📄 rfc1067.txt
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object available for get operations in the relevant MIB view, then the receiving entity sends to the originator of the received message the GetResponse-PDU of identical form, except that the value of the error-status field is noSuchName, and the value of the error-index field is the index of said object name component in the receivedCase, Fedor, Schoffstall, & Davin [Page 19]RFC 1067 SNMP August 1988 message. (2) If, for any object named in the variable-bindings field, the object is an aggregate type (as defined in the SMI), then the receiving entity sends to the originator of the received message the GetResponse-PDU of identical form, except that the value of the error-status field is noSuchName, and the value of the error-index field is the index of said object name component in the received message. (3) If the size of the GetResponse-PDU generated as described below would exceed a local limitation, then the receiving entity sends to the originator of the received message the GetResponse-PDU of identical form, except that the value of the error-status field is tooBig, and the value of the error-index field is zero. (4) If, for any object named in the variable-bindings field, the value of the object cannot be retrieved for reasons not covered by any of the foregoing rules, then the receiving entity sends to the originator of the received message the GetResponse-PDU of identical form, except that the value of the error-status field is genErr and the value of the error-index field is the index of said object name component in the received message. If none of the foregoing rules apply, then the receiving protocol entity sends to the originator of the received message the GetResponse-PDU such that, for each object named in the variable- bindings field of the received message, the corresponding component of the GetResponse-PDU represents the name and value of that variable. The value of the error- status field of the GetResponse- PDU is noError and the value of the error-index field is zero. The value of the request-id field of the GetResponse-PDU is that of the received message.4.1.3. The GetNextRequest-PDU The form of the GetNextRequest-PDU is identical to that of the GetRequest-PDU except for the indication of the PDU type. In the ASN.1 language: GetNextRequest-PDU ::= [1] IMPLICIT SEQUENCE { request-id RequestID,Case, Fedor, Schoffstall, & Davin [Page 20]RFC 1067 SNMP August 1988 error-status -- always 0 ErrorStatus, error-index -- always 0 ErrorIndex, variable-bindings VarBindList } The GetNextRequest-PDU is generated by a protocol entity only at the request of its SNMP application entity. Upon receipt of the GetNextRequest-PDU, the receiving protocol entity responds according to any applicable rule in the list below: (1) If, for any object name in the variable-bindings field, that name does not lexicographically precede the name of some object available for get operations in the relevant MIB view, then the receiving entity sends to the originator of the received message the GetResponse-PDU of identical form, except that the value of the error-status field is noSuchName, and the value of the error-index field is the index of said object name component in the received message. (2) If the size of the GetResponse-PDU generated as described below would exceed a local limitation, then the receiving entity sends to the originator of the received message the GetResponse-PDU of identical form, except that the value of the error-status field is tooBig, and the value of the error-index field is zero. (3) If, for any object named in the variable-bindings field, the value of the lexicographical successor to the named object cannot be retrieved for reasons not covered by any of the foregoing rules, then the receiving entity sends to the originator of the received message the GetResponse-PDU of identical form, except that the value of the error-status field is genErr and the value of the error-index field is the index of said object name component in the received message. If none of the foregoing rules apply, then the receiving protocol entity sends to the originator of the received message the GetResponse-PDU such that, for each name in the variable-bindings field of the received message, the corresponding component of theCase, Fedor, Schoffstall, & Davin [Page 21]RFC 1067 SNMP August 1988 GetResponse-PDU represents the name and value of that object whose name is, in the lexicographical ordering of the names of all objects available for get operations in the relevant MIB view, together with the value of the name field of the given component, the immediate successor to that value. The value of the error-status field of the GetResponse-PDU is noError and the value of the errorindex field is zero. The value of the request-id field of the GetResponse-PDU is that of the received message.4.1.3.1. Example of Table Traversal One important use of the GetNextRequest-PDU is the traversal of conceptual tables of information within the MIB. The semantics of this type of SNMP message, together with the protocol-specific mechanisms for identifying individual instances of object types in the MIB, affords access to related objects in the MIB as if they enjoyed a tabular organization. By the SNMP exchange sketched below, an SNMP application entity