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✏️ Editing: SNMPv2-TC.txt

SNMPv2-TC DEFINITIONS ::= BEGIN

IMPORTS
    TimeTicks         FROM SNMPv2-SMI;

-- definition of textual conventions

TEXTUAL-CONVENTION MACRO ::=

BEGIN
    TYPE NOTATION ::=
                  DisplayPart
                  "STATUS" Status
                  "DESCRIPTION" Text
                  ReferPart
                  "SYNTAX" Syntax

VALUE NOTATION ::=
                   value(VALUE Syntax)      -- adapted ASN.1

DisplayPart ::=
                  "DISPLAY-HINT" Text
                | empty

Status ::=
                  "current"
                | "deprecated"
                | "obsolete"

ReferPart ::=
                  "REFERENCE" Text
                | empty

-- a character string as defined in [2]
    Text ::= value(IA5String)

Syntax ::=   -- Must be one of the following:
                       -- a base type (or its refinement), or
                       -- a BITS pseudo-type
                  type
                | "BITS" "{" NamedBits "}"

NamedBits ::= NamedBit
                | NamedBits "," NamedBit

NamedBit ::=  identifier "(" number ")" -- number is nonnegative

END

DisplayString ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "255a"
    STATUS       current
    DESCRIPTION
            "Represents textual information taken from the NVT ASCII

character set, as defined in pages 4, 10-11 of RFC 854.

To summarize RFC 854, the NVT ASCII repertoire specifies:

- the use of character codes 0-127 (decimal)

- the graphics characters (32-126) are interpreted as
                US ASCII

- NUL, LF, CR, BEL, BS, HT, VT and FF have the special
                meanings specified in RFC 854

- the other 25 codes have no standard interpretation

- the sequence 'CR LF' means newline

- the sequence 'CR NUL' means carriage-return

- an 'LF' not preceded by a 'CR' means moving to the
                same column on the next line.

- the sequence 'CR x' for any x other than LF or NUL is
                illegal.  (Note that this also means that a string may
                end with either 'CR LF' or 'CR NUL', but not with CR.)

Any object defined using this syntax may not exceed 255
            characters in length."
    SYNTAX       OCTET STRING (SIZE (0..255))

PhysAddress ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "1x:"
    STATUS       current
    DESCRIPTION
            "Represents media- or physical-level addresses."
    SYNTAX       OCTET STRING

MacAddress ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "1x:"
    STATUS       current
    DESCRIPTION
            "Represents an 802 MAC address represented in the
            `canonical' order defined by IEEE 802.1a, i.e., as if it
            were transmitted least significant bit first, even though
            802.5 (in contrast to other 802.x protocols) requires MAC
            addresses to be transmitted most significant bit first."
    SYNTAX       OCTET STRING (SIZE (6))

TruthValue ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "Represents a boolean value."
    SYNTAX       INTEGER { true(1), false(2) }

TestAndIncr ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "Represents integer-valued information used for atomic
            operations.  When the management protocol is used to specify
            that an object instance having this syntax is to be
            modified, the new value supplied via the management protocol
            must precisely match the value presently held by the
            instance.  If not, the management protocol set operation
            fails with an error of `inconsistentValue'.  Otherwise, if
            the current value is the maximum value of 2^31-1 (2147483647
            decimal), then the value held by the instance is wrapped to
            zero; otherwise, the value held by the instance is
            incremented by one.  (Note that regardless of whether the
            management protocol set operation succeeds, the variable-
            binding in the request and response PDUs are identical.)

The value of the ACCESS clause for objects having this
            syntax is either `read-write' or `read-create'.  When an
            instance of a columnar object having this syntax is created,
            any value may be supplied via the management protocol.

