Systems and methods ensure that datagrams retain integrity in light of the problems associated with the internetworking protocol's use of datagram identifiers drawn from a first pool of datagram identifiers. The methods involve controlling the use of datagram identifiers to ensure that only certain identifiers are allowable. A second pool of datagram identifiers is created that is different from the first pool. A datagram identifier is drawn from the second pool and assigned to a datagram in a manner that the datagram identifier is controlled from being reused during the lifetime of the datagram. In alternative embodiments the number of available datagram identifiers is either increased through optional header fields, or reduced through tracking allowed datagram identifiers. A first host notifies a second host of an allowed identifier. The second host uses the allowed identifier as a datagram identifier.