|LZS, PPP Stac LZS Compression Protocol|
|Type:||PPP compression protocol.|
|Working groups:||pppext, Point-to-Point Protocol Extensions.|
LZS provides an algorithm for compressing PPP encapsulated packets.
This document describes the use of the Stac LZS data compression algorithm, with single or multiple compression histories, for compressing PPP encapsulated packets.
Starting with a sliding window compression history, similar to LZ1, Stac Electronics developed a new, enhanced compression algorithm identified as Stac LZS. The LZS algorithm is optimized to compress all file types as efficiently as possible. Even string matches as short as two octets are effectively compressed.
The Stac LZS compression algorithm supports both single compression history communication and multiple compression history communication.
A single compression history will require the minimum amount of memory to implement, but may not provide as much compression as a multiple history implementation.
Often, many streams of information are interleaved over the same link. Each virtual link will transmit data that is independent of other virtual links. Using multiple compression histories can improve the compression ratio of a communication link by associating separate compression histories with separate virtual links of communication.
Before any LZS packets may be communicated, PPP must reach the Network-Layer Protocol phase.
When the Compression Control Protocol (CCP) has reached the Opened state, and LZS is negotiated as the primary compression algorithm, exactly one Stac LZS datagram is encapsulated in the PPP Information field.
[RFC 1974] PPP Stac LZS Compression Protocol.