RFC 1103 IP Datagrams over FDDI Networks June 1989 ...--------+--------+--------+ MAC Header | FDDI MAC ...--------+--------+--------+ +--------+--------+--------+ | DSAP=K1| SSAP=K1| Control| 802.2 LLC +--------+--------+--------+ +--------+--------+---------+--------+--------+ |Protocol Id or Org Code =K2| EtherType | 802.2 SNAP +--------+--------+---------+--------+--------+ The total length of the LLC Header and the SNAP header is 8 octets. The K1 value is 170 (decimal). The K2 value is 0 (zero). The control value is 3 (Unnumbered Information). Address Resolution The mapping of 32-bit Internet addresses to 16-bit or 48-bit FDDI addresses must be done via the dynamic discovery procedure of the Address Resolution Protocol (ARP) [2]. Internet addresses are assigned arbitrarily on Internet networks. Each host's implementation must know its own Internet address and respond to Address Resolution requests appropriately. It must also use ARP to translate Internet addresses to FDDI addresses when needed. The ARP protocol has several fields that parameterize its use in any specific context [2]. These fields are: hrd 16 - bits The Hardware Type Code pro 16 - bits The Protocol Type Code hln 8 - bits Octets in each hardware address pln 8 - bits Octets in each protocol address op 16 - bits Operation Code The hardware type code assigned for IEEE 802 networks is 6 [12]. FDDI networks, although not IEEE 802 networks per se, are semantically equivalent and use the same type code. The protocol type code for IP is 2048 [12]. Katz