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Wednesday 28 August 2013

Lan Card


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Lan Card


Network interface controller

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Network interface controller
Network card.jpg
A 1990s Ethernet network interface controller card which connects to the motherboard via the now-obsolete ISA bus. This combination card features both a BNC connector (left) for use in (now obsolete) 10BASE2 networks and an 8P8C connector (right) for use in 10BASE-T networks.
Connects to Motherboard via one of:
Network via one of:
Speeds 10 Mbit/s
100 Mbit/s
1 Gbit/s
10 Gbit/s
up to 160 Gbit/s
Common manufacturers Intel
Realtek
Broadcom
3Com
A network interface controller (NIC) (also known as a network interface card, network adapter, LAN adapter and by similar terms) is a computer hardware component that connects a computer to a computer network.[1]
Early network interface controllers were commonly implemented on expansion cards that plugged into a computer bus; the low cost and ubiquity of the Ethernet standard means that most newer computers have a network interface built into the motherboard.

Purpose

The network controller implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as Ethernet, Wi-Fi or Token Ring. This provides a base for a full network protocol stack, allowing communication among small groups of computers on the same LAN and large-scale network communications through routable protocols, such as IP.
Madge 4/16 Mbit/s TokenRing ISA-16 NIC
Although other network technologies exist (e.g. token ring), Ethernet has achieved near-ubiquity since the mid-1990s.
Every network controller for an IEEE 802 network such as Ethernet, Wi-Fi, or Token Ring, and every FDDI network controller, has a unique 48-bit serial number called a MAC address, which is stored in read-only memory. Every computer on an Ethernet network must have at least one controller. Normally it is safe to assume that no two network controllers will share the same address, because controller vendors purchase blocks of addresses from the Institute of Electrical and Electronics Engineers (IEEE) and assign a unique address to each controller at the time of manufacture.[2]
The NIC allows computers to communicate over a computer network. It is both an OSI layer 1 (physical layer) and layer 2 (data link layer) device, as it provides physical access to a networking medium and, for IEEE 802 networks and FDDI, provides a low-level addressing system through the use of MAC addresses. It allows users to connect to each other either by using cables or wirelessly.

Implementation

An ATM network interface.
Whereas network controllers used to operate on expansion cards that plugged into a computer bus, the low cost and ubiquity of the Ethernet standard means that most new computers have a network interface built into the motherboard. Newer server motherboards may even have dual network interfaces built-in. The Ethernet capabilities are either integrated into the motherboard chipset or implemented via a low-cost dedicated Ethernet chip, connected through the PCI (or the newer PCI express) bus. A separate network card is not required unless additional interfaces are needed or some other type of network is used.
The NIC may use one or more of two techniques to indicate the availability of packets to transfer:
  • Polling is where the CPU examines the status of the peripheral under program control.
  • Interrupt-driven I/O is where the peripheral alerts the CPU that it is ready to transfer data.
and may use one or more of two techniques to transfer packet data:
  • Programmed input/output is where the CPU moves the data to or from the designated peripheral to memory.
  • Direct memory access is where an intelligent peripheral assumes control of the system bus to access memory directly. This removes load from the CPU but requires more logic on the card. In addition, a packet buffer on the NIC may not be required and latency can be reduced.
An Ethernet network controller typically has an 8P8C socket where the network cable is connected. Older NICs also supplied BNC, or AUI connections. A few LEDs inform the user of whether the network is active, and whether or not data transmission occurs. Ethernet network controllers typically support 10 Mbit/s Ethernet, 100 Mbit/s Ethernet, and 1000 Mbit/s Ethernet varieties. Such controllers are designated 10/100/1000 - this means they can support a notional maximum transfer rate of 10, 100 or 1000 Megabits per second.
Some products feature NIC partitioning (NPAR).[3]

Definition

The LAN Card is a 'door' to the network from a computer. Any type of network activity requires a LAN Card - the Internet, network printer, connecting computers together. Today many devices contain a network card: Televisions for their Internet apps, Blu-ray players, mobile phones, VoIP desk phones, even refrigerators. LAN Cards are hardware devices, which can be added to a computer or they can be integrated into the main hardware of the computer.

