Hardware Versus Protocol Addresses

When communicating on the same network segment, a computer can communicate directly by sending directed Address Resolution Protocols (ARP) packets to another computer using the network card's unique MAC address. In TCP/IP networks, the ARP is used in a local broadcast domain to determine the hardware address of another computer by sending out a broadcast packet that contains the computer's IP address. When a computer recognizes an ARP packet that has its IP address, it responds to the ARP request with another packet that tells the original computer what the destination computer's MAC address is. For more information about hardware addresses, which are stored in the local ARP cache and ARP, see Chapter 24, "Overview of the TCP/IP Protocol Suite."

The TCP/IP protocol is pretty much the standard today for local area networks. NetBIOS has been adapted to run over IP, and beginning with NetWare 5, IP is now the preferred protocol used in NetWare LANs. To begin, however, let's look at the older NetBIOS namespace and NetBEUI protocol that were used on Microsoft's first offerings in the LAN environment.