obtaining a transport frame by a network element;

analyzing, by the network element, the transport frame to determine whether or not any vulnerable overhead field values in at least one octet of a header of a mapping layer frame and overhead octets of a transport layer frame have values other than expected values;

obtaining, by the network element, a policy or rule for processing the transport frame in response to a determination that at least one vulnerable overhead field value of the vulnerable overhead field values has a value other than the expected value;

modifying, by the network element, at least one reserved target field value in the transport frame when a determination is made that the at least one vulnerable overhead field value has a value other than the expected value; and

communicating, by the network element, the transport frame with the modified at least one reserved target value over a network or to a mapping layer formatting circuit;

wherein the policy or rule requires that the network element ignore that a given vulnerable overhead field value of the vulnerable overhead field values has a value other than the expected value, and communicate the transport frame over a network when all other ones of the vulnerable overhead field values have the expected values.