Network Working Group Keith McCloghrie Internet Draft Cisco Systems Gary Hanson ADC Kentrox 24 January 1999 The Inverted Stack Table Extension to the Interfaces Group MIB draft-ietf-ifmib-invstackmib-01.txt Status of this Memo This document is an Internet-Draft. 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.'' To learn the current status of any Internet-Draft, please check the ``1id-abstracts.txt'' listing contained in the Internet- Drafts Shadow Directories on ftp.ietf.org (US East Coast), nic.nordu.net (Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). Copyright Notice Copyright (C) The Internet Society (1999). All Rights Reserved. Expires July 1999 [Page 1] Internet Draft Inverted Stack Extension MIB January 99 1. Introduction This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it describes managed objects which provide an inverted mapping of the interface stack table used for managing network interfaces. 2. The SNMP Network Management Framework The SNMP Management Framework presently consists of five major components: o An overall architecture, described in RFC 2271 [1]. 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 RFC 1155 [2], RFC 1212 [3] and RFC 1215 [4]. The second version, called SMIv2, is described in RFC 1902 [5], RFC 1903 [6] and RFC 1904 [7]. o Message protocols for transferring management information. The first version of the SNMP message protocol is called SNMPv1 and described in RFC 1157 [8]. A second version of the SNMP message protocol, which is not an Internet standards track protocol, is called SNMPv2c and described in RFC 1901 [9] and RFC 1906 [10]. The third version of the message protocol is called SNMPv3 and described in RFC 1906 [10], RFC 2272 [11] and RFC 2274 [12]. o Protocol operations for accessing management information. The first set of protocol operations and associated PDU formats is described in RFC 1157 [8]. A second set of protocol operations and associated PDU formats is described in RFC 1905 [13]. o A set of fundamental applications described in RFC 2273 [14] and the view-based access control mechanism described in RFC 2275 [15]. 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 Expires July 1999 [Page 2] Internet Draft Inverted Stack Extension MIB January 99 translations. The resulting translated MIB must be semantically equivalent, except where objects or events are omitted because no translation is possible (e.g., 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 MIB. 3. Interface Sub-Layers and the ifStackTable MIB-II [16] defines objects for managing network interfaces by providing a generic interface definition together with the ability to define media-specific extensions. The generic objects are known as the 'interfaces' group. Experience in defining media-specific extensions showed the need to distinguish between the multiple sub-layers beneath the internetwork- layer. Consider, for example, an interface with PPP running over an HDLC link which uses a RS232-like connector. Each of these sub-layers has its own media-specific MIB module. RFC xxxx [17], the latest definition of the 'interfaces' group, satisfies this need by having each sub-layer be represented by its own conceptual row in the ifTable. It also defines an additional MIB table, the ifStackTable, to identify the "superior" and "subordinate" sub- layers through ifIndex "pointers" to the appropriate conceptual rows in the ifTable. Each conceptual row in the ifStackTable represents a relationship between two interfaces, where this relationship is that the "higher- layer" interface runs "on top" of the "lower-layer" interface. For example, if a PPP module operated directly over a serial interface, the PPP module would be a "higher layer" to the serial interface, and the serial interface would be a "lower layer" to the PPP module. This concept of "higher-layer" and "lower-layer" is the same as embodied in the definitions of the ifTable's packet counters. The ifStackTable is INDEX-ed by the ifIndex values of the two interfaces involved in the relationship. By necessity, one of these ifIndex values must come first, and RFC xxxx chose to have the higher-layer interface first, and the lower-layer interface second. Due to this, it is straight-forward for a Network Management application to read a subset of the ifStackTable and thereby determine the interfaces which run Expires July 1999 [Page 3] Internet Draft Inverted Stack Extension MIB January 99 underneath a particular interface. However, to determine which interfaces run on top of a particular interface, a Network Management application has no alternative but to read the whole table. This is very inefficient when querying a device which has many interfaces, and many conceptual rows in its ifStackTable. This MIB provides an inverted Interfaces Stack Table, the ifInvStackTable. While it contains no additional information beyond that already contained in the ifStackTable, the