RFC4498
Network Working Group G. Keeni Request for Comments: 4498 Cyber Solutions Inc. Category: Experimental May 2006
The Managed Object Aggregation MIB
Status of This Memo
This memo defines an Experimental Protocol for the Internet community. It does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
IESG Note
The content of this RFC was at one time considered by the IETF, and therefore it may resemble a current IETF work in progress or a published IETF work. This RFC is not a candidate for any level of Internet Standard. The IETF disclaims any knowledge of the fitness of this RFC for any purpose and in particular notes that the decision to publish is not based on IETF review for such things as security, congestion control, or inappropriate interaction with deployed protocols. The RFC Editor has chosen to publish this document at its discretion. Readers of this RFC should exercise caution in evaluating its value for implementation and deployment. See RFC 3932 for more information.
Abstract
This memo defines a portion of the Management Information Base (MIB), the Aggregation MIB modules, for use with network management protocols in the Internet community. In particular, the Aggregation MIB modules will be used to configure a network management agent to aggregate the values of a user-specified set of Managed Object instances and to service queries related to the aggregated Managed Object instances.
Contents
The Internet-Standard Management Framework
For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of RFC 3410 RFC3410.
Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. MIB objects are generally accessed through the Simple Network Management Protocol (SNMP).
Objects in the MIB are defined using the mechanisms defined in the Structure of Management Information (SMI). This memo specifies a MIB module that is compliant to the SMIv2, which is described in STD 58, RFC 2578 RFC2578, STD 58, RFC 2579 RFC2579 and STD 58, RFC 2580 RFC2580.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119 RFC2119.
Background
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 termed a 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 instances of these SMOs, one or more times, to monitor the target entity.
There is a cost associated with accessing MOs. 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 MO instances 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 Figure 1. In this example, polling is carried out for 'n' Managed Object instances OID1, OID2, ..., OIDn. It is obvious that a substantial amount of the payload in an SNMP packet consists of the OIDs.
MO Aggregation: The Concept
In this document, a mechanism of MO aggregation for payload compression is defined. The idea is simple: we introduce the concept of an Aggregate MO (AgMO). An AgMO is just another MO as far as the SNMP protocol is concerned. No new protocol operations will be required to handle these MOs. As in the case of any other MO, it requires additional instrumentation at the command responder (agent) and at the (command generator) manager. In this mechanism, the user defines an Aggregate MO (AgMO) corresponding to one or more (predefined) MO instances. Semantically, the value of an AgMO instance will be equivalent to the concatenation of the values of the corresponding MO instances. The order of the concatenation will be determined by the order in which the MO instances are specified in the AgMO definition. With the definitions done, the user can, as and when the necessity arises, do an SNMP 'get' on instances of the AgMO to fetch the value of the constituent MO instances. There is substantial savings on bandwidth, as 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 responses. This is the basic concept of Aggregate Managed Objects. For every AgMO, an ErrorStatus Managed Object is defined. This MO indicates errors, if any, that have been encountered while fetching the values of the constituent MO instances. The error indication is comprised of the index of the MO instance and the corresponding error. If there are no errors, the ErrorStatus Managed Object instance will have a null value. This is the basic concept of Aggregate Managed Objects.
The concepts are explained in Figure 2. An aggregate managed object, AgMOx, has been defined for the MO instances MOI1, ... MOIn. The value of an instance of AgMOx will be a concatenation of the values of MOI1, ... MOIn, in that order.
Polling for MO Instances [MOI1, MOI2, ... MOIn]:
+--------+------+-------+... -+------+------+
Query: |Get req | MOI1 | NULL | | MOIn | NULL |
+--------+------+-------+... -+------+------+
+--------+------+-------+... -+------+------+
Response: |Get resp| MOI1 | Val1 | | MOIn | Valn |
+--------+------+-------+... -+------+------+
Figure 1. Polling for MO instances
Polling for an instance (AgMOIx) of an aggregate MO (AgMOx):
+--------+--------+-------+
Query: |Get req | AgMOIx | NULL |
+--------+--------+-------+
+--------+--------+------------------------+
Response: |Get resp| AgMOIx | Val1,Val2,...,Valn |
+--------+--------+------------------------+
Figure 2. MO aggregation
As 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 instance 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 desired number of samples that will be included in one TAgMO. The value of a TAgMO instance will include the timestamp (sysUpTime) at which the first sample was taken. The start time is not specified when the TAgMO is defined. Implementations may choose to align the start time with the appropriate time boundaries (e.g., seconds, minutes, hours). With the definitions, 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 aggregation.
