A network interface card also known as a network controller or network adapter is a circuit board card fixed on a computer motherboard that enables connection to the network. Without a network card, either ethernet or wireless, a computer cannot connect to the internet. It acts as a physical connection (link/interface) between the computer & a properly terminated transmission cable.
The network interface card converts digital signal from the computer to electrical signal to be transmitted over the cable and vice versa when it reaches the destination computer. It operates at both the physical and data link layer of OSI layers. The types of network adaptors are Ethernet, Wireless, Fiber, and USB card. NIC is made up of components such as MAC address, connection port, processor, interface to the motherboard, and network drivers among others discussed in the article.
Functions of the network card (NIC)
- The NIC acts as a physical link between the computer and the LAN cable.
- It translates data from digital to an electrical signal (analog) for transmission and vice versa when it reaches its destination.
- The network adaptor uses the physical layer in the OSI model to transmit data to other respective layers. It also works at the data link layer.
- It prepares data before it is sent over to the networking media. The preparation will depend on which type of standard data will be transmitted. The most common standard is IEEE 802.3 standards.
Types of Network Interface Cards (NIC)
Types of network adapters can be categorized depending on types of transmission or connection type. Below we discuss different types of network cards available.
- Ethernet NIC: This is the most common card and most computer comes with at least one fixed on their motherboard. An Ethernet network card connects the computer using an ethernet cable terminated with an RJ45. However, if the computer doesn’t have one the user can buy a separate card that can be fixed on the expansion slots available on the computer motherboard.
- Wireless NIC: While ethernet NIC connects cabled network, wireless NIC connects to the wireless network. They have an antenna that is used to transmit and receive signals. When a wireless card is installed on the desktop they come with network drivers.
- Fiber NIC: With the adoption of fiber cable networking we have network cards that are used to connect to fiber network connectors. Most fiber optic network cards have more than one connector to support different fiber connectors.
- USB to ethernet adapter: This is a connector that has on one end a USB port and on the other an ethernet port. It can be used by modern laptops that don’t have an ethernet port to connect to the wired network. The USB side goes to the computer and the ethernet now connects to the cable.
Components of the network adaptor (NIC)
For a network card to function properly it is made up of different parts that each has its function.
- Network port connector: depending on the type of connection that is used port connects to different types of cable terminated. Network ports can be able to support different types of connectors such as RJ45, RJ22, ST, FDDI, SC, and Bionic fiber connectors.
- Interface to the computer motherboard: for the network card to communicate with the computer it requires to interface with the motherboard. There are many types of interfaces that can be used such as PCI, ISA, and PCI Express which is the latest. USB connector act as an external type of connector.
- MAC address: this is the physical address of the computer. Any computer that is connected to the network requires two types of addresses the IP address and the physical address (MAC). Each NIC card has a unique physical address to identify the computer.
- Processor and circuit board: the card processor interprets data and processes all data that passes through it.
- Router capabilities: NIC has routing capabilities to direct the signal and data to the right destination. It is used on the wireless card to route the signal to the right device.
- Network card drivers: drivers are utility software that is specific to the network card that enables the device to function. For preinstalled cards, the drivers are part of the computer programs. However, if you install a new card you will require to install its drivers for compatibility purposes.
- LED light indicator: This is a signal that indicates to the user if the connection is working or not. It should indicate green color when the network is functioning.
- Memory (ROM) is used to store information about the card such as MAC address and others details.
- Speed rating: each network adapter comes with a speed rating to indicate the speed that it can support. The speed rating starts at 10MBPS up to 25Gb. Most common ethernet cards are rated 10 to 1000MBPS.
- Antennae: this is available for the wireless network interface card. It comes with either one or two small antennae to transmit and receives signals.