Network Working Group Glenn Mansfield Keeni INTERNET-DRAFT Cyber Solutions Inc. Expires: February 6, 2003 September 7, 2002 The Aggregation MIB for time based samples of a Managed Object Status of this Memo 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 February 6, 2003. Copyright Notice Copyright (C) The Internet Society (2002). All Rights Reserved. Abstract This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it is used to configure an agent to aggregate values of a (user) specified MO instance sampled at (user) specified intervals for a (user) specified number of times and to service queries related to the aggregated MOs. Expires: February 6, 2003 [Page 1] Internet Draft July 14 2002 Table of Contents 1. Introduction .................................................. 3 2. The SNMP Management Framework ................................. 5 3. The Requirements for Managed Object Aggregation ............... 6 4. MIB Design .................................................... 6 5. The Managed Object Aggregation MIB ............................ 7 6. Intellectual Property .........................................13 7. Acknowledgements ..............................................13 References ........................................................14 Security Considerations ...........................................16 Authors' Addresses ................................................17 Full Copyright Statement ..........................................18 Expires: February 6, 2003 [Page 2] Internet Draft July 14 2002 1. Introduction. For the purpose of management it is necessary to access Managed Objects (MOs). The SNMP framework provides a mechanism for naming and describing managed objects. These objects are accessed via a virtual information store, the Management Information Base (MIB). MIBs have been defined by equipment, protocol and, application developers to provide management access to the managed entities. We will call the MOs defined in these MIBs - simple MOs (SMO). Management applications will access one or more of these MOs, one or more times, to monitor the target entity. There is a cost associated with polling. The cost is the network bandwidth and the packet header processing overhead at the command generator (manager) and the command responder (agent). This cost constrains the number of objects that can be polled and the interval at which polling can be carried out. The overhead reduction can be carried out by reducing the number of query-response packets. This will reduce the packet processing overhead and to some extent the bandwidth. The payloads in a typical SNMP "get" packet and the corresponding response are as shown in Fig. 1. In the example shown in the figure polling is carried out for 'n' Managed Objects (MOs) OID1, OID2, .., OIDn. It is obvious that a substantial amount of the payload in an SNMP packet consists of the OIDs. In [ODC-Dft] OID compression has been proposed by using the OID Delta Compression mechanism. In a companion draft [Aggr-Dft] a mechanism of MO aggregation for payload compression is outlined. In this mechanism the user defines an Aggregate MO (AgMO) corresponding to one or more (predefined) MOs. Semantically, the AgMO will be equivalent to the concatenation of the values of the specified MOs. With the definitions done, the user can, as and when the necessity arises, perform an SNMP "get" on instances of the AgMO to fetch the value of instances of the constituent MOs. There is substantial savings on bandwidth as the only one instance object identifier is carried in the request and the response. In the normal case, instance object identifiers for each of the constituent MO instances would be carried in the requests and the response. In this draft we propose a further refinement of the AgMO. We introduce the Time-based Aggregated Managed Object (TAgMO). The TAgMO is an MO that represents the values of a (user) specified MO sampled at (user) specified intervals for a (user) specified number of times. In this case the user defines a TAgMO by specifying the MO instance that needs to be sampled, the sampling interval and the the desired number of samples that will be included in one TAgMO. The value of a Expires: February 6, 2003 [Page 3] Internet Draft July 14 2002 TAgMO instance will include the timestamp (sysuptime) at which the first sample was taken. With the definitions done the user can do an SNMP "get" on an instance of the TAgMO to fetch the values of the constituent MO instance sampled at the specified intervals. This is the concept of time-based agregation. Polling for MO Instances [MOI1, MOI2, ... MOIn] : +--------+------+-------+... -+------+------+ Query: |Get req | MOI1 | NULL | | MOIn | NULL | +--------+------+-------+... -+------+------+ +--------+------+-------+... -+------+------+ Response: |Get resp| MOI1 | Val1 | | MOIn | Valn | +--------+------+-------+... -+------+------+ Fig. 1 Polling for MO instances Polling for an instance (TAgMOIx) of a time-based aggregate MO [TAgMOx]: TAgMOx = aggr{'n' polled samples of an instance (MOI) of MO at intervals = 'i'} +--------+---------+-------+ Query: |Get req | TAgMOIx | NULL | +--------+---------+-------+ +--------+---------+----------------------------------------+ Response: |Get resp| TAgMOIx | t,Val(t),Val(t+i),...,Val(t + (n-1)*i) | +--------+---------+----------------------------------------+ Fig. 2 Time-based aggregation Expires: February 6, 2003 [Page 4] Internet Draft July 14 2002 2. The SNMP Management Framework The SNMP Management Framework presently consists of five major components: o An overall architecture, described in RFC 2571 [RFC2571]. 