Network Working Group J. Schoenwaelder Internet-Draft TU Braunschweig Expires: December 20, 2001 June 21, 2001 Storage Type MIB draft-schoenw-storage-type-00 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on December 20, 2001. Copyright Notice Copyright (C) The Internet Society (2001). All Rights Reserved. Abstract The second version of the Structure of Management Information (SMIv2) introduced the StorageType textual convention in RFC 2579. It is used to describe the memory realization of rows in conceptual tables. Several standards-track MIB modules make use of this convention. Implementation experience shows that different approaches are used to actually write conceptual rows into non-volatile memory. This memo addresses this question and provides a MIB module which can be used to explicitly commit non-volatile rows into non-volatile memory. Schoenwaelder Expires December 20, 2001 [Page 1] Internet-Draft Storage Type MIB June 2001 Table of Contents 1. The SNMP Management Framework . . . . . . . . . . . . . . . . 3 2. StorageType Interpretations . . . . . . . . . . . . . . . . . 4 3. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. Security Considerations . . . . . . . . . . . . . . . . . . . 11 5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 6. Intellectual Property Notice . . . . . . . . . . . . . . . . . 12 References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 14 A. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 14 Full Copyright Statement . . . . . . . . . . . . . . . . . . . 15 Schoenwaelder Expires December 20, 2001 [Page 2] Internet-Draft Storage Type MIB June 2001 1. The SNMP Management Framework The SNMP Management Framework presently consists of five major components: o An overall architecture, described in RFC 2571 [2]. o Mechanisms for describing and naming objects and events for the purpose of management. The first version of this Structure of Management Information (SMI) is called SMIv1 and described in STD 16, RFC 1155 [3], STD 16, RFC 1212 [4] and RFC 1215 [5]. The second version, called SMIv2, is described in STD 58, RFC 2578 [6], STD 58, RFC 2579 [7] and STD 58, RFC 2580 [8]. o Message protocols for transferring management information. The first version of the SNMP message protocol is called SNMPv1 and described in STD 15, RFC 1157 [9]. A second version of the SNMP message protocol, which is not an Internet standards track protocol, is called SNMPv2c and described in RFC 1901 [10] and RFC 1906 [11]. The third version of the message protocol is called SNMPv3 and described in RFC 1906 [11], RFC 2572 [12] and RFC 2574 [13]. o Protocol operations for accessing management information. The first set of protocol operations and associated PDU formats is described in STD 15, RFC 1157 [9]. A second set of protocol operations and associated PDU formats is described in RFC 1905 [14]. o A set of fundamental applications described in RFC 2573 [15] and the view-based access control mechanism described in RFC 2575 [16]. A more detailed introduction to the current SNMP Management Framework can be found in RFC 2570 [17]. Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Objects in the MIB are defined using the mechanisms defined in the SMI. This memo specifies a MIB module that is compliant to the SMIv2. A MIB conforming to the SMIv1 can be produced through the appropriate translations. The resulting translated MIB must be semantically equivalent, except where objects or events are omitted because no translation is possible (use of Counter64). Some machine readable information in SMIv2 will be converted into textual descriptions in SMIv1 during the translation process. However, this loss of machine readable information is not considered to change the semantics of the Schoenwaelder Expires December 20, 2001 [Page 3] Internet-Draft Storage Type MIB June 2001 MIB. 2. StorageType Interpretations The SMIv2 introduced the StorageType textual convention which is used to describe the memory realization of a conceptual rows. In particular, the StorageType textual convention can be used to mark dynamically created rows as volatile or non-volatile. Several MIBs on the standards-track use this StorageType textual convention for all conceptual tables that support row creation. The StorageType textual convention is defined in RFC 2579 [7] as follows: StorageType ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "Describes the memory realization of a conceptual row. A row which is volatile(2) is lost upon reboot. A row which is either nonVolatile(3), permanent(4) or readOnly(5), is backed up by stable storage. A row which is permanent(4) can be changed but not deleted. A row which is readOnly(5) cannot be changed nor deleted. If the value of an object with this syntax is either permanent(4) or readOnly(5), it cannot be written. Conversely, if the value is either other(1), volatile(2) or nonVolatile(3), it cannot be modified to be permanent(4) or readOnly(5). (All illegal modifications result in a 