IPWorks SNMP 2020 Delphi Edition

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GetBulkRequest Event

Fired when a GetBulkRequest packet is received.


type TGetBulkRequestEvent = procedure (
  Sender: TObject;
  RequestId: Integer;
  MessageId: Integer;
  SNMPVersion: Integer;
  const Community: String;
  const User: String;
  SecurityLevel: Integer;
  const SourceAddress: String;
  SourcePort: Integer;
  NonRepeaters: Integer;
  MaxRepetitions: Integer;
  var ErrorIndex: Integer;
  var ErrorStatus: Integer;
  const ErrorDescription: String;
  var Respond: Boolean
) of Object;

property OnGetBulkRequest: TGetBulkRequestEvent read FOnGetBulkRequest write FOnGetBulkRequest;


This is only available for SNMP versions 2 and 3.

The list of variables in the SNMP packet, including optional values and types, is provided through the Objects collection. Each object is of type SNMPObject. This type describes the Oid, ObjectType, and Value of each SNMP object. These variables must be copied to another location before the event has completed executing, or they may be overridden by other events.

The SourceAddress and SourcePort parameters show the address and port of the sender as reported by the TCP/IP stack.

The MessageId parameter identifies the received request.

For SNMPv3, the User parameter shows the user that was supplied with the packet. This parameter MUST be used together with the SecurityLevel parameter which shows the level of security in the message.

The SecurityLevel parameter shows whether the request has been authenticated. If SecurityLevel is 0, the request has NOT been authenticated (i.e. the packet signature has not been verified). For an authenticated, non encrypted request, SecurityLevel is 1. For an authenticated and encrypted request, SecurityLevel is 2.

To send a response, the Respond parameter must be set to true. By default, this value is false, which means no response will be sent. The ErrorStatus parameter may also be set to a valid SNMP status code (the default value is 0, which represents no error).

The following is a list of valid SNMP status code values:

0 (noError) No error.
1 (tooBig) The response cannot fit in a single SNMP message.
2 (noSuchName) Variable does not exist.
3 (badValue) Invalid value or syntax.
4 (readOnly) Variable is read-only.
5 (genError) Other error (SNMPv1).
6 (noAccess) Access denied.
7 (wrongType) Wrong object type.
8 (wrongLength) Wrong length.
9 (wrongEncoding) Wrong encoding.
10 (wrongValue) Wrong value.
11 (noCreation) No creation.
12 (inconsistentValue) Inconsistent value.
13 (resourceUnavailable) Resource unavailable.
14 (commitFailed) Commit failed.
15 (undoFailed) Undo failed.
16 (authorizationError) Authorization error.
17 (notWritable) Variable is not writable.
18 (inconsistentName) Inconsistent name.

The ErrorIndex parameter indicates the index of the first variable (object) that caused an error. The default value is 0.

Variable indexes start with 0. ErrorIndex has no meaning when ErrorStatus is 0 (no error).

A GetBulkRequest is very similar to a GetNextRequest, the difference is that Getbulk performs a continuous GetNext operation based on the MaxRepitions value. The NonRepeaters value will determine the number of Objects for which a simple GetNext operation should be performed. For the remaining variables, a continuous GetNext operation is performed based on the MaxRepitions value.

So if you send a request containing X objects, the agent will perform N simple GetNext operations and M continuous GetNext operations X - N times. With X being the number of objects received, N being the number of NonRepeaters, and M being the number of MaxRepitions. Thus the SNMPMgr is expecting to receive N + M x (X - N) objects, assuming that each object has M successors.

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IPWorks SNMP 2020 Delphi Edition - Version 20.0 [Build 7941]