how to modify Iperf TCP connection timeout?

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I am using mininet for emulation of a network. My network has a delay of 3000ms(linear topology of 3 switches).When I tried to do iperf I got Connection failed : No route to host error in client. After a lot of time with the help of internet i came to know that this is happening because of large delay of network which causes ACK packet delayed. Thus thia ACK pcket for SYN will client after timeout. So I want to modify this timeout value. How can I do this. I am using iperf2 and ubuntu18.04. ( I think using iperf3 this is possible with --connect-timeout nms)

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rjmcmahon On

iperf 2 doesn't support --connect-timeouts. The preferred way to control that is via the operating system itself, e.g. syn retries. More on that here. We don't think we should be messing with TCP fundamentals directly as we want to separate testing from the things under test.

As an aside, iperf 2.0.14 has a --connect-only option which can be used to measure the TCP 3WHS performance. We also added a --connect-retries for application level retries.

Bob