Compression is implemented in the hardware compression port module installed in the router. Default Compression is disabled. The command compress stac first appeared in Cisco IOS Release 10.3. The compress stac command determines the fastest compression method available on the router. PPP encapsulations support Stacker and Predictor compression algorithms, but the compression port module installed in Cisco 3600 series routers support only Stacker compression over PPP encapsulations.
Compression reduces the size of frames via lossless data compression.
PPP encapsulation supports Stacker compression algorithms. If the majority of your traffic is already compressed files, we recommend that you not use compression. If the files are already compressed, the additional processing time spent in attempting unsuccessfully to compress them again will slow system performance. This command has no arguments or keywords. This command first appeared in Cisco IOS Release 10.0.