 the network and that it understands the protocol to gather whatever information it can from the already faulty net- to which the echo packet belongs. Such packets exist for ISO LLC work. and Xerox XNS protocols. By leaving the monitor permanently connected to the network, it may be used in a proactive role, gathering information about the operation of the network and providing early warnings of possible 61.4.5.2 Representative loading problems. Network monitors provide a means of recording the data that they produce. Compiling this data over a period of time enables When a network monitor provides a packet transmission capability, network managers to observe the changing patterns of usage of the there is usually the means to specify: network. This facilitates forward planning of the growth of the network and can pin-point areas of concern. 1. The length of the packet. 2. The data content of the packet. 61.4.7 Larger networks 3. Whether the packet is to be repeatedly transmitted at a specified interval. As the number and size of LANs continues to grow, it is increasingly necessary to partition individual networks and interconnect them to The purpose of re-transmitting the packet, with an interval speci- form multi-LANs. The connections between LANs filter out lo- fied by the user, is to enable the monitor to simulate additional loads calised traffic, SO that a network monitor at one part of the network on the network. By varying the other parameters, it is possible to cannot, by itself, report completely on the status of another part of generate a load that is representative of, say, adding another group the network. of workstations and a fileserver. This allows the user to investigate the impact of expanding the use of the network. Particular areas of 61.4.7.1 Remote monitoring concern may be the effect on response times for other workstation users, or possibly whether a local bridge can cope with the addi- Simplified remote monitoring devices may be attached to all seg- tional load. ments of the network. These 