Network Interface Cards (NIC)

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A NIC (network interface card) is designed to speak over a computer network. It allows users to attach to every different either by using cables or wirelessly if the NIC could be a wireless NIC (WiFi/WNIC). Each entity on a network, a PC, printer, router, etc., that desires to communicate with other devices should have a NIC if it is to speak over the network. On older computers, the NIC is most likely an growth card, typically PCI or PCI express. High performance cards will value less that $30. NIC functionality is now usually integrated into the motherboard chipset or implemented with an infatuated Ethernet chip on the motherboard.

An analogous scenario is true for laptop computers. At just the once, a PCMCIA network card would be employed in a laptop pc for the NIC just because the PCI card was utilized in desktop pc, however currently, NIC functionality is usually integrated with the motherboard.

Ethernet is that the dominant normal for cable connections for wired computer networks. An Ethernet connector looks almost like a telephone connector, solely larger. This connector is termed "RJ45". Ethernet cables are either a shielded or unshielded cable of four twisted pairs of twenty four AWG connectors, specified at a hundred ohm impedance. Maximum cable length for CATX cables is a hundred meters.

Early versions of Ethernet cables were CAT3 or CAT4 (CAT being short for category). These versions weren't long lived. CAT5 and CAT5e are currently the most commonly used cables (bandwidth of a hundred MHz, a hundred Mbps), with CAT6 (bandwidth of 250 MHz, 1 Gbps) out there and the configuration of the near-future. A CAT7 cable (bandwidth of 600 MHz) specification is in development, and ought to be obtainable in an exceedingly few years.

Every Ethernet NIC has a distinctive serial range called a "media access code" (MAC address) that's used to spot the NIC and associated laptop on the network. No two NIC will have the same address, as a result of the NIC makers should purchase blocks of addresses from the Institute of Electrical and Electronics Engineers (IEEE).

NIC cards are capable of various speeds. Speeds of up to one gigabit per second (Gbps) are now available. 2 NIC will communicate if they differ in speed ratings, but they can communicate at the rate of the slower NIC.

On a very simple network, NIC will be used to link personal computers (PC). If the computers are connected directly to at least one another, the network is a "peer-to-peer" (P2P, additionally referred to as an "circumstantial") network. If computers are connected directly to 1 another, a "cross-over" Ethernet cable is required (additionally referred to as a "Null-Modem cable"). This cable is not "straight-through" like customary Ethernet, however crosses the send and receive connectors, so that send line from pc A connects to the receive line of laptop B.

For networks of a few computers, a "hub" will be used, with all of the computers connected to the hub. Any message sent from any PC will be seen by all of the computers, however solely the computer with the correct MAC address will receive the message. P2P networks are helpful for many purposes. File and printer sharing are the foremost common applications.

Networks with more than four active computers at a time can benefit from employing a "network switch" rather than a hub. A network switch can direct the message to the acceptable destination, instead of each message packet being broadcast across the network. Laptop A will send a message to pc B, whereas simultaneously, pc C sends a message to pc D. This increases the efficiency of the network. This is a easy kind of a server network. An example of a client-server style is a computer server where the purchasers initiate a download or upload of files and therefore the server reacts. The server would also typically be accountable for interacting with printers and different servers on different networks, including satellite networks (SATCOM) or the Internet.

"Latency" is that the delay caused by a network to communicate data. Latency causes not solely slow service, however will result in information loss as well. Latency is typically tested by sending a message packet that is immediately returned to the sending computer. The round-trip time is defined as the latency.

Networking performance will be optimized for either latency or throughput. Networks will use a way known as "interrupt moderation" to increase throughput and lower CPU utilization by queuing message packets and issuing fewer interrupts to the CPU. A network optimized this method would favor large transfers, reducing transfer overhead. CPU and network throughput benefit, however network latency would increase. The alternative is to fragment every message and pipeline the fragments through the network. Multiple methods from supply to destination will permit overlapping. Latency will also be addressed with techniques like prefetching (anticipating the requirement for knowledge requests) and/or using multiple execution threads (multithreading).

There are two indicator LEDs on a typical NIC. One lit inexperienced LED indicates the pc is connected to the network. This can be called the "link" light. The second LED is amber in color. A flashing amber LED indicates message packet collisions are occurring. Occasional collisions are traditional on a busy network, but a frequently lit amber LED is a sign of problems. A quickly flashing link LED (green) could be a network activity indicator, that means that communication is occurring. If the inexperienced link lightweight is off, and also the amber LED is blinking, then the NIC is in "power save" mode.

A wireless network interface controller (WNIC) could be a NIC for connecting to a wireless network (WiFi). The quality for WiFi is IEEE 802.11. A WNIC uses an antenna to speak with an Rf signal, most typically at 2.4 GHz. Wireless connectivity development in recent years has closely paralleled wired connectivity. Like its wired cousin, a wireless card was once integrated with a PCI or PCMCIA add-on card. Now, integrated WNIC's are changing into common, especially for laptop computers.

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This article was published on 2010/12/29