Using CSA hardware compression on Cisco 7000 series routers with RSP7000, Cisco 7200 series routers, and Cisco 7500 series routers removes the compression and decompression responsibilities from the VIP2 or the main processor installed in the router. By using the compress stac command, the router determines the fastest compression method available on the router. When using hardware compression on Cisco 7200 series routers with multiple CSAs, you can optionally specify which CSA is used by the interface to perform compression. If no CSA is specified, the router determines which CSA is used. On Cisco 7000 series routers with RSP700 and on Cisco 7500 series routers, the router uses the CSA on the same VIP2 as the interface.
Compression reduces the size of frames via lossless data compression.
HDLC encapsulations supports the Stacker compression algorithm. PPP and LAPB encapsulations support both predictor and Stacker compression algorithms. When compression is performed in software installed in the router's main processor, it might significantly affect system performance. We recommend that you disable compression if the CPU load exceeds 40 percent. To display the CPU load, use the show process cpu EXEC command.