Dear all, I would also vote for solution 1 or 2. If we choose solution 2 then we should adjust the value as Benoit suggested. Regards, Thomas -- Thomas Dietz E-mail: Thomas.Dietz@netlab.nec.de Network Laboratories Phone: +49 6221 90511-28 NEC Europe Ltd. Fax: +49 6221 90511-55 Kurfuersten-Anlage 36 69115 Heidelberg, Germany http://www.netlab.nec.de > -----Original Message----- > From: owner-psamp@ops.ietf.org > [mailto:owner-psamp@ops.ietf.org] On Behalf Of Juergen Quittek > Sent: Wednesday, December 21, 2005 12:16 PM > To: Andrew Johnson; Benoit Claise > Cc: psamp > Subject: Re: Uniform Probabilistic Sampling in PSAMP-PROTO > > Hi Andrew, > > --On 08.12.2005 16:53 Uhr +0000 Andrew Johnson wrote: > > > Benoit Claise wrote: > > [SNIP] > >> Initially we wanted to model the probability in > [PSAMP-PROTO] with a > >> float, which is allowed by [IPFIX-PROTO]. > >> However, we've got the issue that SMIv2 doesn't support floats. > > > > Although the floating point type is not a base type in SMI there are > > a couple of proposals about how to send them. This extract is from > > the comp.protocols.snmp SNMP FAQ: > > > > http://www.faqs.org/faqs/snmp-faq/part2/ > > =============================================================== > > 2.40.04 > > SUBJECT: Floating Point Numbers in SMI? > > > > You cannot add new base types to the SMI. > > > > For now, the easiest way to have floating point numbers > > in SNMP MIBs is to use the base type OCTET STRING and > > encode the value in ASCII. > > > > This is not the most elegant approach. However, it will work > > between your agent and your management application and it will > > be compliant to the SNMP SMI and protocol specifications. > > > > David Perkins > > =============================================================== > > > > Apparently this method is implemented in the NET-SNMP agent and > > manager. > > (http://ops.ietf.org/lists/mreview/mreview.2004/msg00083.html) > > > > Whether we use the above suggested method or define a new way of > > using unsigned32 the application will have to have some way of > > converting that number before it can be used. > > This would be Solution 4. > I still prefer Solution 1 or Solution 2. > > >> What to do now? > >> > >> _Solution 1: _ > >> We export the probability with a float, and we approximate > this value > >> with the MIB variable. > >> > >> _Solution 2: _ > >> We export the probability with an unsigned32, exactly the > same content > >> as the MIB variable psampSampUniProbProbability > >> > >> _Solution 3: _ > >> We export the probability with two values N, M. > >> This means 2 inter-dependent I.E.s and 2 MIB variables > instead of one. > >> I don't like it too much > >> > >> I'm clearly in favor of solution 1. It's not right that we > would limit > >> IPFIX because of the limitations of SMIv2 > >> Feedback? > >> > >> Side question: if we go for the float solution, should we have a > >> float64? This would give us more precision > >> Note: not yet defined in [IPFIX-PROTO]. > > > > FYI: > > The 32-bit float has 24 bits of precision, i.e. roughly > +/-0.000006%. > > It is 23 bits we are using. Precision would be roughly +/-0.00001% > The Unsigned as Benoit suggests it would have roughly > +/-0.0000001% > > > The 64-bit float has 53 bits of precision, i.e. roughly > +/-0.00000000000001% > > regards > > Thanks, > > Juergen > > > Andrew > > > > -- > > to unsubscribe send a message to psamp-request@ops.ietf.org with > > the word 'unsubscribe' in a single line as the message text body. > > archive: <http://ops.ietf.org/lists/psamp/> > > > > -- > to unsubscribe send a message to psamp-request@ops.ietf.org with > the word 'unsubscribe' in a single line as the message text body. > archive: <http://ops.ietf.org/lists/psamp/> >
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