Hi Bob and Tim, Thank you for responding to my question. sometime today will try increasing the window. Since I am testing this in a virtual environment (OpenStack), it is hard to define the wire limitation. I get UDP throughput somewhere between 100-120 Mbps and TCP throughput between 50-100 Mbps (using 1402 (GENEVE) & 1410 (VXLAN) mss since I am using tunneling protocol).
In the case of UDP that Bob saying. so the limitation you said is in the intermediate network, right? so the client will force to send all packet (by increasing window size) but will get dropped in the intermediate net? Best Regards, Zufar Dhiyaulhaq On Mon, Aug 3, 2020 at 2:05 AM Bob McMahon <bob.mcma...@broadcom.com> wrote: > If the bottleneck is the transmitter's wire that means things will back up > behind that. The network stack on the client will queue packets. Since > it's in a state of oversubscription there is no way for the client to ever > drain the bottleneck so-to-speak. A bottleneck is when the service time is > less than the arrival time. So one host to look more closely at the client > host, where the bottleneck is, to understand. There are two things > happening, iperf is issuing writes() and the network stack is sending > packets. While related, they're different. > > The iperf client issues a write() to cause the sending of a packet. If > the operating system has system buffers it will accept the write() > otherwise it has two choices, block or suspend the write until a system > buffer comes available or error on the write. What I suspect you're seeing > is an os blocking on the write(). Increasing the window size will allow > the os to accept the write and pass the packet to the network stack, which > will in turn drop the packet. Then you'll see packet loss. > > Did you try with a bigger window? > > Bob > > On Fri, Jul 31, 2020 at 4:29 PM Zufar Dhiyaulhaq < > zufardhiyaul...@gmail.com> wrote: > >> Hi Bob, >> >> Thanks for replying. In my understanding, when increasing the bitrate >> above the bandwidth/throughput, it will increase the packet loss right? but >> in my case, I increase to 9 Gbps and still not seeing any packet loss. Did >> increasing window size will increasing packet loss? and why that can happen? >> >> I am trying to simulate packet loss. >> >> Thanks >> >> Best Regards, >> Zufar Dhiyaulhaq >> >> >> On Sat, Aug 1, 2020 at 5:28 AM Bob McMahon <bob.mcma...@broadcom.com> >> wrote: >> >>> Try to increase the window size with -w on the client. This will allow >>> the operating system to accept the write and drop packets within the >>> stack. If the window is too small the operating system will block the >>> write until os buffers are available. >>> >>> Bob >>> >>> On Fri, Jul 31, 2020 at 8:56 AM Zufar Dhiyaulhaq < >>> zufardhiyaul...