Date: Fri, 26 Dec 2003 14:12:10 +0100 From: Max Laier <max@love2party.net> To: "Tanmay Ganacharya" <ganacharya_tanmay@hotmail.com> Cc: freebsd-current@freebsd.org Subject: Re: Recording RTT and RTO values Message-ID: <200312261412.10182.max@love2party.net> In-Reply-To: <BAY9-F62Y8g8WBniF5e00052e64@hotmail.com> References: <BAY9-F62Y8g8WBniF5e00052e64@hotmail.com>
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On Friday 26 December 2003 11:49, Tanmay Ganacharya wrote: > Hello, > > I am a student from the University of Southern California. I am currently > pursuing my master. > I am working on a project in which I need to record the RTT and RTO values > of a TCP connection. > To achieve the same I first re-compiled my kernel to support debug mode. > I then used a simple client server socket program to transfer a file. The > sockets had the debug option set. > Thus the kernel logs were then collected using the trpt command. > But the problem is I am not able to figure out the required RTT and RTO > values from the log. > > The log looks somewhat like the following > 762 ESTABLISHED:input (src=128.8.126.6,32858, > dst=204.57.0.2,1666)f5ac168b@5269bce1(win=f8e0)<ACK> -> ESTABLISHED > rcv_nxt f5ac168b rcv_wnd e240 snd_una 5269bce1 snd_nxt 5269d381 snd_max > 5269d381 > snd_wl1 f5ac168b snd_wl2 5269bce1 snd_wnd f8e0 > > 762 ESTABLISHED:output (src=204.57.0.2,1666, > dst=128.8.126.6,32858)[5269d381..5269d36d)@f5ac168b(win=e240)<ACK> -> > ESTABLISHED > rcv_nxt f5ac168b rcv_wnd e240 snd_una 5269bce1 snd_nxt 5269d929 snd_max > 5269d929 > snd_wl1 f5ac168b snd_wl2 5269bce1 snd_wnd f8e0 > > I am really not able to understand which are the RTT and RTO values in > these. > Please if anyone knows do let me know. It would really be useful. > Also if anyone knows any other methods of recording the RTT and RTO values > of a connection > please do let me know abt it. > I would really be grateful. CC: net@ (current@ isn't exactly the list for this). None of these values are the RTT or RTO values of the connection as the debug is rather sequence number centric. Take a look at "src/sys/netinet/tcp_var.h: struct tcpcb", where you will find short explainations for each field. The value you might be looking for is "int t_rtttime". Modify the printf's in tcp_debug.c to give you the values you need and recompile your kernel. Hope this helps. -- Best regards, | max@love2party.net Max Laier | ICQ #67774661 http://pf4freebsd.love2party.net/ | mlaier@EFnet #DragonFlyBSD
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