might extract the destination address and next hop gateway for each entry in the routing table of a particular network element. Suppose that this routing table has three entries: Destination NextHop Metric 10.0.0.99 89.1.1.42 5 9.1.2.3 99.0.0.3 3 10.0.0.51 89.1.1.42 5 The management station sends to the SNMP agent a GetNextRequest-PDU containing the indicated OBJECT IDENTIFIER values as the requested variable names: GetNextRequest ( ipRouteDest, ipRouteNextHop, ipRouteMetric1 ) The SNMP agent responds with a GetResponse-PDU: GetResponse (( ipRouteDest.9.1.2.3 = "9.1.2.3" ), ( ipRouteNextHop.9.1.2.3 = "99.0.0.3" ), ( ipRouteMetric1.9.1.2.3 = 3 )) The management station continues with: GetNextRequest ( ipRouteDest.9.1.2.3, ipRouteNextHop.9.1.2.3,Case, Fedor, Schoffstall, & Davin [Page 22]RFC 1067 SNMP August 1988 ipRouteMetric1.9.1.2.3 ) The SNMP agent responds: GetResponse (( ipRouteDest.10.0.0.51 = "10.0.0.51" ), ( ipRouteNextHop.10.0.0.51 = "89.1.1.42" ), ( ipRouteMetric1.10.0.0.51 = 5 )) The management station continues with: GetNextRequest ( ipRouteDest.10.0.0.51, ipRouteNextHop.10.0.0.51, ipRouteMetric1.10.0.0.51 ) The SNMP agent responds: GetResponse (( ipRouteDest.10.0.0.99 = "10.0.0.99" ), ( ipRouteNextHop.10.0.0.99 = "89.1.1.42" ), ( ipRouteMetric1.10.0.0.99 = 5 )) The management station continues with: GetNextRequest ( ipRouteDest.10.0.0.99, ipRouteNextHop.10.0.0.99, ipRouteMetric1.10.0.0.99 ) As there are no further entries in the table, the SNMP agent returns those objects that are next in the lexicographical ordering of the known object names. This response signals the end of the routing table to the management station.4.1.4. The GetResponse-PDU The form of the GetResponse-PDU is identical to that of the GetRequest-PDU except for the indication of the PDU type. In the ASN.1 language: GetResponse-PDU ::= [2] IMPLICIT SEQUENCE { request-id RequestID,Case, Fedor, Schoffstall, & Davin [Page 23]RFC 1067 SNMP August 1988 error-status ErrorStatus, error-index ErrorIndex, variable-bindings VarBindList } The GetResponse-PDU is generated by a protocol entity only upon receipt of the GetRequest-PDU, GetNextRequest-PDU, or SetRequest-PDU, as described elsewhere in this document. Upon receipt of the GetResponse-PDU, the receiving protocol entity presents its contents to its SNMP application entity.4.1.5. The SetRequest-PDU The form of the SetRequest-PDU is identical to that of the GetRequest-PDU except for the indication of the PDU type. In the ASN.1 language: SetRequest-PDU ::= [3] IMPLICIT SEQUENCE { request-id RequestID, error-status -- always 0 ErrorStatus, error-index -- always 0 ErrorIndex, variable-bindings VarBindList } The SetRequest-PDU is generated by a protocol entity only at the request of its SNMP application entity. Upon receipt of the SetRequest-PDU, the receiving entity responds according to any applicable rule in the list below: (1) If, for any object named in the variable-bindings field,Case, Fedor, Schoffstall, & Davin [Page 24]RFC 1067 SNMP August 1988 the object is not available for set operations in the relevant MIB view, then the receiving entity sends to the originator of the received message the GetResponse-PDU of identical form, except that the value of the error-status field is noSuchName, and the value of the error-index field is the index of said object name component in the received message. (2) If, for any object named in the variable-bindings field, the contents of the value field does not, according to the ASN.1 language, manifest a type, length, and value that is consistent with that required for the variable, then the receiving entity sends to the originator of the received message the GetResponse-PDU of identical form, except that the value of the error-status field is badValue, and the value of the error-index field is the index of said object name in the received message. (3) If the size of the Get Response type message generated as described below would exceed a local limitation, then the receiving entity sends to the originator of the received message the GetResponse-PDU of identical form, except that the value of the error-status field is tooBig, and the value of the error-index field is zero. (4) If, for any object named in the variable-bindings field, the value of the named object cannot be altered for reasons not covered by any of the foregoing rules, then the receiving entity sends to the originator of the received message the GetResponse-PDU of identical form, except that the value of the error-status field is genErr and the value of the error-index field is the index of said object name component in the received message. If none of the foregoing rules apply, then for each object named in the variable-bindings field of the received message, the corresponding value is assigned to the variable. Each variable assignment specified by the SetRequest-PDU should be effected as if simultaneously set with respect to all other assignments specified in the same message. The receiving entity then sends to the originator of the received message the GetResponse-PDU of identical form except that the value of the error-status field of the generated message is noError and the value of the error-index field is zero.Case, Fedor, Schoffstall, & Davin [Page 25]RFC 1067 SNMP August 19884.1.6. The Trap-PDU
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