A 4-bit field in a datagram or IP packet header. It gives the datagram header length measured in 32-bit words. The size of the data area can be computed by subtracting the length of the header (HLEN) from the total length field, which is 16 bits long - and the maximum possible datagram size is 65,535 octets (so far). All header fields have fixed lengths with the exception of the Options field and the Padding field.

Log in or registerto write something here or to contact authors.