ifInvStackTable has the ifIndex values in its INDEX clause in the reverse order, i.e., the lower-layer interface first, and the higher-layer interface second. As a result, the ifInvStackTable is an inverted version of the same information contained in the ifStackTable. Thus, the ifInvStackTable provides an efficient means for a Network Management application to read a subset of the ifStackTable and thereby determine which interfaces run on top of a particular interface. Expires July 1999 [Page 4] Internet Draft Inverted Stack Extension MIB January 99 4. Definitions IF-INVERTED-STACK-MIB DEFINITIONS ::= BEGIN IMPORTS MODULE-IDENTITY, OBJECT-TYPE, mib-2 FROM SNMPv2-SMI RowStatus FROM SNMPv2-TC MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF ifStackHigherLayer, ifStackLowerLayer FROM IF-MIB; ifInvertedStackMIB MODULE-IDENTITY LAST-UPDATED "9807161200Z" ORGANIZATION "IETF Interfaces MIB Working Group" CONTACT-INFO " Keith McCloghrie Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 US 408-526-5260 kzm@cisco.com" DESCRIPTION "The MIB module which provides the Inverted Stack Table for interface sub-layers." REVISION "9807161200Z" DESCRIPTION "Initial revision." ::= { mib-2 xx } ifInvMIBObjects OBJECT IDENTIFIER ::= { ifInvertedStackMIB 1 } Expires July 1999 [Page 5] Internet Draft Inverted Stack Extension MIB January 99 -- -- The Inverted Interface Stack Group -- ifInvStackTable OBJECT-TYPE SYNTAX SEQUENCE OF IfInvStackEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A table containing information on the relationships between the multiple sub-layers of network interfaces. In particular, it contains information on which sub-layers run 'underneath' which other sub-layers, where each sub-layer corresponds to a conceptual row in the ifTable. For example, when the sub-layer with ifIndex value x runs underneath the sub-layer with ifIndex value y, then this table contains: ifInvStackStatus.x.y=active For each ifIndex value, z, which identifies an active interface, there are always at least two instantiated rows in this table associated with z. For one of these rows, z is the value of ifStackHigherLayer; for the other, z is the value of ifStackLowerLayer. (If z is not involved in multiplexing, then these are the only two rows associated with z.) For example, two rows exist even for an interface which has no others stacked on top or below it: ifInvStackStatus.z.0=active ifInvStackStatus.0.z=active This table contains exactly the same number of rows as the ifStackTable, but the rows appear in a different order." REFERENCE "ifStackTable of RFC xxxx" ::= { ifInvMIBObjects 1 } ifInvStackEntry OBJECT-TYPE SYNTAX IfInvStackEntry MAX-ACCESS not-accessible STATUS current Expires July 1999 [Page 6] Internet Draft Inverted Stack Extension MIB January 99 DESCRIPTION "Information on a particular relationship between two sub- layers, specifying that one sub-layer runs underneath the other sub-layer. Each sub-layer corresponds to a conceptual row in the ifTable." INDEX { ifStackLowerLayer, ifStackHigherLayer } ::= { ifInvStackTable 1 } IfInvStackEntry ::= SEQUENCE { ifInvStackStatus RowStatus } ifInvStackStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-only STATUS current DESCRIPTION "The status of the relationship between two sub-layers. An instance of this object exists for each instance of the ifStackStatus object, and vice versa. For example, if the variable ifStackStatus.H.L exists, then the variable ifInvStackStatus.L.H must also exist, and vice versa. In addition, the two variables always have the same value. However, unlike ifStackStatus, the ifInvStackStatus object is NOT write-able. A network management application wishing to change a relationship between sub-layers H and L cannot do so by modifying the value of ifInvStackStatus.L.H, but must instead modify the value of ifStackStatus.H.L. After the ifStackTable is modified, the change will be reflected in this table." ::= { ifInvStackEntry 1 } Expires July 1999 [Page 7] Internet Draft Inverted Stack Extension MIB January 99 -- conformance information ifInvConformance OBJECT IDENTIFIER ::= { ifInvMIBObjects 2 } ifInvGroups OBJECT IDENTIFIER ::= { ifInvConformance 1 } ifInvCompliances OBJECT IDENTIFIER ::= { ifInvConformance 2 } -- compliance statements ifInvCompliance MODULE-COMPLIANCE STATUS current DESCRIPTION "The compliance statement for SNMPv2 entities which provide inverted information on the layering of network interfaces." MODULE -- this module MANDATORY-GROUPS { ifInvStackGroup } ::= { ifInvCompliances 1 } -- units of conformance ifInvStackGroup OBJECT-GROUP OBJECTS { ifInvStackStatus } STATUS current DESCRIPTION "A collection of objects providing inverted information on the layering of MIB-II interfaces." ::= { ifInvGroups 1 } END Expires July 1999 [Page 8] Internet Draft Inverted Stack Extension MIB January 99 5. Acknowledgements This memo has been produced by the IETF's Interfaces MIB working-group. 