LAN Card types

LAN Card sounds like a credit card, and some LAN Cards look like credit cards.

PCMCI laptop NIC LAN Card
In this image you can see a PCMCIA card, which can be used in a laptop. There are many other ways of connecting the LAN Card to a computer. Some cards are connected via the USB port, some via the PCI port inside of the computer, and some are even embedded inside of the computer. Most laptops today have integrated LAN Cards both for wired and wireless networking.
This next image shows a PCI card, which goes inside of a PC computer. The card shows an Ethernet port, which is the spot where you plug in a network cable. The LAN Card you select often determines the protocols which are used on the network. For example, an Ethernet card will allow communication via the Ethernet protocol. A coax card would allow for a bus topology network and a new set of protocols. A fiber cable would have a different cable plugin and it would likely work with Wide Area Network protocols. The Ethernet port on a LAN Card looks like a phone jack, but it is wider and has more pins.

LAN Card PCI
The image below shows a typical Ethernet cable, or a network cable. This is the plugin, which goes into the LAN Card, or the Network interface controller (NIC).

network cable

Function

The purpose of a LAN Card is to create a physical connection to the network; to provide an open 'door', as it were. The first interface supported by a LAN Card is a physical interface of how the cable plugs into the card. This interface is well defined in technical documentation, which is why standard network cables fit most standard LAN cards. The second function of a LAN Card is to provide a data link. There is a theoretical model in computer networking called OSI - Open Systems Interconnection. This model, or a way of explaining networks, includes 7 layers. The first two layers are the physical layer and data link. Each layer of the OSI model allows for other layers to be independent. Upgrading or changing one layer does not affect others. This means that if plugins change for all LAN cards, other elements like the protocols don't have to change.
The data link function of a LAN Card provides hardware-level sending and receiving of network binary data. Zeros and ones flow from the network into the network card. The card can recognize this flow and it can even check for errors. When you turn on a computer with a LAN Card, it will have two lights, one green and one orange. The orange light will come on when the data link layer is activated. This means that the cable works, there is a network connected, and data bits are flowing. The second light, the green light, comes on once the next layer the network layer is activated (such as an IP network).

LAN Card Types

LAN Card Types can be divided into wireless and conductive (wired) from the perspective of how they connect to the network. At the same time, we can categorize the cards based on how they connect to the computer. LAN Cards can connect to the computer via PCI port, PCMCIA port, USB port, and other ports. Most computers today have LAN Cards integrated into their main board or mother board. This means that you cannot remove the card.
Most computers can have more than one LAN Card inside of them. It's typical for laptops today to have a wireless LAN Card and a wired LAN Card. You could have multiple wired LAN Cards in a computer in order to connect the computer to multiple networks or to increase the speed and capacity of connection to a single network by pooling two or more LAN Cards into a virtual connection. Another reason to have more than one LAN Card in a computer, especially a server, is to build resilience or high availability. If one LAN Card fails, or the network fails, the server will have access to external networks via the second LAN Card and the secondary network.
This is an example of an integrated LAN Card, or Ethernet card on a mother board:
integrated NIC

Summary

LAN Cards are very important today. Most devices connect to networks, primarily to the Internet network. It can be useful to recognize if a computer has a LAN Card. You may look for the Ethernet port. Sometimes you may need to replace a LAN Card. Look for an orange light to see if the card is working at a low layer. Sometimes the card works fine, but the network configuration is wrong. In this case replacing the card may not be necessary. From now on, when you use networks, you will probably think about the 'doors', the LAN Cards creating the connection for you.

Source :- http://simple.wikipedia.org,http://education-portal.com,
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Published By :-
Gayatri Solution Group
{ Jayesh Patel} (Live In :- Gujarat)

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