Polling for 'n' samples of an MO Instance [MOI] at an interval 'i':
Query Time Response
===== ==== ========
+--------+-----+-----------+
|Get req | MOI | NULL | t
+--------+-----+-----------+ : +--------+-----+--------------+
: |Get resp| MOI | Val(t) |
: +--------+-----+--------------+
+--------+-----+-----------+ t+i
|Get req | MOI | NULL | :
+--------+-----+-----------+ : +--------+-----+--------------+
: |Get resp| MOI | Val(t+i) |
X +--------+-----+--------------+
X
:
+--------+-----+-----------+ t+(n-1)i
|Get req | MOI | NULL | :
+--------+-----+-----------+ : +--------+-----+--------------+
: |Get resp| MOI | Val(t+(n-1)i)|
+--------+-----+--------------+
Figure 3. Periodic polling for samples of an MO instance
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' microseconds}
+--------+---------+-------+
Query: |Get req | TAgMOIx | NULL |
+--------+---------+-------+
+--------+---------+--------------------------------------+
Response: |Get resp| TAgMOIx | t,Val(t),Val(t+i),.,Val(t + (n-1)*i) |
+--------+---------+--------------------------------------+
Figure 4. Time-Based aggregation
The TAgMO instance is a "bucket" of data representing the value of the corresponding MO instance sampled at 'i' microsecond intervals, 'n' times (i.e., over a 'n' X 'i' microsecond window). The TAgMO instance value gets updated at 'n' X 'i' microsecond intervals.
The Requirements for Managed Object Aggregation
The general requirements of managed object aggregation are as follows:
o It should lead to fewer packets. o It should lead to less bandwidth consumption. o It should not lead to loss of information.
In the case of Time-Based aggregation, there will 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 AgMOs (Aggregate MOs) and TAgMOs (Time-Based 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".
Note that an aggregate MO can be defined only when all the constituent MO instances of interest are known. This scheme cannot be employed if a manager/application does not know the specific MO instances (of interest) that are serviced by the management target. In such cases, the application may "discover" the MO instances of interest by some means, e.g., by "walking" through the MIB tree on the agent. According to the results of the "walk", the application can define an appropriate aggregate MO that will serve the purpose. Considering the cost involved in this exercise, this method is recommended only if the aggregate MO will be used repeatedly, so that the benefits of aggregation outweigh the costs of configuration.
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 that a large number of users and applications can use the MIB to configure aggregate MOs conveniently.
Two separate MIB modules have been defined. The AggrMIB supports the aggregation of independent MO instances, while TAggrMIB supports the aggregation of several samples of the same MO instance. Both of these MIB modules use the textual conventions defined in RMON-MIB RFC2819 and SNMP-FRAMEWORK-MIB RFC3411.
The AggrMIB is comprised of three tables, described below.
- The aggrCtlTable controls the aggregation process. Each row in
this table defines the attributes of the aggregate object defined in the aggrMOTable.
- The aggrMOTable defines the primary MO-based aggregation, i.e.,
the MOs that will be aggregated.
- The aggrDataTable contains the details of the aggregated object.
The TAggrMIB is comprised of two tables described below.
- The tAggrCtlTable controls the aggregation process. Each row in
this table defines the attributes of the aggregate object defined in the aggrMOTable.
- The tAggrDataTable contains the details of the aggregated object.
