A network processor is an integrated circuit which has a feature set specifically targeted at the networking application domain.
Network processors are typically software programmable devices and would have generic characteristics similar to general purpose central processing units that are commonly used in many different types of equipment and products.
In modern telecommunications networks, information (voice, video, data) is transferred as packet data (termed packet switching) which is in contrast to older telecommunications networks that carried information as analog signals such as in the public switched telephone network (PSTN) or analog TV/Radio networks. The processing of these packets has resulted in the creation of integrated circuits (IC) that are optimised to deal with this form of packet data. Network processors have specific features or architectures that are provided to enhance and optimise packet processing within these networks.
Network processors have evolved into ICs with specific functions. This evolution has resulted in more complex and more flexible ICs being created. The newer circuits are programmable and thus allow a single hardware IC design to undertake a number of different functions, where the appropriate software is installed.
Network processors are used in the manufacture of many different types of network equipment such as:
Reconfigurable Match-Tables [1] [2] were introduced in 2013 to allow switches to operate at high speeds while maintaining flexibility when it comes to the network protocols running on them, or the processing to does to them. P4 [3] is used to program the chips. The company Barefoot Networks was based around these processors and was later purchased by Intel in 2019.
An RMT pipeline relies on three main stages; the programmable parser, [2] the Match-Action tables and the programmable deparser. The parser reads the packet in chunks and processes these chunks to find out which protocols are used in the packet (Ethernet, VLAN, IPv4...) and extracts certain fields from the packet into the Packet Header Vector (PHV). Certain fields in the PHV may be reserved for special uses such as present headers or total packet length. The protocols are typically programmable, and so are the fields to extract. The Match-Action tables are a series of units that read an input PHV, match certain fields in it using a crossbar and CAM memory, the result is a wide instruction that operates on one or more fields of the PHV and data to support this instruction. The output PHV is then sent to the next MA stage or to the deparser. The deparser takes in the PHV as well as the original packet and it's metadata (to fill in missing bits that weren't extracted into the PHV) and then outputs the modified packet as chunks. It's typically programmable as with the parser and may reuse some of the configuration files.
FlexNIC [4] attempts to apply this model to Network Interface Controllers allowing servers to send and receive packets at high speeds while maintaining protocol flexibility and without increasing the CPU overhead.
In the generic role as a packet processor, a number of optimised features or functions are typically present in a network processor, which include:
In order to deal with high data-rates, several architectural paradigms are commonly used:
Additionally, traffic management, which is a critical element in L2-L3 network processing and used to be executed by a variety of co-processors, has become an integral part of the network processor architecture, and a substantial part of its silicon area ("real estate") is devoted to the integrated traffic manager. [5] Modern network processors are also equipped with low-latency high-throughput on-chip interconnection networks optimized for the exchange of small messages among cores (few data words). Such networks can be used as an alternative facility for the efficient inter-core communication aside of the standard use of shared memory. [6]
Using the generic function of the network processor, a software program implements an application that the network processor executes, resulting in the piece of physical equipment performing a task or providing a service. Some of the applications types typically implemented as software running on network processors are: [7]
The protocol stack or network stack is an implementation of a computer networking protocol suite or protocol family. Some of these terms are used interchangeably but strictly speaking, the suite is the definition of the communication protocols, and the stack is the software implementation of them.
Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network, or a cloud computing service, particularly the performance seen by the users of the network. To quantitatively measure quality of service, several related aspects of the network service are often considered, such as packet loss, bit rate, throughput, transmission delay, availability, jitter, etc.
A router is a computer and networking device that forwards data packets between computer networks, including internetworks such as the global Internet.
In telecommunications and computer networking, a network packet is a formatted unit of data carried by a packet-switched network. A packet consists of control information and user data; the latter is also known as the payload. Control information provides data for delivering the payload. Typically, control information is found in packet headers and trailers.
SCADA is a control system architecture comprising computers, networked data communications and graphical user interfaces for high-level supervision of machines and processes. It also covers sensors and other devices, such as programmable logic controllers, which interface with process plant or machinery.
Systems Network Architecture (SNA) is IBM's proprietary networking architecture, created in 1974. It is a complete protocol stack for interconnecting computers and their resources. SNA describes formats and protocols but, in itself, is not a piece of software. The implementation of SNA takes the form of various communications packages, most notably Virtual Telecommunications Access Method (VTAM), the mainframe software package for SNA communications.
A multilayer switch (MLS) is a computer networking device that switches on OSI layer 2 like an ordinary network switch and provides extra functions on higher OSI layers. The MLS was invented by engineers at Digital Equipment Corporation.
A network interface controller is a computer hardware component that connects a computer to a computer network.
DMX512 is a standard for digital communication networks that are commonly used to control lighting and effects. It was originally intended as a standardized method for controlling stage lighting dimmers, which, prior to DMX512, had employed various incompatible proprietary protocols. It quickly became the primary method for linking controllers to dimmers and special effects devices such as fog machines and intelligent lights.
TCP offload engine (TOE) is a technology used in some network interface cards (NIC) 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, where processing overhead of the network stack becomes significant. TOEs are often used as a way to reduce the overhead associated with Internet Protocol (IP) storage protocols such as iSCSI and Network File System (NFS).
Networking hardware, also known as network equipment or computer networking devices, are electronic devices that are required for communication and interaction between devices on a computer network. Specifically, they mediate data transmission in a computer network. Units which are the last receiver or generate data are called hosts, end systems or data terminal equipment.
A computer network is a set of computers sharing resources located on or provided by network nodes. Computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies.
A network socket is a software structure within a network node of a computer network that serves as an endpoint for sending and receiving data across the network. The structure and properties of a socket are defined by an application programming interface (API) for the networking architecture. Sockets are created only during the lifetime of a process of an application running in the node.
DeviceNet is a network protocol used in the automation industry to interconnect control devices for data exchange. It utilizes the Common Industrial Protocol over a Controller Area Network media layer and defines an application layer to cover a range of device profiles. Typical applications include information exchange, safety devices, and large I/O control networks.
OpenFlow is a communications protocol that gives access to the forwarding plane of a network switch or router over the network.
A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any variation of a physical quantity. The protocol defines the rules, syntax, semantics, and synchronization of communication and possible error recovery methods. Protocols may be implemented by hardware, software, or a combination of both.
In digital communications networks, packet processing refers to the wide variety of algorithms that are applied to a packet of data or information as it moves through the various network elements of a communications network. With the increased performance of network interfaces, there is a corresponding need for faster packet processing.
Software-defined networking (SDN) is an approach to network management that enables dynamic and programmatically efficient network configuration to improve network performance and monitoring in a manner more akin to cloud computing than to traditional network management. SDN is meant to improve the static architecture of traditional networks and may be employed to centralize network intelligence in one network component by disassociating the forwarding process of network packets from the routing process. The control plane consists of one or more controllers, which are considered the brains of the SDN network, where the whole intelligence is incorporated. However, centralization has certain drawbacks related to security, scalability and elasticity.
P4 is a programming language for controlling packet forwarding planes in networking devices, such as routers and switches. In contrast to a general purpose language such as C or Python, P4 is a domain-specific language with a number of constructs optimized for network data forwarding. P4 is distributed as open-source, permissively licensed code, and is maintained by the P4 Project, a not-for-profit organization hosted by the Open Networking Foundation.
Deterministic Networking (DetNet) is an effort by the IETF DetNet Working Group to study implementation of deterministic data paths for real-time applications with extremely low data loss rates, packet delay variation (jitter), and bounded latency, such as audio and video streaming, industrial automation, and vehicle control.
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