If memory serves me right, Bob McMahon wrote:
> Curious if iperf2  <https://sourceforge.net/projects/iperf2/>exhibits
> similar behavior?  It shouldn't have an issue with low packet rates.

I would not expect any problems with iperf2...the problems I alluded to
are the result of a bad design choice in iperf3.

Bruce.

> On Mon, Apr 16, 2018 at 2:25 PM, Bruce A. Mah <b...@es.net
> <mailto:b...@es.net>> wrote:
> 
>     If memory serves me right, Michael Fox wrote:
>     > The iperf3 bandwidth option doesn't seem to work (or perhaps I'm not 
> using
>     > it correctly).
>     > 
>     > iPerf3 version 3.1.3 on Ubuntu server and Windows client.
>     > 
>     > I'm trying to test radio links at various bandwidths, ranging from 32 
> Kbps
>     > to 400 Kbps, and various packet sizes, ranging from 256 to 1520 bytes.  
> But
>     > setting the bandwidth down to the link bandwidth (or lower) doesn't 
> slow the
>     > output from the client.
>     > 
>     > Example:  In the example below, bandwidth is clearly set at 128K, but
>     > resulting bandwidth in 200K.
>     > 
>     > How do I get the iperf client to only send at the specified rate?
> 
>     I think the #1 thing you should try is to get newer executables of
>     iperf3.  Starting with iperf-3.2 (3.5 is current now) we re-tuned a
>     bunch of stuff with how the transmitter side paces stuff (or rather we
>     made it so it isn't so horribly broken).  The use cases where this
>     really helps is for UDP, which tended to send packets in huge bursts,
>     and also had difficulty sending at very low bitrates as you are doing.
>     (iperf3 was originally designed for high-speed environments, such as
>     multiple-10Gbps.)
> 
>     If this doesn't work, sending smaller packets might help, although I
>     think controlling the packet size is part of your tests, so that might
>     not be feasible.
> 
>     Bruce.
> 
>     >> iperf3 -c 192.168.8.10 -u -l 1472 -b 128K
>     > Connecting to host 192.168.8.10, port 5201
>     > [  4] local 192.168.7.147 port 59396 connected to 192.168.8.10
>     port 5201
>     > [ ID] Interval           Transfer     Bandwidth       Total Datagrams
>     > [  4]   0.00-1.00   sec  25.9 KBytes   212 Kbits/sec  18
>     > [  4]   1.00-2.00   sec  24.4 KBytes   200 Kbits/sec  17
>     > [  4]   2.00-3.00   sec  24.4 KBytes   200 Kbits/sec  17
>     > [  4]   3.00-4.00   sec  25.9 KBytes   212 Kbits/sec  18
>     > [  4]   4.00-5.00   sec  21.6 KBytes   177 Kbits/sec  15
>     > [  4]   5.00-6.00   sec  24.4 KBytes   200 Kbits/sec  17
>     > [  4]   6.00-7.00   sec  21.6 KBytes   176 Kbits/sec  15
>     > [  4]   7.00-8.00   sec  24.4 KBytes   200 Kbits/sec  17
>     > [  4]   8.00-9.00   sec  23.0 KBytes   189 Kbits/sec  16
>     > [  4]   9.00-10.00  sec  23.0 KBytes   188 Kbits/sec  16
>     > - - - - - - - - - - - - - - - - - - - - - - - - -
>     > [ ID] Interval           Transfer     Bandwidth       Jitter   
>     Lost/Total
>     > Datagrams
>     > [  4]   0.00-10.00  sec   239 KBytes   195 Kbits/sec  0.049 ms 
>     0/165 (0%)
>     > [  4] Sent 165 datagrams
>     >
>     > iperf Done.
>     >
>     >
>     >
>     
> ------------------------------------------------------------------------------
>     > Check out the vibrant tech community on one of the world's most
>     > engaging tech sites, Slashdot.org! http://sdm.link/slashdot
>     > _______________________________________________
>     > Iperf-users mailing list
>     > Iperf-users@lists.sourceforge.net
>     <mailto:Iperf-users@lists.sourceforge.net>
>     > https://lists.sourceforge.net/lists/listinfo/iperf-users
>     <https://lists.sourceforge.net/lists/listinfo/iperf-users>
>     >
> 
> 
> 
>     
> ------------------------------------------------------------------------------
>     Check out the vibrant tech community on one of the world's most
>     engaging tech sites, Slashdot.org! http://sdm.link/slashdot
>     _______________________________________________
>     Iperf-users mailing list
>     Iperf-users@lists.sourceforge.net
>     <mailto:Iperf-users@lists.sourceforge.net>
>     https://lists.sourceforge.net/lists/listinfo/iperf-users
>     <https://lists.sourceforge.net/lists/listinfo/iperf-users>
> 
> 


Attachment: signature.asc
Description: OpenPGP digital signature

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Iperf-users mailing list
Iperf-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/iperf-users

Reply via email to