The Aggregation MIB Modules
AGGREGATE-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY, experimental, Unsigned32,
OBJECT-TYPE, Opaque
FROM SNMPv2-SMI
OwnerString
FROM RMON-MIB
RowStatus, StorageType, TEXTUAL-CONVENTION
FROM SNMPv2-TC
MODULE-COMPLIANCE, OBJECT-GROUP
FROM SNMPv2-CONF
SnmpAdminString
FROM SNMP-FRAMEWORK-MIB;
aggrMIB MODULE-IDENTITY
LAST-UPDATED "200604270000Z" -- 27th April, 2006
ORGANIZATION "Cyber Solutions Inc. NetMan Working Group"
CONTACT-INFO
" Glenn Mansfield Keeni
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: [email protected]
Support Group E-mail: [email protected]"
DESCRIPTION
"The MIB for servicing aggregate objects.
Copyright (C) The Internet Society (2006). This
version of this MIB module is part of RFC 4498;
see the RFC itself for full legal notices.
"
REVISION "200604270000Z" -- 27th April, 2006
DESCRIPTION "Initial version, published as RFC 4498."
::= { experimental 123 }
AggrMOErrorStatus ::= TEXTUAL-CONVENTION
STATUS current
DESCRIPTION
"This data type is used to model the error status of the
constituent MO instances. The error status for a
constituent MO instance is given in terms of two elements:
o The moIndex, which indicates the position of the MO
instance (starting at 1) in the value of the aggregated
MO instance.
o The moError, which indicates the error that was
encountered in fetching that MO instance.
The syntax in ASN.1 Notation will be
ErrorStatus :: = SEQUENCE {
moIndex Integer32,
moError SnmpPduErrorStatus
}
AggrMOErrorStatus ::= SEQUENCE OF {
ErrorStatus
}
Note1: The command responder will supply values for all
constituent MO instances, in the same order in
which the MO instances are specified for the AgMO.
If an error is encountered for an MO instance, then
the corresponding value will have an ASN.1 value NULL,
and an error will be flagged in the corresponding
AggrMOErrorStatus object.
Only MOs for which errors have been encountered will
have their corresponding moIndex and moError values
set.
Note2: The error code for the component MO instances will be
in accordance with the SnmpPduErrorStatus TC defined
in the DISMAN-SCHEDULE-MIB RFC3231.
Note3: The command generator will need to know
constituent MO instances and their order to correctly
interpret AggrMOErrorStatus.
"
SYNTAX Opaque (SIZE (0..1024))
AggrMOValue ::= TEXTUAL-CONVENTION
STATUS current
DESCRIPTION
"This data type is used to model the aggregate
MOs. It will have a format dependent on the constituent
MOs, a sequence of values. The syntax in ASN.1 Notation will
be
MOValue :: = SEQUENCE {
value ObjectSyntax
}
where 'value' is the value of a constituent MO instance.
AggrMOValue :: = SEQUENCE OF {
MOValue
}
Note: The command generator will need to know the
constituent MO instances and their order to
correctly interpret AggrMOValue."
SYNTAX Opaque (SIZE (0..1024))
AggrMOCompressedValue ::= TEXTUAL-CONVENTION
STATUS current
DESCRIPTION
"This data type is used to model the compressed
aggregate MOs."
SYNTAX OCTET STRING (SIZE (0..1024))
-- -- The aggregation control table -- There will be a row for each aggregate MO --
aggrCtlTable OBJECT-TYPE
SYNTAX SEQUENCE OF AggrCtlEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A table that controls the aggregation of the MOs."
::= {aggrMIB 1}
aggrCtlEntry OBJECT-TYPE
SYNTAX AggrCtlEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A row of the control table that defines one aggregated
MO.
Entries in this table are required to survive a reboot
of the managed entity depending on the value of the
corresponding aggrCtlEntryStorageType instance.
"
INDEX {aggrCtlEntryID }
::= {aggrCtlTable 1 }
AggrCtlEntry ::= SEQUENCE {
aggrCtlEntryID
SnmpAdminString,
aggrCtlMOIndex
Unsigned32,
aggrCtlMODescr
SnmpAdminString,
aggrCtlCompressionAlgorithm
INTEGER,
aggrCtlEntryOwner
OwnerString,
aggrCtlEntryStorageType
StorageType,
aggrCtlEntryStatus
RowStatus
}
aggrCtlEntryID OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE(1..32))
MAX-ACCESS not-accessible
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."
