PL-3
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PL-3 or POS-PHY Level 3 was the name of the interface that the interface SPI-3 is based on. It was proposed by PMC-Sierra to the Optical Internetworking Forum and adopted in June of 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.
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.
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.
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 and SPI-3 were highly successful interfaces with many semiconductor devices produced to it.
