Bugzilla – Bug 199
ProbeRequestTimeout too large
Last modified: 2008-07-01 13:32:34 EDT
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In bug #177 the BeaconInterval default value was changed to 100 ms. ProbeRequestTimeout is now set to 500 ms, which I think is too large. I think it should be half the BeaconInterval by default, as before. http://telecom.inescporto.pt/~gjc/Screenshot-(Untitled)%20-%20Wireshark-1.png My real life captures show me that, in a particular case, all ProbeResponses arrive within 24 ms. I think waiting no more than 50 ms by default seems reasonable. Arguably 100 ms would not be a bad value either. I don't have any hard value on this; only the device firmware knows...
diff -r 362f1a144828 src/devices/wifi/nqsta-wifi-mac.cc --- a/src/devices/wifi/nqsta-wifi-mac.cc Tue Jun 03 18:15:08 2008 +0100 +++ b/src/devices/wifi/nqsta-wifi-mac.cc Tue Jun 03 19:17:12 2008 +0100 @@ -63,7 +63,7 @@ NqstaWifiMac::GetTypeId (void) .SetParent<WifiMac> () .AddConstructor<NqstaWifiMac> () .AddAttribute ("ProbeRequestTimeout", "XXX", - TimeValue (Seconds (0.5)), + TimeValue (Seconds (0.05)), MakeTimeAccessor (&NqstaWifiMac::m_probeRequestTimeout), MakeTimeChecker ()) .AddAttribute ("AssocRequestTimeout", "XXX", PS: the reason why this value is critical is because it affects how much time it takes to do an active scanning sweeping all the 12 or so WiFi channels available. I am no WiFi expert, but as far as I know the STA needs to spend at least ProbeRequestTimeout in each channel; mutiply that time by 12, and...
looks good. please, commit.