When the network management portion of the system is re-
            initialized, the value of every object instance having this
            syntax must either be incremented from its value prior to
            the re-initialization, or (if the value prior to the re-
            initialization is unknown) be set to a pseudo-randomly
            generated value."
    SYNTAX       INTEGER (0..2147483647)

AutonomousType ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "Represents an independently extensible type identification
            value.  It may, for example, indicate a particular sub-tree
            with further MIB definitions, or define a particular type of
            protocol or hardware."
    SYNTAX       OBJECT IDENTIFIER

InstancePointer ::= TEXTUAL-CONVENTION
    STATUS       obsolete
    DESCRIPTION
            "A pointer to either a specific instance of a MIB object or
            a conceptual row of a MIB table in the managed device.  In
            the latter case, by convention, it is the name of the
            particular instance of the first accessible columnar object
            in the conceptual row.

The two uses of this textual convention are replaced by
            VariablePointer and RowPointer, respectively."
    SYNTAX       OBJECT IDENTIFIER

VariablePointer ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "A pointer to a specific object instance.  For example,
            sysContact.0 or ifInOctets.3."
    SYNTAX       OBJECT IDENTIFIER

RowPointer ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "Represents a pointer to a conceptual row.  The value is the
            name of the instance of the first accessible columnar object
            in the conceptual row.

For example, ifIndex.3 would point to the 3rd row in the
            ifTable (note that if ifIndex were not-accessible, then
            ifDescr.3 would be used instead)."
    SYNTAX       OBJECT IDENTIFIER

RowStatus ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "The RowStatus textual convention is used to manage the
            creation and deletion of conceptual rows, and is used as the
            value of the SYNTAX clause for the status column of a
            conceptual row (as described in Section 7.7.1 of [2].)

The status column has six defined values:

- `active', which indicates that the conceptual row is
                 available for use by the managed device;

- `notInService', which indicates that the conceptual
                 row exists in the agent, but is unavailable for use by
                 the managed device (see NOTE below); 'notInService' has
                 no implication regarding the internal consistency of
                 the row, availability of resources, or consistency with
                 the current state of the managed device;

- `notReady', which indicates that the conceptual row
                 exists in the agent, but is missing information
                 necessary in order to be available for use by the
                 managed device (i.e., one or more required columns in
                 the conceptual row have not been instanciated);

- `createAndGo', which is supplied by a management
                 station wishing to create a new instance of a
                 conceptual row and to have its status automatically set
                 to active, making it available for use by the managed
                 device;

- `createAndWait', which is supplied by a management
                 station wishing to create a new instance of a
                 conceptual row (but not make it available for use by
                 the managed device); and,
                 - `destroy', which is supplied by a management station
                 wishing to delete all of the instances associated with
                 an existing conceptual row.

Whereas five of the six values (all except `notReady') may
            be specified in a management protocol set operation, only
            three values will be returned in response to a management
            protocol retrieval operation:  `notReady', `notInService' or
            `active'.  That is, when queried, an existing conceptual row
            has only three states:  it is either available for use by
            the managed device (the status column has value `active');
            it is not available for use by the managed device, though
            the agent has sufficient information to attempt to make it
            so (the status column has value `notInService'); or, it is
            not available for use by the managed device, and an attempt
            to make it so would fail because the agent has insufficient
            information (the state column has value `notReady').

NOTE WELL

This textual convention may be used for a MIB table,
                 irrespective of whether the values of that table's
                 conceptual rows are able to be modified while it is
                 active, or whether its conceptual rows must be taken
                 out of service in order to be modified.  That is, it is
                 the responsibility of the DESCRIPTION clause of the
                 status column to specify whether the status column must
                 not be `active' in order for the value of some other
                 column of the same conceptual row to be modified.  If
                 such a specification is made, affected columns may be
                 changed by an SNMP set PDU if the RowStatus would not
                 be equal to `active' either immediately before or after
                 processing the PDU.  In other words, if the PDU also
                 contained a varbind that would change the RowStatus
                 value, the column in question may be changed if the
                 RowStatus was not equal to `active' as the PDU was
                 received, or if the varbind sets the status to a value
                 other than 'active'.

