Subject: [ipfix-protocol] Observation Domain ID uniqueness

From: Benoit Claise <[email-masked]>
Date: Tue, 30 May 2006 17:08:30 +0200

Dear all,

I know it was addressed a couple of times on the mailing list. However, 
while discussing with Lutz Mark and Paul Aitken, I think we discovered 
the issue

the definition of the observation domain id differs between
ipfix-arch and ipfix-proto.

-in ipfix-arch the id is unique within the ipfix device
-in ipfix-proto the id is unique to the exporting process

------------------------------------------------------------

[ARCH]
5.4.  Observation Domain

   The Observation Domain is a logical block that presents a single
   identity for a group of Observation Points within an IPFIX Device.
   Each {Observation Point, Metering Process} pair belongs to a single
   Observation Domain.  An IPFIX Device could have multiple Observation
   Domains, each of which has a subset of the total set of Observation
   Points in it.  Each Observation Domain must carry a unique ID within
   the context of an IPFIX Device.  Note that in case of multiple
   Observation Domains, a unique ID per Observation Domain must be
   transmitted as a parameter to the Exporting Function.  That unique ID
   is referred to as the IPFIX Observation Domain ID.

[PROTO]
3.3
   Observation Domain ID
           A 32-bit identifier of the Observation Domain that is
           locally unique to the Exporting Process.  The Exporting
           Process uses the Observation Domain ID to uniquely identify
           to the Collecting Process the Observation Domain that
           metered the Flows.  Collecting Processes SHOULD use the
           combination of the Exporter (exporterIPv4Address,
           exporterIPv6Address, or exportingProcessId) and the
           Observation Domain ID field to separate different export
           streams originating from the same Exporting Process.  The
           Observation Domain ID SHOULD be 0 when no specific
           Observation Domain ID is relevant for the entire IPFIX
           Message.  For example, when exporting the Exporting Process
           Statistics, or in case of hierarchy of Collector when
           aggregated data records are exported.

We think that the Observation Domain Id should be unique per IPFIX 
Device, and not per Exporting Process.
Otherwise, we could end up in the following situation: one sysadmin 
configures a set of observation points with observation domain 1, while 
a second sysadmin configures another set of observation points (on a 
different line card for example) with the same observation domain Id.
If each observation domain exports using its own exporting process with 
the source IP address, how would the collector differentiate the 
template IDs?

Also, the terminology sections of IFPIX-PROTO and IPFIX-ARCH are not in 
sync.
Multiple small changes (including in the terminology sections) should be 
inserted. For example: IPFIX-PROTO observation domain definition says 
"In the IPFIX Message it generates, the Observation Domain includes its 
Observation Domain ID, which is unique per Exporting Process. "

Feedback?

Regards, Benoit.

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