Re: [IPFIX] exporting ranges in IPFIX

Hi, Paul, all,

As for adding the port block range IEs, this makes sense as there is (1) no generic range mechanism for IPFIX and (2) no way to report blocks of ports semantically consistent with that required by draft-ietf-behave-lsn-requirements.

Two comments, neither particularly IPFIX-specific:

First, there is a danger here, of course, that self-inconsistent information can be reported using either the step size or number of ports in block for stepped ranges: simply report a step or count greater than the range. This should of course be treated in the descriptions of the IEs...

Second, it's not clear that the proposed solution covers the applications envisioned by the draft in question; from section 5: 

   Note that this list is not exhaustive.  There is a continuum of
   behavior that a CGN may choose to implement.  For example, a CGN
   could use scattered port sets of consecutive port sets.

The stepped-range thing seems a little hackish to me, but I'm not at all familiar with how things are done on CGNs. What about disjoint stepped ranges? What about uneven steps? Hacks are great, but they should at least address the whole problem, I think. However, I suppose these IEs plus structured data would handle every reasonable case... if that's the approach, that should also be mentioned.

Cheers,

Brian

On Jun 8, 2012, at 11:06 PM, Paul Aitken wrote:

> Dear all,
> 
> I've had two feedbacks requesting a range start / range end mechanism. So I propose to request four fields:
> 
>   Port block start:           16 bits
>   Port block end:             16 bits
>   Port block step size        16 bits
>   Number of ports in block    16 bits
> 
> These can be reported in whatever way best matches the implementation.
> 
> eg, { start, step, number }, { start, end, step }, { start, end, number }.
> 
> The default step size will be 1, so { start, end } indicates a contiguous range.
> 
> Finally, I've upped the step size from 8 bits to 16 bits to allow step sizes > 255.
> 
> Any further feedback?
> 
> Thanks,
> P.
> 
> 
> On 05/06/12 16:29, Paul Aitken wrote:
>> Dear IPFIX experts,
>> 
>> As far as I know, IPFIX doesn't have a generic mechanism for reporting ranges.
>> 
>> I'm looking for a way to report bulk port allocation per section 5 of http://tools.ietf.org/html/draft-ietf-behave-lsn-requirements-05.
>> 
>> This method would be useful for reporting port ranges in draft-tsou-behave-natx4-log-reduction-02 and draft-bajko-pripaddrassign-04.
>> 
>> So I propose to request three new IPFIX Information Elements:
>> 
>>   Port block start:           16 bits
>>   Port block step size         8 bits
>>   Number of ports in block    16 bits
>> 
>> 
>> However, there could be better ways to export a "range" which don't require three new IEs each time. Do you forsee a need for a such a mechanism?
>> 
>> Shall I proceed with my request to IANA? If so, should I write a short ID explaining how the three IEs should be used together?
>> 
>> Thanks,
>> P.
>> 
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> 
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