Желілік интерфейс контроллері

Hardware component that connects a computer to a network

A network interface controller (NIC, also known as a network interface card,) is a computer hardware component that connects a computer to a computer network. 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, or is contained into a USB connected dongle. Modern network interface controllers offer advanced features such as interrupt and DMA interfaces to the host processors, support for multiple receive and transmit queues, partitioning into multiple logical interfaces, and on controller network traffic processing such as the TCP offload engine.

The network controller implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as Ethernet or Wi Fi. This provides a base for a full network protocol stack, allowing communication among computers on the same local area network (LAN) and large scale network communications through routable protocols, such as Internet Protocol (IP). The NIC allows computers to communicate over a computer network, either by using cables or wirelessly. The NIC is both a physical layer and data link layer device, as it provides physical access to a networking medium and, for IEEE 802 and similar networks, provides a low level addressing system through the use of MAC addresses that are uniquely assigned to network interfaces.

Multiqueue NICs provide multiple transmit and receive queues, allowing packets received by the NIC to be assigned to one of its receive queues. The NIC may distribute incoming traffic between the receive queues using a hash function. Each receive queue is assigned to a separate interrupt; by routing each of those interrupts to different CPUs or CPU cores, processing of the interrupt requests triggered by the network traffic received by a single NIC can be distributed improving performance. The hardware based distribution of the interrupts, described above, is referred to as receive side scaling (RSS). Purely software implementations also exist, such as the receive packet steering (RPS), receive flow steering (RFS), Further performance improvements can be achieved by routing the interrupt requests to the CPUs or cores executing the applications that are the ultimate destinations for network packets that generated the interrupts. This technique improves locality of reference and results in higher overall performance, reduced latency and better hardware utilization because of the higher utilization of CPU caches and fewer required context switches. With multi queue NICs, additional performance improvements can be achieved by distributing outgoing traffic among different transmit queues. By assigning different transmit queues to different CPUs or CPU cores, internal operating system contentions can be avoided. This approach is usually referred to as transmit packet steering (XPS). Some NICs provide a TCP offload engine to offload processing of the entire TCP/IP stack to the network controller. It is primarily used with high speed network interfaces, such as Gigabit Ethernet and 10 Gigabit Ethernet, for which the processing overhead of the network stack becomes significant. Some NICs offer integrated field programmable gate arrays (FPGAs) for user programmable processing of network traffic before it reaches the host computer, allowing for significantly reduced latencies in time sensitive workloads. Moreover, some NICs offer complete low latency TCP/IP stacks running on integrated FPGAs in combination with userspace libraries that intercept networking operations usually performed by the operating system kernel; Solarflare's open source OpenOnload network stack that runs on Linux is an example. This kind of functionality is usually referred to as user level networking.