Internet Draft Convention for Defining Traps Sep 90 A Convention for Defining Traps for use with the SNMP Tue Sep 25 17:01:28 1990 Marshall T. Rose (editor) Performance Systems International, Inc. 5201 Great America Parkway Suite 3106 Santa Clara, CA 95054 US mrose@psi.com 1. Status of this Memo This memo describes a straight-forward approach towards defining traps used with the SNMP. It is specifically intended for use by the authors of experimental MIBs, and emphasizes a concise descriptive approach. Use of this approach is fully consistent with the Internet-standard network management framework. Distribution of this memo is unlimited. Please send comments to: Marshall T. Rose . M.T. Rose (editor) [Page 1] Internet-Draft Convention for Defining Traps Sep 90 2. Historical Perspective As reported in RFC 1052, IAB Recommendations for the Development of Internet Network Management Standards [1], a two-prong strategy for network management of TCP/IP-based internets was undertaken. In the short-term, the Simple Network Management Protocol (SNMP), defined in RFC 1067, was to be used to manage nodes in the Internet community. In the long-term, the use of the OSI network management framework was to be examined. Two documents were produced to define the management information: RFC 1065, which defined the Structure of Management Information (SMI), and RFC 1066, which defined the Management Information Base (MIB). Both of these documents were designed so as to be compatible with both the SNMP and the OSI network management framework. This strategy was quite successful in the short-term: Internet-based network management technology was fielded, by both the research and commercial communities, within a few months. As a result of this, portions of the Internet community became network manageable in a timely fashion. As reported in RFC 1109, Report of the Second Ad Hoc Network Management Review Group [2], the requirements of the SNMP and the OSI network management frameworks were more different than anticipated. As such, the requirement for compatibility between the SMI/MIB and both frameworks was suspended. This action permitted the operational network management framework, based on the SNMP, to respond to new operational needs in the Internet community by producing MIB-II. In May of 1990, the core documents were elevated to "Standard Protocols" with "Recommended" status. As such, the Internet- standard network management framework consists of: Structure and Identification of Management Information for TCP/IP-based internets, RFC 1155 [3], which describes how managed objects contained in the MIB are defined; Management Information Base for Network Management of TCP/IP-based internets, which describes the managed objects contained in the MIB, RFC 1156 [4]; and, the Simple Network Management Protocol, RFC 1157 [5], which defines the protocol used to manage these objects. M.T. Rose (editor) [Page 2] Internet-Draft Convention for Defining Traps Sep 90 3. Defining Traps Due to its initial requirement to be protocol-independent, the Internet-standard SMI does not provide a means for defining traps. Instead, the SNMP defines a few standardized traps and provides a means for management enterprises to transmit enterprise-specific traps. However, with the introduction of experimental MIBs, some of which have a need to define experiment-specific traps, a convenient means of defining traps is desirable. The TRAP- TYPE macro is suggested for this purpose: TRAP-TYPE MACRO ::= BEGIN TYPE NOTATION ::= "ENTERPRISE" enterprise (VALUE OBJECT IDENTIFIER) VarPart DescrPart ReferPart VALUE NOTATION ::= value (VALUE INTEGER) VarPart ::= "VARIABLES" "{" VarTypes "}" | empty VarTypes ::= VarType | VarTypes "," VarType VarType ::= vartype (VALUE ObjectName) DescrPart ::= "DESCRIPTION" description (VALUE DisplayString) | empty ReferPart ::= "REFERENCE" reference (VALUE DisplayString) | empty END M.T. Rose (editor) [Page 3] Internet-Draft Convention for Defining Traps Sep 90 3.1. Mapping of the TRAP-TYPE macro It should be noted that the expansion of the TRAP-TYPE macro is something which conceptually happens during implementation and not during run-time. 3.1.1. Mapping of the ENTERPRISE clause The ENTERPRISE clause, which must be present, defines the management enterprise under whose registration authority this trap is defined (for a discussion on delegation of registration authority, see the SMI [3]). This value is placed inside the enterprise field of the SNMP Trap-PDU. By convention, if the value of the ENTERPRISE clause is "snmp" as defined in MIB-II, then instead of using this value, the value of sysObjectID is placed in the enterprise field of the SNMP Trap-PDU. This provides a simple means of using the TRAP-TYPE macro to represent the existing standard SNMP traps; it is not intended to provide a means to define additional standard SNMP traps. 3.1.2. Mapping of the VARIABLES clause The VARIABLES clause, which need not be present, defines the ordered sequence of MIB objects which are contained within every instance of the trap type. Each variable is placed, in order, inside the variable-bindings field of the SNMP Trap- PDU. Note that at the option of the agent, additional variables may follow in the variable-bindings field. 