@gmail.com> wrote: >>> >>>> Hi Folks, >>>> >>>> I have a problem with iperf3, I try to simulate packet loss with Iperf3 >>>> with increasing the bitrate above the bandwidth. But packet loss output not >>>> increasing. >>>> >>>> Ubuntu 18.04 >>>> Iperf 3.7.3 >>>> >>>> I don't know why this is happening? Is there any bug with Iperf? this >>>> sounds stupid for me. >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> *ubuntu@vm1:~$ iperf3 -c 192.168.0.92 --udp -t 20 --bitrate 9000m -R >>>> -Viperf 3.7Linux vm1 4.15.0-112-generic #113-Ubuntu SMP Thu Jul 9 23:41:39 >>>> UTC 2020 x86_64Control connection MSS 1390Setting UDP block size to >>>> 1390Time: Fri, 31 Jul 2020 15:53:39 GMTConnecting to host 192.168.0.92, >>>> port 5201Reverse mode, remote host 192.168.0.92 is sending Cookie: >>>> geu5ktrvwtalkelbszen5ym4rzxfp5xgzwdy Target Bitrate: 9000000000[ 5] >>>> local 192.168.0.226 port 47999 connected to 192.168.0.92 port 5201Starting >>>> Test: protocol: UDP, 1 streams, 1390 byte blocks, omitting 0 seconds, 20 >>>> second test, tos 0[ ID] Interval Transfer Bitrate >>>> Jitter Lost/Total Datagrams[ 5] 0.00-1.00 sec 13.8 MBytes 116 >>>> Mbits/sec 0.081 ms 269/10704 (2.5%) [ 5] 1.00-2.00 sec 13.7 MBytes >>>> 115 Mbits/sec 0.085 ms 0/10346 (0%) [ 5] 2.00-3.00 sec 13.6 >>>> MBytes 114 Mbits/sec 0.035 ms 126/10365 (1.2%) [ 5] 3.00-4.00 sec >>>> 12.8 MBytes 107 Mbits/sec 0.033 ms 279/9946 (2.8%) [ 5] 4.00-5.00 >>>> sec 13.5 MBytes 113 Mbits/sec 0.051 ms 262/10427 (2.5%) [ 5] >>>> 5.00-6.00 sec 13.2 MBytes 111 Mbits/sec 0.058 ms 0/9965 (0%) [ 5] >>>> 6.00-7.00 sec 13.3 MBytes 111 Mbits/sec 0.044 ms 32/10047 (0.32%) >>>> [ 5] 7.00-8.00 sec 13.0 MBytes 109 Mbits/sec 0.053 ms 43/9874 >>>> (0.44%) [ 5] 8.00-9.00 sec 13.0 MBytes 109 Mbits/sec 0.042 ms >>>> 34/9847 (0.35%) [ 5] 9.00-10.00 sec 13.6 MBytes 114 Mbits/sec >>>> 0.055 ms 78/10305 (0.76%) [ 5] 10.00-11.00 sec 13.5 MBytes 113 >>>> Mbits/sec 0.070 ms 0/10171 (0%) [ 5] 11.00-12.00 sec 13.1 MBytes >>>> 110 Mbits/sec 0.047 ms 0/9851 (0%) [ 5] 12.00-13.00 sec 13.3 MBytes >>>> 112 Mbits/sec 0.034 ms 0/10055 (0%) [ 5] 13.00-14.00 sec 13.4 >>>> MBytes 112 Mbits/sec 0.040 ms 36/10136 (0.36%) [ 5] 14.00-15.00 sec >>>> 13.9 MBytes 117 Mbits/sec 0.055 ms 437/10921 (4%) [ 5] 15.00-16.00 >>>> sec 13.2 MBytes 111 Mbits/sec 0.043 ms 25/9964 (0.25%) [ 5] >>>> 16.00-17.00 sec 13.2 MBytes 110 Mbits/sec 0.043 ms 21/9942 (0.21%) >>>> [ 5] 17.00-18.00 sec 12.9 MBytes 108 Mbits/sec 0.046 ms 0/9702 >>>> (0%) [ 5] 18.00-19.00 sec 13.4 MBytes 112 Mbits/sec 0.050 ms >>>> 208/10294 (2%) [ 5] 19.00-20.00 sec 13.5 MBytes 113 Mbits/sec >>>> 0.048 ms 0/10152 (0%) - - - - - - - - - - - - - - - - - - - - - - - - >>>> -Test Complete. Summary Results:[ ID] Interval Transfer >>>> Bitrate Jitter Lost/Total Datagrams[ 5] 0.00-20.04 sec 269 >>>> MBytes 113 Mbits/sec 0.000 ms 0/203058 (0%) sender[ 5] 0.00-20.00 >>>> sec 267 MBytes 112 Mbits/sec 0.048 ms 1850/203014 (0.91%) receiver* >>>> >>>> Thank you >>>> >>>> Best Regards, >>>> Zufar Dhiyaulhaq >>>> _______________________________________________ >>>> Iperf-users mailing list >>>> Iperf-users@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/iperf-users >>>> >>>
_______________________________________________ Iperf-users mailing list Iperf-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/iperf-users
