- PL-3
PL-3 or POS-PHY Level 3 was the name of the interface that the
Optical Internetworking Forum 'sSPI-3 Interoperability Agreement is based on. It was proposed byPMC-Sierra to theOptical Internetworking Forum and adopted in June of2000 . The name means Packet Over SONET Physical layer level 3. PL-3 was developed by PMC-Sierra in conjunction with theSATURN Development Group .Context
There are two broad categories of chip-to-chip interfaces. The first, exemplified by
PCI-Express andHyperTransport , supports reads and writes of memory addresses. The second broad category carries user packets over 1 or more channels and is exemplified by theIEEE 802.3 family ofMedia Independent Interface s and theOptical Internetworking Forum family ofSystem Packet Interface 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 thePacket over SONET andOptical 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 statusThere 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.
Trivia
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".PL-3 in the marketplace
PL-3 and
SPI-3 were highly successful interfaces with many semiconductor devices produced to it.ee also
*
System Packet Interface
*SPI-4.2 External links
* [http://www.oiforum.com/public/impagreements.html OIF Interoperability Agreements]
Wikimedia Foundation. 2010.