rfc1448.txt

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          Case, McCloghrie, Rose & Waldbusser                  [Page 17]





          RFC 1448        Protocol Operations for SNMPv2      April 1993


              Response (( sysUpTime.0 =  "123471" ),
                        ( ipNetToMediaNetAddress.1.9.2.3.4 =
                                                         "9.2.3.4" ),
                        ( ipRoutingDiscards.0 =  "2" ))

          This response signals the end of the table to the SNMPv2
          entity acting in a manager role.


          4.2.3.  The GetBulkRequest-PDU

          A GetBulkRequest-PDU is generated and transmitted at the
          request of a SNMPv2 application.  The purpose of the
          GetBulkRequest-PDU is to request the transfer of a potentially
          large amount of data, including, but not limited to, the
          efficient and rapid retrieval of large tables.

          Upon receipt of a GetBulkRequest-PDU, the receiving SNMPv2
          entity processes each variable binding in the variable-binding
          list to produce a Response-PDU with its request-id field
          having the same value as in the request.  Processing begins by
          examining the values in the non-repeaters and max-repetitions
          fields.  If the value in the non-repeaters field is less than
          zero, then the value of the field is set to zero.  Similarly,
          if the value in the max-repetitions field is less than zero,
          then the value of the field is set to zero.

          For the GetBulkRequest-PDU type, the successful processing of
          each variable binding in the request generates zero or more
          variable bindings in the Response-PDU.  That is, the one-to-
          one mapping between the variable bindings of the GetRequest-
          PDU, GetNextRequest-PDU, and SetRequest-PDU types and the
          resultant Response-PDUs does not apply for the mapping between
          the variable bindings of a GetBulkRequest-PDU and the
          resultant Response-PDU.

          The values of the non-repeaters and max-repetitions fields in
          the request specify the processing requested.  One variable
          binding in the Response-PDU is requested for the first N
          variable bindings in the request and M variable bindings are
          requested for each of the R remaining variable bindings in the
          request.  Consequently, the total number of requested variable
          bindings communicated by the request is given by N + (M * R),
          where N is the minimum of: a) the value of the non-repeaters
          field in the request, and b) the number of variable bindings





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          RFC 1448        Protocol Operations for SNMPv2      April 1993


          in the request; M is the value of the max-repetitions field in
          the request; and R is the maximum of: a) number of variable
          bindings in the request - N, and b)  zero.

          The receiving SNMPv2 entity produces a Response-PDU with up to
          the total number of requested variable bindings communicated
          by the request.  The request-id shall have the same value as
          the received GetBulkRequest-PDU.

          If N is greater than zero, the first through the (N)-th
          variable bindings of the Response-PDU are each produced as
          follows:

          (1)  The variable is located which is in the lexicographically
               ordered list of the names of all variables which are
               accessible by this request and whose name is the first
               lexicographic successor of the variable binding's name in
               the incoming GetBulkRequest-PDU.  The corresponding
               variable binding's name and value fields in the
               Response-PDU are set to the name and value of the located
               variable.

          (2)  If the requested variable binding's name does not
               lexicographically precede the name of any variable
               accessible by this request, i.e., there is no
               lexicographic successor, then the corresponding variable
               binding produced in the Response-PDU has its value field
               set to `endOfMibView', and its name field set to the
               variable binding's name in the request.

          If M and R are non-zero, the (N + 1)-th and subsequent
          variable bindings of the Response-PDU are each produced in a
          similar manner.  For each iteration i, such that i is greater
          than zero and less than or equal to M, and for each repeated
          variable, r, such that r is greater than zero and less than or
          equal to R, the (N + ( (i-1) * R ) + r)-th variable binding of
          the Response-PDU is produced as follows:

          (1)  The variable which is in the lexicographically ordered
               list of the names of all variables which are accessible
               by this request and whose name is the (i)-th
               lexicographic successor of the (N + r)-th variable
               binding's name in the incoming GetBulkRequest-PDU is
               located and the variable binding's name and value fields
               are set to the name and value of the located variable.





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          RFC 1448        Protocol Operations for SNMPv2      April 1993


          (2)  If there is no (i)-th lexicographic successor, then the
               corresponding variable binding produced in the Response-
               PDU has its value field set to `endOfMibView', and its
               name field set to either the last lexicographic
               successor, or if there are no lexicographic successors,
               to the (N + r)-th variable binding's name in the request.

          While the maximum number of variable bindings in the
          Response-PDU is bounded by N + (M * R), the response may be
          generated with a lesser number of variable bindings (possibly
          zero) for either of two reasons.

          (1)  If the size of the message encapsulating the Response-PDU
               containing the requested number of variable bindings
               would be greater than either a local constraint or the
               maximum message size of the request's source party, then
               the response is generated with a lesser number of
               variable bindings.  This lesser number is the ordered set
               of variable bindings with some of the variable bindings
               at the end of the set removed, such that the size of the
               message encapsulating the Response-PDU is approximately
               equal to but no greater than the minimum of the local
               constraint and the maximum message size of the request's
               source party.  Note that the number of variable bindings
               removed has no relationship to the values of N, M, or R.

          (2)  The response may also be generated with a lesser number
               of variable bindings if for some value of iteration i,
               such that i is greater than zero and less than or equal
               to M, that all of the generated variable bindings have
               the value field set to the `endOfMibView'.  In this case,
               the variable bindings may be truncated after the (N + (i
               * R))-th variable binding.

          If the processing of any variable binding fails for a reason
          other than listed above, then the Response-PDU is re-formatted
          with the same values in its request-id and variable-bindings
          fields as the received GetBulkRequest-PDU, with the value of
          its error-status field set to `genErr', and the value of its
          error-index field is set to the index of the failed variable
          binding.

