ISPPlanet Network Management System Series - SNMP ToolChest

Status Monitoring
SNMP managers typically use repeatedly polling with SNMP GETs, complemented by agent-generated TRAP or INFORM messages, to monitor network status. Although it lacks a utility to receive TRAPs, the SNMP ToolChest makes extensive use of poll-based monitoring and analysis.

SmartBrowser (right) can be configured to poll several device interfaces and apply a single analysis expression. Numerous pre-packaged expressions provide on-the-fly analysis of polled MIB objects. For example, Ethernet, WAN, ATM, and Token-Ring expressions include transmit and receive utilization, packet rate, and link errors appropriate for each media. Expressions available at the IP level include packet rate, ping rate, and the percentage of management traffic and errors. A configurable threshold is compared to each expression result—values that exceed this threshold are flagged in red.

Additional real-time monitoring tasks are performed by RouterScope (left). Like SmartBrowser, RouterScope accepts a list of IP addresses and polls these devices at a configurable interval. But Router-Scope polls many routing-related objects at once and performs more extensive analysis, computing forwarding rate and comparing ICMP, IP, and Cisco-specific objects to hard-coded thresholds (customizable by updating the Tcl).

A third monitoring tool, IPScope (right), continuously monitors end-to-end reachability. This unique tool actually plots the forward and reverse paths between a pair of devices, then polls each node and link in these paths. IPScope analyzes retrieved values and compares them against GUI-settable thresholds: for example, % CPU busy for nodes or % receive or transmit utilization for links. Violations are indicated by icon color changes.

These three tools provide significant added value over raw object polling by performing real-time analysis and thresholding. But visual cues are only effective when a human is watching; simple audible or email notifications would make these tools even more powerful.

Go to Part 5: Performance Monitoring / Final Words