howto debug slow WLAN connection?

Hi there,

My Lenovo T61P (ubuntu 8.10) is happily connecting to my WLAN router
at home;
I can ping the WLAN router and the gateway modem of my provider with
zero delay ...

BUT - anything that goes out to the internet takes .... forever.
Sometimes it is a bit faster;
but in general the connection is way "slower" compared to my old
Windows XP experience.

The really strange thing - as soon as I invoke the AT&T vpn client to
connect to my
companies intranet ... the problems are gone.

Websites that would take a minute to load before are now showing up
within seconds.

To me that sounds like some DNS or whatever problem - but I specified
the same
DNS servers for my connection that I am using with my Windows XP
installation.

[ I disabled DHCP; so all my machines have a defined setup ]

So - where should I look to find the root cause for this problem?
It is really annoying to see that my otherwise nice Linux installation
is giving me such troubles ...

regards, eg

cccOn Mar 4, 4:27*am, ibupro...@painkiller.example.tld (Moe Trin)
wrote:
> On Tue, 3 Mar 2009, in the Usenet newsgroup comp.os.linux.networking, in
> article <6e3a2df9-bfbd-4abc-a4cb-bcea3d2fe...@g38g2000yqd.googlegroups.com>,

> What EXACTLY is slow? * Once you "connect", is the connection from
> that specific site rapid?

Initial connect is slow ... entering the address; and then its wait
wait wait;
as soon as the page starts showing initial content, speed seems
normal.

> * * * * * inet6 addr: fe80::260:97ff:fe32:4a6a/64 Scope:Link
>
> The key is that 'inet6' line - you'll also see one in the loopback. *A

Yes, the ip6 stuff is there.

> VERY WELL KNOWN problem is misconfigured DNS servers that ignore IPv6

Knowledge depends on the domains you are familiar with.
I know what IPv6 is about; but didnt know about this problem.

> You say you're running Ubuntu 8.10 - *Open your blacklist file (sudo
> nano /etc/modprobe.d/blacklist), then add the line "blacklist ipv6" to
> that file (without the quotes). *Reboot, and try again. *Others have
> reported fixing the problem by adding three lines to
> /etc/modporbe.d/aliases:
> * *alias net-pf-10 ipv6 off
> * *alias net-pf-10 off
> * *alias ipv6 off
> (There may be a 'alias net-pf-10 ipv6' line - change it as above).

The line is in the alias file; I changed it accordingly; but no
effect.
Same for the blacklist approach. (yes, when running ifconfig after
the changes, the ipv6 entries are gone).

At least you had some good ideas; upon first reading I thought
"oh yes, this must be it".

so, thank you very much for the moment,

On Mar 10, 1:40*am, ibupro...@painkiller.example.tld (Moe Trin) wrote:

> OK - you mention 'page' above, and I'm assuming you are seeing this
> problem while using a browser. Wouldn't be Firefox, would it? *I don't

Not really. My first choice is Opera; I tried Firefox too - same
behaviour.
And I saw similiar things when ping'ing a server name - it would take
"forever" before the first packages are reported.

> * */usr/sbin/tcpdump -ni eth0 -s 512 port 53

I will give it a try. Good opportunity to learn something
about wireshark ;-)

> You're welcome! *Let's see if we can fix the problem.

Hope so,

On Mar 10, 9:00*pm, ibupro...@painkiller.example.tld (Moe Trin) wrote:

> Are you using 'ping' directly from the command line? *That would

ping from command line.

> [compton ~]$ grep host /etc/host.conf
> order hosts,bind

yeah, that is what i have.

> * hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4

me too.

> What _may_ cause a .local lookup is if /etc/resolv.conf has a 'domain'
> or 'search' line. *Apple (originators of the mDNS protocol Avahi is

See below ... I gave my laptop to our support crew to install ubuntu;
I guess
they followed our companies guide line ... that recommends to install
resolv.conf.d

This package creates the /etc/resolv.conf from different input files;
and in my environment the result looks like:
----
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by
resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE
OVERWRITTEN
nameserver x.abc... whatever
nameserver x.abc....whatever2 (two DNS servers from our company, valid
IP addresses)
search mysite.de.ibm.com

search mysite.de.ibm.com de.ibm.com ibm.com
-----

where "mysite" boils down to the city I am working in ... what makes
perfect sense, as most machines
I am talking to will be named something.mysite.de.ibm.com

Anyway; I will give a try at home to remove all these entries ... just
to see what happens.
But that wont be a good solution; as I assume that the two DNS + first
search entries were
created from some dynamic file (whereas the last search is from my
resolv.conf.d/tail file).

besides that I will create some dumps; just to learn a bit.

Yeah, got it.

I created a resolv.conf file ... just listing the DNS servers I need
for my
WLAN at home. After restarting the network service, everything is
fine.

I guess I will add a script so I can overwrite the default resolv.conf
script
manually when I am at home. When I am at work, the one that is
created by resolvconf.d will be good enough ;-)

Thx for your patience and help, I did learn some things!

Yeah, I start to really not like the mix of various concepts, too.
Especially as
it turns out that my domain is now NOT set in the first place.

The resolvconf package will automatically rebuild the resolv.conf on
startup.
Using files I can influence; and using OTHER files it picks for
itself; I couldnt find
documentation about who the various files in the resolvconf/run
directory are used.

Even niecer is that AT&T dialer will also dump some content into the
resolv.conf file
when active.

Now my home WLAN works fine ... but because of several 'search'
strings
(and a less good one being the last) i have to now the domain names
for the
machines I want to talk to.

Long story short: I want to update to Ubuntu jaunty within the next
weeks;
and then i will install all stuff myself and avoid all this auto-magic
things.