Also note that whenever any elements of a row exist, the
            RowStatus column must also exist.

To summarize the effect of having a conceptual row with a
            status column having a SYNTAX clause value of RowStatus,
            consider the following state diagram:

(1) goto B or C, depending on information available to the
            agent.

(2) if other variable bindings included in the same PDU,
            provide values for all columns which are missing but
            required, and all columns have acceptable values, then
            return noError and goto D.

(3) if other variable bindings included in the same PDU,
            provide legal values for all columns which are missing but
            required, then return noError and goto C.

(4) at the discretion of the agent, the return value may be
            either:

inconsistentName:  because the agent does not choose to
                 create such an instance when the corresponding
                 RowStatus instance does not exist, or

inconsistentValue:  if the supplied value is
                 inconsistent with the state of some other MIB object's
                 value, or

noError: because the agent chooses to create the
                 instance.

If noError is returned, then the instance of the status
            column must also be created, and the new state is B or C,
            depending on the information available to the agent.  If
            inconsistentName or inconsistentValue is returned, the row
            remains in state A.

(5) depending on the MIB definition for the column/table,
            either noError or inconsistentValue may be returned.

(6) the return value can indicate one of the following
            errors:

wrongValue: because the agent does not support
                 notInService (e.g., an agent which does not support
                 createAndWait), or

inconsistentValue: because the agent is unable to take
                 the row out of service at this time, perhaps because it
                 is in use and cannot be de-activated.

(7) the return value can indicate the following error:

inconsistentValue: because the agent is unable to
                 remove the row at this time, perhaps because it is in
                 use and cannot be de-activated.

(8) the transition to D can fail, e.g., if the values of the
            conceptual row are inconsistent, then the error code would
            be inconsistentValue.

NOTE: Other processing of (this and other varbinds of) the
            set request may result in a response other than noError
            being returned, e.g., wrongValue, noCreation, etc.

Conceptual Row Creation

There are four potential interactions when creating a
            conceptual row:  selecting an instance-identifier which is
            not in use; creating the conceptual row; initializing any
            objects for which the agent does not supply a default; and,
            making the conceptual row available for use by the managed
            device.

Interaction 1: Selecting an Instance-Identifier

The algorithm used to select an instance-identifier varies
            for each conceptual row.  In some cases, the instance-
            identifier is semantically significant, e.g., the
            destination address of a route, and a management station
            selects the instance-identifier according to the semantics.

In other cases, the instance-identifier is used solely to
            distinguish conceptual rows, and a management station
            without specific knowledge of the conceptual row might
            examine the instances present in order to determine an
            unused instance-identifier.  (This approach may be used, but
            it is often highly sub-optimal; however, it is also a
            questionable practice for a naive management station to
            attempt conceptual row creation.)

Alternately, the MIB module which defines the conceptual row
            might provide one or more objects which provide assistance
            in determining an unused instance-identifier.  For example,
            if the conceptual row is indexed by an integer-value, then
            an object having an integer-valued SYNTAX clause might be
            defined for such a purpose, allowing a management station to
            issue a management protocol retrieval operation.  In order
            to avoid unnecessary collisions between competing management
            stations, `adjacent' retrievals of this object should be
            different.

Finally, the management station could select a pseudo-random
            number to use as the index.  In the event that this index

was already in use and an inconsistentValue was returned in
            response to the management protocol set operation, the
            management station should simply select a new pseudo-random
            number and retry the operation.

A MIB designer should choose between the two latter
            algorithms based on the size of the table (and therefore the
            efficiency of each algorithm).  For tables in which a large
            number of entries are expected, it is recommended that a MIB
            object be defined that returns an acceptable index for
            creation.  For tables with small numbers of entries, it is
            recommended that the latter pseudo-random index mechanism be
            used.

Interaction 2: Creating the Conceptual Row

Once an unused instance-identifier has been selected, the
            management station determines if it wishes to create and
            activate the conceptual row in one transaction or in a
            negotiated set of interactions.

