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 variation of a physical quantity. The protocol defines the rules, syntax, semantics, and synchronization of ...
. It is the name of the
interface 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) f ...
's
SPI-3 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
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) f ...
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 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). The L in PL stands for "Layer".
Context
There are two broad categories of chip-to-chip interfaces. The first, exemplified by
PCI-Express and
HyperTransport
HyperTransport (HT), formerly known as Lightning Data Transport, is a technology for interconnection of computer Processor (computing), processors. It is a bidirectional Serial communication, serial/Parallel communication, parallel high-Bandwi ...
, 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 of 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 the Institute of Electrical and Electro ...
family of
Media Independent Interface
The media-independent interface (MII) was originally defined as a standard interface to connect a Fast Ethernet (i.e., ) medium access control (MAC) block to a PHY chip. The MII is standardized by IEEE 802.3u and connects different types of ...
s and 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) f ...
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 typical ...
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 la ...
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 SONET 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
SPI-3 were highly successful interfaces with many semiconductor devices produced to it.
See also
*
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 typical ...
*
SPI-4.2
External links
OIF Interoperability Agreements
Network protocols