nly one OID can be obtained at one time from the agent of a target device. The Manager passes the details of the query to the JMX Agent and, in turn, the JMX Agent performs an SNMP set/get/getnext on the target device's agent. The process is illus- trated in Figure 12.14. The NMS-Framework MIB has a proxy table in the proxy service module, where all proxy details are stored. 12.10.4.2.3 Trivial File Transfer Protocol (TFTP) TFTP is the forerunner protocol of File Transfer Protocol (FTP). TFTP is less complex than FTP and does not have all the features of FTP. TFTP is well suited to enabl- ing simple devices without memory, such as routers and switches, to obtain their bootstrap information. In the case of JMX Agent as a client of FMS, the transaction is between fault man- agement system and the device, where a TFTP server is running. The system can be SNMP get/ Proxy service getNext/set Manager Device Result Agent Result Figure 12.14 JMX agent acting as proxy. OSS for Telecom Networks Master Agent forwards queries under MIB-2 JMX Agent to SubAgent SubAgent listening listening on port 8001 on port 161 Master Agent registers SubAgent MIB-2 Agent as SubAgent responds Figure 12.15 Relationship between master and sub-agent. instructed to get a file, for example the device configuration files, by TFTP from a device to the fault management system. The system can also be instructed to put a file, for example log files of fault Management, into the device with TFTP service. The Manager ensures transfer of files between FMS and the device with a TFTP service. To invoke TFTP service through the MIB browser of the Manager, the user must modify the values of the attributes of the NMS-Framework MIB: server name, port number, source file, destination file, TFTP mode and request, to get/put a file. 12.10.4.2.4 Registering the Sub-agent The JMX Agent acts as the Master Agent and any number of sub-agents can be registered with the Master Agent. Any agent can be registered as a sub-agent to the JMX Agent. By using this facility, th