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#1 2013-01-17 22:01:18

borncrusader
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Registered: 2013-01-17
Posts: 5

[SOLVED] Problems with WiFi connectivity

I have connectivity issues on certain WiFi links (eg. certain locations in my university library), but things seem to work fine on Windows. I have a Dell Studio laptop which sports an Intel WiFi Link 5100 adapter and I use the iwlwifi kernel driver. I'm at loss trying to find where the actual issue is! The kernel logs point to absolutely nothing and I even set my klogd logging rate to debug.

Let me know if someone has experienced something similar and got it fixed. If you need more information for debugging, let me know too.

Last edited by borncrusader (2013-01-30 21:32:15)

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#2 2013-01-17 22:30:02

Blasphemist
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Registered: 2013-01-17
Posts: 40

Re: [SOLVED] Problems with WiFi connectivity

Could you describe the failure please?

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#3 2013-01-18 02:40:13

borncrusader
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Registered: 2013-01-17
Posts: 5

Re: [SOLVED] Problems with WiFi connectivity

I'm not sure what the failure is. All I can notice is that I cannot access anything on my network. However, NetworkManager reports that the WiFi connection is still established.

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#4 2013-01-18 03:16:05

Trilby
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From: Massachusetts, USA
Registered: 2011-11-29
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Re: [SOLVED] Problems with WiFi connectivity

You can't access anything at all, or does it go in and out, or is it slow (eg a long lag before loading a web page)?

You say it's on certain networks - can we assume then that wireless is working well on other networks?

How do you connect?


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#5 2013-01-18 18:28:58

borncrusader
Member
Registered: 2013-01-17
Posts: 5

Re: [SOLVED] Problems with WiFi connectivity

Trilby wrote:

You can't access anything at all, or does it go in and out, or is it slow (eg a long lag before loading a web page)?

You say it's on certain networks - can we assume then that wireless is working well on other networks?

How do you connect?

I can't access anything at all. But of course I don't get a "No Connection Found" error from my browser. The browser apparently still is requesting the page. So does utilities like ping which don't inform that there is no route to the host.

And yes, it happens only on certain networks. I'm suspecting the WiFi version mismatch to be a problem. My hardware doesn't support 802.11n as far as I know, but even though 802.11n is backwards-compatible to 802.11a/b/g, there might be possibilities of my machine missing WiFi cycles to transmit to the base station. But, this is my hunch and I'm really not sure how I can confirm this. I'm sure there is some kind of a troubleshooting utility on linux, but I'm not sure which one to use.

I believe you are asking about what utilities I use to connect. I'm using NetworkManager with an nm-applet.

Last edited by borncrusader (2013-01-18 18:30:07)

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#6 2013-01-18 19:31:29

Trilby
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From: Massachusetts, USA
Registered: 2011-11-29
Posts: 14,779
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Re: [SOLVED] Problems with WiFi connectivity

Can you try using the manual connection methods - at least temporarily for troubleshooting.  Network manager and other such tools hide far to many of the steps to allow you to know what is actually happening.

It sounds like there may be a problem with the dhcp client.  When you can't connect, check the contents of /etc/resolve.conf.  Also try pinging first "google.com" then "8.8.8.8" to see if you get different results.


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#7 2013-01-23 16:13:17

borncrusader
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Registered: 2013-01-17
Posts: 5

Re: [SOLVED] Problems with WiFi connectivity

Trilby wrote:

Can you try using the manual connection methods - at least temporarily for troubleshooting.  Network manager and other such tools hide far to many of the steps to allow you to know what is actually happening.

It sounds like there may be a problem with the dhcp client.  When you can't connect, check the contents of /etc/resolve.conf.  Also try pinging first "google.com" then "8.8.8.8" to see if you get different results.

I tried the manual connection methods - with iw, dhcpd. Yet, I had the same problem. What is more frustrating is that the kernel logs don't indicate anything. I initially thought it was because of the IPv6 solicitation requests that dhcpcd sends, but even disabling the entire IPv6 stack in the kernel seems to have no effect on this issue. Digging through, I came across this bug - https://bugs.launchpad.net/ubuntu/+sour … ug/1057582 and I guess that my problem is related to the one mentioned there. I do remember sometimes seeing NetworkManager logs related to roaming in my syslog. And a week before I got the following warning in the syslog which I sent to the iwlwifi maintenance team, but there has been no response yet!