'wrongValue' error.) Every usage of this textual convention is required to specify the columnar objects which a permanent(4) row must at a minimum allow to be writable." SYNTAX INTEGER { other(1), -- eh? volatile(2), -- e.g., in RAM nonVolatile(3), -- e.g., in NVRAM permanent(4), -- e.g., partially in ROM readOnly(5) -- e.g., completely in ROM } Note that the text in the DESCRIPTION clause does not make any explicit statements when a conceptual row is actually written to non- volatile storage. One possible interpretation is that rows must be committed to non-volatile storage on each set operation which modifies a row. However, many implementations prefer to not write to non-volatile storage on each set operation. There are two main reasons for this: Schoenwaelder Expires December 20, 2001 [Page 4] Internet-Draft Storage Type MIB June 2001 1. Writing non-volatile storage is on some systems time and/or resource consuming. Committing rows to non-volatile memory during the set operation is thus considered too expensive. 2. Some management applications create and configure rows by sending a sequence of set requests. Committing the row to non-volatile storage on every single set operation is too costly, especially on systems that can only commit complex system configurations to non-volatile memory. Implementations therefore use different strategies: 1. Some systems update the non-volatile storage on each set operation. 2. Some systems first return a positive response to the set operation and they write the modified variables to non-volatile storage at some later point in time when there are no more changes. 3. Some systems first return a positive response to the set operation and they delay the actual write to non-volatile storage to some external event (e.g. shutdown of the agent, pushing of a global write button). 4. Some systems first return a positive response to the set operation and they write the modified variables when a logical row operation has completed. (For example, an incomplete conceptual row is not saved in non-volatile storage until it is complete and activated.) It seems that delayed writes to non-volatile storage are common practice. However, since this behavior is right now completely implementation dependent, there is no simple mechanism a management application can use to learn how a given device implements the StorageType textual convention and therefore it is unclear when a row is actually written to stable storage. Commonly used command line interfaces of network devices follow a paradigm where explicit commands trigger the storage of the device configuration (or logical parts of the device configuration) in non- volatile storage. Operational experience with these interfaces suggests that it is (i) valuable to have explicit control when configuration data is written to non-volatile storage and (ii) efficient to implement on networking devices. This document therefore proposes to introduce new MIB objects which can be used by management applications to control when non-volatile Schoenwaelder Expires December 20, 2001 [Page 5] Internet-Draft Storage Type MIB June 2001 conceptual rows are written to stable storage. The MIB supports multiple "write buttons" to support implementations which use different mechanisms in different parts of the MIBs to save rows in non-volatile storage. All "write buttons" are registered in a common table so that management applications can easily find them. The table is organized so that sub-agents can register rows in the table easily. In addition, there is a global "write button" which basically causes all write buttons in the table to be triggered. The objects defined in the MIB support slow write transactions where the time required to commit data to non-volatile storage is much larger than the time for processing set operations. Status objects report the progress of writing data to non-volatile storage. A management application can poll these status objects in order to detect when the write has completed and whether there were any errors. An alternative approach would have been to introduce "write button" scalars in various MIB modules that use the StorageType textual convention. However, this leads to serious problems for management applications to find the right scalars for the right set of MIB objects. Furthermore, it would be hard to realize a global "write button" in a master/subagent environment without specific protocol support. 