Re: [IPFIX] draft-claise-export-application-info-in-ipfix-05

Andrew, Chris,
> On 03/28/2012 06:48 AM, Chris Inacio wrote:
>> http://tools.ietf.org/html/draft-claise-export-application-info-in-ipfix-05 
>>
>>
>> ClassEngineID + SelectorID - shouldn't this be 32-bits and possible 
>> to be shortened using reduced size encoding?  I'm not sure there is 
>> any advantage to saying you won't know until you see the Engine ID; 
>> and seriously, from an implementation point of view; building the 
>> decoder, I'm not going to care while parsing the information.  I will 
>> only care when doing the human display level - when I have to do the 
>> lookups.  For the protocol, (on the wire,) I prefer a 32-bit field.
> Hi Chris,
>
> I don't see how it can be just 32-bits since according to section 4.2  
> classificationEngineId=12(PANA-L2) + selectorId = 6 bytes.
>
> I'm also not sure I agree on using reduced size encoding.  If NetFlow 
> v9 is being exported and you are trying to minimize your encoding size 
> you don't have much choice.  The problem I have with the reduced size 
> encoding described for legacy protocols is that an applicationId that 
> should be common to anyone implementing this draft (1..1 for example) 
> can actually be encoded  encoded 5 different ways.  Gross.  I'd prefer 
> to burn some extra bytes for v9 rather than try and deal with the 
> normalizing different encodings, but I think that genie is already out 
> of the bottle.
>
> I definitely wouldn't want to see that continue in IPFIX since we have 
> a perfectly nice variable length octetArray.  With a variable length 
> octetArray at least equivalent applicationIds can be matched without 
> having to decompose them.
Exactly.

And what if, in the future, we have a registry, which is even bigger 
than the ones we have today?
With variable length, we're ready.

Regards, Benoit.

>
> -Andrew
>
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