RFC 2089 (rfc2089) - Page 3 of 12

V2ToV1 Mapping SNMPv2 onto SNMPv1 within a bi-lingual SNMP agent

RFC 2089                         V2toV1                     January 1997


2.1  Mapping SNMPv2 error-status into SNMPv1 error-status

   With the new SNMPv2 protocol (RFC 1905 [1]) we get a set of error-
   status values that return the cause of an error in much more detail.
   But an SNMPv1 manager does not understand such error-status values.

   So, when the instrumentation code returns response data and uses an
   SNMPv2 error-status to report on the success or failure of the
   requested operation and if the original SNMP request is an SNMPv1
   request, then we must map such an error-status into an SNMPv1 error-
   status when composing the SNMP response PDU.

   The SNMPv2 error status is mapped to an SNMPv1 error-status using
   this table:

             SNMPv2 error-status    SNMPv1 error-status
             ===================    ===================
             noError                noError
             tooBig                 tooBig
             noSuchName             noSuchName
             badValue               badValue
             readOnly               readOnly
             genErr                 genErr
             wrongValue             badValue
             wrongEncoding          badValue
             wrongType              badValue
             wrongLength            badValue
             inconsistentValue      badValue
             noAccess               noSuchName
             notWritable            noSuchName
             noCreation             noSuchName
             inconsistentName       noSuchName
             resourceUnavailable    genErr
             commitFailed           genErr
             undoFailed             genErr
             authorizationError     noSuchName

2.2  Mapping SNMPv2 exceptions into SNMPv1

   In SNMPv2 we have so called exception values. These will allow an
   SNMPv2 response PDU to return as much management information as
   possible, even if one or more of the requested variables do not
   exist.  SNMPv1 does not support exception values, and thus does not
   return the value of management information when any error occurs.

   When multiple variables do not exist, an SNMPv1 agent can return only
   a single error and index of a single variable.  The agent determines
   by its implementation strategy which variable to identify as the



Wijnen & Levi                Informational