Wednesday, February 3, 2016

Troubleshooting Cisco Aironet 1520




I spent all day working on an Aironet 1520 recently.  Here is my brain dump.



Short of opening the front panel, most of what you need for troubleshooting is located on the bottom (photo above).  In particular are 3 things:  Ethernet port (far left whole), 4 LEDs (next to Ethernet port) and the Reset button which is accessed by removing the Phillips Head screw (far right).

If you do need to connect a console cable, open the front panel and you will see two RJ-45 ports.  The console port is not labeled as such, but it is the black (not chrome) RJ-45 closest to the bottom of the unit.

CAUTION NOTES::
- when the RF1 and RF2 lights are GREEN, try to limit your exposure to the unit by less than 6 ft.

- do not carry the unit by holding on to the Omni directional antennas.  They break easily.

- do not power the AP by using a POE port on the switch or an injector that was not specifically designed to be used with the 1520.  The 1520 does not use the regular POE standard.  Only use the big silver injector that is designed to go with this unit.


My troubleshooting tips:
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- The LEDs on the bottom tell you quite a lot about what is going on.  Ideally you want all four to be green.

- I made a video about the LED boot up sequence which you can find here:




  •  LEDs will be hard to see during the daylight unless you are just a couple feet away from them.  Trying to read the LED status from the ground will be tough.  Red is quite a bit easier to see than Green.
  •  Troubleshooting will be more convenient if you an take the unit down from it's high mounting location and work on it on the ground.  I decided to set it up on a 4 ft ladder so it wasn't laying on the ground (which would inhibit good reception).



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  • Removal of the Ethernet cable is made much easier if you stick a small flat instrument (small flat blade screw driver) in the access hole to depress the locking tab down while you pull out the Ethernet cord.
  • Factory reset: while the unit is powered-on, remove the phillips screw from the bottom exterior (it's the only one) and that will give you access to a reset button.  Depressing the reset button for 10 secs and then releasing will factory reset the unit.
  • Antennas, be sure you have the proper type antenna for each of the 4 antenna connectors.  Each is labeled.  There are THREE 2.4ghz antennas and ONE 5ghz antennas.
  • Do not operate the unit without the 2.4Ghz Antenna connected.
  • Check for competing Wifi devices in close proximity. If you are having connection problems (reception issues), you may to discover and eliminate sources of Wifi (other un-authorized Wifi AP's, Personal MIFI devices).  Use a program like Net Stumbler or InSSIDer to help discover theses.
  • NO uplink LED:  there is something wrong with the network connection.  Check your cabling.
  • If you can't get a connection (as in a mesh peer-to-peer), consider taking the injector and the unit to a location slightly closer to it's nearest peer.  Then, power on the unit and wait 5 mins. Even though you may not have the unit plugged into the network, you should still at least see the unit's mac address appear on the mess network (check the controller software).  This will at least prove the unit is capable of connecting. (maybe there is RF interference at the normal location that is preventing the unit from connecting).
  • Check the switch port settings where your 1520's Ethernet connects.  If the switch is a POE, then your inline power setting need to be "off" or "Never" instead of Auto.

Here's a "getting started" guide I got from Cisco that really helped me with the LED stats.

Cisco Aironet Quick Start guide






Thursday, January 28, 2016

RJ-45 corrosion

Something to check if you are having network connection issues, shine a flashlight into the RJ45 socket to check for corrosion (or pin damage).  I see this a lot on floor jacks and in restaurants.

Any place where the jack would be exposed to moisture.  Another problem is grime build-up.  This happens a lot in commercial kitchens when oily steam permeates the air and condenses on the pins inside the jack.