That's how iperf works as is with -u UDP. The -b bandwidth setting
combined with the -l payload length settings are used to calculate the
interpacket gap or delay. The period is defined by this computed
interpacket delay. Note that iperf is an application so the period sets
the socket writes(). What the underlying TCP stack, the operating system,
and the network driver do after that are out of iperf's control.
Bob
On Sun, May 27, 2018 at 6:05 AM, Ashish Kashinath <akash...@eng.ucsd.edu>
wrote:
> sorry for being unclear there. Perhaps I got the terminology wrong but I
> meant a periodic stream of udp bytes. Say if we have a UDP datagram size of
> 1KB. Say I would like to send at 1MBps. Then I would want a UDP datagram
> every 1ms.( In other words I don't want a bursty flow but rather a uniform
> stream of traffic).Is that possible with iperf?
>
>
> On Sunday, May 27, 2018, Bob McMahon <bob.mcma...@broadcom.com> wrote:
>
>> I'm not sure what is meant by "synchronous instead of isochronous."
>>
>> Bob
>>
>> On Sat, May 26, 2018 at 12:25 AM, Ashish Kashinath <akash...@eng.ucsd.edu
>> > wrote:
>>
>>> Thanks for this! Is there a way to generate synchronous udp traffic
>>> instead of it being isochronous?
>>>
>>> Regards,
>>>
>>> On Thu, May 24, 2018 at 8:08 PM, Bob McMahon <bob.mcma...@broadcom.com>
>>> wrote:
>>>
>>>> Not sure on iperf3.
>>>>
>>>> iperf 2.0.11 <https://sourceforge.net/projects/iperf2/?source=navbar>
>>>> supports isochronous traffic to better emulate things like video streams
>>>> and will burst packets. It requires ./configure --enable-isochronous
>>>> before make.
>>>>
>>>> The client command line option is --isochronous=<n
>>>> fps>:<mean>,<variance> and optionally --ipg <n milliseconds> (defaults to 5
>>>> us)
>>>>
>>>> A way to send a burst every 1/60 seconds is something like
>>>> --isochronous=60:20m,0
>>>>
>>>> [root@localhost iperf2-code]# iperf -c 192.168.1.4 -u -i 1 -e
>>>> --isochronous=60:20m,0
>>>> ------------------------------------------------------------
>>>> Client connecting to 192.168.1.4, UDP port 5001 with pid 25669
>>>> UDP isochronous: 60 frames/sec mean=20.0 Mbit/s, variance=0.00 bit/s,
>>>> Period/IPG=16.67/0.005 ms
>>>> UDP buffer size: 208 KByte (default)
>>>> ------------------------------------------------------------
>>>> [ 3] local 192.168.1.1 port 49458 connected with 192.168.1.4 port 5001
>>>> [ ID] Interval Transfer Bandwidth Write/Err PPS
>>>> frames:tx/missed/slips
>>>> [ 3] 0.00-1.00 sec 2.39 MBytes 20.0 Mbits/sec 1741/0 1741 pps
>>>> 60/0/0
>>>> [ 3] 1.00-2.00 sec 2.38 MBytes 20.0 Mbits/sec 1740/0 1740 pps
>>>> 60/0/0
>>>> [ 3] 2.00-3.00 sec 2.39 MBytes 20.0 Mbits/sec 1741/0 1741 pps
>>>> 60/0/0
>>>> [ 3] 3.00-4.00 sec 2.39 MBytes 20.0 Mbits/sec 1741/0 1741 pps
>>>> 60/0/0
>>>> [ 3] 4.00-5.00 sec 2.38 MBytes 20.0 Mbits/sec 1740/0 1740 pps
>>>> 60/0/0
>>>> [ 3] 5.00-6.00 sec 2.39 MBytes 20.0 Mbits/sec 1744/0 1744 pps
>>>> 60/0/0
>>>> [ 3] 6.00-7.00 sec 2.42 MBytes 20.3 Mbits/sec 1763/0 1734 pps
>>>> 61/0/0
>>>> [ 3] 7.00-8.00 sec 2.38 MBytes 20.0 Mbits/sec 1740/0 1740 pps
>>>> 60/0/0
>>>> [ 3] 8.00-9.00 sec 2.38 MBytes 20.0 Mbits/sec 1740/0 1740 pps
>>>> 60/0/0
>>>> [ 3] 0.00-10.02 sec 23.9 MBytes 20.0 Mbits/sec 17429/0 1740
>>>> pps 600/0/0
>>>> [ 3] Sent 17429 datagrams
>>>> [ 3] Server Report:
>>>> [ 3] 0.0-10.0 sec 23.9 MBytes 20.0 Mbits/sec 62.411 ms 0/17429
>>>> (0%)
>>>>
>>>> Bob
>>>>
>>>> On Thu, May 24, 2018 at 3:02 PM, Ashish Kashinath <
>>>> akash...@eng.ucsd.edu> wrote:
>>>>
>>>>> Hi iperf-users. I am trying to use iperf to generate periodic stream
>>>>> of packets.
>>>>>
>>>>> Presently, I am using the command:
>>>>>
>>>>> iperf3 -c 192.168.1.60 -u -i 1 -b 750M -l 1K -t 600 to generate
>>>>> traffic of bandwidth 750Mb per second for 600 seconds.
>>>>>
>>>>> I am enabling UDP mode with a flag of -u and using a datagram size of
>>>>> 1KB using -l switch.
>>>>>
>>>>> Would this work in burst mode or would it generate a periodic stream
>>>>> of packets?
>>>>>
>>>>> --
>>>>> Regards,
>>>>> Ashish Kashinath
>>>>>
>>>>> ------------------------------------------------------------
>>>>> ------------------
>>>>> 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
>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
> --
> Regards,
> Ashish Kashinath
> UIUC|UCSD|Intel Corp.
>
>
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