Interaction 2a: Creating and Activating the Conceptual Row

The management station must first determine the column
            requirements, i.e., it must determine those columns for
            which it must or must not provide values.  Depending on the
            complexity of the table and the management station's
            knowledge of the agent's capabilities, this determination
            can be made locally by the management station.  Alternately,
            the management station issues a management protocol get
            operation to examine all columns in the conceptual row that
            it wishes to create.  In response, for each column, there
            are three possible outcomes:

- a value is returned, indicating that some other
                 management station has already created this conceptual
                 row.  We return to interaction 1.

- the exception `noSuchObject' is returned, indicating
                 that the agent does not implement the object-type
                 associated with this column or that there is no
                 conceptual row for which this column would be
                 accessible in the MIB view used by the retrieval.  As
                 such, the management station can not issue any
                 management protocol set operations to create an
                 instance of this column.

Once the column requirements have been determined, a
            management protocol set operation is accordingly issued.
            This operation also sets the new instance of the status
            column to `createAndGo'.

When the agent processes the set operation, it verifies that
            it has sufficient information to make the conceptual row
            available for use by the managed device.  The information
            available to the agent is provided by two sources:  the
            management protocol set operation which creates the
            conceptual row, and, implementation-specific defaults
            supplied by the agent (note that an agent must provide
            implementation-specific defaults for at least those objects
            which it implements as read-only).  If there is sufficient
            information available, then the conceptual row is created, a
            `noError' response is returned, the status column is set to
            `active', and no further interactions are necessary (i.e.,
            interactions 3 and 4 are skipped).  If there is insufficient
            information, then the conceptual row is not created, and the
            set operation fails with an error of `inconsistentValue'.
            On this error, the management station can issue a management
            protocol retrieval operation to determine if this was
            because it failed to specify a value for a required column,
            or, because the selected instance of the status column
            already existed.  In the latter case, we return to
            interaction 1.  In the former case, the management station
            can re-issue the set operation with the additional
            information, or begin interaction 2 again using
            `createAndWait' in order to negotiate creation of the
            conceptual row.

NOTE WELL

Regardless of the method used to determine the column
                 requirements, it is possible that the management
                 station might deem a column necessary when, in fact,
                 the agent will not allow that particular columnar
                 instance to be created or written.  In this case, the
                 management protocol set operation will fail with an
                 error such as `noCreation' or `notWritable'.  In this
                 case, the management station decides whether it needs
                 to be able to set a value for that particular columnar
                 instance.  If not, the management station re-issues the
                 management protocol set operation, but without setting
                 a value for that particular columnar instance;
                 otherwise, the management station aborts the row
                 creation algorithm.

Interaction 2b: Negotiating the Creation of the Conceptual
            Row

The management station issues a management protocol set
            operation which sets the desired instance of the status
            column to `createAndWait'.  If the agent is unwilling to
            process a request of this sort, the set operation fails with
            an error of `wrongValue'.  (As a consequence, such an agent
            must be prepared to accept a single management protocol set
            operation, i.e., interaction 2a above, containing all of the
            columns indicated by its column requirements.)  Otherwise,
            the conceptual row is created, a `noError' response is
            returned, and the status column is immediately set to either
            `notInService' or `notReady', depending on whether it has
            sufficient information to (attempt to) make the conceptual
            row available for use by the managed device.  If there is
            sufficient information available, then the status column is
            set to `notInService'; otherwise, if there is insufficient
            information, then the status column is set to `notReady'.
            Regardless, we proceed to interaction 3.

Interaction 3: Initializing non-defaulted Objects

The management station must now determine the column
            requirements.  It issues a management protocol get operation
            to examine all columns in the created conceptual row.  In
            the response, for each column, there are three possible
            outcomes:

- a value is returned, indicating that the agent
                 implements the object-type associated with this column
                 and had sufficient information to provide a value.  For
                 those columns to which the agent provides read-create
                 access (and for which the agent allows their values to
                 be changed after their creation), a value return tells
                 the management station that it may issue additional
                 management protocol set operations, if it desires, in
                 order to change the value associated with this column.

