Intermittent packet loss with 3945 wireless

cata00 · #1 18th September 2007, 05:29 AM

Hi all,

Sorry if this has been asked before -- I searched this forum and Google and couldn't find a fix.

I'm runing Fedora 7 on an Acer TravelMate 8204WLMi laptop with the 3945BGA wireless chipset. When I connect to my WAP, the connection works intermittently. It's always on for 5 seconds, then off for 2 seconds, and this is very repeatable. Here's a ping to my router (look at the non-consecutive icmp_seq's):

Code:

[cata@piticu ~]$ ping 10.0.1.1
PING 10.0.1.1 (10.0.1.1) 56(84) bytes of data.
64 bytes from 10.0.1.1: icmp_seq=2 ttl=64 time=1.07 ms
64 bytes from 10.0.1.1: icmp_seq=3 ttl=64 time=1.00 ms
64 bytes from 10.0.1.1: icmp_seq=4 ttl=64 time=1.00 ms
64 bytes from 10.0.1.1: icmp_seq=5 ttl=64 time=1.01 ms
64 bytes from 10.0.1.1: icmp_seq=6 ttl=64 time=1.00 ms
64 bytes from 10.0.1.1: icmp_seq=9 ttl=64 time=1.02 ms
64 bytes from 10.0.1.1: icmp_seq=10 ttl=64 time=1.01 ms
64 bytes from 10.0.1.1: icmp_seq=11 ttl=64 time=1.12 ms
64 bytes from 10.0.1.1: icmp_seq=12 ttl=64 time=1.15 ms
64 bytes from 10.0.1.1: icmp_seq=13 ttl=64 time=1.16 ms
64 bytes from 10.0.1.1: icmp_seq=16 ttl=64 time=1.08 ms
64 bytes from 10.0.1.1: icmp_seq=17 ttl=64 time=1.10 ms
64 bytes from 10.0.1.1: icmp_seq=18 ttl=64 time=1.08 ms

--- 10.0.1.1 ping statistics ---
18 packets transmitted, 13 received, 27% packet loss, time 16999ms
rtt min/avg/max/mdev = 1.002/1.066/1.166/0.064 ms

From Windows, the connection works perfectly. Sadly, there are no unencrypted networks around my apartment, so I cannot try a different network. Conversely, I had a friend over just today, running an up-to-date Fedora 7 on am Intel 4965 chipset, and his connection worked flawlessly. My connection is encrypted with WPA-PSK. I use NetworkManager to connect. Before Fedora7 I had FC6 with ipw3945 and it was working fine. Here is some information that may be relevant:

Code:

[root@piticu ~]# lspci|grep -i wireless
05:00.0 Network controller: Intel Corporation PRO/Wireless 3945ABG Network Connection (rev 02)
[root@piticu ~]# rpm -qa|grep -i 3945
iwl3945-firmware-2.14.1.5-1

Any ideas? And BTW, thanks for this wonderful forum, you're usually the first Google result whenever I have Fedora issues and you're always helpful.

cata00 · #2 18th September 2007, 05:34 AM

You might need this bit of info too

Code:

[root@piticu ~]# iwconfig wlan0
wlan0     IEEE 802.11g  ESSID:"piticu_network"  
          Mode:Managed  Frequency:2.447 GHz  Access Point: 00:14:51:6B:D3:E7   
          Bit Rate=54 Mb/s   
          Retry min limit:7   RTS thr:off   Fragment thr=2346 B   
          Encryption key:C599-43F5-39BA-4B88-B1DA-0A71-E4EE-C7A1-7379-30C5-7C99-9656-F5EE-E539-DB35-C7C4 [2]
          Link Quality=81/100  Signal level=-53 dBm  Noise level=-84 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

ppesci · #3 18th September 2007, 06:06 AM

Your connection is better than mine but i don't have the packet loss error.

Only a guess, but my configuration does not support 54 Mb/s.

Open the file /etc/sysconfig/networking/devices/ifcfg-wlan0 and if you see the line:

RATE='54 Mb/s'

change to:

RATE='11 Mb/s'

to see if your wireless work better. If it doesn't work, can you put the otput of the file here?. Only a guess. I suppose ndiswrapper get hog with high transference bit rates, and then, you keep losing some packets.

HTH

cata00 · #4 18th September 2007, 07:01 AM

Thanks for your prompt response! My /etc/sysconfig/networking/ifcfg-wlan0 file contained the line

RATE=Auto

I changed that to

RATE='11 Mb/s'

but I'm still seeing the same behavior (ping loses 2 packets out of every 7). Also, I'm performing this test with no network load, just pinging the router, and I don't use ndiswrapper at all (it's not even installed).

