Network Interface Card

Why NIC

In the early days of computing, individual computers

operated as stand-alone systems. In order to transfer

files between computers, you had to use a portable

storage medium such as a floppy disk.

However, in modern day computers, connecting to a

network is essential.

A computer uses a network interface card (NIC) to

become part of a network.

Network Interface Card

Also known as a Network Adapter.

Integrated circuit board that plugs into the internal circuitry of the computer.

Allows the members of a local-area network to communicate with each other.

NIC is the physical interface from the computer or peripheral to the medium.

The Medium may be physical cable, such as twisted pair wiring, coaxial cable, fiber optic or even wireless.

Network Cards Convert Data from Parallel to Serial, and vice versa

Most computers use parallel data lines internally to send data between the CPU and the adapter cards. This is called a Bus.

Most networking media transmit data in a single

line, called serial transmission.

The NIC translates parallel into serial for outgoing

messages and serial into parallel for incoming

messages.

LAN Card

The LAN (Local Area Network) 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, and so on.

Today many devices contain a network card, including televisions for their Internet apps, Blu-ray players, mobile phones, VoIP, desk phones, and even refrigerators.

LAN Card Types

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.

Ethernet port, which is the spot where you plug in a

network cable. The LAN card you select often

determines the protocols that are used on the network.

Functions of LAN Card

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 through which the

cable plugs into the card.

The second function of LAN card is to provide a

data link.

IP Address

An Internet Protocol address (IP address) is a numerical label assigned to

each device (e.g., computer, printer) participating in a computer

network that uses theInternet Protocol for communication.

Explicit address

It is an identifier for a computer or a device on a TCP\IP network

Network using TCP\IP protocol routes message based on IP address of the

destination

Its role can be categorized as

Name-indicating what we seek

Address-indicating where it is

Route-indicating how to get it

IP Address is software configurable.

IP currently uses 32 bits split into four sections separated

by dots.

i.e. 165.255.110.133 – These are decimal values.

Only used in certain network protocols such as TCP/IP

An IP address serves two principal functions: host

or network interface identification and

location addressing.

The MAC Address

NICs have a unique identifier, called a Media Access

Control (MAC) address.

It is programmed into a ROM chip on the NIC.

It’s a 48-bit number, written as six two-digit hexadecimal

numbers separated by colons.

The first part identifies the manufacturer.

The second part is unique to each NIC.

Ethernet Connection

The most widely used network connection for

personal computers is an Ethernet connection.

Since Ethernet is so widely used, most modern

computers have a NIC built into the motherboard.

An Ethernet connection uses a standard interface

known as a RJ45 connector. RJ stands for

registered jack.

The Basic Ethernet Frame Format

It contains the following seven fields :

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Preamble (PRE)—Consists of 7 bytes and is an alternating pattern of ones and zeros that tells the receiving stations that a frame is coming.

Start-of-frame delimiter (SOF)—Consists of 1 byte.

Destination address (DA)—Consists of 6 bytes and identifies which station should receive the frame.

Source addresses (SA)—Consists of 6 bytes and it identifies the sending station.

Length/Type—Consists of 4 bytes and indicates the number of MAC-client data bytes.

Data—Is a sequence of 1500 bytes maximum.

Frame check sequence (FCS)—Consists of 4 bytes and this sequence contains a 32-bit cyclic redundancy check (CRC).

Basic MAC Data Frame Format

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Transmission order, left to right, bit

serial.

D

Configuring a Network Interface Card

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This involves three settings:

Interrupt Request line (IRQ)

Base Input/Output (I/O) port

Base memory address

In older computers, the user needed to supply the

IRQ and base I/O port. Currently Plug and Play

operating systems have automated this task and

default values are normally assigned.