6. References [1] Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for Describing SNMP Management Frameworks", RFC 2271, Cabletron Systems, Inc., BMC Software, Inc., IBM T. J. Watson Research, January 1998 [2] Rose, M., and K. McCloghrie, "Structure and Identification of Management Information for TCP/IP-based Internets", RFC 1155, Performance Systems International, Hughes LAN Systems, May 1990 [3] Rose, M., and K. McCloghrie, "Concise MIB Definitions", RFC 1212, Performance Systems International, Hughes LAN Systems, March 1991 [4] M. Rose, "A Convention for Defining Traps for use with the SNMP", RFC 1215, Performance Systems International, March 1991 [5] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Structure of Management Information for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1902, SNMP Research,Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc., International Network Services, January 1996. [6] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Textual Conventions for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1903, SNMP Research, Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc., International Network Services, January 1996. [7] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Conformance Statements for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1904, SNMP Research, Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc., International Network Services, January 1996. [8] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple Network Management Protocol", RFC 1157, SNMP Research, Performance Systems International, Performance Systems International, MIT Laboratory for Computer Science, May 1990. Expires July 1999 [Page 9] Internet Draft Inverted Stack Extension MIB January 99 [9] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Introduction to Community-based SNMPv2", RFC 1901, SNMP Research, Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc., International Network Services, January 1996. [10] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Transport Mappings for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1906, SNMP Research, Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc., International Network Services, January 1996. [11] Case, J., Harrington D., Presuhn R., and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", RFC 2272, SNMP Research, Inc., Cabletron Systems, Inc., BMC Software, Inc., IBM T. J. Watson Research, January 1998. [12] Blumenthal, U., and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", RFC 2274, IBM T. J. Watson Research, January 1998. [13] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Protocol Operations for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1905, SNMP Research, Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc., International Network Services, January 1996. [14] Levi, D., Meyer, P., and B. Stewart, MPv3 Applications", RFC 2273, SNMP Research, Inc., Secure Computing Corporation, Cisco Systems, January 1998. [15] Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP)", RFC 2275, IBM T. J. Watson Research, BMC Software, Inc., Cisco Systems, Inc., January 1998. [16] McCloghrie, K., and M. Rose, "Management Information Base for Network Management of TCP/IP-based internets - MIB-II", RFC 1213, Hughes LAN Systems, Performance Systems International, March 1991. [17] McCloghrie, K., and F. Kastenholz, "The Interface Group MIB", Internet Draft, Cisco Systems, Argon Networks, July 1998. Expires July 1999 [Page 10] Internet Draft Inverted Stack Extension MIB January 99 7. Security Considerations This MIB contains only readable objects whose values provide little information of value to a would-be attacker. 8. Authors' Addresses Keith McCloghrie Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 Phone: 408-526-5260 Email: kzm@cisco.com" Gary Hanson ADC Kentrox 14375 NW Science Park Drive Portland, Oregon, 97229 Phone: (800)733-5511 x6333 Email: gary@kentrox.com Expires July 1999 [Page 11] Internet Draft Inverted Stack Extension MIB January 99 9. Full Copyright Statement Copyright (C) The Internet Society (1998). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." Expires July 1999 [Page 12] Internet Draft Inverted Stack Extension MIB January 99 Table of Contents 1 Introduction .................................................... 2 2 The SNMP Network Management Framework ........................... 2 3 Interface Sub-Layers and the ifStackTable ....................... 3 4 Definitions ..................................................... 5 5 Acknowledgements ................................................ 9 6 References ...................................................... 9 7 Security Considerations ......................................... 11 8 Authors' Addresses .............................................. 11 9 Full Copyright Statement ........................................ 12 Expires July 1999 [Page 13]