Wireless Sniffer for Troubleshooting


I am very familiar with 802.11-based networks but the Canopy system is new to me. I am experiencing a problem where the network drops out for a period of 25-30 seconds every five minutes or so. This occurs usually between 5PM and 10PM most days. Sniffing with Ethereal does not provide much of a clue.

There is no evidence of a SM, AP, or BH loosing its link during these dropouts. My intuition tells me that it might be an interference source. If I were to troubleshoot a problem like this on a 802.11 network I would fire up Aeropeek and look to correlate MAC-level retransmissions with the service drop-outs. Is there a tool like Aeropeek for the Canopy network that can sniff raw management and control frames? Do you have any other ideas how to track this problem down.


I’m also curious as to which technique folks are using to measure their RF interference issues.

We had similar “drop off” issues, we resolved them by getting good trend baselines & logging from our layer 2/Canopy network, then correlating issues.

Do you have trends/baselines for your network via PRTG/Cacti/Syslog?

Are you using an alerting system like Nagios/WhatsUp?

SNMP traps from the APs?

Are you using VLANs? How many SMs & APs do you have?

One option to your RF problem would be to change the AP that has lost connection with your SM over to a SM, only if all of your subs have lost connection to that AP, then go to expanded stats and spectrum analyzer; this should give you a good idea of what is running in your area.

Also if possible check it from the clients location as well. I have ran into problems where clients had a 5.8Ghz ( as well as 2.4 and 900Mhz(rare) ) and depending on the time of day those phones would jump near the same channel that the canopy SM was fixed on causing the SM to drop large amounts of packets and in some cases drop, although that was vary rare, also seen this with wireless routers and the 2400 SM’s.

Oh one more note; welcome to the world of unlicensed RF band; anything can run on it, so it can be a pain, get used to it. :twisted:

use an SM or switch AP to SM to do a spectrum scan… compare this with what you see during the time when it is fine…

run an SNMP poll to the RSSI, jitter, dbm and see if there is a pattern…

run link efficiency tests and see what the downlink/uplink this may indicate a problem and also which side it may be at…

finally the only sure way to do this would be to get a spectrum analyser, and see what is going on in your spectrum…