Internet woes
chip33az at netscape.net
chip33az at netscape.net
Mon Jun 25 09:44:33 MST 2007
I hate replying to my own message, but this is what Mandriva wrote about it.
See also Image:bug_small.png
<http://wiki.mandriva.com/en/Image:Bug_small.png> Bug #27073
<http://qa.mandriva.com/show_bug.cgi?id=27073>. If this does not resolve
the problem, there is another possibility. Most Linux distributions,
including Mandriva, enable a kernel feature called TCP window scaling.
This is useful for increasing the speed of transfers over very high
bandwidth connections. However, a change was made in the default values
for TCP window scaling in kernel 2.6.17, which seems to cause very slow
network performance for some users with some internet sites. To see if
TCP window scaling is the problem, you can disable it with this command:
sysctl -w net.ipv4.tcp_window_scaling=0
If this resolves the problem, you can make the change permanent by
adding this line to the file /etc/sysctl.conf :
net.ipv4.tcp_window_scaling=0
This will disable TCP window scaling at every boot. If you do use a very
high bandwidth network connection - for instance, you regularly transfer
large files over a local 100Mbit or 1Gbit network - you may notice that
disabling TCP window scaling results in slower performance over this
connection. In this case, you could try restoring the pre-2.6.17 default
settings rather than disabling TCP window scaling entirely. To do this,
add the following line to /etc/sysctl.conf, instead of (not in addition
to) the previously suggested one:
net.ipv4.tcp_rmem=4096 87380 174760
This will change the default window scaling settings at every boot.
chip33az at netscape.net wrote:
> When I installed Ubuntu on a laptop at home, my Internet performance
> was horrible. I had installed Ubuntu before, but never had any
> issues. I then installed Etch, same issue, same laptop. I tried
> other OS's without any success. I then tried an older version of
> Debian and it worked fine. I searched Google and found a little blurp
> about window size and routers and the newer kernels.
>
> I don't know if this will help you, but with the machine running, open
> a terminal window, go to root mode and cat
> /proc/sys/net/ipv4/tcp_window_scaling. If it is set to 1, change it
> to 0 with echo "0" > /proc/sys/net/ipv4/tcp_window_scaling. Close FF
> and try again.
>
> The difference was night and day for me.
>
> There are a few work arounds, but if this works and you want a
> permanent solution, add "net.ipv4.tcp_window_scaling=0" to
> /etc/sysctl.conf.
>
> I know there are other settings, but this worked well for me.
>
> Motheaton28 at aol.com wrote:
>> Kenneth wrote:
>>
>>> --- "Robert N. Eaton" <Motheaton28 at aol.com> wrote:
>>>
>>>
>>>> In Fedora 7 Thunderbird doesn't connect at all: it times out. Firefox
>>>> connects to a very few sites and doesn't seem to finish the connection,
>>>> no matter how long it tries. Seems like a software problem, but _which_
>>>> software? SELinux? Firewall?
>>>>
>>> When firefox doesn't connect, what does the status bar say it's doing?
>>> looking up host, waiting for reply?
>>>
>>> What's the output of "ifconfig -a" ?
>>>
>>>
>> [bob at localhost sbin]$ ./ifconmfig -a
>> eth0 Link encap:Ethernet HWaddr 00:05:5D:34:C3:19
>> inet addr:192:168:0:3 Bcast:192:168:0:255 Mask:255:255:255:0 inet6
>> addr fe80::255:5dff:fe34:c319/64 Scope:Link
>> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
>> RX packets:8 errors:0 dropped:0 overruns:0 frame:0
>> TX packets:57 errors:0 dropped:0 overruns:0 carrier:0
>> collisions:0 txqueuelen:1000
>> RX bytes:2195 (2.1 KB) TX bytes:10602 (10.3 KiB)
>> Interrupt:20 Base address:0x4000
>>
>> eth1 Link encap:Ethernet HWaddr 00:50:8D:E5:8D:12
>> BROADCAST MULTICAST MTU:1500 Metric:1
>> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>> TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
>> collisions:0 txqueuelen:1000
>> RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
>> Interrupt:16 Base address:0x8000
>>
>> lo Link encap:Local loopback
>> inet addr:127.0.0.1 Mask:255.0.0.0
>> inet6 addr: ::1/128 Scope:Host
>> UP LOOPBACK RUNNING MTU:16436 Metric:1
>> RX packets:10274 errors:0 dropped:0 overruns:0 frame:0
>> TX packets:10274 errors:0 dropped:0 overruns:0 carrier:0
>> collisions:0 txqueuelen:0
>> RX bytes:89837264 (85.6 Mib) TX bytes:89837264 (85.6 MiB)
>>
>> [bob at localhost sbin]$
>>
>> If there are any errors, it's my typing. This is worse than sneakernet;
>> I couldn't figure a protocol to write the ./ifconfig -a output to a
>> floppy and then cut and paste in WinXP Thunderbird. I had to print it
>> out and then reboot into WinXP, open Thunderbird, type it in by hand,
>> and I'm a lousy typist.
>>
>> Bob
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