3.1.3. Mapping of the DESCRIPTION clause The DESCRIPTION clause, which need not be present, contains a textual definition of the trap type. Note that in order to conform to the ASN.1 syntax, the entire value of this clause must be enclosed in double quotation marks, although the value may be multi-line. Further, note that if the MIB module does not contain a textual description of the object type elsewhere then the DESCRIPTION clause must be present. M.T. Rose (editor) [Page 4] Internet-Draft Convention for Defining Traps Sep 90 3.1.4. Mapping of the REFERENCE clause The REFERENCE clause, which need not be present, contains a textual cross-reference to a trap, event, or alarm, defined in some other MIB module. This is useful when de-osifying a MIB produced by some other organization. 3.1.5. Mapping of the TRAP-TYPE value The value of an invocation of the TRAP-TYPE macro is the (integer) number which is uniquely assigned to the trap by the registration authority indicated by the ENTERPRISE clause. This value is placed inside the specific-trap field of the SNMP Trap-PDU, and the generic-trap field is set to "enterpriseSpecific(6)". By convention, if the value of the ENTERPRISE clause is "snmp" as defined in MIB-II, then the value of an invocation of the TRAP-TYPE macro is placed inside the generic-trap field of the SNMP Trap-PDU, and the specific-trap field is set to 0. This provides a simple means of using the TRAP-TYPE macro to represent the existing standard SNMP traps; it is not intended to provide a means to define additional standard SNMP traps. M.T. Rose (editor) [Page 5] Internet-Draft Convention for Defining Traps Sep 90 3.2. Usage Example Consider a simple example of an enterprise-specific trap that is sent when a communication link failure is encountered: myEnterprise OBJECT IDENTIFIER ::= { enterprises 9999 } myLinkDown TRAP-TYPE ENTERPRISE myEnterprise VARIABLES { ifIndex } DESCRIPTION "A myLinkDown trap signifies that the sending SNMP application entity recognizes a failure in one of the communications links represented in the agent's configuration." ::= 2 M.T. Rose (editor) [Page 6] Internet-Draft Convention for Defining Traps Sep 90 4. Acknowledgements The editor acknowledges the comments of the following individuals: Jeffrey Case, UTK and SNMP Research James Davin, MIT-LCS Mark Fedor, PSI Keith McCloghrie, HLS Martin Schoffstall, PSI Wengyik Yeong, PSI M.T. Rose (editor) [Page 7] Internet-Draft Convention for Defining Traps Sep 90 5. References [1] V. Cerf, IAB Recommendations for the Development of Internet Network Management Standards. Internet Working Group Request for Comments 1052. Network Information Center, SRI International, Menlo Park, California, (April, 1988). [2] V. Cerf, Report of the Second Ad Hoc Network Management Review Group, Internet Working Group Request for Comments 1109. Network Information Center, SRI International, Menlo Park, California, (August, 1989). [3] M.T. Rose and K. McCloghrie, Structure and Identification of Management Information for TCP/IP-based internets, Internet Working Group Request for Comments 1155. Network Information Center, SRI International, Menlo Park, California, (May, 1990). [4] K. McCloghrie and M.T. Rose, Management Information Base for Network Management of TCP/IP-based internets, Internet Working Group Request for Comments 1156. Network Information Center, SRI International, Menlo Park, California, (May, 1990). [5] J.D. Case, M.S. Fedor, M.L. Schoffstall, and J.R. Davin, Simple Network Management Protocol, Internet Working Group Request for Comments 1157. Network Information Center, SRI International, Menlo Park, California, (May, 1990). [6] Information processing systems - Open Systems Interconnection - Specification of Abstract Syntax Notation One (ASN.1), International Organization for Standardization. International Standard 8824, (December, 1987). [7] M.T. Rose (editor), Management Information Base for Network Management of TCP/IP-based internets: MIB-II, Internet Working Group Request for Comments 1158. Network Information Center, SRI International, Menlo Park, California, (May, 1990). M.T. Rose (editor) [Page 8] Internet-Draft Convention for Defining Traps Sep 90 Table of Contents 1 Status of this Memo ................................... 1 2 Historical Perspective ................................ 2 3 Defining Traps ........................................ 3 3.1 Mapping of the TRAP-TYPE macro ...................... 4 3.1.1 Mapping of the ENTERPRISE clause .................. 4 3.1.2 Mapping of the VARIABLES clause ................... 4 3.1.3 Mapping of the DESCRIPTION clause ................. 4 3.1.4 Mapping of the REFERENCE clause ................... 5 3.1.5 Mapping of the TRAP-TYPE value .................... 5 3.2 Usage Example ....................................... 6 4 Acknowledgements ...................................... 7 5 References ............................................ 8 M.T. Rose (editor) [Page 9] ------- End of Forwarded Message