- the exception `noSuchInstance' is returned,
                 indicating that the agent implements the object-type
                 associated with this column, and that this column in at
                 least one conceptual row would be accessible in the MIB
                 view used by the retrieval were it to exist. However,
                 the agent does not have sufficient information to
                 provide a value, and until a value is provided, the
                 conceptual row may not be made available for use by the
                 managed device.  For those columns to which the agent
                 provides read-create access, the `noSuchInstance'
                 exception tells the management station that it must
                 issue additional management protocol set operations, in
                 order to provide a value associated with this column.

If the value associated with the status column is
            `notReady', then the management station must first deal with
            all `noSuchInstance' columns, if any.  Having done so, the
            value of the status column becomes `notInService', and we
            proceed to interaction 4.

Interaction 4: Making the Conceptual Row Available

Once the management station is satisfied with the values
            associated with the columns of the conceptual row, it issues
            a management protocol set operation to set the status column
            to `active'.  If the agent has sufficient information to
            make the conceptual row available for use by the managed
            device, the management protocol set operation succeeds (a
            `noError' response is returned).  Otherwise, the management
            protocol set operation fails with an error of
            `inconsistentValue'.

NOTE WELL

A conceptual row having a status column with value
                 `notInService' or `notReady' is unavailable to the
                 managed device.  As such, it is possible for the
                 managed device to create its own instances during the
                 time between the management protocol set operation
                 which sets the status column to `createAndWait' and the
                 management protocol set operation which sets the status
                 column to `active'.  In this case, when the management
                 protocol set operation is issued to set the status
                 column to `active', the values held in the agent
                 supersede those used by the managed device.

If the management station is prevented from setting the
            status column to `active' (e.g., due to management station
            or network failure) the conceptual row will be left in the
            `notInService' or `notReady' state, consuming resources
            indefinitely.  The agent must detect conceptual rows that
            have been in either state for an abnormally long period of
            time and remove them.  It is the responsibility of the
            DESCRIPTION clause of the status column to indicate what an
            abnormally long period of time would be.  This period of
            time should be long enough to allow for human response time
            (including `think time') between the creation of the
            conceptual row and the setting of the status to `active'.
            In the absence of such information in the DESCRIPTION
            clause, it is suggested that this period be approximately 5
            minutes in length.  This removal action applies not only to
            newly-created rows, but also to previously active rows which
            are set to, and left in, the notInService state for a
            prolonged period exceeding that which is considered normal
            for such a conceptual row.

Conceptual Row Suspension

When a conceptual row is `active', the management station
            may issue a management protocol set operation which sets the
            instance of the status column to `notInService'.  If the
            agent is unwilling to do so, the set operation fails with an
            error of `wrongValue' or `inconsistentValue'.  Otherwise,
            the conceptual row is taken out of service, and a `noError'
            response is returned.  It is the responsibility of the
            DESCRIPTION clause of the status column to indicate under
            what circumstances the status column should be taken out of
            service (e.g., in order for the value of some other column
            of the same conceptual row to be modified).

Conceptual Row Deletion

For deletion of conceptual rows, a management protocol set
            operation is issued which sets the instance of the status
            column to `destroy'.  This request may be made regardless of
            the current value of the status column (e.g., it is possible
            to delete conceptual rows which are either `notReady',
            `notInService' or `active'.)  If the operation succeeds,
            then all instances associated with the conceptual row are
            immediately removed."
    SYNTAX       INTEGER {
                     -- the following two values are states:
                     -- these values may be read or written
                     active(1),
                     notInService(2),
                     -- the following value is a state:
                     -- this value may be read, but not written
                     notReady(3),
                     -- the following three values are
                     -- actions: these values may be written,
                     --   but are never read
                     createAndGo(4),
                     createAndWait(5),
                     destroy(6)
                 }

TimeStamp ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "The value of the sysUpTime object at which a specific
            occurrence happened.  The specific occurrence must be

defined in the description of any object defined using this
            type.

