Re: [IPFIX] NetFlow v9 to IPFIX conversion

Hi Petr,

On 01/06/2015 07:03 AM, Petr Velan wrote:
> Hello all,
>
> I'm not sure whether this is the right place to ask, but we
> encountered following problem when converting NetFlow v9 messages to
> IPFIX.
>
> Some vendors (I've heard of ntop) are using elements IDs large than
> 32767 in NetFlow v9. When converting messages with these elements to
> IPFIX, they are considered to be Enterprise Numbers. To generate
> proper IPFIX message, we need to do one of the following:
> a) Generate a list of the elements and map them to PEN of the correct
> vendor. However, this would result in an attempt to cover all possible
> elements that anybody used in NetFlow v9. Moreover, we would still
> have to somehow handle the cases where the element is unknown
This should help with ntop/nprobe

Recent versions of nprobe (since version 5.5.5 I think) all use the
following mapping.

PEN = 35632 and IPFIXID = (v9ID - 57472)

For example, one v9 IE that nprobe exports is MYSQL_SERVER_VERSION
57667.  The IPFIX equivalent would be
MYSQL_SERVER_VERSION(35632/195).

The nprobe docs have a complete list.

Older versions of nprobe (pre ~2010) use IEs not in RFC 3954, but later
allocated in IANA.  There is no good way to convert those v9 exports to
IPFIX.

-Andrew

> b) Request a PEN for NetFlow compatibility and just add this PEN for
> every element that has ID larger than 32767.
>
> Personally, I believe that the b) is more general and error-prone. Do
> you think, that it would be possible to dedicate whole PEN to this cause?
>
> Thank you for any opinions,
>
> Petr Velan
>
>
>
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