2.5.1. Metaframe Format and Framing Layer Control Word
The Enhanced PCS supports programmable metaframe lengths from 5 to 8192 words. However, for stability and performance, Intel recommends you set the frame length to no less than 128 words. In simulation, use a smaller metaframe length to reduce simulation times. The payload of a metaframe could be pure data payload and a Burst/Idle control word from the MAC layer.
The framing control words include:
- Synchronization (SYNC)—for frame delineation and lane alignment (deskew)
- Scrambler State (SCRM)—to synchronize the scrambler
- Skip (SKIP)—for clock compensation in a repeater
- Diagnostic (DIAG)—provides per-lane error check and optional status message
To form a metaframe, the Enhanced PCS frame generator inserts the framing control words and encapsulates the control and data words read from the TX FIFO as the metaframe payload.