TCP/IP Illustrated, Vol. 1: The Protocols (Addison-Wesley Professional Computing Series)

5.2 RARP Packet Format

The format of an RARP packet is almost identical to an ARP packet (Figure 4.3). The only differences are that the frame type is 0 —8035 for an RARP request or reply, and the op field has a value of 3 for an RARP request and 4 for an RARP reply.

As with ARP, the RARP request is broadcast and the RARP reply is normally unicast.