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Odd ping-pattern on WLAN

By froogger ·
I'm administrating a WLAN (802.11b) mostly used by handheld computers. They've been behaving oddly lately, and the usual pingerpointing between supplier of database, server and communication has started.

I wont go into detail with the problems, but generally the Windows CE client operating on a MSIE-interface towards the webserver seem to timeout frequently.

Troubleshooting this I pinged a handheld with 5 second intervals for about 15 minutes. What I found looked strange to me, but might be normal behvaiour with WLAN AFAIK.

The pingreply started out fine at about 10-15 ms, then on the next ping it increased about 12 ms every seven pings (ca), until it peaks at about 105 ms, only to drop straight back down to a low ping again. This pattern repeated in cycles of about 45 seconds.

The pattern was very consistent and resulted in a jagged graph that almost looks intentional. But I'm not sure that it's supposed to look like that, I'm too inexperienced with WLANs and wonder whether we have an issue with ARP broadcasts or whatnot. We've ordered some manageable switches to investigate this further, but while we're waiting for those I figured I might hear around if someone knows what a normal behaviour from a handheld on a WLAN is.

Note: I don't get that pattern from pinging any nodes cabled into the network. I only see it when pinging the handheld WinCE computers who are connected via wireless access (Proxim Orinoco AP-600, if you know it).

Any thoughts on the matter is appreciated.

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by BFilmFan In reply to Odd ping-pattern on WLAN

Have you sniffed the network to see what traffic is flowing around? That would be my first suggestion.

And no, that isn't normal behavior.

In addition, I enjoyed your new term "pingerpointing" and intend to use it today when someone on the WAN team breaks something and blames the Active Directory team! ha-ha

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by sgt_shultz In reply to Odd ping-pattern on WLAN

i'd be calilng orinoco what did they say? do you have much info about what may have changed in any of these lately...
yes, love pingerpointing! wow, AD team, what a concept....
so anyway, don't know about wi-fi either but put a wawbuck down you got hardware problem. you imply all wireless wkstns are affected so, while a ms update simultaneous across all w/o me knowing about it is possible, i am guessing it is not them. your only other single point is the wi-fi on the orinco, yes?
any remodeling happening? stuff being moved. wiring being moved. new satellite broadcast recver installed (am looking for interference and noise) something attenuating wi-fi signal...or maybe you will just blink and say wow we just updtted the bios on that orinoco. they got da bomb website. email them is quick and easy. cut and paste your post.
i also would like to know what traffic.

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by froogger In reply to Odd ping-pattern on WLAN

Thanks for replying, and yup, I will mail the supplier of the APs. We're quite busy this season, supplying all the stores with X-mas merchandise, so when my heartbeat has slowed down to normal 90 bpm (I'm a caffeine addict), then I will.

As for traffic, it's only IP, mostly port 80, 443, 445, 1494 (Citrix). Not much strange stuff since we've outsourced all servers and run the major apps on either web interface or Citrix clients.

The Orinoco APs (16) haven't been tested or anything, but they've remained untouched since day one way back. Interference that comes in such a fashion sounds unlikely, and shouldn't affect all APs (I've moved the handheld around and tested several locations).
It's a warehouse, so moving stuff is what we do, as for cables, we've moved a few, but on different segments, so I don't suppose this is it (although I wont rule it out).
No satellite or other radio equipment is installed (to my knowledge).

I'll keep this question open and update it whenever I get around to a conclusion. Today the LAN ping is peaking at insane 1700 ms, while WAN pings stay low at a hundreth of this, so something highly irregular is going on.

BTW, 'pingerpointing' was a typo, but it looks good, so I'll start using it :)

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