3. Definitions SNMP-STORAGE-MIB DEFINITIONS ::= BEGIN IMPORTS MODULE-IDENTITY, OBJECT-TYPE, snmpModules, Unsigned32 FROM SNMPv2-SMI DateAndTime, AutonomousType FROM SNMPv2-TC MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF SnmpAdminString FROM SNMP-FRAMEWORK-MIB; snmpStorageMIB MODULE-IDENTITY LAST-UPDATED "200106210000Z" ORGANIZATION "IETF" CONTACT-INFO "Juergen Schoenwaelder (Editor) TU Braunschweig Schoenwaelder Expires December 20, 2001 [Page 6] Internet-Draft Storage Type MIB June 2001 Bueltenweg 74/75 38106 Braunschweig, Germany Phone: +49 531 391-3289 EMail: schoenw@ibr.cs.tu-bs.de Send comments to ." DESCRIPTION "This MIB modules provides objects that allow management applications to commit non-volatile conceptual rows to stable storage." REVISION "200106210000Z" DESCRIPTION "The initial revision, published as RFC XXXX." ::= { snmpModules xxx } snmpStorageObjects OBJECT IDENTIFIER ::= { snmpStorageMIB 1 } snmpStorageConformance OBJECT IDENTIFIER ::= { snmpStorageMIB 2 } snmpStorageGlobControl OBJECT-TYPE SYNTAX INTEGER { nop(1), write(2) } MAX-ACCESS read-write STATUS current DESCRIPTION "Setting this object to write(2) causes the agent to sync not yet committed non-volatile MIB data to stable storage. Setting this object to write(2) while the value of the snmpStorageGlobStatus object is writing(3) leads to an inconsitent value error. Setting this object to nop(1) always succeeds and has no effect. Management applications are advised to make use of the snmpSetSerialNo object defined in the SNMPv2-MIB to coordinate their use of this object." ::= { snmpStorageObjects 1 } snmpStorageGlobStatus OBJECT-TYPE SYNTAX INTEGER { other(1), dirty(2), -- can probably not be implemented ? writing(3), -- perhaps we only need 'idle' and finished(4), -- 'inProgress'? error(5) } MAX-ACCESS read-only STATUS current Schoenwaelder Expires December 20, 2001 [Page 7] Internet-Draft Storage Type MIB June 2001 DESCRIPTION "This object reports the current status of the write operation." ::= { snmpStorageObjects 2 } snmpStorageGlobError OBJECT-TYPE SYNTAX SnmpAdminString MAX-ACCESS read-only STATUS current DESCRIPTION "This object contains a descriptive error message if the last attempt to write global stable storage has failed." ::= { snmpStorageObjects 3 } snmpStorageGlobErrorTime OBJECT-TYPE SYNTAX DateAndTime MAX-ACCESS read-only STATUS current DESCRIPTION "The data and time when the snmpStorageGlobError was last updated. The value '0000000000000000'H is returned if snmpStorageGlobError has not yet been updated after the initialization." ::= { snmpStorageObjects 4 } snmpStorageTable OBJECT-TYPE SYNTAX SEQUENCE OF SnmpStorageEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "" ::= { snmpStorageObjects 5 } snmpStorageEntry OBJECT-TYPE SYNTAX SnmpStorageEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "" INDEX { snmpStorageIndex } ::= { snmpStorageTable 1 } SnmpStorageEntry ::= SEQUENCE { snmpStorageIndex Unsigned32, snmpStorageDescr SnmpAdminString, snmpStorageID AutonomousType, snmpStorageControl INTEGER, snmpStorageStatus INTEGER, snmpStorageError SnmpAdminString, Schoenwaelder Expires December 20, 2001 [Page 8] Internet-Draft Storage Type MIB June 2001 snmpStorageErrorTime DateAndTime } snmpStorageIndex OBJECT-TYPE SYNTAX Unsigned32 (1..4294967295) MAX-ACCESS not-accessible STATUS current DESCRIPTION "The index which uniquely identifies a row in the snmpStorageTable." ::= { snmpStorageEntry 1 } snmpStorageDescr OBJECT-TYPE SYNTAX SnmpAdminString MAX-ACCESS read-only STATUS current DESCRIPTION "A textual description which explains the scope of MIB data which is controlled by this row." ::= { snmpStorageEntry 2 } snmpStorageID OBJECT-TYPE SYNTAX AutonomousType MAX-ACCESS read-only STATUS current DESCRIPTION "" ::= { snmpStorageEntry 3 } snmpStorageControl OBJECT-TYPE SYNTAX INTEGER { nop(1), write(2) } MAX-ACCESS read-write STATUS current DESCRIPTION "Setting this object to write(2) causes the agent to sync not yet committed non-volatile MIB data to stable storage. Setting this object to write(2) while the value of the snmpStorageStatus object is writing(3) leads to an inconsitent value error. Setting this object to nop(1) always succeeds and has no effect. Management applications are advised to make use of the snmpSetSerialNo object defined in the SNMPv2-MIB to coordinate their use of this object." ::= { snmpStorageEntry 4 } Schoenwaelder Expires December 20, 2001 [Page 9] Internet-Draft Storage Type MIB June 2001 snmpStorageStatus OBJECT-TYPE SYNTAX INTEGER { other(1), dirty(2), writing(3), finished(4), error(5) } MAX-ACCESS read-only STATUS current DESCRIPTION "This object reports the current status of the write operation." ::= { snmpStorageEntry 5 } snmpStorageError OBJECT-TYPE SYNTAX SnmpAdminString MAX-ACCESS read-only STATUS current DESCRIPTION "This object contains a descriptive error message if the last attempt to write into stable storage has failed." ::= { snmpStorageEntry 6 } snmpStorageErrorTime OBJECT-TYPE SYNTAX DateAndTime MAX-ACCESS read-only STATUS current DESCRIPTION "The data and time when the snmpStorageError was last updated. The value '0000000000000000'H is returned if snmpStorageError has not yet been updated after the initialization." ::= { snmpStorageEntry 7 } snmpStorageCompliances OBJECT IDENTIFIER ::= { snmpStorageConformance 1 } snmpStorageGroups OBJECT IDENTIFIER ::= { snmpStorageConformance 2 } snmpStorageCompliance MODULE-COMPLIANCE STATUS current DESCRIPTION "" MODULE -- this module MANDATORY-GROUPS { snmpStorageGlobalGroup } GROUP snmpStorageGroup DESCRIPTION "Implementation of this group is only mandatory for systems that support multiple write buttons for different sets of MIB objects." Schoenwaelder Expires December 20, 2001 [Page 10] Internet-Draft Storage Type MIB June 2001 ::= { snmpStorageCompliances 1 } snmpStorageGlobalGroup OBJECT-GROUP OBJECTS { snmpStorageGlobControl, snmpStorageGlobStatus, snmpStorageGlobError, snmpStorageGlobErrorTime } STATUS current DESCRIPTION "" ::= { snmpStorageGroups 1 } snmpStorageGroup OBJECT-GROUP OBJECTS { snmpStorageDescr, snmpStorageID, snmpStorageControl, snmpStorageStatus, snmpStorageError, snmpStorageErrorTime } STATUS current DESCRIPTION "" ::= { snmpStorageGroups 2 } END 4. Security Considerations There are a number of management objects defined in this MIB that have a MAX-ACCESS clause of read-write and/or read-create. Such objects may be considered sensitive or vulnerable in some network environments. The support for SET operations in a non-secure environment without proper protection can have a negative effect on network operations. SNMPv1 by itself is not a secure environment. Even if the network itself is secure (for example by using IPSec), even then, there is no control as to who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB. It is recommended that the implementers consider the security features as provided by the SNMPv3 framework. Specifically, the use of the User-based Security Model RFC 2574 [RFC2574] and the View- based Access Control Model RFC 2575 [RFC2575] is recommended. It is then a customer/user responsibility to ensure that the SNMP entity giving access to an instance of this MIB, is properly configured to give access to the objects only to those principals (users) that have legitimate rights to indeed GET or SET (change/create/delete) them. Schoenwaelder Expires December 20, 2001 [Page 11] Internet-Draft Storage Type MIB June 2001 5. Acknowledgments The author would like to thank David Harrington, Jon Saperia, Steve Waldbusser for their comments and suggestions. 6. Intellectual Property Notice The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Harrington, D., Presuhn, R. and B. Wijnen, "An Architecture for Describing SNMP Management Frameworks", RFC 2571, April 1999. [3] Rose, M. and K. McCloghrie, "Structure and Identification of Management Information for TCP/IP-based Internets", STD 16, RFC 1155, May 1990. [4] Rose, M. and K. McCloghrie, "Concise MIB Definitions", STD 16, RFC 1212, March 1991. [5] Rose, M., "A Convention for Defining Traps for use with the SNMP", RFC 1215, March 1991. [6] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M. and S. Waldbusser, "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999. Schoenwaelder Expires December 20, 2001 [Page 12] Internet-Draft Storage Type MIB June 2001 [7] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M. and S. Waldbusser, "Textual Conventions for SMIv2", STD 58, RFC 2579, April 1999. [8] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M. and S. Waldbusser, "Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999. [9] Case, J., Fedor, M., Schoffstall, M. and J. Davin, "A Simple Network Management Protocol (SNMP)", STD 15, RFC 1157, May 1990. [10] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Introduction to Community-based SNMPv2", RFC 1901, January 1996. [11] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Transport Mappings for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1906, January 1996. [12] Case, J., Harrington, D., Presuhn, R. and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", RFC 2572, April 1999. [13] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", RFC 2574, April 1999. [14] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Protocol Operations for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1905, January 1996. [15] Levi, D., Meyer, P. and B. Stewart, "SNMP Applications", RFC 2573, April 1999. [16] Wijnen, B., Presuhn, R. and K. McCloghrie, "View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP)", RFC 2575, April 1999. [17] Case, J., Mundy, R., Partain, D. and B. Stewart, "Introduction to Version 3 of the Internet-standard Network Management Framework", RFC 2570, April 1999. Schoenwaelder Expires December 20, 2001 [Page 13] Internet-Draft Storage Type MIB June 2001 Author's Address Juergen Schoenwaelder TU Braunschweig Bueltenweg 74/75 38106 Braunschweig Germany Phone: +49 531 391-3266 EMail: schoenw@ibr.cs.tu-bs.de Appendix A. Open Issues o How do we best describe the scope of a write button? o Should we just provide a TC an simply point to MIB specific scalars that use this TC? o Is the error handling mechanism over-designed? o Do we ever clear the error message like we do it in the DISMAN- SCRIPT-MIB? Schoenwaelder Expires December 20, 2001 [Page 14] Internet-Draft Storage Type MIB June 2001 Full Copyright Statement Copyright (C) The Internet Society (2001). All Rights Reserved. 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