How to change advertised window (rwnd)?

[Ruth T. Howell]

Is there anyway to change value of rwnd in ns3? Because when I read publication, they have discussed that they change the value of rwnd to limit throughput, and they setup experiment on DummyNet tool, and I want to setup again this experiment on NS3. Right now, I only know how to change receive buffer size on NS3.

[Matt Anonyme]

Hi,

I suggest that you give the reference of your paper and ask them directly how they did it. Most likely they will be happy that someone is interested in their work and share their code with you if not done already.
Indeed, you can't change the advertised window without changing the code (which in tcp-socket-base.cc).

Cheers.

[Ruth T. Howell]

Thank for your reply, Matt. I also think changing the code in tcp-socket-base.cc, but I realize that they have some functions to change rwnd value, but all of them is protected function, so I think maybe the simulation will have problem if I change this value. I also think access ACK segment but I do not find the some method or class in ns3 mentioned ACK segment. I read on wiki: https://en.wikipedia.org/wiki/TCP_tuning. They use RWIN to limit throughput. Does they use receive buffer size to limit throughput? Because I try to change buffer size and it works (limit throughput of connection).

Vào 20:54:17 UTC+7 Thứ Tư, ngày 24 tháng 8 năm 2016, Matt Anonyme đã viết:

[Nat P]

Il giorno mercoledì 24 agosto 2016 16:50:14 UTC+2, Ruth T. Howell ha scritto:

Thank for your reply, Matt. I also think changing the code in tcp-socket-base.cc, but I realize that they have some functions to change rwnd value, but all of them is protected function, so I think maybe the simulation will have problem if I change this value. I also think access ACK segment but I do not find the some method or class in ns3 mentioned ACK segment. I read on wiki: https://en.wikipedia.org/wiki/TCP_tuning. They use RWIN to limit throughput. Does they use receive buffer size to limit throughput? Because I try to change buffer size and it works (limit throughput of connection).

In ns-3 the rwnd value is connected to the buffer size (as you can check easily in the source code). So, decreasing the buffer results in a decrease of rwnd.

Nat