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 [RFC1155], STD 16, RFC 1212 [RFC1212] and RFC 1215 [RFC1215]. The second version, called SMIv2, is described in STD 58, RFC 2578 [RFC2578], RFC 2579 [RFC2579] and RFC 2580 [RFC2580]. 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 [RFC1157]. A second version of the SNMP message protocol, which is not an Internet standards track protocol, is called SNMPv2c and described in RFC 1901 [RFC1901] and RFC 1906 [RFC1906]. The third version of the message protocol is called SNMPv3 and described in RFC 1906 [RFC1906], RFC 2572 [RFC2572] and RFC 2574 [RFC2574]. o Protocol operations for accessing management information. The first set of protocol operations and associated PDU formats is described in STD 15, RFC 1157 [RFC1157]. A second set of protocol operations and associated PDU formats is described in RFC 1905 [RFC1905]. o A set of fundamental applications described in RFC 2573 [RFC2573] and the view-based access control mechanism described in RFC 2575 [RFC2575]. A more detailed introduction to the current SNMP Management Framework can be found in RFC 2570 [RFC2570]. 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 Expires: February 6, 2003 [Page 5] Internet Draft July 14 2002 readable information is not considered to change the semantics of the MIB. 3. The Requirements for Managed Object aggregation The general requirements of managed object aggregation are as follows: o It should lead to lesser number of packets o It should lead to lesser bandwidth consumption It should not o lead to loss of information In case of time-based aggregation there may be a delay involved in getting the actual data. The minimum delay in this case will be the duration of the aggregation. The manager application is expected to configure aggregate MOs with care so that the response size is not too large. In case the resultant response size is larger than the maximum acceptable message size of the originator or larger than the local maximum message size then the error-status field will be set to "tooBig". 4. MIB Design. The basic principle has been to keep the MIB as simple as possible and at the same time to make it flexible enough so that a large number of users and applications can use the MIB to configure aggregate MOs conveniently. The MIB comprises of two tables described below. - The tAggrCtlTable controls the aggregation process. Each row in this table defines the attributes of aggregate object defined in the aggrMOTable. - The tAggrDataTable contains the details of the aggregated object The size of the table may be decided by implementations. Expires: February 6, 2003 [Page 6] Internet Draft July 14 2002 5. The Time Based Managed Object Aggregation MIB. TIME-AGGREGATE-MIB DEFINITIONS ::= BEGIN IMPORTS MODULE-IDENTITY, experimental, Integer32, OBJECT-TYPE, Opaque FROM SNMPv2-SMI OwnerString FROM RMON-MIB RowStatus, TEXTUAL-CONVENTION FROM SNMPv2-TC MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF SnmpAdminString FROM SNMP-FRAMEWORK-MIB; tAggrMIB MODULE-IDENTITY LAST-UPDATED "200207140000Z" -- 14th July 2002 ORGANIZATION "Cyber Solutions NetMan Working Group" CONTACT-INFO " Glenn Mansfield Postal: Cyber Solutions Inc. 6-6-3, Minami Yoshinari Aoba-ku, Sendai, Japan 989-3204. Tel: +81-22-303-4012 Fax: +81-22-303-4015 E-mail: glenn@cysols.com Support Group E-mail: mibsupport@cysols.com" DESCRIPTION " The MIB for servicing tAggregate objects." ::= { experimental 123 } -- will be assigned by IANA Expires: February 6, 2003 [Page 7] Internet Draft July 14 2002 TAggrMOErrorStatus ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "This data type is used to model the error status of the sampled MO instance. The error status for a sampled MO instance is given in terms of two elements - o the moIndex which indicates the sample number of the MO instance (starting at 1) in the value of the time aggregated MO instance. o the moError which indicates the error that was encountered in sampling that MO instance. The syntax in ASN.1 Notation will be ErrorStatus :: = SEQUENCE { moIndex Integer32, moError Integer32 } TAggrMOErrorStatus ::= SEQUENCE OF { ErrorStatus } Note: the command responder will supply values for all the