Lots of RX CRC ERRORS with REALTEK PCI card

Lots of RX CRC ERRORS with REALTEK PCI card

Im using a REALTEK RTL8180 PCI card and it works ok.

but the utility for it shows a lot of RX CRC ERRORS

TX OK 8725
RX OK 1723
RX CRC ERRORS (0-500) 9000 (AND RISING)
RX CRC ERRORS (500-1000) 0
RX CRC ERRORS (> 1000)

What can this possibly mean !

On 26 Jun 2005 14:00:42 -0700, "sam1967" <(E-Mail Removed)>
wrote:

>Lots of RX CRC ERRORS with REALTEK PCI card
>
>Im using a REALTEK RTL8180 PCI card and it works ok.
>
>but the utility for it shows a lot of RX CRC ERRORS
>
>TX OK 8725
>RX OK 1723
>RX CRC ERRORS (0-500) 9000 (AND RISING)
>RX CRC ERRORS (500-1000) 0
>RX CRC ERRORS (> 1000)
>
>What can this possibly mean !

Interference, multipath, reflections, co-channel users, cordless
phone, microwave oven, X10 TV remote, wireless TIVO, wireless rabbit,
WiMax, Frequency Hopping Spread Spectrum radios, HomeRF, Bluetooth,
Zigbee, Proxim Lynx, burglar alarm doppler, 2.4GHz wireless keyboard,
harmonics of CPU noise, magnetic field pickup from transformer or
flyback, power supply noise, RF lighting, noisy wall wart, 2.4Ghz ham
radio operation, and whatever else I forgot.

Try changing access point channels (1, 6 or 11) and see if it helps.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558

Jeff

Thanks yet again. In your experience have you seen such a high level
of RX Errors and for the link to still function ?
Is it quite acceptable for this level in your experience or would you
definitely want to tweak some settings to reduce it ?

Jeff

I changed the channel to channel 1 and RX CRC ERRORS all but
disappeared. I am waiting for some RangeLAN PC Cards I bought from the
US to arrive so I can have a look at the competing frequencies in my
area. That was also thanks to a tip from you.

Thanks again

On 27 Jun 2005 03:10:37 -0700, "sam1967" <(E-Mail Removed)>
wrote:

>Thanks yet again. In your experience have you seen such a high level
>of RX Errors and for the link to still function ?
>Is it quite acceptable for this level in your experience or would you
>definitely want to tweak some settings to reduce it ?

It depends on the cause. A wired ethernet connection will typically
have about 1-5% errors caused by collisions. My dedicated wireless
bridge links typically run about 3-5% with ocassional very short term
excursions as high as 30% caused by microwave ovens. I have a
marginal cross town link that runs about 15% average and getting worse
by the month. You're apparently running at 50% or higher error rate,
which is totally unacceptable.

CRC errors are basically corrupted packets arriving at the receive
end. The sources can be numerous, complex, and mutual interactive.
In some cases, the radio link can cause these errors in its heroic
attempt to maximize transmission speed or deal with a bottleneck (i.e.
sending more data than the link can handle). Since you've supplied
absolutely zero detail as to what you're doing, where the numbers are
coming from, and with what hardware, I won't speculate as to the cause
or nature of the packet loss.

However, I can suggest that you consider a few tweaks which may help.
1. Turn on CTS/RTS flow.
2. Lower the fragmentation threshold so that you are sending smaller
packets with a higher probability of arriving.
3. Fix the data rate to the slowest OFDM speed (6Mbits/sec) to
improve receive sensitivity.
4. Improve the path by using larger antennas to increase fade margin.
5. Use directional antennas to reduce interference pickup from the
sides (but not inline).
6. Monitor and graph using SNMP and MRTG to get a feel for the
extent, time, and severity of any interference, atmospherics, or path
problems.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558

ive just noted down those 6 tips in my handbook,.

thanks again.