As can be seen, the DUAL packet format is very minimal. As an example, where IP is used over DUAL on a Class-C subnet, the overall DUAL link header is 5 octets: 1 for protocol/address, 1 for source, 1 for destination and 2 for the checksum. This compares well with the 19 octets required for the AX.25 header when transmitting IP data, a saving of 74%for the link header.