  Jan 17 13:31:18 localhost kernel: [ 9061.963513] ------------[ cut here ]------------
  Jan 17 13:31:18 localhost kernel: [ 9061.963537] WARNING: at drivers/net/wireless/iwlwifi/dvm/tx.c:1187 iwlagn_rx_reply_tx+0x9af/0x9e0 [iwldvm]()
  Jan 17 13:31:18 localhost kernel: [ 9061.963539] Hardware name: Studio 1555
  Jan 17 13:31:18 localhost kernel: [ 9061.963540] Modules linked in: ablk_helper cryptd aes_x86_64 aes_generic bnep bluetooth snd_hda_codec_hdmi fuse
  Jan 17 13:31:18 localhost kernel: [ 9061.963616] Pid: 0, comm: swapper/0 Tainted: G           O 3.6.11-1-ARCH #1
  Jan 17 13:31:18 localhost kernel: [ 9061.963618] Call Trace:
  Jan 17 13:31:18 localhost kernel: [ 9061.963620]  <IRQ>  [<ffffffff81055c7f>] warn_slowpath_common+0x7f/0xc0
  Jan 17 13:31:18 localhost kernel: [ 9061.963631]  [<ffffffff81055cda>] warn_slowpath_null+0x1a/0x20
  Jan 17 13:31:18 localhost kernel: [ 9061.963637]  [<ffffffffa052916f>] iwlagn_rx_reply_tx+0x9af/0x9e0 [iwldvm]
  Jan 17 13:31:18 localhost kernel: [ 9061.963642]  [<ffffffff81092e08>] ? load_balance+0xf8/0x870
  Jan 17 13:31:18 localhost kernel: [ 9061.963646]  [<ffffffff8108df45>] ? sched_clock_local+0x25/0xa0
  Jan 17 13:31:18 localhost kernel: [ 9061.963651]  [<ffffffffa0532a73>] iwl_rx_dispatch+0xa3/0x110 [iwldvm]
  Jan 17 13:31:18 localhost kernel: [ 9061.963655]  [<ffffffff81275100>] ? unmap_single+0x30/0x70
  Jan 17 13:31:18 localhost kernel: [ 9061.963662]  [<ffffffffa0406ff0>] iwl_irq_tasklet+0xe30/0x1140 [iwlwifi]
  Jan 17 13:31:18 localhost kernel: [ 9061.963665]  [<ffffffff81088b35>] ? check_preempt_curr+0x75/0xa0
  Jan 17 13:31:18 localhost kernel: [ 9061.963670]  [<ffffffff8105f2a3>] tasklet_action+0x63/0xd0
  Jan 17 13:31:18 localhost kernel: [ 9061.963673]  [<ffffffff8105e8f8>] __do_softirq+0xc8/0x240
  Jan 17 13:31:18 localhost kernel: [ 9061.963677]  [<ffffffff8149b7fc>] call_softirq+0x1c/0x30
  Jan 17 13:31:18 localhost kernel: [ 9061.963682]  [<ffffffff81017585>] do_softirq+0x65/0xa0
  Jan 17 13:31:18 localhost kernel: [ 9061.963684]  [<ffffffff8105ed96>] irq_exit+0x96/0xc0
  Jan 17 13:31:18 localhost kernel: [ 9061.963688]  [<ffffffff8149c053>] do_IRQ+0x63/0xe0
  Jan 17 13:31:18 localhost kernel: [ 9061.963692]  [<ffffffff8149356a>] common_interrupt+0x6a/0x6a
  Jan 17 13:31:18 localhost kernel: [ 9061.963694]  <EOI>  [<ffffffff8101cf33>] ? native_sched_clock+0x13/0x80
  Jan 17 13:31:18 localhost kernel: [ 9061.963703]  [<ffffffffa0163246>] ? acpi_idle_enter_bm+0x264/0x2a4 [processor]
  Jan 17 13:31:18 localhost kernel: [ 9061.963707]  [<ffffffffa0163242>] ? acpi_idle_enter_bm+0x260/0x2a4 [processor]
  Jan 17 13:31:18 localhost kernel: [ 9061.963712]  [<ffffffff813639e9>] cpuidle_enter+0x19/0x20
  Jan 17 13:31:18 localhost kernel: [ 9061.963715]  [<ffffffff813640d6>] cpuidle_idle_call+0xa6/0x330
  Jan 17 13:31:18 localhost kernel: [ 9061.963718]  [<ffffffff8101eedf>] cpu_idle+0xbf/0x130
  Jan 17 13:31:18 localhost kernel: [ 9061.963721]  [<ffffffff8146d4dc>] rest_init+0x80/0x84
  Jan 17 13:31:18 localhost kernel: [ 9061.963725]  [<ffffffff818c0c45>] start_kernel+0x3d1/0x3de
  Jan 17 13:31:18 localhost kernel: [ 9061.963727]  [<ffffffff818c0673>] ? repair_env_string+0x5e/0x5e
  Jan 17 13:31:18 localhost kernel: [ 9061.963730]  [<ffffffff818c0356>] x86_64_start_reservations+0x131/0x135
  Jan 17 13:31:18 localhost kernel: [ 9061.963733]  [<ffffffff818c045a>] x86_64_start_kernel+0x100/0x10f
  Jan 17 13:31:18 localhost kernel: [ 9061.963735] ---[ end trace 8c1535e32403f028 ]---

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#8 2013-01-30 21:30:33

borncrusader
Member
Registered: 2013-01-17
Posts: 5

Re: [SOLVED] Problems with WiFi connectivity

Apparently my problem was related to the bug mentioned here - https://bugzilla.redhat.com/show_bug.cgi?id=812259

Setting the 5ghz_disabled kernel module option thus preventing the driver from making spurious roaming attempts between the bands, seems to have solved the problem for now.

As for the warning I had mentioned, I got a reply from one of the developers and apparently that has been fixed as well.

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#9 2013-03-10 16:03:59

tianchaos
Member
Registered: 2013-03-10
Posts: 1

Re: [SOLVED] Problems with WiFi connectivity

borncrusader wrote:

Apparently my problem was related to the bug mentioned here - https://bugzilla.redhat.com/show_bug.cgi?id=812259

Setting the 5ghz_disabled kernel module option thus preventing the driver from making spurious roaming attempts between the bands, seems to have solved the problem for now.

As for the warning I had mentioned, I got a reply from one of the developers and apparently that has been fixed as well.

I think I'm having the same problem on my wireless card. I tried to disable the 5ghz but it does not work.
Also, I have tried what is said in the following website but still can not get it working.
https://wiki.archlinux.org/index.php/Le … nkPad_X200
I just started to use Arch recently instead of Ubuntu. My WIFI works quite well under ubuntu 12.04.

Last edited by tianchaos (2013-03-11 03:00:57)

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