What is Inverse ARP?
Inverse ARP (InARP) is a network protocol used to dynamically map a known interface protocol address (IPv4 or IPv6) to a Media Access Control (MAC) address. Unlike the traditional Address Resolution Protocol (ARP), which resolves IP addresses to MAC addresses, Inverse ARP resolves MAC addresses to IP addresses.
Basic Concepts of Network Address Resolution
Network address resolution is the process of mapping network layer addresses to data link layer addresses within a network. There are two main protocols commonly used for address resolution: ARP and InARP.
Address Resolution Protocol (ARP)
ARP is a protocol used for mapping Internet Protocol (IP) addresses to MAC addresses. When a host wants to send data to another host within the same network, it needs to know the MAC address of the destination host. ARP allows the host to send an ARP request broadcast message, asking “Who has this IP address?”, and the host with the corresponding IP address responds with its MAC address. Once the MAC address is obtained, the host can then send the data to the destination.
Inverse Address Resolution Protocol (InARP)
Inverse ARP, as mentioned earlier, performs the reverse process. It maps MAC addresses to IP addresses instead of IP addresses to MAC addresses. In some networking scenarios, it becomes necessary for a device to discover the IP address of a connected device when only the MAC address is known.
InARP is typically used in Frame Relay and ATM (Asynchronous Transfer Mode) networks. In these networks, a device requires the IP address of a connected device to establish a logical connection. InARP allows the device to send an InARP request to its local router or network switch, asking “What is the IP address of this MAC address?”. The router or switch with the mapping information responds with the corresponding IP address. Once the IP address is obtained, the device can establish the logical connection.
InARP plays a crucial role in simplifying the process of establishing connections in Frame Relay and ATM networks, reducing manual configuration requirements and enhancing network efficiency.
In conclusion, Inverse ARP (InARP) is a network protocol that resolves MAC addresses to IP addresses. Unlike ARP, it is primarily used in Frame Relay and ATM networks to facilitate address resolution in a reverse manner. By providing a dynamic mapping between MAC and IP addresses, InARP simplifies the process of establishing connections and improves network efficiency.
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