tcp modify and test

Hi,

I have to do some tests on tcp slow start for my final thesis. I
modified tcp_init_cwnd in tcp_input.c and tcp_select_initial_window in
tcp.h. Here I set cwnd to the value I want to test. So I have changed
both to the same value, did this on both my server and my client.

Was this enough? Are there any other values I havt to change?

I controlled the result with tcpdump. But most time it started with 3
packets, sometimes with 6 packets. Even if the initial window is
bigger for example 12. May it be that the first acknowledge is too
fast to send more packages?

I use Red Hat Linux 7.2 and a switched 100 MBit network. If I ping the
other host I get an RTT of 165 usec.

Thanks for your help.
Stephan

On 21 Sep 2003 12:00:29 -0700, (E-Mail Removed) (Stephan Absmeier)
wrote:

>I have to do some tests on tcp slow start for my final thesis. I
>modified tcp_init_cwnd in tcp_input.c and tcp_select_initial_window in
>tcp.h. Here I set cwnd to the value I want to test. So I have changed
>both to the same value, did this on both my server and my client.
>Was this enough? Are there any other values I havt to change?

"Enough" for what? What are you trying to do?


>I controlled the result with tcpdump. But most time it started with 3
>packets, sometimes with 6 packets. Even if the initial window is
>bigger for example 12.

What's "example 12"????


>May it be that the first acknowledge is too
>fast to send more packages?

Post the packet trace. If not, I don't know what you're talking about.



--
Fernando Gont
e-mail: (E-Mail Removed)

[To send a personal reply, please remove the ANTISPAM tag]

In article <(E-Mail Removed)>,
Fernando Gont <(E-Mail Removed)> wrote:
>On 21 Sep 2003 12:00:29 -0700, (E-Mail Removed) (Stephan Absmeier)
>wrote:
>>I controlled the result with tcpdump. But most time it started with 3
>>packets, sometimes with 6 packets. Even if the initial window is
>>bigger for example 12.
>
>What's "example 12"????

"for example 12" = "such as 12", i.e. he used 12 packets instead of 3 or 6.

--
Barry Margolin, (E-Mail Removed)
Level(3), Woburn, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.