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 Subject :Odd entry from the Wi-Fi scan.. 2014-12-29- 13:36:39 
WB6TAE
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Joined: 2014-05-01- 23:48:12
Posts: 70
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My node is a Rocket-M2 with a RocketDish RD-2G24. When I run a Wi-Fi scan I always see my own node in the results. I am sure it is me since the MAC address is the same as the "Access Point" reported by the iwinfo command on the node.

My question is: why am I seeing my own node in the scan output when I am connected to the mesh? 

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 Subject :Re:Odd entry from the Wi-Fi scan.. 2014-12-29- 13:42:24 
KG6JEI
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All nodes on the same channel and same SSID share the same ISSID  address, they are in the same format as a MAC address but technically are not actually a MAC and do not identify a single price of hardware.

What you are seeing is the strongest received device at that point when you have other modes around becauzs of the lower layers only passing up the strongest signal to the basic strength counter.

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 Subject :Re:Odd entry from the Wi-Fi scan.. 2014-12-29- 13:48:21 
WB6TAE
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Joined: 2014-05-01- 23:48:12
Posts: 70
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Thanks.  That is probably the case. I have a PicoStation I have been playing with inside the house.

And, thanks also for the explanation of the ISSID. I knew it wasn't the actual MAC address, but wasn't sure exactly what it was.

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 Subject :Re:Odd entry from the Wi-Fi scan.. 2014-12-29- 14:18:34 
WB6TAE
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Joined: 2014-05-01- 23:48:12
Posts: 70
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Just to be sure I understand... When I perform a wifi scan on a node I am connected to (about 3 miles away)  I see my ISSID. My previous experience was that connected nodes did not appear in the wifi scan. And, in fact, none of the other nodes that are connected appear in that scan.

Also, I disconnected the PicoStation and still see my own ISSID when I do a wifi scan on my local node. I do have neighbors with Wi-Fi hubs that I also see, but no other ad-hoc nodes at all.  It is almost like one chain on the Rocket is seeing the other, and also transmitting 2 separate signals.

Does this still jive with your explanation?

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 Subject :Re:Odd entry from the Wi-Fi scan.. 2014-12-29- 17:03:42 
KG6JEI
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Joined: 2013-12-02- 19:52:05
Posts: 516
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Yes it does.

What happens  is when the device first starts it looks for another existing device advertising a network with the same name.  If the name doesn't exist it will generate an ID locally (exact method depends on the software brining up the interface but it's suppsoe to be in a manner that no two devices will generate the same ID) and begin advertising the network.

Every wifi beacon frame contains what is known as the TSF field, it is the wifi network time. It starts at 0 microseconds and goes up for each microsecond of time that passes on the wifi network.

When you have two devices who couldn't see each other before that now can see each other the TSF is compared, the network with the higher TSF is assumed to be the longer lived network and the device will roll it's ID to match the identifier of the longer lived network thereby inheriting thr same ID.

From these two methods EVERY device in the mesh will have the same IBSS/BSS identifier (sorry mislabeled it earlier) as it propagates through the network.

If you logged into the remote bode you should see it claims the same address as well as the network it is joined to/advertising

Literally every device in an ADHOC network will have this same association this is how the device knows when looking at wifi packets that the packet is meant for its network as names (BroadBandHamnet-20-v3) are a human nicety and are not actually used at the lower levels of hardware.


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 Subject :Re:Odd entry from the Wi-Fi scan.. 2014-12-31- 05:40:28 
WB6TAE
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Joined: 2014-05-01- 23:48:12
Posts: 70
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Ok, I think I've got it.  One question though... A Wi-Fi scan on any node shows a single entry for the network, regardless of how many actual connections are currently present. Following your response, above, that makes sense.  So, I am just wondering, in this case, does the signal strength (Sig) represent the best signal of all connected nodes?

Happy New Year.

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 Subject :Re:Odd entry from the Wi-Fi scan.. 2014-12-31- 13:22:43 
KG6JEI
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It represents the strongest single being received in the wifi scan.

There was an interesting patch shown by Joe AE6XE in one of the forums recently that showed each node individually. I haven't had time to test it personally, but in theory it looked right and it should be able to show each individual node strength broken out. It looks promising but isn't a part of the builds yet.

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 Subject :Re:Odd entry from the Wi-Fi scan.. 2015-01-01- 07:06:47 
AE6XE
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Joined: 2013-11-05- 00:09:51
Posts: 116
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Replace (only available on ubnt) /usr/local/bin/wscan with:

https://drive.google.com/file/d/0B2bEy75HhwWhRTl3aHpLanEybFk/view?usp=sharing

Joe AE6XE

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Last Edited On: 2015-01-01- 07:07:31 By AE6XE for the Reason
 Subject :Re:Odd entry from the Wi-Fi scan.. 2015-01-04- 05:29:25 
WB6TAE
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Joined: 2014-05-01- 23:48:12
Posts: 70
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Thanks Joe... that did the trick!
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