As discussed in this chapter, any administrator using Network Access Servers to provide users or sites remote access to a network has to find ways to manage the modems, lines, and calls that are being made through these servers and this part of the network. The primary method of doing so is to monitor the number of calls, call duration, call failure reasons, and traffic passed during calls. This data can be gathered through CLI show commands, SNMP, and log data.
CLI commands are recommended over the use of SNMP variables because not all information needed is accessible through MIBs and because the polling of modem variables can have an adverse affect on the router CPU.
Because a customer's perception of a network is often driven by its "remote" access performance, the area of monitoring performance and fault becomes increasingly important. After you have personally explored the variables, captured them, and trended them for your environment, you may wish to look at the use of RMON events and alarms for proactive fault management.