Semi-active replication of SNMP objects in agent groups applied for fault management

It is often useful to examine management information base (MIB) objects of a faulty agent in order to determine why it is faulty. This paper presents a new framework for semi-active replication of SNMP management objects in local area networks. The framework is based on groups of agents that communicate with each other using reliable multicast. A group of agents provides fault-tolerant object functionality. An SNMP service is proposed that allows replicated MIB objects of a faulty agent of a given group to be accessed through fault-free agents of that group. The presented framework allows the dynamic definition of agent groups, and management objects to be replicated in each group. A practical fault-tolerant tool for local area network fault management was implemented and is presented. The system employs SNMP agents that interact with a group communication tool. As an example, we show how the examination of TCP-related objects of faulty agents have been used in the fault diagnosis process. The impact of replication on network performance is evaluated