RADLAN-SNMPv2 DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY, Counter32              FROM SNMPv2-SMI
    TEXTUAL-CONVENTION                      FROM SNMPv2-TC;

TruthValue ::= INTEGER {
     true (1),
     false (2)
}

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:


                                         STATE
              +--------------+-----------+-------------+-------------
              |      A       |     B     |      C      |      D
              |              |status col.|status column|
              |status column |    is     |      is     |status column
    ACTION    |does not exist|  notReady | notInService|  is active
--------------+--------------+-----------+-------------+-------------
set status    |noError    ->D|inconsist- |inconsistent-|inconsistent-
column to     |       or     |   entValue|        Value|        Value
createAndGo   |inconsistent- |           |             |
              |         Value|           |             |
--------------+--------------+-----------+-------------+-------------
set status    |noError  see 1|inconsist- |inconsistent-|inconsistent-
column to     |       or     |   entValue|        Value|        Value
createAndWait |wrongValue    |           |             |
--------------+--------------+-----------+-------------+-------------
set status    |inconsistent- |inconsist- |noError      |noError
column to     |         Value|   entValue|             |
active        |              |           |             |
              |              |     or    |             |
              |              |           |             |
              |              |see 2   ->D|see 8     ->D|          ->D
--------------+--------------+-----------+-------------+-------------
set status    |inconsistent- |inconsist- |noError      |noError   ->C
column to     |         Value|   entValue|             |
notInService  |              |           |             |
              |              |     or    |             |      or
              |              |           |             |
              |              |see 3   ->C|          ->C|see 6
--------------+--------------+-----------+-------------+-------------
set status    |noError       |noError    |noError      |noError   ->A
column to     |              |           |             |      or
destroy       |           ->A|        ->A|          ->A|see 7
--------------+--------------+-----------+-------------+-------------
set any other |see 4         |noError    |noError      |see 5
column to some|              |           |             |
value         |              |      see 1|          ->C|          ->D
--------------+--------------+-----------+-------------+-------------

    (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 `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. For those
         columns to which the agent provides read-create access,
         the `noSuchInstance' exception tells the management
         station that it should supply a value for this column
         when the conceptual row is to be created.

         - 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.

         - 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.

    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)
}

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

--Counter64  ::= Counter32
-- Unsigned32 ::= INTEGER

-- zeroDotZero OBJECT-IDENTITY
--     STATUS      current
--     DESCRIPTION
--         "A value used for null identifiers."
-- ::= { 0 0 }

END

