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Re: FC1 -> FC2: very slow xDSL connection...



> >
> > On Thursday 24 June 2004 16:21, Andrea Giuliano wrote:
> >
> > > It's an Ethernet ADSL modem, namely the Siemens Gigaset. I'll try
> > > tcpdump as soon as possible.
> >
> > Many times looking at tcpdump in one terminal window and trying things
in
> > another has given me the big clue :-)  I would be looking at the DNS
> > resolution behaviour (UDP port 53 traffic) especially hard first.
>
> I tried yesterday night, but the output is quite complicated. I only
> noticed, while Epiphany was trying to access Google, many lines with
> "www.google.it" and, I think, the actual IP address for Google. This
> should mean that DNS is not the problem here. Also, "traceroute
> www.google.it" immediately outputs several lines with IP addresses and
> times in milliseconds, but it starts printing "*" after some lines,
> which should mean that Google could not be reached but, at the same
> time, that the name was resolved immediately. The same conclusion comes
> from a "ping www.google.it", which answers immediately everytime is
> issued.
>
> > > > You should consider turning off ECN as a test too since some routers
> > > > choke on it.
> > > > echo 0 > /proc/sys/net/ipv4/tcp_ecn
> > >
> > > What's that?
> >
> > Explicit Congestion Notification.  It is a bit in the TCP header, I
think.
> > Some router devices cannot handle seeing it and have a mental attack.
FC2
> > can issue it by default.
> >
> It's 0 already.
>
> > > > Also, what is your network setup like generally?
> > >
> > > Well, I started configuring eth0 and ppp0, but in an Italian document
I
> > > found a different suggestion: remove eth0 (using the "Network" menù
> > > item), then add an xDSL connection with just a name ("Alice"),
username
> >
> > Heh, I just got wifi working here using a similar trick :-)
> > system-config-network is really cool once you can get it started with
such an
> > ifcfg-* file.
> >
> > I have no experience with ADSL unfortunately, but I would imagine you
can do
> > tcpdump -i Alice and just see traffic headed down there.
> >
> > - -Andy
> Thanks, I think we are making some progress!



perhaps (most probably)  you should change your mtu settings of your eth0
card
common is 1490 or 1492




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