If sysUpTime is reset to zero as a result of a re-
            initialization of the network management (sub)system, then
            the values of all TimeStamp objects are also reset.
            However, after approximately 497 days without a re-
            initialization, the sysUpTime object will reach 2^^32-1 and
            then increment around to zero; in this case, existing values
            of TimeStamp objects do not change.  This can lead to
            ambiguities in the value of TimeStamp objects."
    SYNTAX       TimeTicks

TimeInterval ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "A period of time, measured in units of 0.01 seconds."
    SYNTAX       INTEGER (0..2147483647)

DateAndTime ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "2d-1d-1d,1d:1d:1d.1d,1a1d:1d"
    STATUS       current
    DESCRIPTION
            "A date-time specification.

field  octets  contents                  range
            -----  ------  --------                  -----
              1      1-2   year*                     0..65536
              2       3    month                     1..12
              3       4    day                       1..31
              4       5    hour                      0..23
              5       6    minutes                   0..59
              6       7    seconds                   0..60
                           (use 60 for leap-second)
              7       8    deci-seconds              0..9
              8       9    direction from UTC        '+' / '-'
              9      10    hours from UTC*           0..13
             10      11    minutes from UTC          0..59

* Notes:
            - the value of year is in network-byte order
            - daylight saving time in New Zealand is +13

For example, Tuesday May 26, 1992 at 1:30:15 PM EDT would be
            displayed as:

1992-5-26,13:30:15.0,-4:0

Note that if only local time is known, then timezone
            information (fields 8-10) is not present."
    SYNTAX       OCTET STRING (SIZE (8 | 11))

StorageType ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "Describes the memory realization of a conceptual row.  A
            row which is volatile(2) is lost upon reboot.  A row which
            is either nonVolatile(3), permanent(4) or readOnly(5), is
            backed up by stable storage.  A row which is permanent(4)
            can be changed but not deleted.  A row which is readOnly(5)
            cannot be changed nor deleted.

If the value of an object with this syntax is either
            permanent(4) or readOnly(5), it cannot be written.
            Conversely, if the value is either other(1), volatile(2) or
            nonVolatile(3), it cannot be modified to be permanent(4) or
            readOnly(5).  (All illegal modifications result in a
            'wrongValue' error.)

Every usage of this textual convention is required to
            specify the columnar objects which a permanent(4) row must
            at a minimum allow to be writable."
    SYNTAX       INTEGER {
                     other(1),       -- eh?
                     volatile(2),    -- e.g., in RAM
                     nonVolatile(3), -- e.g., in NVRAM
                     permanent(4),   -- e.g., partially in ROM
                     readOnly(5)     -- e.g., completely in ROM
                 }

TDomain ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
          "Denotes a kind of transport service.

Some possible values, such as snmpUDPDomain, are defined in
          the SNMPv2-TM MIB module.  Other possible values are defined
          in other MIB modules."
    REFERENCE    "The SNMPv2-TM MIB module is defined in RFC 1906."
    SYNTAX       OBJECT IDENTIFIER

TAddress ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
          "Denotes a transport service address.

A TAddress value is always interpreted within the context of a
          TDomain value.  Thus, each definition of a TDomain value must
          be accompanied by a definition of a textual convention for use
          with that TDomain.  Some possible textual conventions, such as
          SnmpUDPAddress for snmpUDPDomain, are defined in the SNMPv2-TM
          MIB module.  Other possible textual conventions are defined in
          other MIB modules."
    REFERENCE    "The SNMPv2-TM MIB module is defined in RFC 1906."
    SYNTAX       OCTET STRING (SIZE (1..255))

END

MR SKB