[LUGSB] How to fix wireless reliability problems on campus

[Richard Yao]

Dear Ahmed,

I neglected to mention that I found out about this when
troubleshooting wireless connectivity problems on campus. There was no
site that recommended setting these to fix wireless connectivity
problems, but I remembered seeing them set on Windows, Linksys routers
and the Verizon Fios router, so I decided to try them and they fixed
things.

After seeing that they made things better and reading about them in
greater depth, I did several Google searches to find websites where
people have suggested using these settings to fix wireless
connectivity problems. I did not find a single reference and it might
be that I am the first Linux user to suggest that these settings are
useful for client devices.

Yours truly,
Richard Yao

On Wed, Sep 14, 2011 at 10:57 AM, Richard Yao <ryao at cs.stonybrook.edu> wrote:
> Dear Ahmed,
>
> Not all drivers support these settings. In my case, I use the iwlagn
> driver, which does not support "auto". You can try it on your hardware
> and check that the setting is reflected in the output of iwconfig.
> These settings actually hurt performance in areas where you only have
> a handful of devices using Wi-Fi, so implementing "auto" in Linux
> wireless drivers so that these settings are only used when necessary
> would be a good idea.
>
> As I said in my first email, I plan to take this to the kernel mailing
> list. As an addendum, I request that everyone send me the output of
> the following commands and information on whether or not this helps.
>
> cat /etc/lsb-release
> lspci -n
> uname -srvmpio
>
> That way I will have some of idea of where it helps and where it
> doesn't before I talk to the kernel developers about this.
>
> Here are some references that have more information on these subjects:
>
> http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/Linux.Wireless.mac.html
> http://www.arnetminer.org/viewpub.do?pid=36668
>
> Yours truly,
> Richard Yao
>
> On Wed, Sep 14, 2011 at 10:41 AM, Ahmed Hassan <ahmed at linuxism.com> wrote:
>> Where did you read from?
>> Why don't you make it auto instead?
>>
>>
>> On Wed, Sep 14, 2011 at 10:34 AM, Ahmed Hassan <ahmed at linuxism.com> wrote:
>>>
>>> RTS/CTS adds a handshake before each packet transmission to make sure that
>>> the channel is clear.
>>>
>>> Fragmentation allows to split an IP packet in a burst of smaller fragments
>>> transmitted on the medium
>>>
>>> http://linux.die.net/man/8/iwconfig
>>>
>>> On Wed, Sep 14, 2011 at 10:30 AM, Tony Biondo <tonyb at tonybox.net> wrote:
>>>>
>>>> What exactly do these settings do?
>>>>
>>>> On Wed, Sep 14, 2011 at 9:37 AM, Richard Yao <ryao at cs.stonybrook.edu>
>>>> wrote:
>>>> > Dear Everyone:
>>>> >
>>>> > For reference purposes, here is a speed test of WolfieNet-Secure after
>>>> > doing this:
>>>> >
>>>> > http://www.speedtest.net/result/1482432493.png
>>>> >
>>>> > I could not connect to WolfieNet-Secure from my current location
>>>> > before I did that tweak, so you can consider any test done prior to my
>>>> > tweak to have 0 bandwidth both ways with infinite ping times. For the
>>>> > record, my wireless card is an Intel Ultimate-N 6300, so your speeds
>>>> > will likely be somewhat slower with wireless G.
>>>> >
>>>> > Yours truly,
>>>> > Richard Yao
>>>> >
>>>> > On Wed, Sep 14, 2011 at 9:17 AM, Richard Yao <ryao at cs.stonybrook.edu>
>>>> > wrote:
>>>> >> Dear Everyone,
>>>> >>
>>>> >> If you have problems connecting to Wi-Fi on campus, try the following:
>>>> >>
>>>> >> iwconfig wlan0 rts 2347 frag 2346
>>>> >>
>>>> >> You will want to change the name from wlan0 to whatever your wireless
>>>> >> card's name is. You might also want to put it in /etc/local or
>>>> >> whatever your distribution's init system stores custom boot commands.
>>>> >> It will not fix wireless deadzones like Javits 111, but it should
>>>> >> enable you to connect to the campus wireless anywhere anyone else can
>>>> >> connect. As an added bonus, your download/upload speeds will be higher
>>>> >> too.
>>>> >>
>>>> >> I had been having issues with wireless reliability on campus since I
>>>> >> started using Linux and this semester, the improvements that were made
>>>> >> to campus Wi-Fi made it particularly acute. Configuring these settings
>>>> >> fixed it for me. Now Network Manager behaves comparably to the Windows
>>>> >> Wireless Zero Configuration. It seems that these settings were meant
>>>> >> to deal with this exact situation and that Windows has them enabled by
>>>> >> default. I assume Mac OS X also had them enabled by default given just
>>>> >> how bad things are on campus without them.
>>>> >>
>>>> >> Let me know if it works for you. If all goes well, I will post to the
>>>> >> kernel mailing list in a week or two informing them of the situation
>>>> >> so we can get these settings set by default, like on Windows. i.e. You
>>>> >> are all guinea pigs.
>>>> >>
>>>> >> Yours truly,
>>>> >> Richard Yao
>>>> >>
>>>> > _______________________________________________
>>>> > lugsb mailing list
>>>> > lugsb at fsl.cs.sunysb.edu
>>>> > To unsubscribe from this list, go to:
>>>> > http://www.fsl.cs.sunysb.edu/mailman/listinfo/lugsb
>>>> >
>>>> _______________________________________________
>>>> lugsb mailing list
>>>> lugsb at fsl.cs.sunysb.edu
>>>> To unsubscribe from this list, go to:
>>>> http://www.fsl.cs.sunysb.edu/mailman/listinfo/lugsb
>>>
>>
>>
>> _______________________________________________
>> lugsb mailing list
>> lugsb at fsl.cs.sunysb.edu
>> To unsubscribe from this list, go to:
>> http://www.fsl.cs.sunysb.edu/mailman/listinfo/lugsb
>>
>