Abstract: Information is added to an encapsulated payload in a data field of a frame subsequently to placing a checksum into a checksum field of a header encapsulating the payload, wherein the checksum has been determined from byte values of the header and the payload, yet having the checksum remaining detectable as valid upon interpretation of the header and the payload. A signature field that contains the information is inserted into the data field. The signature field has a checksum cheater subfield. A one's complement of a checksum determined from byte values of the information is then placed into the checksum cheater subfield. Accordingly, the checksum in the checksum field of the header remains valid.