::= { aggrCtlEntry 1 }
aggrCtlMOIndex OBJECT-TYPE
SYNTAX Unsigned32 (1..2147483647)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"A pointer to a group of MOs identified by aggrMOEntryID
in the aggrMOTable. This is the group of MOs that will
be aggregated."
::= { aggrCtlEntry 2 }
aggrCtlMODescr OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE(0..64))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"A textual description of the object that is
being aggregated."
::= {aggrCtlEntry 3}
-- only one compression algorithm is defined as of now.
aggrCtlCompressionAlgorithm OBJECT-TYPE
SYNTAX INTEGER {
none (1),
deflate (2)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The compression algorithm that will be used by
the agent to compress the value of the aggregated
object.
The deflate algorithm and corresponding data format
specification is described in RFC 1951. It is
compatible with the widely used gzip utility.
"
REFERENCE
"RFC1951 : DEFLATE Compressed Data Format Specification
version 1.3
"
DEFVAL { none }
::= {aggrCtlEntry 4}
aggrCtlEntryOwner OBJECT-TYPE
SYNTAX OwnerString
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The entity that created this entry."
::= {aggrCtlEntry 5}
aggrCtlEntryStorageType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object defines whether the parameters defined in
this row are kept in volatile storage and lost upon
reboot or backed up by non-volatile (permanent)
storage.
Conceptual rows having the value 'permanent' need not
allow write-access to any columnar objects in the row.
"
::= {aggrCtlEntry 6}
aggrCtlEntryStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The row status variable, used according to row
installation and removal conventions.
Objects in a row can be modified only when the value of
this object in the corresponding conceptual row is not
'active'.
Thus, to modify one or more of the objects in this
conceptual row,
a. change the row status to 'notInService',
b. change the values of the row, and
c. change the row status to 'active'.
The aggrCtlEntryStatus may be changed to 'active' if
all the MOs in the conceptual row have been assigned
valid values.
"
::= {aggrCtlEntry 7}
-- -- The Table of primary(simple) MOs --
aggrMOTable OBJECT-TYPE
SYNTAX SEQUENCE OF AggrMOEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The table of primary(simple) MOs that will be aggregated.
Each row in this table represents a MO that will be
aggregated. The aggrMOEntryID index is used to identify
the group of MOs that will be aggregated. The
aggrMOIndex instance in the corresponding row of the
aggrCtlTable will have a value equal to the value of
aggrMOEntryID. The aggrMOEntryMOID index is used to
identify an MO in the group.
"
::= {aggrMIB 2}
aggrMOEntry OBJECT-TYPE
SYNTAX AggrMOEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A row of the table that specifies one MO.
Entries in this table are required to survive a reboot
of the managed entity depending on the value of the
corresponding aggrMOEntryStorageType instance.
"
INDEX { aggrMOEntryID, aggrMOEntryMOID }
::= {aggrMOTable 1 }
AggrMOEntry ::= SEQUENCE {
aggrMOEntryID
Unsigned32,
aggrMOEntryMOID
Unsigned32,
aggrMOInstance
OBJECT IDENTIFIER,
aggrMODescr
SnmpAdminString,
aggrMOEntryStorageType
StorageType,
aggrMOEntryStatus
RowStatus
}
aggrMOEntryID OBJECT-TYPE
SYNTAX Unsigned32 (1..2147483647)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An index uniquely identifying a group of MOs
that will be aggregated."
::= { aggrMOEntry 1 }
aggrMOEntryMOID OBJECT-TYPE
SYNTAX Unsigned32 (1..65535)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An index to uniquely identify an MO instance in the
group of MO instances that will be aggregated."
::= { aggrMOEntry 2 }
aggrMOInstance OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The OID of the MO instance, the value of which will
be sampled by the agent."
::= { aggrMOEntry 3 }
aggrMODescr OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE(0..64))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"A textual description of the object that will
be aggregated."
::= {aggrMOEntry 4}
aggrMOEntryStorageType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object defines whether the parameters defined in
this row are kept in volatile storage and lost upon
reboot or backed up by non-volatile (permanent)
storage.
Conceptual rows having the value 'permanent' need not
allow write-access to any columnar objects in the row.
"
::= {aggrMOEntry 5}
aggrMOEntryStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The row status variable, used according to row
installation and removal conventions.
