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ImplementationEdit

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 the following techniques to indicate the availability of packets to transfer:

1. Polling is where the CPU examines the status of the peripheral under program control.

2. Interrupt-driven I/O is where the peripheral alerts the CPU that it is ready to transfer data.

Also, NICs may use one or more of the following techniques to transfer packet data:

1. Programmed input/output is where the CPU moves the data to or from the designated peripheral to memory.

2. Direct memory access is where an intelligent peripheral assumes control of thesystem 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 latencycan be reduced.

An Ethernet network controller typically has an 8P8C socket where the network cable is connected. Older NICs also supplied BNC, orAUI 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, and1000 Mbit/s Ethernet varieties. Such controllers are designated as “10/100/1000“, meaning that they can support a notional maximum transfer rate of 10, 100 or 1000 Mbit/s. 10 Gigabit Ethernet NICs are also available, and, as of November 2014, are beginning to be available on computer motherboards.[3][4]