samplings of the MO instance. If an error is encountered for a sample then the corresponding value will have an ASN.1 value NULL and, an error flagged in the corresponding TAggrMOErrorStatus object. Only MOs for which errors have been encountered will have the corresponding moIndex and moError values set. " SYNTAX Opaque (SIZE (0..1024)) TimeAggrMOValue ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "This data type is used to model the time aggregated MOs. It will be a sequence of values. The syntax in ASN.1 Notation will be MOValue :: = SEQUENCE { value ObjectSyntax } TimeAggrMOValue ::= SEQUENCE OF { MOSampleValue } Where, the first MOSampleValue will always be the timestamp of the first sample in the aggregated object. The subsequent values are the values of the MO instance sampled at the specified intervals for the specified number of times. Note: the command generator will need to know the the constituent Expires: February 6, 2003 [Page 8] Internet Draft July 14 2002 MO instance and the sampling interval to correctly interpret TimeAggrMOValue." SYNTAX Opaque (SIZE (0..1024)) CompressedTimeAggrMOValue ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "This data type is used to model the compressed tAggregate MOs. " SYNTAX Opaque (SIZE (0..1024)) -- -- The tAggregation control table -- There will be a row for each tAggregate MO -- tAggrCtlTable OBJECT-TYPE SYNTAX SEQUENCE OF TAggrCtlEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION " A table that controls the tAggregation of the MOs." ::= {tAggrMIB 1} tAggrCtlEntry OBJECT-TYPE SYNTAX TAggrCtlEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A row of the control table that defines one tAggregated MO." INDEX {tAggrEntryID } ::= {tAggrCtlTable 1 } Expires: February 6, 2003 [Page 9] Internet Draft July 14 2002 TAggrCtlEntry ::= SEQUENCE { tAggrEntryID SnmpAdminString, tAggrMOInstance OBJECT IDENTIFIER, tAggrAgMODescr SnmpAdminString, tAggrInterval Gauge32, tAggrSamples Gauge32, tAggrCompressionAlgorithm Integer32, tAggrEntryOwner OwnerString, tAggrEntryStatus RowStatus } tAggrEntryID OBJECT-TYPE SYNTAX SnmpAdminString (SIZE(1..32)) MAX-ACCESS read-only STATUS current DESCRIPTION " A locally-unique administratively assigned name for this aggregated MO. It is used as an index to uniquely identify this row in the table." ::= { tAggrCtlEntry 1 } tAggrMOInstance OBJECT-TYPE SYNTAX OBJECT IDENTIFIER MAX-ACCESS read-create STATUS current DESCRIPTION " The sampled values of this MO instance will be aggregated by the tAggrMOObject. " ::= { tAggrCtlEntry 2 } tAggrAgMODescr OBJECT-TYPE SYNTAX SnmpAdminString (SIZE(0..64)) MAX-ACCESS read-create STATUS current DESCRIPTION " A textual description of the aggregate object." ::= {tAggrCtlEntry 3} Expires: February 6, 2003 [Page 10] Internet Draft July 14 2002 tAggrInterval OBJECT-TYPE SYNTAX Gauge32 MAX-ACCESS read-create STATUS current DESCRIPTION " The interval at which the MO pointed at by tAaggrInstance, will be sampled for time-based aggregation." ::= {tAggrCtlEntry 4} tAggrSamples OBJECT-TYPE SYNTAX Gauge32 MAX-ACCESS read-create STATUS current DESCRIPTION " The number of times at which the MO pointed at by tAaggrInstance, will be sampled for time-based aggregation." ::= {tAggrCtlEntry 5} tAggrCompressionAlgorithm OBJECT-TYPE SYNTAX INTEGER { none (1) } MAX-ACCESS read-create STATUS current DESCRIPTION " The Compression algorithm that will be used by the agent to compress the tAggregated object." ::= {tAggrCtlEntry 6} tAggrEntryOwner OBJECT-TYPE SYNTAX OwnerString MAX-ACCESS read-create STATUS current DESCRIPTION " The entity that created this entry." ::= {tAggrCtlEntry 7} tAggrEntryStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-create STATUS current DESCRIPTION "The row status variable, used according to row installation and removal conventions." ::= {tAggrCtlEntry 8} Expires: February 6, 2003 [Page 11] Internet Draft July 14 2002 -- -- tAggrDataTable: The Table of Data. Each row represents a Data set. -- tAggrEntryID is the key to the table. -- of instances of the tAggregated MO that will be present in the table. -- tAggrDataTable OBJECT-TYPE SYNTAX SEQUENCE OF TAggrDataEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION " Each row of this table contains information about an tAggregateMO indexed by tAggrEntryID." ::= {tAggrMIB 2} tAggrDataEntry OBJECT-TYPE SYNTAX TAggrDataEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION " Entry containing information pertaining an tAggregate MO." INDEX {tAggrEntryID} ::= {tAggrDataTable 1 } TAggrDataEntry ::= SEQUENCE { tAggrDataRec TimeAggrMOValue, tAggrDataRecC CompressedTimeAggrMOValue } tAggrDataRec OBJECT-TYPE SYNTAX TimeAggrMOValue MAX-ACCESS read-only STATUS current DESCRIPTION "The snapshot value of the tAggregated MO." ::= { tAggrDataEntry 1} tAggrDataRecC OBJECT-TYPE SYNTAX CompressedTimeAggrMOValue MAX-ACCESS read-only STATUS current DESCRIPTION " The compressed value of the