The ever increasing size of networks has resulted in a corresponding escalation of administration costs and lengthy deployment cycles. Clearly, more scalable and flexible network management systems are required to replace existing centralised services. The work described in this paper forms part of a new network management system that fuses dynamic extensibility, Java Management Extension (JMX), and mobile agents. The primary focus is on integration with the many widely deployed legacy SNMPbased network management systems. One of the primary contributions is the design of a generic SNMP adaptor to enable JMX compliant agents to be accessed by SNMP-based management applications. A set of SNMP APIs have been developed to support the development of the SNMP adaptor. A number of other tools have been developed to support the SNMP adaptor, these include: a Management Information Base (MIB) compiler that automatically generates MBeans representing a given SNMP MIB; and a SNMP proxy service...