Objects in a row can be modified only when the value of
this object in the corresponding conceptual row is not
'active'.
Thus, to modify one or more of the objects in this
conceptual row,
a. change the row status to 'notInService',
b. change the values of the row, and
c. change the row status to 'active'.
The aggrMOEntryStatus may be changed to 'active' iff
all the MOs in the conceptual row have been assigned
valid values.
"
::= {aggrMOEntry 6}
-- -- aggrDataTable: The Table of Data. Each row represents a Data
-- set. aggrCtlEntryID is the key to the table.
-- It is used to identify instances of the
-- aggregated MO that are present in the table.
--
aggrDataTable OBJECT-TYPE
SYNTAX SEQUENCE OF AggrDataEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Each row of this table contains information
about an aggregateMO indexed by aggrCtlEntryID."
::= {aggrMIB 3}
aggrDataEntry OBJECT-TYPE
SYNTAX AggrDataEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Entry containing information pertaining to
an aggregate MO."
INDEX {aggrCtlEntryID}
::= {aggrDataTable 1 }
AggrDataEntry ::= SEQUENCE {
aggrDataRecord
AggrMOValue,
aggrDataRecordCompressed
AggrMOCompressedValue,
aggrDataErrorRecord
AggrMOErrorStatus
}
aggrDataRecord OBJECT-TYPE
SYNTAX AggrMOValue
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The snapshot value of the aggregated MO.
Note that the access privileges to this object will be
governed by the access privileges of the component
objects. Thus, an entity attempting to access an
instance of this MO MUST have access rights to all the
component instance objects and this MO instance.
"
::= { aggrDataEntry 1}
aggrDataRecordCompressed OBJECT-TYPE
SYNTAX AggrMOCompressedValue
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The compressed value of the aggregated MO.
The compression algorithm will depend on the
aggrCtlCompressionAlgorithm given in the corresponding
aggrCtlEntry. If the value of the corresponding
aggrCtlCompressionAlgorithm is (1) 'none', then the value
of all instances of this object will be a string of zero
length.
Note that the access privileges to this object will be
governed by the access privileges of the component
objects. Thus, an entity attempting to access an instance
of this MO MUST have access rights to all the component
instance objects and this MO instance.
"
::= { aggrDataEntry 2}
aggrDataErrorRecord OBJECT-TYPE
SYNTAX AggrMOErrorStatus
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The error status corresponding to the MO instances
aggregated in aggrDataRecord (and
aggrDataRecordCompressed)."
::= { aggrDataEntry 3}
-- Conformance information
aggrConformance OBJECT IDENTIFIER ::= { aggrMIB 4 }
aggrGroups OBJECT IDENTIFIER ::= { aggrConformance 1 }
aggrCompliances OBJECT IDENTIFIER ::= { aggrConformance 2 }
-- Compliance statements
aggrMibCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMP entities
that implement the AGGREGATE-MIB."
MODULE -- this module
MANDATORY-GROUPS { aggrMibBasicGroup }
::= { aggrCompliances 1 }
-- Units of conformance
aggrMibBasicGroup OBJECT-GROUP
OBJECTS {
aggrCtlMOIndex,
aggrCtlMODescr,
aggrCtlCompressionAlgorithm,
aggrCtlEntryOwner,
aggrCtlEntryStorageType,
aggrCtlEntryStatus,
aggrMOInstance,
aggrMODescr,
aggrMOEntryStorageType,
aggrMOEntryStatus,
aggrDataRecord,
aggrDataRecordCompressed,
aggrDataErrorRecord
}
STATUS current
DESCRIPTION
"A collection of objects for aggregation of MOs."
::= { aggrGroups 1 }
END
TIME-AGGREGATE-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY, experimental,
OBJECT-TYPE, Opaque, Integer32
FROM SNMPv2-SMI
OwnerString
FROM RMON-MIB
RowStatus, StorageType, TEXTUAL-CONVENTION
FROM SNMPv2-TC
MODULE-COMPLIANCE, OBJECT-GROUP
FROM SNMPv2-CONF
SnmpAdminString
FROM SNMP-FRAMEWORK-MIB;
tAggrMIB MODULE-IDENTITY
LAST-UPDATED "200604270000Z" -- 27 April 2006
ORGANIZATION "Cyber Solutions Inc. NetMan Working Group"
CONTACT-INFO
" Glenn Mansfield Keeni
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: [email protected]
Support Group E-mail: [email protected]"
DESCRIPTION
"The MIB for servicing Time-Based aggregate
objects.
