Mac Dearman wrote:

I tend to believe you will find your answer on your network -vs- "big bad
leak" somewhere and the only real suggestion I can offer you would be to do
what we do here when we start having weird issues

[ snip: Mac's good advice on how to track down broadcast storms and other network-related problems ]

If it were a backhaul problem, though, wouldn't I see high latency on my backhaul links? I haven't, to date.

Here's one of the (many) experiments I've done in the past (this one was yesterday, actually): I logged into an affected AP, while the problem was happening, and firewalled off THE WHOLE INTERNET except for one IP address, that being the PC in my office I was using to log into that AP. Then, from that AP, I pinged a CPE associated with it. The problem persisted, high packet loss and 5000-10000 millisecond latency.

I quickly undid my changes on that AP, then did exactly the same thing on another AP, about twenty miles away, with a different radio card, on a different channel, connected to me through a different backhaul link, and saw exactly the same performance (high packet loss, obscene latency, et cetera).

Meanwhile, pings to and through our backhaul links, to the APs themselves, various managed switches at tower locations, and so on, never skipped a beat. (Heck, most of 'em improved a bit, since there wasn't as much pesky customer traffic going through them. :)

For that matter, why do I have three towers with a mixture of 2.4GHz and "other" APs (two with a 900MHz AP, one with a 5.3GHz AP and a 5.8GHz AP) and the non-2.4 customers aren't affected? Keep in mind that, for annoying historical reasons, much of our network is still "flat," bridged addresses flying willy-nilly across four counties. If it were a network storm, I'd expect it to hit all our towers, on all channels, and not conveniently skip over the most geographically remote ones.

There's also all the nasty logistical problems of my company not having twenty extra hands that we can just have sitting at all our towers for days, or weeks, at a time, waiting for a problem that shows up completely randomly, hoping I can call everyone to start unplugging stuff before the problem magically goes away, but that's another issue altogether ;)

Last, remember this really is amazingly random, and usually only shows up for a minute or two at a time, brief enough that I only see it in our logs well after the fact. (Yesterday it visited us for a good twenty minutes, long enough for customers to really notice, and for me to have time to dig into it again.)

I certainly don't mean to sound dismissive of any suggestions, it's just that I've tried most of the "obvious" ones before.

David Smith
WISPA Wireless List:



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