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
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Copyright Notice
Copyright (C) The Internet Society (1999). All Rights Reserved.
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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
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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
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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.
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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 }
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--
-- 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
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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 }
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-- 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
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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.
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[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.
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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
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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."
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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
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