TLP Digest Rules

For any TLP, a value of 1b in the TD field indicates the presence of the TLP Digest field including an ECRC value at the end of the TLP
• A TLP where the TD field value does not correspond with the observed size (accounting for the data payload, if present) is a Malformed TLP
♦ This is a reported error associated with the Receiving Port (see Section 6.2)
If an intermediate or ultimate PCI Express Receiver of the TLP does not support ECRC checking, the Receiver must ignore the TLP Digest4
• If the Receiver of the TLP supports ECRC checking, the Receiver interprets the value in the TLP Digest field as an ECRC value, according to the rules in Section 2.7.1