 STARTING ENDING DATA LINK VERIFICATION DESTINATION SOURCE DELIMITER ADDRESS FIELD DELIMITER ADDRESS FIELD LAYER Figure 16.25 Structure of an SNMP protocol The Simple Network Management Protocol 16/23 transport. CMOT uses CMIP protocols but over TCP/IP transport. Table 16.6 Traps used in SNMP Similarly one could have SNMP transported over OSI (SNOO?), but the advantages of this are not evident. The aim of CMOT was to Trap sent Description allow designs to carry out CMIP prototyping before OSI transport became available, and for deploying CMIP over the large existing coldStart Agent is initialising and this may give a base of the TCP/IP environments. changed configuration Figure 16.27 shows the structure of CMOT. The application layer warmStart Agent is re-initialising and the configuration is OSI, the transport layer is TCP/UDP and the network layer is IP. will not change The presentation layer consists of a Lightweight Presentation Proto- col (LLP), defined in RFC 1085, which provides a means for linkDown One of the agent's links has failed carrying OSI applications over the TCP/IP environment. linkUp One of the agent's links has (re) started authenticationP A message has been received by the agent MANAGER MANAGED RESOURCE ailure which fails SNMP authentication procedure MANAGER MANAGED egpNeighbourL A neighbour has gone down resulting in the APPLICATION OBJECTS loss of EGP peer-peer mapping MESSAGES MESSAGES Table 16.7 Protocol errors returned by an SNMP agent following a management request CMISE CMISE Error Meaning noError Standard response tooBig Response too big noSuch Unknown variable badValue Wrong value type readOnly Variable of read-only type genError Generic error Figure 16.27 Communications within CMOT In order to bridge the gap between SNMP and OSI a working group, called the OSI Internet Management (OIM) working group was set up to develop a protocol for transition from SNMP to OSI. Although SNMP is widely supported, CMOT has very few im- This protocol has been called CMOT, the transport of CMIP over