2010-04-23 - ARP/RARP PROTOCOLS.COM-OOS
ARP/RARP
RFC826 http://www.cis.ohio-state.edu/htbin/rfc/rfc826.html
RFC1293 http://www.cis.ohio-state.edu/htbin/rfc/rfc1293.html
This RFC has been replaced by RFC 2390.
The information on this page will be updated to suit the new RFC in the near future.
RFC1390 http://www.cis.ohio-state.edu/htbin/rfc/rfc1390.html
TCP/IP uses the Address Resolution Protocol (ARP) and the Reverse Address Resolution Protocol (RARP) to initialize the use of Internet addressing on an Ethernet or other network that uses its own media access control (MAC). ARP allows a host to communicate with other hosts when only the Internet address of its neighbors is known. Before using IP, the host sends a broadcast ARP request containing the Internet address of the desired destination system.
The ARP/RARP header structure is shown in the illustration below.
16 | 32 bits | ||
 | | ||
ARP/RARP header structure | |||
Hardware type
Specifies a hardware interface type for which the sender requires a response.
Protocol type
Specifies the type of high-level protocol address the sender has supplied.
HLen
Hardware address length.
PLen
Protocol address length.
Operation
The values are as follows:
| 1 | ARP request. |
| 2 | ARP response. |
| 3 | RARP request. |
| 4 | RARP response. |
| 5 | Dynamic RARP request. |
| 6 | Dynamic RARP reply. |
| 7 | Dynamic RARP error. |
| 8 | InARP request. |
| 9 | InARP reply. |
Sender hardware address
HLen bytes in length.
Sender protocol address
PLen bytes in length.
Target hardware address
HLen bytes in length.
Target protocol address
PLen bytes in length.
