Low TX rate (1 Mbps) from hostap 0.3.7 to prism2_usb (subversion r1715)

[Chris Rankin]

Hi,

I have been investigating the curious performance problem when prism2_usb links with hostap-0.3.7,
and it seems to be down to the firmware. For example, here are the results of FTPing 100MB back
and forth when the prism2_usb device contains firmware 1.7.4:

hostap to prism2_usb(1.7.4):

ftp> get trailer_final_1000_dl.zip get.zip
local: get.zip remote: trailer_final_1000_dl.zip
227 Entering Passive Mode (192,168,1,1,186,140)
150 Opening BINARY mode data connection for trailer_final_1000_dl.zip (99292202 bytes).
226 Transfer complete.
99292202 bytes received in 203 secs (4.8e+02 Kbytes/sec)

prism2_usb(1.7.4) to hostap:

ftp> put get.zip put.zip
local: get.zip remote: put.zip
227 Entering Passive Mode (192,168,1,1,82,8)
150 Opening BINARY mode data connection for put.zip.
226 Transfer complete.
99292202 bytes sent in 247 secs (3.9e+02 Kbytes/sec)

And for USB firmware 1.7.6:

prism2_usb(1.7.6) to hostap:

ftp> put trailer_final_1000_dl.zip put.zip
local: trailer_final_1000_dl.zip remote: put.zip
227 Entering Passive Mode (192,168,1,1,249,205)
150 Opening BINARY mode data connection for put.zip.
226 Transfer complete.
99292202 bytes sent in 243 secs (4e+02 Kbytes/sec)

hostap to prism2_usb(1.7.6):

ftp> get put.zip get.zip
local: get.zip remote: put.zip
227 Entering Passive Mode (192,168,1,1,224,174)
150 Opening BINARY mode data connection for put.zip (99292202 bytes).
226 Transfer complete.
99292202 bytes received in 200 secs (4.8e+02 Kbytes/sec)

And finally for USB firmware 1.8.3:

prism2_usb(1.8.3) to hostap:

ftp> put trailer_final_1000_dl.zip put.zip
local: trailer_final_1000_dl.zip remote: put.zip
227 Entering Passive Mode (192,168,1,1,56,48)
150 Opening BINARY mode data connection for put.zip.
226 Transfer complete.
99292202 bytes sent in 810 secs (1.2e+02 Kbytes/sec)

hostap to prism2_usb(1.8.3):

ftp> get put.zip get.zip
local: get.zip remote: put.zip
227 Entering Passive Mode (192,168,1,1,172,18)
150 Opening BINARY mode data connection for put.zip (99292202 bytes).
226 Transfer complete.
99292202 bytes received in 3.39e+03 secs (29 Kbytes/sec)

As you can see, hostap has *real* trouble when the USB adapter contains firmware 1.8.3.; although
the USB adapter keeps operating at 11 Mbps, the hostap device (MA301 PLX adapter) keeps dropping
down to 1 Mbps. This affects hostap's TX path more than its RX path, but even the RX path has a
more than 3-fold drop in performance.

Does anyone have any idea what the 1.8.3 USB firmware does that hostap hates so much, please? The
hostap device is running firmware 0.3.0/1.7.1.

Thanks,
Chris


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