Tag Archives: Cisco WLC 4400 Series

Cisco WLC 4400 Catastrophic Bug

I would like to make you all aware about catastrophic bug that affects (or may potentially affect) you. It applies to legacy eol/eos wireless controllers (Cisco WLC 4400 series), which are still massively deployed in many companies. A friend of mine has asked me to help troubleshooting very strange problem they’ve been experiencing for some time. Here’s a story and workaround. Read more …

Finding Cisco Tx Power Levels

Tx Power Level is an important variable that, in combination with antenna gain, influences coverage patterns. Cisco wireless controller dynamically adjusts transmit power levels according to current RF conditions, access point’s capabilities and local regulatory domain recommendations, that may vary per band and/or channel. We, as an engineers, should be capable to confirm current Tx Power level, list of all supported Tx Power levels and antenna gain (if applicable). No coverage or heatmap approximations can be made without this information. With this post I will provide a number of different useful CLI commands that may be used to quickly find Tx Power levels information per-AP and in bulk. Read more …

Recovering bricked Cisco WLC 4400

Getting back to my bricked WLC. Well, ex-bricked WLC. If you missed that post – check it out here.

I have spent few months trying to find a fix to this. I tried different ways, including unofficial talks with Cisco TAC engineers. Although they tried to be polite, no one wanted to go deep into my problem. No one cares about End of life device without hardware support. Well, no one except myself. Simply because I didn’t want to spend few more hundreds to buy one extra working controller for my lab. And, I managed to reanimate it. Cure is soooo simple… You’ll be surprised. Read more …

How to literally kill Cisco WLC 4402

This post is a warning. Only to make people aware of a “VERY VERY BAD PRACTICE”. I have managed to kill my lab Cisco WLC 4402 yesterday. We all know that routers and switches (even Standalone APs) can be upgraded through the recovery mode (it’s when the boot process is being interrupted). Some devices, like access points, support TFTP recovery, others can only be updated via XMODEM. Cisco WLC 4400 is different, completely different. If you interrupt the boot process by pressing ESC, it will provide you with the recovery menu, where one of the options is “Manually update images”. This is what I tried yesterday, unluckily. Read more …