Benoit and Andrew, --On 3/2/06 11:22 PM +0100 Benoit Claise wrote:
Andrew Johnson wrote:One comment inline: Benoit Claise wrote:Dear all, We need a way of specifying the accuracy of our reported information, as PSAMP frameworks specifies: "the Report Stream must include information that enables the accuracy of measurements to be determined.". Here is some proposed text. _Section 7.4.4 Accuracy Report Interpretation_ In order for the Collecting Process to determine the inherent accuracy of the reported quantities (for example timestamps), the PSAMP Device SHOULD send an Accuracy Report Interpretation. The Accuracy Report Interpretation MUST be exported by an Option Template Record with a double scope that contains the TemplateId [PSAMP-INFO] and the Information Element for which the accuracy is required.If we make the templateId optional then you can have a mechanism for setting the accuracy for all uses of an element. Is this useful / desirable? It seems to me it is, since the measuring accuracy on a router (or measurement device) will generally be fixed.Good point. "The Accuracy Report Interpretation MUST be exported by an Option Template Record with a double scope that contains the TemplateId [PSAMP-INFO] and the Information Element for which the accuracy is required. " becomes "The Accuracy Report Interpretation MUST be exported by an Option Template Record with a scope that contains the Information Element for which the accuracy is required. In case the accuracy is specific to a template, a second scope containing the templateId value MUST be added to the Option Template Record." Regards, Benoit.AndrewThe accuracy SHOULD be reported either with the fixedAccuracy Information Element [PSAMP-INFO], or with the proportionalAccuracy Information Element [PSAMP-INFO]. Accuracy Report Interpretation using the fixedAccuracy Information Element Scope: TemplateId InformationElementId Non-scope: fixedAccuracy Accuracy Report Interpretation using the proportionalAccuracy Information Element Scope: TemplateId InformationElementId Non-scope: proportionalAccuracy For example, the accuracy of an Information Element whose Abstract Data Type is dateTimeMilliSeconds [IPFIX-INFO], for which the unit is specified as milliseconds, can be specified with the fixedAccuracy Information Element with the milliseconds units. In this case, the accuracy is the Information Element value +/- the value reported in the fixedAccuracy. For example, the accuracy of an Information Element to estimate the accuracy of a sampled flow, for which the unit would be specified in octets, can be specified with the proportionalAccuracy Information Element with the octet units. In this case, the accuracy is the Information Element value +/- the value reported in the proportionalAccuracy time Information Element value. Alternatively to reporting either the fixedAccuracy Information Element or the proportionalAccuracy Information Element in the Accuracy Report Interpretation, both Information Elements MAY be present. This scenario could help in more complex situations where the system clock drifts, on the top of having its own accuracy, during the duration of a measurement. If the accuracy of a reported quantity changes on the Metering Process, a new Accuracy Report Interpretation MUST be generated. The Collecting Process MUST keep the accuracy of the latest Accuracy Report Interpretation. Example 1 (to be developed) Records (using template 12): 1. Scope: TemplateId = 5, InformationElementId = 152 Non-scope: fixedAccuracy = 2 => we have a accuracy of +/- 2ms)
The example does not (yet) show how the unit (ms) is determined.
Example 2 (to be developed): 1. Scope: TemplateId = 5, InformationElementId = 152 Non-scope: proportionalAccuracy = 0.005 => we had an accuracy of +/- 0.5% --------------------- For the PSAMP information model: fixedAccuracy Description: Describes the accuracy of an Information Element, as a negative and positive relative error in absolute value.
What about Description Specifies the maximum possible difference (positive or negative) between the reported value and the actual value for a given Information Element. ?
Abstract Data Type: float64 ElementId: 320 Status: current Units: The units of the Information Element for which is accuracy is specified. proportionalAccuracy Description: Describes the accuracy of an Information Element as a negative and positive relative error, expressed as a value between 0 and 1.
What about Description Specifies the maximum possible ratio (positive or negative) between the error (difference between reported value and the actual value) and the actual reported value for a given Information Element. ? Thanks, Juergen
Abstract Data Type: float64 ElementId: 321 Status: current Units: None informationElementID Description: Contains the ID of another Information Element. Abstract Data Type: unsigned16 Data Type Semantics: identifier ElementId: 303 Status: current Units: None Regards, Benoit.-- to unsubscribe send a message to psamp-request@ops.ietf.org with the word 'unsubscribe' in a single line as the message text body. archive: <http://ops.ietf.org/lists/psamp/>
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