Networking —

AppleTalk Addressing

Like the other protocols discussed, the AppleTalk protocol uses a two-part addressing schemea node and a network section. The node portion of the address is assigned automatically when the system is first brought up onto the network. It is a randomly generated number and then broadcast to the entire network. If a duplicate node address is assigned, another will be assigned and rebroadcast to the network. The network portion of the address is assigned by the network administrator.

The actual AppleTalk address is 24 bits long with 16 bits used for the network address and 8 bits for the node address. AppleTalk addresses are expressed in decimal format, with the network and node addresses separated by a period. An example of an AppleTalk address might be 4.67. The 4 represents the network number, and 67 is the node number.

AppleTalk Interoperability

AppleTalk was designed for the purpose of being used on Apple networks and, as such, is not natively supported by most of the other major operating systems. Because of this, today, other protocols such as TCP/IP are a more common choice, even for Apple-based networks. In fact, Macintosh systems themselves support the use of TCP/IP. AppleTalk can be configured to work with other platforms, but, given the proliferation of TCP/IP, this is not widely done.

AppleTalk Routing

The earliest implementations of AppleTalk were not routable, but later versions were. Routing functionality for AppleTalk is provided by the RTMP protocol. RTMP provides similar functionality to the RIP protocol used with IPX/SPX and TCP/IP networks.

AppleTalk Naming

AppleTalk networks use logical hostnames, making systems readily recognizable on the network. The network address-to-hostname resolution is handled by the NBP protocol in the AppleTalk protocol suite. It performs a similar function to that provided by DNS on a TCP/IP network.