Subject: [ipfix-req] sampling section

From: Tanja Zseby <[email-masked]>
Date: Fri, 17 May 2002 16:25:25 +0200

Hi Benoit,

here comes the section on sampling. I will also add Sebastians comments 
to the security section and send you a new version today.

Regards
Tanja

5.2 Sampling

Sampling describes the systematic or random selection of a subset of 
elements (the sample) out of a set of elements (the parent population). 
Usually the purpose of applying sampling techniques is to estimate a 
parameter of the parent population by using only the elements of the 
subset. In IPFIX sampling techniques can be applied for instance to 
select a subset of packets out of all packets of a flow or to select a 
subset of flows out of all flows on a link. Sampling methods differ in 
their sampling strategy (e.g. systematic or random) and in the event 
that triggers the selection of an element. The selection of one packet 
can for instance be triggered by its arrival time (time-based sampling), 
by its position in the flow (count-based sampling) or by the packet 
content (content-based sampling).
The metering process MAY support measuring traffic by packet sampling. 
If sampling is supported the sampling method and its parameters MUST be 
well defined. If the sampling parameters are changed during operation, 
the new sampling parameters MUST be indicated to all collectors 
receiving  the affected flow records. If the sampling method is changed 
during operation, the new sampling method with its parameters MUST be 
indicated to all collectors receiving  the affected flow records.

comments:
-  I didnt remove "systematic or random selection" because I think it is 
useful to see that this are attributes to the selection process (which 
defines the sampling method)
- I didnt add the sentence "The IPFIX requirements don't impose any 
sampling methods but," because I think this is clear, because sampling 
has a MAY.

-- 
Dipl.-Ing. Tanja Zseby			    	      	
FhI FOKUS/Global Networking			Email: [email-masked]	
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)
--------------------------------------------------------------------------------------

--
Help        mailto:[email-masked] and say "help" in message body
Unsubscribe mailto:[email-masked] and say
"unsubscribe ipfix" in message body
Archive     http://ipfix.doit.wisc.edu/archive/