A blog with tips, tricks and tutorials to help you prepare your CCIE Wireless lab exam.

Thursday, November 5, 2009

Locating RFID Tags

Does your controller automatically track RFID tags? Well, supposedly yes, or at least some of them, the Aeroscout tags. You can check this by using:

(Cisco Controller) >show rfid config

RFID Tag data Collection......................... Enabled
RFID timeout.................................... 1200 seconds
RFID mobility.................................... Oui:00:14:7e : Vendor:pango State:Disabled

Your controller tracks tags (the Aeroscout tags), but not Pango tags. You can enable Pango tags tracking with the command:

config rfid mobility pango enable

If you do not enable this specific tracking, Pango RFID tags may be seen, but only if they associate to the wireless infrastructure (because then they will probe like normal clients, and will appear as blue "wireless clients" icons instead of yellow "tags"). You have to configure them to associate to the infrastructure...

RFID tracking might be disabled on the controller... with the command:

config rfid status disable

In that case, RFID tracking might be enabled on the Location Appliance and WCS, but no tag location will be reported...

Last funny trick... you probably know that RFID tags send a message at configurable intervals, on configurable channels (you need to configure them to decide which channel(s), which interval, at which power level and which speed (usually 1 or 2 Mbps) they will send). So how long after your RFID tag sent its last message should your controller decide that the RFID tag is gone/dead and stop reporting it to the Location Appliance? You can decide of this timeout with the command:

config rfid timeout

A good value for this parameter is... between 3 and 8 times the emission interval. So if your tag is configured to send its signal every 5 minutes, a good value is between 15 and 40 minutes.

4 comments:

  1. Good stuff here Jerome! Do you take requests? I have noticed on the Cisco Community the there are a lot of questions regarding Mobility Domains/Lists/Groups, RF Groups, etc. The Cisco documentation is about as clear as milk if you know what I mean.

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  2. Good info Jerome! I have a question that's been bugging me for a while, because I can't get a consistent answer when I ask it. Maybe you have some experience with this!

    For wireless deployments where coverage is good, we typically disable the 1Mbps and 2Mbps rates (and also 5.5, 6, and 9Mbps if coverage is great). Would the fact that the 1M and 2M rates are disabled prevent us from tracking AeroScout RFID tags in the future? I've been told conflicting answers, and I've never had the opportunity to test it in a lab. My gut is telling me that the location awareness would still work even with the lower rates disabled, for the same reason that a Rogue AP can be detected even if it's beaconing on a speed that isn't supported by the lightweight wireless system. Have you ever tested anything like this?

    Regards,
    Steve

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  3. Hey Steve,
    Location awareness would still work. When you capture the frames, you can see that what changes is the list of supported rates in the AP beacons and probes responses, but tags sending at 1 Mbps are still detected perfectly well. Funny detail, a wireless client sending a probe request at 1 Mbps gets an answer from the AP... but at the AP lowest mandatory rates, which shows that the AP is till functional for the lower rates, it's just that it does not allow its clients (and an RFID tag is not a client) to use the lower rates...

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  4. Thanks Jerome -- that makes perfect sense. Have a happy 2010!

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