An SNMP-based implementation of the adaptive distributed system-level diagnosis algorithm for LAN fault management

Fault management is a key functional area of network management systems, but current SNMP-based applications often implement rudimentary diagnosis mechanisms. Although the field of distributed system-level fault diagnosis has been flourishing for years, and a large number of mostly theoretical results have been devised, these results are not yet widely applied to network management systems. This paper presents the application of distributed diagnosis results to practical SNMP-based fault management. We implemented a modified version of the adaptive distributed system-level diagnosis algorithm using SNMP facilities. Two important modifications were introduced in the algorithm.: (1) to permit management of a variety of agents our implementation includes tested-only nodes, in addition to those that both test and are tested; (2) recognizing the need for a network management station (NMS) that doesn´t tolerate large diagnosis delays, SNMP traps are used; the result is a diagnosis scheme that has high resilience to network faults and at the same time avoids inconvenient delays. The impact of the diagnosis on the performance of the network is analyzed in terms of the overhead imposed by SNMP diagnosis messages. The influence of both the number of nodes and the testing interval on the demand of bandwidth by the diagnosis process were evaluated, and it is shown that for common LAN capacities, diagnosis consumes less than 1% of the available bandwidth