I have a location with more that one access point. THe users on the location feel a bad connection - and sometimes they are kicked off the wireles network. When I look with Netsumbler I get this screen:
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Why do I see all the black lines in the dump.?.
There are not to many access points close to each other (the other have a very small signal and are on nonoverlapping channels).
Do you have any clue about this?. Have you seen it somewhere before?
Is that 2, 3, 4, 5, or more access points? Can we be a bit less vague? (Yes, it makes a difference).
The connection has to be lost for a long time in order for the access point to initiate a disconnect. Since I have no clue what hardware is being used, I can't offer any suggestions on how to increase the time to disconnect.
That looks fairly normal.
Collisions, interference, signals from outer space. Basically, the black lines are packet loss the ocurrs when a noise or interference hit coincides with a probe request from Netstumbler or a response from the unspecified access point.
If they're on non-overlapping channels, they should be seen or heard on your access point. It's the ones with the "very small signal" that are probably causing some problems.
Sure, but you're doing it wrong. Use ping instead of Netstumbler. It will give you real numbers. Also, Netstumbler indicates signal strength, which is not by itelf a good indication of packet loss or reliability. You can have a very strong signal, but a little interference will still cause considerable packet loss.
Actually, use fping or some other ping probe that's better than the marginal ping shipped with Windoze. (Windoze) (Linux)
Ping your access point or nearby router. If you see something like this mess: Reply[19] from 192.168.1.50: bytes=32 time=2.3 ms TTL=127 Reply[20] from 192.168.1.50: bytes=32 time=38.4 ms TTL=127 Reply[21] from 192.168.1.50: bytes=32 time=34.7 ms TTL=127 Reply[22] from 192.168.1.50: bytes=32 time=2.4 ms TTL=127 Reply[23] from 192.168.1.50: bytes=32 time=2.5 ms TTL=127 Reply[24] from 192.168.1.50: bytes=32 time=2.6 ms TTL=127 Reply[25] from 192.168.1.50: bytes=32 time=2.5 ms TTL=127 Reply[26] from 192.168.1.50: bytes=32 time=22.9 ms TTL=127 Reply[27] from 192.168.1.50: bytes=32 time=19.0 ms TTL=127 Reply[28] from 192.168.1.50: bytes=32 time=2.4 ms TTL=127 Reply[29] from 192.168.1.50: bytes=32 time=2.3 ms TTL=127 then you have an interference problem. "Normal" ping time is about
2.5 msec. However the larger delays are caused by retransmissions induced by interfernce, reflections, co-channel users, noise, etc. If you let it run for a while, you'll probably see a pattern. If you have traffic at the same time, ICMP ping will probably be at a lower priority and the packets will be lost or delayed. Try it without any traffic if possible. It's also fun to graph the results.
The black lines you are seeing is interference. open up the picture to show the channel numbers the three signals are on. The only channels that do not interfere with each other are channels 1, 6, 11.
However, a strong signal on channel 1 could interfere with a weaker signal on channel 6, a strong signal on channel 6 could interfere with channel 11 and vis versa.
For a good connection you should see all GREEN across the graph from your access point, any black lines show interference and the red shows noise. From your graph you have probably got a 10-15 db difference between the signal and the noise, this ain't much when it's coupled to the gaps in the signal caused by the noise.
check netstumbler for all the channels and find one as far away from the others as you can, then set your access point to that channel, then you should see the graph all green with some noise , maybe if your lucky,
Your graphs are pretty common when in a conjested area with more than two access points.
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