Copyright (C) The Internet Society (2006). This
version of this MIB module is part of RFC 4498;
see the RFC itself for full legal notices.
"
REVISION "200604270000Z" -- 27th April, 2006
DESCRIPTION "Initial version, published as RFC 4498."
::= { experimental 124 }
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 SnmpPduErrorStatus
}
TAggrMOErrorStatus ::= SEQUENCE OF {
ErrorStatus
}
Note1: The command responder will supply values for all
the samples 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
will be flagged in the corresponding
TAggrMOErrorStatus object.
Only MOs for which errors have been encountered will
the corresponding moIndex and moError values be set.
Note2: The error code for the component MO instances will be
in accordance with the SnmpPduErrorStatus TC defined
in the DISMAN-SCHEDULE-MIBRFC3231.
"
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
MOSampleValue :: = SEQUENCE {
value ObjectSyntax
}
TimeAggrMOValue ::= SEQUENCE OF {
MOSampleValue
}
where the first MOSampleValue, if any, 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
constituent 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
TAgMOs."
SYNTAX Opaque (SIZE (0..1024))
-- -- The Time-Based aggregation control table --
tAggrCtlTable OBJECT-TYPE
SYNTAX SEQUENCE OF TAggrCtlEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The Time-Based aggregation control table. It controls
the aggregation of the samples of MO instances. There
will be a row for each TAgMO.
"
::= {tAggrMIB 1}
tAggrCtlEntry OBJECT-TYPE
SYNTAX TAggrCtlEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A row of the control table that defines one Time-Based
aggregate MO (TAgMO)."
INDEX {tAggrCtlEntryID }
::= {tAggrCtlTable 1 }
TAggrCtlEntry ::= SEQUENCE {
tAggrCtlEntryID
SnmpAdminString,
tAggrCtlMOInstance
OBJECT IDENTIFIER,
tAggrCtlAgMODescr
SnmpAdminString,
tAggrCtlInterval
Integer32,
tAggrCtlSamples
Integer32,
tAggrCtlCompressionAlgorithm
INTEGER,
tAggrCtlEntryOwner
OwnerString,
tAggrCtlEntryStorageType
StorageType,
tAggrCtlEntryStatus
RowStatus
}
tAggrCtlEntryID OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE(1..32))
MAX-ACCESS not-accessible
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 }
tAggrCtlMOInstance OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The sampled values of this MO instance will be
aggregated by the TAgMO.
"
::= { tAggrCtlEntry 2 }
tAggrCtlAgMODescr OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE(0..64))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"A textual description of the aggregate object."
::= {tAggrCtlEntry 3}
tAggrCtlInterval OBJECT-TYPE
SYNTAX Integer32
UNITS "micro seconds"
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The interval, in microseconds, at which the MO instance
pointed at by tAggrInstance will be sampled for
Time-Based aggregation.
"
::= {tAggrCtlEntry 4}
tAggrCtlSamples OBJECT-TYPE
SYNTAX Integer32
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The number of times at which the MO instance referred
to by tAggrInstance will be sampled for Time-Based
aggregation."
::= {tAggrCtlEntry 5}
-- only one compression algorithm is defined as of now.
tAggrCtlCompressionAlgorithm OBJECT-TYPE
SYNTAX INTEGER {
none (1),
deflate (2)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The compression algorithm that will be used by
the agent to compress the value of the TAgMO.
The deflate algorithm and corresponding data format
specification is described in RFC 1951. It is
compatible with the widely used gzip utility.
"
REFERENCE
"RFC1951 : DEFLATE Compressed Data Format Specification
version 1.3
"
DEFVAL { none }
::= {tAggrCtlEntry 6}
tAggrCtlEntryOwner OBJECT-TYPE
SYNTAX OwnerString
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"A textual description of the entity that created
this entry.
