AppleTalk Address Resolution Protocol (AARP)

What is AppleTalk Address Resolution Protocol (AARP)?
AppleTalk Address Resolution Protocol (AARP) maps the AppleTalk node address used by the datagram delivery protocol to the underlying data link layer addresses. AppleTalk is a protocol suite with an open, peer-to-peer architecture that runs on a wide variety of transmission media. The AARP resolves AppleTalk addresses at the physical level, e.g. B. Mandatory Address Control (MAC).

The AARP assigns the physical hardware addresses of the computers to the temporarily assigned AppleTalk network addresses. AARP corresponds functionally to the Address Resolution Protocol (ARP). The AARP table enables management of the address mapping table on the managed device. With this protocol, the AppleTalk hosts on Apple computers can generate their own network addresses. It was included in the original 1984 Macintosh version.

An AppleTalk computer sends AARP test packets. It asks for a network address and waits to hear from controllers such as routers. If no addresses are provided, a single one is randomly selected from base subnet 0. To improve performance, successful addresses are written to non-volatile RAM and used as default addresses in the future.

AARP assigns hardware addresses to network addresses. When an AppleTalk protocol has data to send, it passes the network address of the destination node to the appropriate AARP. The AARP then provides the hardware address associated with the network address and checks the active management technology (AMT) to see if the network address is associated with any other hardware address. If it is already assigned, the address is passed to the requesting AppleTalk protocol, which it uses to communicate with the target. If the address is not assigned, AARP broadcasts and prompts the node to use the network address to provide its respective hardware address.

When the request reaches the node, it responds with the hardware address. If there is no node with the specified network address at the same time, no response will be sent. After several attempts, AARP assumes that the protocol address is not in use and returns an error to the requesting AppleTalk protocol. When responses are received, the hardware address is linked to the network address in the AMT and passed to the AppleTalk Protocol, which it then uses to communicate with the destination node.

AARP has precisely defined options for getting the controller devices to overwrite standard mechanisms. The concept enables routers to provide information on known addresses and names. In large networks where AARP causes problems with the introduction of new nodes looking for addresses, router inclusion reduces chattiness. The implementation of AARP in AppleTalk simplifies the use of the network system.