It was a USB soho NIC installed inside the monitor surround by metal on most sides. It can be a number of things and in fact was most of the above!
One thing is clear and something important to drive home. Its sitting still, directly under an access point. I see this in the capture window playing over and over and over again. Last month during a presales demo it worked fine with no issues. It is not uncommon to see CRC frames with odd bits flipped.Ĭustomer stated their new medical cart that transmit high resolution images is crawling. Getting closer to the transmitting radios will often lower your CRC rate. This simply means my sniffer could not properly read the frame. If you answered this is a CRC you would be correct. I open my packet sniffer and capture this. In fact they said they couldn't connect to WiFi at times. This was impacting the entire cell and not just the phones.Ĭustomer complained of poor WiFi performance. Note when a client sends a duration value, clients who can demodulate this frame will use this value and reset their clocks to busy. In the end it was a firmware bug on the handset due to an interoperability with a specific configuration and 802.11n access points. The duration value caught my attention during troubleshooting. If you answered duration timer you would be correct. I open my sniffer and see frames much like this one. They would connect to the wifi network and then disconnect and display Locating Network Services.
The cameras were causing interference across channels 1 - 6, causing high retry rates.Īfter a recent firmware update a number of Cisco 7925 phones exhibited an odd behavior. There were old security cameras operating on 2.4 no longer in use but still powered. I turned on WiSpy, low and behold layer 1 interference. While the noise reference on channel was within reason the packet capture was a "bit" misleading displaying a -92. The retry counter was above 30% for channel 6. If you answered retry bit you would be right.
What “bit" could be a clue that might contribute to a slow network ? It's never really preformed right since it was installed.ĭuring my packet capture I observed a lot of frames with a similar “bit" being marked. These are real customer issues on real networks with real problems.Ĭustomer complained of slow WiFi performance in a specific part of the warehouse. Keep in mind sometimes the obvious is not so obvious. While frames don’t lie understanding 802.11 is important to see the truth. I challenge YOU with 4 real world examples. Digging deep into the Stefanick archives of real world 802.11 issues.