Wifi Notes

This page is largely a personal collection of notes from my discussions with AdrianChadd on the FreeBSD wireless networking stack and how to work effectively with the stack.

Debugging pre-requisites

Enable iwn(4) debugging to syslog with sysctl dev.iwn.0.debug=0x1
Ensure you have a kernel with option IWN_DEBUG added

Debugging with experimental traffic

In order to verify the rates and performance of the iwn(4) it is recommended that you have a local wireless network (WLAN) which attaches to a traditional LAN. The network should look something like this:

          +––––––––––––––––+                           
          | Router/Gateway |                           
          +––––––––––––––+–+                           
                  ^      |                             
                  |      |    +–––––––––––––+          
                  |      +–––>+ Wireless AP |          
                  |           +–––––––––––+–+          
                  |                       v            
+–––––––––––––––––+–––+              +––––+–––––––––––+
| FreeBSD workstation |              | FreeBSD laptop |
+–––––––––––––––––––––+              +––––––––––––––––+

On the workstation set up iperf
Enable the debugging flags above on the laptop
Use iperf + UDP to determine whether the laptop is seeing sends or receives experience performance degradation

Disorganized Notes

Look at iwn_rate_to_plcp() for reversing the plcp debug flag
- (if_iwn.c)
Look at TX_STATUS code for the status flag (if_iwnreg.h)
Learn how to compile the wireless stack as modules entirely instead of in
- the kernel object