Lantronix MPS100 EPS Reference Manual - Page 214
Simple Network Management Protocol. SNMP allows a TCP/IP host running
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rwho rwho SAP service SNMP subnet mask Glossary A UNIX feature that enables network hosts to know what users and systems are on the network without actively connecting to them. If rwho is enabled on a host, it both sends and receives network broadcasts containing this information. The packets generally contain the host's name, IP address, and the number and names of the users on the system. Because the broadcasts are periodic (typically 30 seconds to two minutes), hosts that are seen with rwho and then removed from the local host table will reappear later. Rwho usually has to be enabled explicitly on the host system, and may not be enabled on large network environments where the extra network traffic is unacceptable. In this case hosts can be added to the local host table by hand. Service Advertising Protocol. SAP packets, along with RIP packets, allow the Server to broadcast its known routes and services to the network and obtain this information from other routers on the network. Any device on a network that can be connected to and accessed, such as a printer, modem, or a remote computer. Network users can generally see the services available on the network because the nodes that provide these services "advertise" them to the world. In the case of LAT, each service node sends out occasional network messages called multicasts describing what services it is providing and which users are connected to them. The concept of services is specific to LAT and local area networks. TCP/IP and other wide area networks have no such facility. The service will occasionally be used to refer to anything that can be connected, whether LAT or not. Simple Network Management Protocol. SNMP allows a TCP/IP host running an SNMP application to query other nodes for network-related statistics and error conditions. The other hosts, which provide SNMP agents, respond to these queries and allow a single host to gather network statistics from many other network nodes. The Server provides this SNMP agent only; it cannot generate queries to other hosts. It only responds to them. A "filter" that tells the Server whether a node is on the local network or a remote network. The Server supports Telnet connections across networks through the use of gateways, using gateway hosts to forward messages across network boundaries. The Server uses the subnet mask as a filter; if the Server's IP address and the remote IP address appear the same after the filter, the remote host is assumed to be on the same local network. Otherwise, the gateway is used. The mask itself is a list of bits that should be enabled in the result-a 1 in the mask means to let that bit in the IP address through, and 0 means do not. For example, address 192.1.2.22 with mask 255.255.0.0 becomes 192.1.0.0. For network purposes, host 192.1.5.12 is on the same network, based on the mask specified. In this case, a gateway would not need to be accessed. A host at Glossary-6