tAggregated MO." ::= { tAggrDataEntry 2} Expires: February 6, 2003 [Page 12] Internet Draft July 14 2002 -- Conformance information tAggrConformance OBJECT IDENTIFIER ::= { tAggrMIB 3 } tAggrGroups OBJECT IDENTIFIER ::= { tAggrConformance 1 } tAggrCompliances OBJECT IDENTIFIER ::= { tAggrConformance 2 } -- Compliance statements tAggrDataCompliance MODULE-COMPLIANCE STATUS current DESCRIPTION "The compliance statement for SNMP entities which implement the AGGREGATE-MIB." MODULE -- this module MANDATORY-GROUPS { tAggrDataGroup } ::= { tAggrCompliances 1 } -- Units of conformance tAggrDataGroup OBJECT-GROUP OBJECTS { tAggrEntryID, tAggrMOInstance, tAggrAgMODescr, tAggrInterval, tAggrSamples, tAggrCompressionAlgorithm, tAggrEntryOwner, tAggrEntryStatus, tAggrDataRec, tAggrDataRecC } STATUS current DESCRIPTION " A collection of objects for tAggregation of MOs." ::= { tAggrGroups 1 } END Expires: February 6, 2003 [Page 13] Internet Draft July 14 2002 6. Intellectual Property 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. 7. Acknowledgements This draft is the product of discussions and deliberations carried out in the WIDE-netman group and the IETF-EOS-WG. Expires: February 6, 2003 [Page 14] Internet Draft July 14 2002 References [ODC-Dft] Schoenwaelder, J. "SNMP Payload Compression", Work In Progress http://www.ietf.org/internet-drafts/internet-draft/draft-irtf- nmrg-snmp-compression-01.txt, April, 2001. [Aggr-Dft] Keeni G. "MO Aggregation MIB", Work in Progress http://www.cysol.co.jp/contrib/draft-glenn-mo-aggr-mib-02.txt July, 2002. [RFC2571] Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for Describing SNMP Management Frameworks", RFC 2571, April 1999 [RFC1155] Rose, M., and K. McCloghrie, "Structure and Identification of Management Information for TCP/IP-based Internets", STD 16, RFC 1155, May 1990 [RFC1212] Rose, M., and K. McCloghrie, "Concise MIB Definitions", STD 16, RFC 1212, March 1991 [RFC1215] M. Rose, "A Convention for Defining Traps for use with the SNMP", RFC 1215, March 1991 [RFC2578] 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 [RFC2579] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M., and S. Waldbusser, "Textual Conventions for SMIv2", STD 58, RFC 2579, April 1999 [RFC2580] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M., and S. Waldbusser, "Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999 [RFC1157] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple Network Management Protocol", STD 15, RFC 1157, May 1990. [RFC1901] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Introduction to Community-based SNMPv2", RFC 1901, January 1996. [RFC1906] 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. [RFC2572] Case, J., Harrington D., Presuhn R., and B. Wijnen, "Message Expires: February 6, 2003 [Page 15] Internet Draft July 14 2002 Processing and Dispatching for the Simple Network Management Protocol (SNMP)", RFC 2572, April 1999 [RFC2574] Blumenthal, U., and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", RFC 2574, April 1999 [RFC1905] 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. [RFC2573] Levi, D., Meyer, P., and B. Stewart, "SNMPv3 Applications", RFC 2573, April 1999 [RFC2575] Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based Access Control Model (VACM) for the Simple Network [RFC2570] Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction to Version 3 of the Internet-standard Network Management Framework", RFC 2570, April 1999 Expires: February 6, 2003 [Page 16] Internet Draft July 14 2002 Security Considerations There are management objects defined in this MIB that have a MAX- ACCESS clause of read-write and read-create. There is the risk that an intruder can alter or create any management objects of this MIB via direct SNMP SET operations. So, care must be taken to put in place the security provisions of SNMP for authentication and access control. Not all versions of SNMP provide features for such a secure environment. SNMPv1 by itself is such an insecure 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 (read) and SET (write) the objects in this MIB. It is strongly recommended that the implementors consider the security features as provided by the SNMPv3 framework. Specifically, the use of the User-based Security Model RFC 2274 [RFC2274] and the View-based Access Control Model RFC 2275 [RFC2275] 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 those objects only to those principals (users) that have legitimate rights to access them. Expires: February 6, 2003 [Page 17] Internet Draft July 14 2002 Authors' Addresses Glenn Mansfield Keeni Cyber Solutions Inc. 6-6-3 Minami Yoshinari Aoba-ku, Sendai 989-3204 Japan Phone: +81-22-303-4012 EMail: glenn@cysols.com Expires: February 6, 2003 [Page 18] Internet Draft July 14 2002 Full Copyright statement "Copyright (C) The Internet Society (date). All Rights Reserved. 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