Invalid Packets on capture

[ehouser]

What exactly are the invalid packets on captures, and what would be considered to be problems when seeing them? For example, I did multiple captures and on each one, the average is around 25% invalid? Is that high and if so, what could be the cause?

[Joel]

Invalid frames are a normal by-product of packet capture. When we capture packets, we can understand most of them, but some of them are garbled and don't pass the CRC checksum that we do to make sure that the packet is good.

It's similar to eavesdropping on a conversation. You can understand most of it, but sometimes you have to fill in the blanks on your own. Fortunately, the human brain is pretty good at doing that. Wi-Fi chipsets? No so much.

I'd be okay with a 25 percent invalid rate, although physically moving closer to the devices and checking for interference with a spectrum analyzer would both be good steps to improve it.