Scriv needs to hire a good consultant to come check things out!

big grin

Anyway, I've seen things like this before.  Not this bad, but close enough.

There have been a few causes.

First, as I recall, this ONLY effects towers within a 15 mile radius. But it effects ALL towers within that "cell". right?????

Assuming I remember that part correctly. I've seen CPE lock it's self into a tx mode. It'll still work, but will drive the system nuts.

I've seen customers download or upload massive files (usually ptp stuff) and open up hundreds of connections and whack a tower. If it's the right tower and interferes with the other towers anywhere near it.

I've been knocked offline by towers over 30 miles away! OK, that was a ptp wmux system with 8' dishes and 30dB of tx power, but still, it happened. With the new gear I'm using these days I can detect ap's 30+ miles away. If conditions are JUST right, that could add quite a bit of noise locally.

There are times when radios go bad and start transmitting OUT of band. I've seen wifi stuff flood the whole band.

Amps can do that too.

USUALLY it's the ap's that take it in the shorts when something like this happens. After all, they are all up above the trees etc.

I've also seen computers take out entire networks when they get infected. If you don't have client to client blocking enabled on your ap's they could be massively overloaded with traffic that you'll not be able to see with a scan tool at the router, it could be traffic that's not even ip traffic! Remember, most of the gear we use with pass netbeui, ipx, appletalk etc. I think the fact that towers that have routers on them between the OTHER ap's and the backhaul should prevent this.

Is it possible that your 900 and 5 gig gear ALWAYS has a router at the cpe and the 2.4 doesn't? As I recall the Waverider gear, the ap is a router, that would keep things that would flow on a switch off of the 900 system.

Are there any towers that are sectorized that point in a direction that makes them unaffected?

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----- Original Message ----- From: "David E. Smith" <[EMAIL PROTECTED]>
To: <>
Sent: Friday, October 27, 2006 9:39 AM
Subject: [WISPA] "The Gremlin," redux

This problem was mentioned back in May (see ) but
it's still here, and I thought it might be worthwhile to bounce it off
folks again, to see if anyone has any new insights.

Occasionally, completely at random, many of our 2.4GHz APs start showing
high packet loss (usually 20-30%) and high latency (upwards of ten
seconds - not milliseconds, full seconds) for a few minutes at a time.

It always clears itself up eventually, usually after a minute or two,
but sometimes it won't go away for ten or fifteen minutes. It's
especially annoying when it happens in the middle of the day and all
those itchy business customers call in at once.

Random facts and tidbits:

* I've watched our network traffic, using Mikrotik's torch and StarOS'
beacon tools, and I don't see anything that looks like a DDOS, either
entering or leaving our network.
* It doesn't affect all our towers, just most of them. Specifically, our
most remote towers (geographically, not in terms of network topology)
are "safe."
* (This is the Lonnie Nunweiler clause) It affects equally towers that
are bridged, routed, and hybrid bridged/routed.
* I don't think it's a backhaul problem, because towers on several
different kinds of backhaul links are affected simultaneously. (We've
got a mix of Alvarion and Trango gear for backhauls, and at least one
ancient YDI EX-1.) Also, there's no problem talking between tower
locations; pings between different APs take 10ms or so, just like they
normally do.
* It only affects our 2.4GHz customers - folks on 900MHz gear, 5.3GHz,
and 5.8GHz connections don't have any issues while things are going sour.

Basically, it looks like someone's got a big giant massive "something"
that spews out insane amounts of 2.4GHz interference, that somehow
knocks out all our customers within about a fifteen-mile radius, and
they turn it on every so often.

Does that conclusion sound reasonable? And if it does, what the heck can
I do about it?


David Smith
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