10.3
Optimizing Traffic Flow with Data Compression
10.3.3 Payload compression
Payload compression (also known as per-virtual-circuit compression) compresses only the data portion of the data stream. The header is left intact.

When designing an internetwork, the customer cannot assume that an application will go over point-to-point lines. If link compression is used, the header may not be readable at a particular hop, however, the customer can use payload compression instead.

When using payload compression, the header is left unchanged and packets can be switched through a WAN packet network. Payload compression is appropriate for virtual network services such as X.25, Switched Multimegabit Data Service (SMDS), Frame Relay, and ATM. It uses the STAC compression method discussed previously.