IPv4 Protocol Suite
Internet Protocol Version 4 (IPv4) is the core protocol in the TCP/IP protocol suite. IPv4 protocol suite includes Address Resolution Protocol (ARP), Reverse Address Resolution Protocol (RARP), Internet Control Message Protocol (ICMP), Transmission Control Protocol (TCP), and User Datagram Protocol (UDP).
As shown in Figure 1, ARP and RARP work between the data link layer and the network layer for address resolution. ICMP works between the network layer and the transport layer to ensure correct forwarding of IP datagrams.
ARP
ARP maps an IP address to a MAC address. ARP can be implemented in dynamic or static mode. ARP provides some extended functions, such as proxy ARP, gratuitous ARP, and ARP security.
RARP
RARP maps a MAC address to an IP address.
ICMP
ICMP works at the network layer to ensure correct forwarding of IP datagrams. ICMP allows hosts and devices to report errors during packet transmission. An ICMP message is encapsulated in an IP datagram as the data, and a header is added to the ICMP message to form an IP datagram.