How do I unsubscribe from this please? -----Original Message----- From: Bruce A. Mah <b...@es.net> Sent: 17 December 2020 15:27 To: Prachi Choudhary <prachichoudhary2...@gmail.com> Cc: iperf-users@lists.sourceforge.net Subject: Re: [Iperf-users] Issue with Iperf3 3.1.3 when using high datagram length
If memory serves me right, Prachi Choudhary wrote: > I was trying to benchmark network performance using Iperf3 version 3.1.3. > > I see that when I use a high datagram length (-l) on UDP Protocol, the > receiver does not receive any packets and the bits per second at the > receiver side shows as 0. > > I also tried to use the option "--udp-counters-64bit", the behavior > observed is still the same. > > Command run on server: iperf3 -s --json Command run on client: iperf3 > -c server_ip --json -u -w 4m -i 1 --bandwidth > 1000000000 -t 20 --length 30000 --get-server-output > --udp-counters-64bit > > We see after running for some seconds, the server stops receiving packets. > > Do we know why this could be happening and what can be done? First, please note that iperf 3.1.3 is several years old (3.9 is current as of this writing). Newer versions contain a number of bug/security fixes and new features. You are trying to make iperf3 send UDP packets with 30000 bytes of payload. That’s way too large for most networks (Ethernet has a maximum packet size of 1500 bytes, or somewhere around 9000 bytes if jumbo frames are in use). So the IP layer on the sending host will need to break up those UDP packets to several smaller IP packets before sending them, to be reassembled into the original datagram on the receiving host (look up “IP fragmentation”). The catch is that if any of the fragments are lost, the entire datagram gets lost. I suspect that might be contributing to the problem you’re seeing. Do you have an actual use case for sending (almost) 30KB UDP packets? Bruce. _______________________________________________ Iperf-users mailing list Iperf-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/iperf-users
