Date: Tue, 25 Feb 2003 21:10:52 -0800 (PST) From: Minghua Chen <minghua@eecs.berkeley.edu> Subject: Re: tcptrace about TCP RTT calculation when packet truncation happens Message-ID: <Pine.SOL.4.44.0302252046580.8581-100000@nima.EECS.Berkeley.EDU>
Today I tried to get RTT statistics on both sender and receiver sides,
sender is a fixed host, receiver is a mobile host. Receiver is connected
to sender via a 802.11b interface, and in the other experiment via CDMA
data network.
However, I still can not get correct RTT statistics. On receiver side, it
provides only incorrect RTT statistics, on sender side, it even does not
provide any RTT statistics! I use command like this:
tcptrace -l -r -n test.dump
where test.dump is the dump file given by windump (tcpdump windows
version)
Also, I notice that in both cases, the packets are all truncated, which
make me wonder whether it is because of truncation that the RTT statistics
can not work. So I try to do experiment on two desktops connected by
ethernet, where packet truncation is not supposed. However, the two
machines I can control is seperate by a NAT device, so the packet still
get truncated (shown in tcptrace result) and the RTT still not correct,
could somebody do the experiment or give me an answer why I can not get
correct RTT statistics? Thanks
Minghua
On Tue, 25 Feb 2003 uaca@alumni.uv.es wrote:
> On Mon, Feb 24, 2003 at 02:44:41PM -0800, Minghua Chen wrote:
> > Hi,
> [...]
> > Any suggestions on how can i get the correct RTT in my senario?
>
> this is a topic covered some time ago (3 or 4 months ago or something more)
>
> tcprace can only meassure RTT in one of the ends, it uses the same method
> that the TCP stacks (is supossed) they use, here is were it comes the needed
> to put the dumping utility in one of the two ends
>
> Ulisses
>
>
>
> >
> > Thanks
> >
> > Minghua
> >
> > -------------- examples of RTT raw file of the FTP data packets:
> > 2629228319 196
> > 2629230103 0
> > 2629231563 0
> > 2629234483 0
> > 2629235943 0
> > 2629238863 0
> > 2629240323 0
> > 2629243243 0
> > 2629244703 102
> > 2629246487 0
> > 2629247947 0
> > 2629250867 0
> > 2629252327 0
> > 2629255247 0
> > 2629256707 0
> > 2629259627 0
> > 2629261087 107
> > 2629262871 0
> > 2629264331 0
> > 2629265791 174
> > 2629268711 0
> > 2629270171 136
> > 2629271631 157
> > 2629273091 0
> > 2629274551 117
> > 2629277471 0
> > 2629277795 100
> > 2629279255 120
> > 2629280715 0
> > 2629283635 0
> > 2629285095 0
> > 2629286555 164
> > 2629289475 0
> > 2629290935 126
> > 2629293855 0
> > 2629294179 108
> > 2629295639 126
> > 2629297099 0
> > 2629298559 170
> > 2629301479 0
> > 2629302939 152
> > 2629304399 173
> > 2629305859 0
> > 2629307319 114
> > 2629310239 0
> > 2629312023 0
> > 2629313483 0
> > 2629316403 0
> > 2629317863 0
> > 2629320783 0
> > 2629322243 0
> > 2629325163 0
> > 2629326623 177
> > 2629328407 0
> > 2629329867 0
> > 2629332787 0
> > 2629334247 0
> > 2629337167 0
> > 2629338627 0
> > 2629341547 0
> > 2629343007 142
> >
> >
> >
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