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Re: [perfsonar-user] Clarity on Iperf Results Collected


Chronological Thread 
  • From: Szymon Trocha <szymon.trocha@man.poznan.pl>
  • To: "Tshabalala, Devine (Mr) (s210051701)" <s210051701@live.nmmu.ac.za>, "perfsonar-user@internet2.edu" <perfsonar-user@internet2.edu>
  • Cc: Roderick Mooi <rmooi@CSIR.CO.ZA>, Shukri Wiener <shuwie@tenet.ac.za>, Kevin Draai <kdraai@csir.co.za>, "Kudyachete Gratitude (Mr) (Summerstrand North Campus)" <Gratitude.Kudyachete2@nmmu.ac.za>
  • Subject: Re: [perfsonar-user] Clarity on Iperf Results Collected
  • Date: Mon, 22 Jun 2015 14:51:37 +0200
  • Organization: PCSS
Hi,

W dniu 2015-06-22 o 02:04, Tshabalala, Devine (Mr) (s210051701) pisze:

Hi


I am trying to do some experiments using iperf and netflow tools. Therefore l tested my point to point link to create a network baseline using iperf tool. The results on figure below were obtained. In addition , l configured nfdump as my netflow collector and nfsen for


Do you use sampling for NetFlow?

graphical presentation. My question is; why is there difference in results presented by iperf tool and nfsen though it is the same link. My expectation was to see the results reflected on iperf command line to be similar to that on nfsen.



Furthermore, according to my theoretical understanding, iperf fills the gap of unutilized bandwidth. So, l generated some traffic from one end device to other transferring packets at a rate of roughly 47.5Mbps average. After some time, l run iperf tool at the same time to see its effect on the normal network transfer rate. l was expecting iperf results to be roughly be +- 50Mbps ( i.e. filling the remaining gap). Unfortunate, iperf results were lower than my expectations as indicated on the below figure. What could be the reason for such difference, or am l interpreting my results wrongly?


Did you see any packet loss in the traffic?

I also see that for one flow you are sending large packets (Bps 1500) and for the other very small (46).


If it is meant to be that way, therefore my interpretation will be 47.5Mbps + 15.3 Mbps= 62.8 Mbps, hence leaving me with a question of; 97.5Mbps - 62.8Mps = 34.7Mbps (where did it disappear to). Please help.


Thank you


Kind regards

DevineTshabalala

Masters Student

Department School of ICT : l.T. Communication Networks

(North Campus)
Tel: 078 491 6130

 

A successful man is one who can lay a firm foundation with the bricks others have thrown at him and
Action is the foundational key to all success. 




-- 
Szymon Trocha

Poznań Supercomputing & Netw. Center ::: NETWORK OPERATION CENTER
Tel. +48 618582022 ::: http://noc.man.poznan.pl

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