Data Link Layer Services

The Data Link Layer is responsible for reliably exchanging information with its counterpart on the opposite side of the Link.
Initialization and power management services:

• Accept power state Requests from the Transaction Layer and convey to the Physical Layer
• Convey active/reset/disconnected/power managed state to the Transaction Layer

Data protection, error checking, and retry services:

• CRC generation
• Transmitted TLP storage for Data Link level retry
• Error checking
• TLP acknowledgment and retry Messages
• Error indication for error reporting and logging

PCI Express cards