ABSTRACT
In this chapter we continue to acquire a foundation of knowledge concerning both Ethernet LANs and the TCP/IP protocol suite by focusing attention upon the data link and network layer addressing as well as the Internet Protocol (IP), to include the Address Resolution Protocol (ARP) and both versions of Internet Control Message Protocol (ICMP). IP represents both the network layer protocol in the TCP/IP protocol suite and the data delivery mechanism, which enables packets to be routed from source to destination. However, when data are delivered to a device, such as a workstation on a LAN or even a computer accessing the Internet via a cable modem, the physical interface at the data link layer represents a 48-bit Media Access Control (MAC) address, while the IP address at the network layer is either a 48-bit IPv4 address or a 128-bit IPv6 address. Thus a mechanism is required to deliver the IP addressed data to the physical 48-bit hardware address. That mechanism is ARP.
