The Reverse Address Resolution Protocol (RARP) is an obsolete computer

communication protocol A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax, semantics and synchroniza ...

used by a

client computer In computing, a client is a piece of computer hardware or software that accesses a service made available by a server as part of the client–server model of computer networks. The server is often (but not always) on another computer system, ...

to request its Internet Protocol (

IPv4 Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 was the first version d ...

) address from a

computer network A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...

, when all it has available is its link layer or hardware address, such as a

MAC address A media access control address (MAC address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking te ...

. The client broadcasts the request and does not need prior knowledge of the network topology or the identities of servers capable of fulfilling its request. RARP is described in

Internet Engineering Task Force The Internet Engineering Task Force (IETF) is a standards organization for the Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements an ...

(IETF) publication RFC 903. It has been rendered obsolete by the

Bootstrap Protocol The Bootstrap Protocol (BOOTP) is a computer networking protocol used in Internet Protocol networks to automatically assign an IP address to network devices from a configuration server. The BOOTP was originally defined in RFC 951. While some par ...

(BOOTP) and the modern

Dynamic Host Configuration Protocol The Dynamic Host Configuration Protocol (DHCP) is a network management protocol used on Internet Protocol (IP) networks for automatically assigning IP addresses and other communication parameters to devices connected to the network using a cli ...

(DHCP), which both support a much greater feature set than RARP. RARP requires one or more server hosts to maintain a database of mappings of Link Layer addresses to their respective protocol addresses.

Media Access Control In IEEE 802 LAN/MAN standards, the medium access control (MAC, also called media access control) sublayer is the layer that controls the hardware responsible for interaction with the wired, optical or wireless transmission medium. The MAC sublay ...

(MAC) addresses need to be individually configured on the servers by an administrator. RARP is limited to serving only

IP address An Internet Protocol address (IP address) is a numerical label such as that is connected to a computer network that uses the Internet Protocol for communication.. Updated by . An IP address serves two main functions: network interface ident ...

es. Reverse ARP differs from the

Inverse Address Resolution Protocol The Address Resolution Protocol (ARP) is a communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address. This mapping is a critical function ...

(InARP) described in RFC 2390, which is designed to obtain the IP address associated with a local Frame Relay data link connection identifier. InARP is not used in

Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...

Modern Day Uses

Although the original uses for RARP have been superseded by different protocols, some modern day protocols use RARP to handle MAC migration, particularly in virtual machines, using a technique originating in

QEMU QEMU is a free and open-source emulator (Quick EMUlator). It emulates the machine's central processing unit, processor through dynamic binary translation and provides a set of different hardware and device models for the machine, enabling it t ...

. Examples are: * Cisco's Overlay Transport Virtualization (OTV). RARP is used to update the layer 2 forwarding tables when a MAC address moves between data centers. *

VMware vSphere VMware vSphere (formerly VMware Infrastructure 4) is VMware's cloud computing virtualization platform. It includes an updated vCenter Configuration Manager, as well as vCenter Application Discovery Manager, and the ability of vMotion to mov ...

's vMotion.https://blogs.vmware.com/vsphere/2013/07/vxlan-series-how-vmotion-impacts-the-forwarding-table-part-6.html RARP is used when a VM MAC moves between hosts.

References

{{reflist Internet protocols Internet Standards Link protocols

Modern Day Uses

See also

References