I'm involved in some ad hoc networking research, and recently I've
encountered some weird behavior that is causing partitioning of our
First, about our set-up: we have twenty PC's, running OpenBSD 2.9,
spread out among two floors of our building. Each is equipped with an
Aironet 340 PCI card running in ad hoc mode and with matching SSID's.
The firmware is version 4.25.10.
Until recently, this set-up was working fine for us, and all the nodes
were setting matching BSSIDs and forming a contiguous network. Last
week, however, the network partitioned itself seemingly without
reason: now there are two sets of nodes, one with a sensible BSSID
(00:02:2d:1f:3a:4a), and one with BSSID ff:ff:ff:ff:ff:ff. The two
sets of nodes are unable to communicate with each other, despite
physical proximity (in one case, one node from each set are in the
same room). However, within the nodes of each set, operation is
continuing as normal.
Has anyone ever seen anything like this? It's possible that this
happened as a side effect of some nodes rebooting for the sake of
software upgrades: is there any way that multiple nodes coming up
simultaneously could result in this weird condition? If so, is the
"all ones" address treated specially, preventing the cards from later
settling on a single BSSID?
Within the last few weeks, we've also had some PCMCIA WaveLAN cards
join in the network. I've noticed that they misbehave on occasion,
for example sometimes choosing their own BSSID despite being within
range of the Aironet hosts. Could their presence have led to this
situation? Or, could the unusual situation with the Aironet cards
cause the WaveLAN cards' misbehavior?
Simply rebooting all the nodes will almost certainly correct this
problem, but I'm hesitant to do so until I have a better understanding
of why this has occurred. As our network continues to grow, such a
solution will grow more and more impractical if this ever happens
I would appreciate any insight or advice anyone can provide. Thanks