Bugzilla – Bug 269
ad-hoc problem for Dell D505
Last modified: 2005-10-23 03:28:18
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We see no such problem on our Compaq X1000 and IBM T40, so this problem seems to be only related to Dell D505. steps: 1, On ibm t40: % modprobe ipw2200 % iwconfig eth1 mode ad-hoc essid testing channel 2 % ifconfig eth1 192.168.2.20 up 2, On dell d505: % modprobe ipw2200 % iwconfig eth1 mode ad-hoc essid testing channel 2 % ifconfig eth1 192.168.2.21 up % ping 192.168.2.20 it displays: Destination Host Unreachable. but if we use a Compaq X1000 instead of D505 and redo the above steps,we can communicate with the ibm t40. but if we change the steps a little, we can communicate using d505. steps: 1, On ibm t40: % modprobe ipw2200 % iwconfig eth1 mode ad-hoc essid testing channel 2 % ifconfig eth1 192.168.2.20 up 2, On dell d505: % modprobe ipw2200 % iwconfig eth1 mode ad-hoc % iwconfig eth1 essid testing channel 2 % ifconfig eth1 192.168.2.21 up % ping 192.168.2.20 this time, we can communicate with the ibm t40.
The ad-hoc code has seen some significant rework. Please retest with v0.13
Please re-test in 0.13 or later.
test it again in 0.13, but this time after the association is established and the static IP is assigned, the two laptop can't communicate with each other. the PING gives message: Destination Host Unreachable.
Please provide the output of "netstat -nr".
another thing... verify that both machines agree on bssid. Since we are setting both the channel and essid on both machines, we could end up with two ad-hoc networks. (We shouldn't, but if we had a problem with the first scan then we would fall in to the path for creating a new network.)
ok, after moving my setup to my home office, I am not seeing this problem, and it is not a routing problem. No need for more information since I can reproduce it now. As a side note, if I force an association from one particular machine of mine (also a dell, but a different model dell) by doing a "iwpriv eth1 set_mode 4", then I can start pinging between the two machines.
s/am not/am/ There was a mistake in my first sentence. I AM seeing the bug.
Even though iwconfig shows the correct bssid, outgoing packets are using what ever the previous bssid was. This causes the reported "Destination Host Unreachable" because the Dell system's arp response uses the wrong bssid, so the other machine in the network ignores the packets.
Indeed, if we don't set channel on both laptops to avoid creating two ad-hoc networks, then ad-hoc mode works well: 1, On Compaq X1000: % modprobe ipw2200 % iwconfig eth1 mode ad-hoc essid testing channel 2 % ifconfig eth1 192.168.2.20 up 2, On Dell D505: % modprobe ipw2200 % iwconfig eth1 mode ad-hoc essid testing % ifconfig eth1 192.168.2.21 up % ping 192.168.2.20 we can see ping comes back with data.
Created an attachment (id=103) [details] ad-hoc preemption fix Well, as it ends up this is actually a preemption bug. It just so happens that my Dell system was built with preemption enabled, and my other two systems were not. We were sending a host command to create a new ad-hoc network, and then storing our bssid in private data in the next line of code. With preemption enabled it is actually possible for the return notification to execute before we get to the next line of code. The fix will be in v0.14, and here is a patch for who ever wants it.
fixed in v0.14
can't verify the fix, because we can't set correct channel under ad-hoc, see bug 413. will verify this when bug 413 is fixed.
verified in 0.15.