Network Interface Cards (Nic)

A Nic (network interface card) is designed to delineate over a computer network. It allows users to join together to each other either by using cables or wirelessly if the Nic is a wireless Nic (WiFi/Wnic). Every entity on a network, a Pc, printer, router, etc., that needs to delineate with other devices must have a Nic if it is to delineate over the network. On older computers, the Nic is probably an expansion card, regularly Pci or Pci express. High operation cards can cost less that . Nic functionality is now often integrated into the motherboard chipset or implemented with a dedicated Ethernet chip on the motherboard.

A similar situation is true for laptop computers. At one time, a Pcmcia network card would be used in a laptop computer for the Nic just as the Pci card was used in desktop computer, but now, Nic functionality is often integrated with the motherboard.

Cables For Network

Ethernet is the dominant approved for cable connections for wired computer networks. An Ethernet connector looks similar to a telephone connector, only larger. This connector is called "Rj45". Ethernet cables are either a shielded or unshielded cable of four twisted pairs of 24 Awg connectors, specified at 100 ohm impedance. Maximum cable length for Catx cables is 100 meters.

Early versions of Ethernet cables were Cat3 or Cat4 (Cat being short for category). These versions were not long lived. Cat5 and Cat5e are currently the most generally used cables (bandwidth of 100 Mhz, 100 Mbps), with Cat6 (bandwidth of 250 Mhz, 1 Gbps) available and the configuration of the near-future. A Cat7 cable (bandwidth of 600 Mhz) specification is in development, and should be available in a few years.

Each Ethernet Nic has a unique serial amount called a "media access code" (Mac address) that is used to recognize the Nic and linked computer on the network. No two Nic will have the same address, because the Nic manufacturers must purchase blocks of addresses from the originate of Electrical and Electronics Engineers (Ieee).

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

On a very simple network, Nic can be used to link personal computers (Pc). If the computers are linked directly to one another, the network is a "peer-to-peer" (P2P, also called an "ad hoc") network. If computers are linked directly to one another, a "cross-over" Ethernet cable is needed (also called a "Null-Modem cable"). This cable is not "straight-through" like approved Ethernet, but crosses the send and receive connectors, so that send line from computer A connects to the receive line of computer B.

For networks of a few computers, a "hub" can be used, with all of the computers linked to the hub. Any message sent from any Pc will be seen by all of the computers, but only the computer with the strict Mac address will receive the message. P2P networks are beneficial for many purposes. File and printer sharing are the most common applications.

Networks with more than four active computers at a time will advantage from using a "network switch" instead of a hub. A network switch will direct the message to the approved destination, instead of each message packet being broadcast across the network. Computer A can send a message to computer B, while simultaneously, computer C sends a message to computer D. This increases the efficiency of the network. This is a simple form of a server network. An example of a client-server originate is a computer server where the clients launch a download or upload of files and the server reacts. The server would also often be responsible for interacting with printers and other servers on other networks, along with satellite networks (Satcom) or the Internet.

"Latency" is the delay caused by a network to delineate data. Latency causes not only slow service, but can consequent in data loss as well. Latency is regularly tested by sending a message packet that is immediately returned to the sending computer. The round-trip time is defined as the latency.

Networking operation can be optimized for either latency or throughput. Networks can use a technique known as "interrupt moderation" to growth throughput and lower Cpu utilization by queuing message packets and issuing fewer interrupts to the Cpu. A network optimized this way would favor large transfers, reducing change overhead. Cpu and network throughput benefit, but network latency would increase. The alternative is to fragment each message and pipeline the fragments through the network. Multiple paths from source to destination can allow overlapping. Latency can also be addressed with techniques such as prefetching (anticipating the need for data requests) and/or using Multiple operation threads (multithreading).

There are two indicator Leds on a typical Nic. A particular lit green Led indicates the computer is linked to the network. This is called the "link" light. The second Led is amber in color. A flashing amber Led indicates message packet collisions are occurring. Occasional collisions are normal on a busy network, but a frequently lit amber Led is an indication of problems. A speedily flashing link Led (green) is a network operation indicator, meaning that transportation is occurring. If the green link light is off, and the amber Led is blinking, then the Nic is in "power save" mode.

A wireless network interface controller (Wnic) is a Nic for connecting to a wireless network (WiFi). The approved for WiFi is Ieee 802.11. A Wnic uses an antenna to delineate with an Rf signal, most often at 2.4 Ghz. Wireless connectivity development in new 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 becoming common, especially for laptop computers.

Network Interface Cards (Nic)