XO -> XO ping problem

[Javier Cardona]

Dan,

> Linksys WRT54g HW v2, firmware v4.x-something.  I don't think it's
> WDS-enabled at all, WDS doesn't show up anywhere in the interface, but I
> could be wrong.

That fooled us in the past:  although WDS is not mentioned anywhere in
the documentation or the configuration pages, the WRT54g *does*
lazy-WDS.  I have wireshark captures to prove it... :)

Javier


>
> > Javier
> >
> >
> > On 6/27/07, Dan Williams <dcbw at redhat.com> wrote:
> > > Javier,
> > >
> > > We're observing an interesting problem here, replicated in at least 3
> > > different locations (Waltham (me), Toronto (tamtam), Arlington
> > > (dilinger)) on a bunch of different builds (406.x, 432, 451) with
> > > different hardware (B1, B2, B3) and different firmware (5.220.10.p5,
> > > 5.220.11.p5).  In all 3 locations, nothing is doing mesh networking at
> > > all.
> > >
> > > The problem is that when connected in infrastructure mode, two XOs
> > > cannot ping each _other_, but other normal laptops connected to the same
> > > AP can ping each XO, and the XO can both ping the normal laptop and
> > > external sites like google.
> > >
> > > For my investigation of this problem, I turned off NetworkManager
> > > completely and booted up in runlevel 3.
> > >
> > > On both laptops I have, I did:
> > >
> > > chkconfig --level 345 NetworkManager off
> > > chkconfig --level 345 dhcdbd off
> > > chkconfig --level 345 network off
> > > nano /etc/inittab (set runlevel 3 as default)
> > > <reboot>
> > > iwconfig eth0 essid foobar key <blah> mode managed
> > > dhclient -1 eth0
> > >
> > > and then tried to ping each other XO from the other, and to ping google,
> > > and to ping my ThinkPad T42.  The XOs always failed to ping each other,
> > > but could both ping google and my T42.
> > >
> > > Digging further into the issue, I found via wireshark/ethereal on my
> > > thinkpad that I can see the ARP request from XO1 -> XO2, but XO2 never
> > > sends an ARP reply back (as seen from wireshark).  Turning on RX & TX
> > > debugging in the driver on the XO2 shows the "SendSinglePacket succeeds"
> > > message for (apparently) each ARP request XO2 receives, which I
> > > interpret to mean that XO2 is actually trying to send the ARP reply, but
> > > that the reply gets lost between the host_to_card() function and the
> > > radio.  I can actually try to get the hexdump of the outgoing tx packets
> > > if that would help.
> > >
> > > However, running tcpdump on both machines has interesting results.  The
> > > pinging XO1 shows the pings in the dump, but the dump from the XO2 being
> > > pinged shows only LLC frames, and no ICMP frames.  tcpdump isn't getting
> > > any pings.  If you want the tcpdumps I can send you a link.
> > >
> > > Thoughts?  Can you try to replicate with, say, build 451 and debug the
> > > issue as well?
> > >
> > > Thanks,
> > > Dan
> > >
> > >
> > >
> >
> >
>
>


-- 
Javier Cardona
cozybit Inc.
p 415 974 6770
f 415 974 6771
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