IP DATAGRAM
Various options can be included to IP header, e.g., source route, record route and timestamp. Header with no function has H. LEN field value 5; data starts immediately after DESTINATION IP ADDRESS. Options are included between DESTINATION IP ADDRESS and packet data in multiples of 32 bits. Header with 96 bits of function has H. LEN field value 8.
DATAGRAM TRANSMISSION AND FRAMES:
IP Internet layer has basic tasks: It creates datagram, calculates next hop and gives to network interface layer. Network interface layer has basic tasks: It related next hop address to hardware address and makes datagram for transmission. But hardware frame doesn't understand IP how datagram is send.