Re: Iperf Algorithm

To: iperf-users --at-- dast.nlanr.net
Subject: Re: Iperf Algorithm
From: Jon Dugan <jdugan --at-- ncsa.uiuc.edu>
Date: Mon, 24 May 2004 14:49:25 -0500
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On Mon, May 24, 2004 at 03:04:33AM -0300, Marcelo Oks wrote:
> Hi, I wanted to know how Iperf do to find out the bandwidth. I am writing an
> essay and I'd like to include this information but I've not been able to
> find it in Internet. If someone can help me I'll be extremely thankful.

  Iperf has no internal algorithm for determining the available bandwidth.
  Instead, it opens a TCP connection and sends as much data as TCP will allow.
  TCP controls the rate at which data is sent.  It is more accurate to say
  that Iperf will measure the achievable throughput between a pair of hosts
  rather than then bandwidth of the path between them.

  For a detailed explaination of how TCP works see TCP Illustrated, Vol. 1 by
  W. Richard Stevens or Internetworking With TCP/IP, Vol. 1 by Douglas E.
  Comer.  Alternatively you could read RFC 793 which defines TCP:

    http://www.faqs.org/rfcs/rfc793.html

  Keep in mind that there a several RFCs which amend the original definition
  of TCP.

Jon
-- 
Jon Dugan             |  Senior Network Engineer, NCSA Network Research
jdugan --at-- ncsa.uiuc.edu  |  269 CAB, 605 E Springfield, Champaign, IL 61820
217-244-7715          |  http://www.ncsa.uiuc.edu/~jdugan/

References:
- Iperf Algorithm
  - From: Marcelo Oks

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