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.
Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs). At low transmission rates data can also be transferred via an electrical interface. The method was developed to replace the plesiochronous digital hierarchy (PDH) system for transporting large amounts of telephone calls and data traffic over the same fiber without the problems of synchronization.
In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer; The layer most closely associated with the physical connection between devices. This layer may be implemented by a PHY chip.
In telecommunication and data transmission, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels.
The Serial Peripheral Interface (SPI) is a synchronous serial communication interface specification used for short-distance communication, primarily in embedded systems. The interface was developed by Motorola in the mid-1980s and has become a de facto standard. Typical applications include Secure Digital cards and liquid crystal displays.
The System Management Bus is a single-ended simple two-wire bus for the purpose of lightweight communication. Most commonly it is found in computer motherboards for communication with the power source for ON/OFF instructions.
Packet over SONET/SDH, abbreviated POS, is a communications protocol for transmitting packets in the form of the Point to Point Protocol (PPP) over SDH or SONET, which are both standard protocols for communicating digital information using lasers or light emitting diodes (LEDs) over optical fibre at high line rates. POS is defined by RFC 2615 as PPP over SONET/SDH. PPP is the Point to Point Protocol that was designed as a standard method of communicating over point-to-point links. Since SONET/SDH uses point-to-point circuits, PPP is well suited for use over these links. Scrambling is performed during insertion of the PPP packets into the SONET/SDH frame to solve various security attacks including denial-of-service attacks and the imitation of SONET/SDH alarms. This modification was justified as cost-effective because the scrambling algorithm was already used by the standard used to transport ATM cells over SONET/SDH. However, scrambling can optionally be disabled to allow a node to be compatible with another node that uses the now obsoleted RFC 1619 version of Packet over SONET/SDH which lacks the scrambler.
Spatial Reuse Protocol is a networking protocol developed by Cisco. It is a MAC-layer protocol for ring-based packet internetworking that is commonly used in optical fiber ring networks. Ideas from the protocol are reflected in parts of the IEEE 802.17 Resilient Packet Ring (RPR) standard.
The Optical Internetworking Forum (OIF) is a prominent non-profit consortium that was founded in 1998. It promotes the development and deployment of interoperable computer networking products and services through implementation agreements (IAs) for optical networking products and component technologies including SerDes devices.
A passive optical network (PON) is a fiber-optic telecommunications technology for delivering broadband network access to end-customers. Its architecture implements a point-to-multipoint topology in which a single optical fiber serves multiple endpoints by using unpowered (passive) fiber optic splitters to divide the fiber bandwidth among the endpoints. Passive optical networks are often referred to as the last mile between an Internet service provider (ISP) and its customers.
The System Packet Interface (SPI) family of Interoperability Agreements from the Optical Internetworking Forum specify chip-to-chip, channelized, packet interfaces commonly used in synchronous optical networking and Ethernet applications. A typical application of such a packet level interface is between a framer or a MAC and a network processor. Another application of this interface might be between a packet processor ASIC and a traffic manager device.
SPI-4.2 is a version of the System Packet Interface published by the Optical Internetworking Forum. It was designed to be used in systems that support OC-192 SONET interfaces and is sometimes used in 10 Gigabit Ethernet based systems.
PL-4 or POS-PHY Level 4 was the name of the interface that the interface SPI-4.2 is based on. It was proposed by PMC-Sierra to the Optical Internetworking Forum. The name means Packet Over SONET Physical layer level 4. PL-4 was developed by PMC-Sierra in conjunction with the Saturn Development Group.
The SATURN Development Group was an important industry forum that enabled the specification of chip-to-chip interfaces for the communications industry. It was co-founded in 1992 by PMC-Sierra and Sun Microsystems. Several significant specifications were completed through its actions including PL-2, PL-3, and PL-4. Many important semiconductor devices were developed to these specifications. SATURN was also influential in the specification of the ATM Forum's physical layer "UTOPIA" standards.
SPI-3 or System Packet Interface Level 3 is the name of a chip-to-chip, channelized, packet interface widely used in high-speed communications devices. It was proposed by PMC-Sierra based on their PL-3 interface to the Optical Internetworking Forum and adopted in June 2000. PL-3 was developed by PMC-Sierra in conjunction with the SATURN Development Group.
SerDes Framer Interface is a standard for telecommunications abbreviated as SFI. Variants include:
TFI-5 in computer networking is a standardized TDM Fabric to Framer Interface by the Optical Internetworking Forum (OIF) that allow both framer components and switch components from multiple vendors to inter-operate facilitating the development of add/drop multiplexers, TDM cross connect and grooming switches. The TFI-5 standard includes link integrity monitoring, connection management and mapping mechanisms for both SONET/SDH and non-SONET/SDH clients such as Ethernet and Fibre Channel.
UniPro is a high-speed interface technology for interconnecting integrated circuits in mobile and mobile-influenced electronics. The various versions of the UniPro protocol are created within the MIPI Alliance, an organization that defines specifications targeting mobile and mobile-influenced applications.
In wired computer networking, including the Internet, a hop occurs when a packet is passed from one network segment to the next. Data packets pass through routers as they travel between source and destination. The hop count refers to the number of network devices through which data passes from source to destination.
The Common Electrical I/O (CEI) refers to a series of influential Interoperability Agreements (IAs) that have been published by the Optical Internetworking Forum (OIF). CEI defines the electrical and jitter requirements for 3.125, 6, 11, 25-28, and 56 Gbit/s electrical interfaces.