Dear all, Thomas Dietz wrote:
Dear all,as you may have seen a new version of draft-ietf-ipfix-mib was published. Changes in this version are: - removed global ipfixExportVersion - added version information per Transport Session - removed ipfixTemplateObservationDomainId and ipfixTemplateId as index in the ipfixExportTable - minor editorial fixes One point that recently was raised by Gerhard is still open: - add Observation Domain Id into the Observation Point table if possible
Let me explain this issue a bit more. We have the following Observation Point table: ipfixObservationPointTable(6) |+-ipfixObservationPointEntry(1) [ipfixObservationPointGroupId,ipfixObservationPointIndex]
| + Unsigned32 ipfixObservationPointGroupId(1) + Unsigned32 ipfixObservationPointIndex(2) + PhysicalIndexOrZero ipfixObservationPointPhysicalEntity(3) + Enumeration ipfixObservationPointPhysicalEntityDirection(4)From this table, it is not possible to retrieve the Observation Domain ID of an Observation Point.
If an IPFIX Exporter establishes a Transport Session to a Collector, there is an entry in the Transport Session table. Associated to this entry, we have the Templates in the Template table. There, we can finally find the Observation Domain ID.
This procedure is quite complicated and does not work if no Transport Sessions are established.
Possible solutions:1) We do not care because nobody is interested in the mapping between Observation Points and Observation Domains.
2) We add ipfixObservationPointObservationDomainId to the Observation Point table (as a normal parameter, not as an index).
Personally, I prefer solution 2.There is a related issue regarding the relationship between Observation Domain and Metering Process.
RFC5101 says:
Observation Domain
An Observation Domain is the largest set of Observation Points for
which Flow information can be aggregated by a Metering Process.
Some people interpreted this definition as if only packets of a single
Observation Domain may enter a Metering Process/Cache. In this case, it
follows that Observations Points sharing the same
ipfixObservationPointGroupId must have identical Observation Domain ID
values. This fact could be added in the description clause of
ipfixObservationPointGroupId:
"All Observation Points belonging to the same group must belong to the same Observation Domain."However, I understand the definition differently. IMO, it does not say that packets from different Observation Domains must not enter the same Metering Process. It just says that a single Flow Record only accounts packets of a single Observation Domain. To achieve this, it is sufficient that the Metering Process/Cache treats the Observation Domain ID as an additional Flow Key.
It would be nice to get to an agreement regarding the understanding of the relationship between Observation Domain and Metering Process.
The outcome does not only concern the IPFIX-MIB, but also the configuration data model.
Best regards, Gerhard -- Dipl.-Ing. Gerhard Münz Chair for Network Architectures and Services (I8) Technische Universität München - Department of Informatics Boltzmannstr. 3, 85748 Garching bei München, Germany Phone: +49 89 289-18008 Fax: +49 89 289-18033 E-mail: muenz at net.in.tum.de WWW: http://www.net.in.tum.de/~muenz
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