Subject: [ipfix-protocol] Options Template Record Format section

From: Benoit Claise <[email-masked]>
Date: Wed, 04 May 2005 12:26:03 +0200

Dear all,

It has been brought to my attention that the section 3.4.2 "Options 
Template Record Format" is not too clear.
This is right. The following sentence is misleading:

   The Options Template Record (and its corresponding Data Record) is 
   used to supply information about the Metering Process rather than 
   supplying information about IP Flows. 

I would like to propose the following improvements for the section 3.4.2 
and 3.4.2.1, mainly done by moving text between the 2 sections.
Note that these would be already inline with 
http://ipfix.doit.wisc.edu/archive/2784.html

3.4.2   Options Template Record Format 
    
_   Thanks to the notion of scope, The Options Template Record gives the
   Exporter the ability to provide additional information to the 
   Collector which would not be possible with Flow Records alone. 

   One Options Template Record example is the "Flow Keys", which 
   reports the Flow Keys for a template, which is defined as the scope.  
   Another example is the "Template configuration", which reports the
   configuration sampling parameter(s) for the template, which is 
   defined as the scope. _

 3.4.2.1 Scope  
    
_   The scope, which is only available in the Options Template Set, 
   gives the context of the reported Information Elements in the 
   Data Records.  Note that the IPFIX Message Header already contains 
   the Source ID (the identifier of the Observation Domain). If not 
   zero, this Source ID can be considered as an implicit scope for 
   the Data Records in the IPFIX Message. _
    
   Multiple scope fields MAY be present in the Options Template Record, 
   in which case, the composite scope is the combination of the scopes. 
   For example, if the two scopes are defined as "metering process" and 
   "template", the combined scope is this template for this metering 
   process.  The order of the scope fields, as defined in the Options 
   Template Record, is irrelevant in this case. However, if the order 
   of the scope fields in the Option Template Record is relevant, the 
   order of the scope fields MUST be used.  For example, if the first 
   scope defines the filtering function, while the second scope defines 
   the sampling function, the order of the scope is important. Applying 
   the sampling function first, followed by the filtering function, 
   would lead to potentially different Data Records than applying the 
   filtering function first, followed by the sampling function.  In 
   this case, the Collector deduces the function order by looking at 
   the order of the scope in the Options Template Record.  
    
   The scope is an Information Element specified in the IPFIX 
   Information Model [IPFIX-INFO]. An IPFIX compliant implementation of 
   the Collecting Process SHOULD support this minimum set of 
   Information Elements as scope: LineCardId, TemplateId, 
   exporterIPv4Address, exporterIPv6Address, and ingressInterface.  
   Note that other Information Elements such as meteringProcessId, 
   exportingProcessId, sourceId, etc. are also valid scopes. The IPFIX 
   protocol doesn't prevent the use of any Information Elements for 
   scope. However some Information Element types don't make sense if 
   specifed as scope. For example: the counter Information Elements. 
 
   Finally, note that the _Scope Field Count _MAY NOT be zero. 

Any feedback or objections?

Regards, Benoit.