Here's my ifcfg-wlan0 file:

Code:

# Intel Corporation PRO/Wireless 3945ABG Network Connection                     
DEVICE=wlan0
ONBOOT=no
BOOTPROTO=dhcp
HWADDR=00:13:02:21:a9:ba
NETMASK=
DHCP_HOSTNAME=
IPADDR=
DOMAIN=
TYPE=Wireless
USERCTL=no
IPV6INIT=no
PEERDNS=yes
ESSID=
CHANNEL=1
MODE=Master
RATE=Auto

ppesci · #5 18th September 2007, 07:15 AM

Can you change:

MODE=Master

to

MODE=Auto

I know at the end, the mode used is Managed, but is better to declare straight in this way in the config file.

ppesci · #6 18th September 2007, 07:31 AM

BTW: I suppose you are using ndiswrapper because you have a rev 02, and this revision has been reported with some problem with linux driver. Many ppl solved this using ndiswrapper. Search for 3945abg in this forum.

cata00 · #7 18th September 2007, 07:42 AM

Still no luck

I tried MODE=Auto and I'm seeing the same symptoms.

With respect to ndiswrapper, are you saying that there's a temporary problem with support for rev 02? I'm sure I had wireless working perfectly with FC6, without ndiswrapper (although I was using ipw3945, not iwl3945). I'd be happier to use Fedora's driver, but I can give the WIndows driver a try.

ppesci · #8 18th September 2007, 07:51 AM

That card is not my card but y saw some problems with this rev 02 card. May be ndiswrapper work fine. If you can try, do it. Remember to use a W2000 driver if possible, and no Vista driver.

bbfuller · #9 18th September 2007, 09:48 AM

Hello cata00

I notice in your first post that you are using the iwl3945 drivers that come with f7 for your card.

These were supposed to replace the older ipw3945 drivers but have been a very hit and miss affair as to whether they work or not - or indeed how well they work.

I have a 3945 rev02 in my laptop and I gave up on those drivers as soon a someone pointed out that you can revert to the older ipw3945 drivers without too much trouble.

That course of action has become so popular that rpm's to automate the process are available from third party repositories now.

There is a howto here:

Quote:

http://www.fedoraguide.info/index.ph...#Intel_IPW3945

that I followed.

Two provisos:

It's still not always straightforward to get a WPA connection. I've got four wireless machines that I have access to and the one thing that is noticable is how different they are at authenticating. My 3945 won't connect at boot, will connect manually from NetworkManager for about 10 seconds, fail, be manually connected again and then stays connected as long as I wish, so persevere with it if you go this route.

Some people have reported that even using this automated method it is necessary to stop the iwl3945 driver from loading.

If you need to do that add:

Code:

blacklist iwl3945
blacklist mac80211

to the end of the file /etc/modprobe.d/blacklist

Hope it works for you.

cata00 · #10 18th September 2007, 05:57 PM

ipw3945 worked like a charm! Pinging my router no longer loses packets and my download speeds are back to normal. Thank you both so much! Here's what I did, for future reference.

Code:

rpm -i http://ftp.freshrpms.net/pub/freshrpms/fedora/linux/7/freshrpms-release/freshrpms-release-1.1-1.fc.noarch.rpm

Edited /etc/yum.repos.d and set enabled=0 (optional, but I prefer to keep third-party repos disabled)

Code:

yum --enablerepo=freshrpms install  dkms-ipw3945

Blacklisted the old modules:

Code:

[root@piticu ~]# cat >> /etc/modprobe.d/blacklist
# Added by cata to use ipw3945 instead of iwl3945
blacklist iwl3945
blacklist mac80211

Rebooted. Here, I tried to hot-swap the modules with modprobe -r iwl3945 and modprobe -r mac80211, but the latter one claimed it was still in use. So I just rebooted.

Removed leftovers from the old wireless device (it was called wlan0):

Code:

updatedb
locate wlan0|xargs rm -fv

Ran System -> Administration -> Network. Checked that my wireless card is detected under the Hardware tab. Went to the Devices tab and created a new wireless device (it's called eth1 this time).

Made sure ipw3945d was running:

Code:

[root@piticu ~]# service ipw3945d status
ipw3945d (pid 3356) is running...

Restarted NetworkManager, which connected to my access point without problems.

nt4cats · #11 22nd September 2007, 03:30 PM

I'm running F7 with a similar card to you folks [Intel Corporation PRO/Wireless 3945ABG Network Connection (rev 02)] -- and I would much prefer to use the 'built-in' support for the card. This way updates (especially the kernel) are EASY.

It wasn't until kernel-2.6.22.4-65.fc7 and iwl3945-firmware-2.14.1.5-1 that I was finally rock-solid stable with things. This lasted for about 6 weeks until I updated (not sure if it was my kernel-2.6.22.5-76.fc7, dbus, or a NetworkManager update that broke it). Now I do not auto-connect to a wireless network upon boot -- and the first attempt to connect stays on for 5 seconds and then drops. The second (manual) attempt to connect works and stays online.

The development guys know about this and are working on it -- see this thread for details.

I'm willing to stick with two-tries-to-connect until the next batch of updates.