[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Hashing function for PSAMP

Hi Benoit,

I remember that we decided that you MUST implement at least one of the selection method described in the draft in order to be PSAMP compliant.
So I agree, it is sufficient to implement either a sampling or a filtering method. We explicitely decided not to favor one scheme over another. The hash-section just gives recommendations for the case that someone decided to implement a hash-based scheme. I see no reason to change this decision.

Regards
Tanja
P.S.: if you have time, can you call me and give me the list of typos that you have on your paper version ? Or we make a short editing session at the IETF ?

Benoit Claise wrote:

Dear all,

Regarding PSAMP compliance, I was under the impression that the agreement was (even If I could not find a trace of it, after looking approx. 30 sec ;)):
If you want to be PSAMP compliant, you MUST implement at least one of the "method" described in the draft.
So I concluded that one filtering or one sampling mechanism would be sufficient.

Now, the discussion below is about a compulsory hash function.

Can we please clarify the situation regarding PSAMP compliance, so where is/are the MUST(s):
- MUST implement one of the filtering or sampling mechanism (note: hashing is a filtering function)?
- Or MUST implement one of the filtering and one of the sampling mechanism (note: hashing is a filtering function)?
- Or MUST implement one of the filtering, sampling, or hashing mechanism?
- Or MUST implement one of the filtering, sampling, and hashing mechanism?
- Or something else?

From there, we will deduce if we even need a compulsory hash function...

Regards, Benoit.

Dear all,

Currently, the packet selection document has IPSX mandatory for packet
selection and CRC32 mandatory for packet digest.

The problem I see with this recommendation is that IPSX is not suitable
for IPv6.  It does not sound like a good idea to have it mandatory for
IPv6 systems.

Here are two alternatives:

1. Make IPSX mandatory for IPv4 packet selection and BOB mandatory
  for IPv6 packet selection.
  Then, with BOB implemented anyway, we should then replace CRC32
  with BOB for packet digest, because both perform similarly and
  there is no good reason for forcing implementors to support also
  a third hash function.

2. Just make BOB mandatory for packet selection and packet digest.
  This would simplify implementation, because only a single function
  is required.  For packet digest this should be OK, see 1.
  A disadvantage is that BOB is slower than IPSX by factor 7.
  An advantage is, that BOB is free of IPR, while IPSX is protected
  by a patent.

Does anybody have a preferences for 1., 2., or the current choice?

Thanks,

Juergen 





--
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/>


--
Dipl.-Ing. Tanja Zseby
Fraunhofer Institute FOKUS Email: zseby@fokus.fraunhofer.de
Kaiserin-Augusta-Allee 31 Phone: +49-30-3463-7153
D-10589 Berlin, Germany Fax: +49-30-3463-8153
-------------------------------------------------------------------------------------- "Living on earth is expensive but it includes a free trip around the sun." (Anonymous)
--------------------------------------------------------------------------------------


--
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/>