PL-3 or POS-PHY Level 3 is a

network protocol A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax, semantics and synchroniza ...

. It is the name of the

interface Interface or interfacing may refer to: Academic journals * ''Interface'' (journal), by the Electrochemical Society * ''Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics'' * '' Inte ...

that the

Optical Internetworking Forum 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) fo ...

SPI-3 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 Foru ...

Interoperability Agreement is based on. It was proposed by

PMC-Sierra PMC-Sierra was a global fabless semiconductor company with offices worldwide that developed and sold semiconductor devices into the storage, communications, optical networking, printing, and embedded computing marketplaces. On January 15, 2016, ...

to the

and adopted in June 2000. The name means Packet Over SONET Physical layer level 3. PL-3 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 specificati ...

. The name is an acronym of an acronym of an acronym as the P in PL stands for "POS-PHY" and the S in POS-PHY stands for "SONET" (

Synchronous Optical Network 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 ...

). The L in PL stands for "Layer".

Context

There are two broad categories of chip-to-chip interfaces. The first, exemplified by

PCI-Express PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe or PCI-e, is a high-speed serial computer expansion bus standard, designed to replace the older PCI, PCI-X and AGP bus standards. It is the common mot ...

and

HyperTransport HyperTransport (HT), formerly known as Lightning Data Transport, is a technology for interconnection of computer processors. It is a bidirectional serial/parallel high-bandwidth, low- latency point-to-point link that was introduced on April 2 ...

, supports reads and writes of memory addresses. The second broad category carries user packets over 1 or more channels and is exemplified by the

IEEE 802.3 IEEE 802.3 is a working group and a collection standards defining the physical layer and data link layer's media access control (MAC) of wired Ethernet. The standards are produced by the working group of Institute of Electrical and Electronics Eng ...

family of

Media Independent Interface The media-independent interface (MII) was originally defined as a standard interface to connect a Fast Ethernet (i.e., ) media access control (MAC) block to a PHY chip. The MII is standardized by IEEE 802.3u and connects different types of PHYs ...

s and the

family of

System Packet Interface 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 typic ...

s. Of these last two, the family of System Packet Interfaces is optimized to carry user packets from many channels. The family of System Packet Interfaces is the most important packet-oriented, chip-to-chip interface family used between devices in the

Packet over SONET 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 lase ...

and Optical Transport Network, which are the principal protocols used to carry the internet between cities.

Applications

It was designed to be used in systems that support

OC-48 Optical Carrier transmission rates are a standardized set of specifications of transmission bandwidth for digital signals that can be carried on Synchronous Optical Networking (SONET) fiber optic networks. Transmission rates are defined by rate of t ...

SONET 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 diode ...

interfaces . A typical application of PL-3 (SPI-3) is to connect a framer device to a network processor. It has been widely adopted by the high speed networking marketplace.

Technical details

The interface consists of (per direction): * 32 TTL signals for the data path * 8 TTL signals for control * one TTL signal for clock * 8 TTL signals for optional additional multi-channel status There are several clocking options. The interface operates around 100 MHz. Implementations of SPI-3 (PL-3) have been produced which allow somewhat higher clock rates. This is important when overhead bytes are added to incoming packets.

PL-3 in the marketplace

PL-3 and

were highly successful interfaces with many semiconductor devices produced to it.

External links

OIF Interoperability Agreements
Network protocols

Context

Applications

Technical details

PL-3 in the marketplace

See also

External links