Lantronix MPS100 EPS Reference Manual - Page 18
encapsulated, services, multicasts, Show Services, Show Nodes
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LAT Concepts 2.5 LAT Digital Equipment Corporation's LAT (Local Area Transport) networking software is designed to ease the process of accessing and managing local area networks. LAT is significantly different from other protocols in two important ways. First, LAT is not routable. There is no way to divide LAT networks into smaller subnetworks and use routers to reduce traffic between nodes. Second, LAT is a timer-driven protocol. Packets are expected at certain intervals, and the protocol cannot adapt to slow network links dynamically. For these reasons, LAT traffic over wide areas is typically carried inside (or encapsulated in) TCP/IP or IPX/SPX packets. The latter two protocols are fully routable, and can handle wide-area, slow network links. Note: If LAT is bridged across slow links, session time-outs and errors are likely. LAT software is built around the concept of services. A service may be provided by a dedicated device, such as a printer, or by a network host. A device that offers one or more services, such as your Server, is called a node. In general, all services offered by the Server are associated with one or more ports; exceptions to this rule will be noted later. Figure 2-2 shows an example of services offered on a network. Figure 2-2: Example of Network Services LANtronix PWR EPS4 OK NET RCV XMT 10 Node Vax2, with service Vax2 (logins to other users) Node Server_1, offering service "modem" Node Phred, a computer offering services "LaserPrinter" (for printing) and "Phred" (for logins) Nodes advertise their services to the network by broadcasting occasional messages about them. These messages, referred to as multicasts, contain the node's name and its list of services. By monitoring multicast messages, all hosts on the network know what nodes and services are available and can provide this information to their interactive users. The Show Services and Show Nodes commands display this information. 2-4