"
::= {tAggrCtlEntry 7}
tAggrCtlEntryStorageType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object defines whether the parameters defined in
this row are kept in volatile storage and lost upon
reboot or backed up by non-volatile (permanent)
storage.
Conceptual rows having the value 'permanent' need not
allow write-access to any columnar objects in the row.
"
::= {tAggrCtlEntry 8}
tAggrCtlEntryStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The row status variable, used according to row
installation and removal conventions.
Objects in a row can be modified only when the value of
this object in the corresponding conceptual row is not
'active'.
Thus, to modify one or more of the objects in this
conceptual row,
a. change the row status to 'notInService',
b. change the values of the row, and
c. change the row status to 'active'.
The tAggrCtlEntryStatus may be changed to 'active' iff
all the MOs in the conceptual row have been assigned
valid values.
"
::= {tAggrCtlEntry 9}
--
-- tAggrDataTable: The data table.
--
tAggrDataTable OBJECT-TYPE
SYNTAX SEQUENCE OF TAggrDataEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This is the data table. Each row of this table contains
information about a TAgMO indexed by tAggrCtlEntryID.
tAggrCtlEntryID is the key to the table. It is used to
identify instances of the TAgMO that are present in the
table.
"
::= {tAggrMIB 2}
tAggrDataEntry OBJECT-TYPE
SYNTAX TAggrDataEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Entry containing information pertaining
to a TAgMO."
INDEX {tAggrCtlEntryID}
::= {tAggrDataTable 1 }
TAggrDataEntry ::= SEQUENCE {
tAggrDataRecord
TimeAggrMOValue,
tAggrDataRecordCompressed
CompressedTimeAggrMOValue,
tAggrDataErrorRecord
TAggrMOErrorStatus
}
tAggrDataRecord OBJECT-TYPE
SYNTAX TimeAggrMOValue
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The snapshot value of the TAgMO."
::= { tAggrDataEntry 1}
tAggrDataRecordCompressed OBJECT-TYPE
SYNTAX CompressedTimeAggrMOValue
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The compressed value of the TAgMO.
The compression algorithm will depend on the
tAggrCtlCompressionAlgorithm given in the corresponding
tAggrCtlEntry. If the value of the corresponding
tAggrCtlCompressionAlgorithm is (1) 'none', then the
value of all instances of this object will be a string
of zero length.
Note that the access privileges to this object will be
governed by the access privileges of the corresponding MO
instance. Thus, an entity attempting to access an
instance of this MO MUST have access rights to the
instance object pointed at by tAggrCtlMOInstance and this
MO instance.
"
::= { tAggrDataEntry 2}
tAggrDataErrorRecord OBJECT-TYPE
SYNTAX TAggrMOErrorStatus
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The error status corresponding to the MO instance
samples aggregated in tAggrDataRecord (and
tAggrDataRecordCompressed)."
::= { tAggrDataEntry 3}
-- Conformance information
tAggrConformance OBJECT IDENTIFIER ::= { tAggrMIB 3 }
tAggrGroups OBJECT IDENTIFIER ::= { tAggrConformance 1 }
tAggrCompliances OBJECT IDENTIFIER ::= { tAggrConformance 2 }
-- Compliance statements
tAggrMibCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMP entities
that implement the TIME-AGGREGATE-MIB."
MODULE -- this module
MANDATORY-GROUPS { tAggrMibBasicGroup }
::= { tAggrCompliances 1 }
-- Units of conformance
tAggrMibBasicGroup OBJECT-GROUP
OBJECTS {
tAggrCtlMOInstance,
tAggrCtlAgMODescr,
tAggrCtlInterval,
tAggrCtlSamples,
tAggrCtlCompressionAlgorithm,
tAggrCtlEntryOwner,
tAggrCtlEntryStorageType,
tAggrCtlEntryStatus,
tAggrDataRecord,
tAggrDataRecordCompressed,
tAggrDataErrorRecord
}
STATUS current
DESCRIPTION
"A collection of objects for Time-Based aggregation
of MOs."
