of 723.1 Kbit/s while the 2.0 version reaches speeds of 3 Mbit/s. Versions of the latest generation, the 3.0 and 4.0, make it possible to transmit large amounts of data because we have developed a technology that, when required by the abundance of data, also takes advantage of the free Wi-Fi. Version 4.0, compared to 3.0, lowers the levels of consumption of the devices.