The loss of multi-channel alignment (MCA) in the XAUI PCS IP can be caused by two types of factors:
- Any condition that can cause a burst of invalid 8b10b characters to the PCS/SERDES QUAD :
- disturbing the SERDES inputs by physically breaking the line
- stopping the reference clock to the PCS/SERDES QUAD
- Corrupting data (invalid 8b10b characters).
- A condition that can prevent the /A/ channel alignment character (K28.3) from simultaneously being received on all four lanes for 4 consecutive times. This condition causes the MCA logic in the XAU PCS IP to lose alignment as shown in the IEEE 802.3ae specification PCS deskew State diagram.