::= { tAggrGroups 1 }
END
Security Considerations
There are management objects in the MIB modules defined in this document that have a MAX-ACCESS clause of 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. The objects and corresponding vulnerabilities are discussed below.
The following MOs are used to configure an agent that implements the aggregate MIB modules.
aggrCtlMOIndex,
aggrCtlMODescr,
aggrCtlCompressionAlgorithm,
aggrCtlEntryOwner,
aggrCtlEntryStorageType,
aggrCtlEntryStatus,
aggrMOInstance,
aggrMODescr,
aggrMOEntryStorageType,
aggrMOEntryStatus,
tAggrCtlMOInstance,
tAggrCtlAgMODescr,
tAggrCtlInterval,
tAggrCtlSamples,
tAggrCtlCompressionAlgorithm,
tAggrCtlEntryOwner,
tAggrCtlEntryStorageType,
tAggrCtlEntryStatus,
Access to these objects may be abused to affect the operation of the data collection system. In particular,
- by changing the value of an instance of aggrCtlEntryStatus,
tAggrCtlEntryStatus, aggrMOEntryStatus, or tAggrMOEntryStatus
to 'notInService' or 'destroy', the data aggregation operation
for the corresponding entry will become unavailable to the
management system.
- by changing the value of an instance of aggrMOInstance or
tAggrCtlMOInstance, the data aggregation operation may be
subverted. This may result in wrong information being fed to
the management system.
- by adding several rows in the aggrMOTable corresponding to an
aggregate MO, it is possible to make the value of the aggregate
MOs very large. A similar effect may be achieved by
manipulating the value of the tAggrCtlSamples instance
corresponding to a Time-Based aggregate MO. This could result
in very heavy management traffic and/or fragmentation of
response packets. In some cases the responder may refuse to
send the data and will simply respond with an error message
indicating that the response packet size is too big.
An entity attempting to access an instance of an aggregated MO MUST have access rights to all the component instance objects and the aggregate MO instance. An implementation MUST follow this requirement. Lax adherence to this requirement will breach the security model and make the system vulnerable to illegal accesses.
SNMP versions prior to SNMPv3 did not include adequate security. Even if the network itself is secure (for example by using IPSec), 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 module.
It is RECOMMENDED that implementers consider the security features as provided by the SNMPv3 framework (see RFC3410, section 8), including full support for the SNMPv3 cryptographic mechanisms (for authentication and privacy).
Further, deployment of SNMP versions prior to SNMPv3 is NOT RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to enable cryptographic security. It is then a customer/operator responsibility to ensure that the SNMP entity giving access to an instance of this MIB module 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.
IANA Considerations
The MIB modules in this document use the following IANA-assigned OBJECT IDENTIFIER values, recorded in the SMI Numbers registry:
Descriptor OBJECT IDENTIFIER value
-----------------------
aggrMIB { experimental 123 } tAggrMIB { experimental 124 }
References
Normative References
RFC2119 Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
RFC2578 McCloghrie, K., Perkins, D., and J. Schoenwaelder,
"Structure of Management Information Version 2 (SMIv2)",
STD 58, RFC 2578, April 1999.
RFC2579 McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Textual
Conventions for SMIv2", STD 58, RFC 2579, April 1999.
RFC2580 McCloghrie, K., Perkins, D., and J. Schoenwaelder,
"Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999.
RFC2819 Waldbusser, S., "Remote Network Monitoring Management
Information Base", STD 59, RFC 2819, May 2000.
RFC3411 Harrington, D., Presuhn, R., and B. Wijnen, "An
Architecture for Describing Simple Network Management
Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
December 2002.
RFC3231 Levi, D. and J. Schoenwaelder, "Definitions of Managed
Objects for Scheduling Management Operations", RFC 3231, January 2002.
RFC1951 Deutsch, P., "DEFLATE Compressed Data Format Specification
version 1.3", RFC 1951, May 1996.
Informative References
RFC3410 Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for Internet-
Standard Management Framework", RFC 3410, December 2002.
10. Acknowledgements
This document is the product of discussions and deliberations carried out in the WIDE-netman group. Bert Wijnen and Glenn Waters reviewed the document and provided valuable comments.
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: [email protected]
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