          Otherwise, the value of the Response-PDU's error-status field
          is set to `noError', and the value of its error-index field to
          zero.





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          RFC 1448        Protocol Operations for SNMPv2      April 1993


          The generated Response-PDU (possibly with an empty variable-
          bindings field) is then encapsulated into a message.  If the
          size of the resultant message is less than or equal to both a
          local constraint and the maximum message size of the request's
          source party, it is transmitted to the originator of the
          GetBulkRequest-PDU.  Otherwise, the resultant message is
          discarded.


          4.2.3.1.  Another Example of Table Traversal

          This example demonstrates how the GetBulkRequest-PDU can be
          used as an alternative to the GetNextRequest-PDU.  The same
          traversal of the IP net-to-media table as shown in Section
          4.2.2.1 is achieved with fewer exchanges.

          The SNMPv2 entity acting in a manager role begins by sending a
          GetBulkRequest-PDU with the modest max-repetitions value of 2,
          and containing the indicated OBJECT IDENTIFIER values as the
          requested variable names:

              GetBulkRequest [ non-repeaters = 1, max-repetitions = 2 ]
                              ( sysUpTime,
                                ipNetToMediaPhysAddress,
                                ipNetToMediaType )

          The SNMPv2 entity acting in an agent role responds with a
          Response-PDU:

              Response (( sysUpTime.0 =  "123456" ),
                        ( ipNetToMediaPhysAddress.1.9.2.3.4 =
                                                   "000010543210" ),
                        ( ipNetToMediaType.1.9.2.3.4 =  "dynamic" ),
                        ( ipNetToMediaPhysAddress.1.10.0.0.51 =
                                                    "000010012345" ),
                        ( ipNetToMediaType.1.10.0.0.51 =  "static" ))

          The SNMPv2 entity acting in a manager role continues with:

              GetBulkRequest [ non-repeaters = 1, max-repetitions = 2 ]
                              ( sysUpTime,
                                ipNetToMediaPhysAddress.1.10.0.0.51,
                                ipNetToMediaType.1.10.0.0.51 )







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          RFC 1448        Protocol Operations for SNMPv2      April 1993


          The SNMPv2 entity acting in an agent role responds with:

              Response (( sysUpTime.0 =  "123466" ),
                        ( ipNetToMediaPhysAddress.2.10.0.0.15 =
                                                   "000010987654" ),
                        ( ipNetToMediaType.2.10.0.0.15 =
                                                        "dynamic" ),
                        ( ipNetToMediaNetAddress.1.9.2.3.4 =
                                                        "9.2.3.4" ),
                        ( ipRoutingDiscards.0 =  "2" ))

          This response signals the end of the table to the SNMPv2
          entity acting in a manager role.


          4.2.4.  The Response-PDU

          The Response-PDU is generated by a SNMPv2 entity only upon
          receipt of a GetRequest-PDU, GetNextRequest-PDU,
          GetBulkRequest-PDU, SetRequest-PDU, or InformRequest-PDU, as
          described elsewhere in this document.

          If the error-status field of the Response-PDU is non-zero, the
          value fields of the variable bindings in the variable binding
          list are ignored.

          If both the error-status field and the error-index field of
          the Response-PDU are non-zero, then the value of the error-
          index field is the index of the variable binding (in the
          variable-binding list of the corresponding request) for which
          the request failed.  The first variable binding in a request's
          variable-binding list is index one, the second is index two,
          etc.

          A compliant SNMPv2 entity acting in a manager role must be
          able to properly receive and handle a Response-PDU with an
          error-status field equal to `noSuchName', `badValue', or
          `readOnly'.  (See Section 3.1.2 of [10].)

          Upon receipt of a Response-PDU, the receiving SNMPv2 entity
          presents its contents to the SNMPv2 application which
          generated the request with the same request-id value.








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          RFC 1448        Protocol Operations for SNMPv2      April 1993


          4.2.5.  The SetRequest-PDU

          A SetRequest-PDU is generated and transmitted at the request
          of a SNMPv2 application.

          Upon receipt of a SetRequest-PDU, the receiving SNMPv2 entity
          determines the size of a message encapsulating a Response-PDU
          with the same values in its request-id, error-status, error-
          index and variable-bindings fields as the received
          SetRequest-PDU.  If the determined message size is greater
          than either a local constraint or the maximum message size of
          the request's source party, then an alternate Response-PDU is
          generated, transmitted to the originator of the SetRequest-
          PDU, and processing of the SetRequest-PDU terminates
          immediately thereafter.  This alternate Response-PDU is
          formatted with the same values in its request-id field as the
          received SetRequest-PDU, with the value of its error-status
          field set to `tooBig', the value of its error-index field set
          to zero, and an empty variable-bindings field.  This alternate
          Response-PDU is then encapsulated into a message.  If the size
          of the resultant message is less than or equal to both a local
          constraint and the maximum message size of the request's
          source party, it is transmitted to the originator of the
          SetRequest-PDU.  Otherwise, the resultant message is
          discarded.  Regardless, processing of the SetRequest-PDU
          terminates.

          Otherwise, the receiving SNMPv2 entity processes each variable
          binding in the variable-binding list to produce a Response-
          PDU.  All fields of the Response-PDU have the same values as
          the corresponding fields of the received request except as
          indicated below.

          The variable bindings are conceptually processed as a two
          phase operation.  In the first phase, each variable binding is
          validated; if all validations are successful, then each
          variable is altered in the second phase.  Of course,
          implementors are at liberty to implement either the first, or
          second, or both, of the these conceptual phases as multiple
          implementation phases.  Indeed, such multiple implementation
          phases may be necessary in some cases to ensure consistency.

          The following validations are performed in the first phase on
          each variable binding until they are all successful, or until
          one fails: