Re: Recording RTT and RTO values

From: Max Laier (max_at_love2party.net)
Date: 12/26/03

  • Next message: Ruslan Ermilov: "cpp -traditional broken?"
    To: "Tanmay Ganacharya" <ganacharya_tanmay@hotmail.com>
    Date: Fri, 26 Dec 2003 14:12:10 +0100
    
    

    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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  • Next message: Ruslan Ermilov: "cpp -traditional broken?"

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