Re: howto debug slow WLAN connection?

On Tue, 3 Mar 2009, in the Usenet newsgroup comp.os.linux.networking, in
article <6e3a2df9-bfbd-4abc-a4cb-bcea3d2fef1a@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
edgue wrote:

NOTE: Posting from groups.google.com (or some web-forums) dramatically
reduces the chance of your post being seen. Find a real news server.

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.

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

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

Look at the output of the command /sbin/ifconfig -a and note if you
are showing something like:

eth0 Link encap:Ethernet HWaddr 00:60:97:32:4A:6A
inet addr:192.0.2.11 Bcast:192.0.2.255 Mask:255.255.255.0
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
VERY WELL KNOWN problem is misconfigured DNS servers that ignore IPv6
DNS queries - use that search engine you are posting from to find a
copy of RFC4074:

4074 Common Misbehavior Against DNS Queries for IPv6 Addresses. Y.
Morishita, T. Jinmei. May 2005. (Format: TXT=13073 bytes)
(Status: INFORMATIONAL)

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).

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.

That's probably because your windoze isn't prepared for the eventual
adoption of IPv6. If you don't know what IPv6 is, you may want to
read the HOWTO that should be on your system in /usr/share/HOWTO/

523843 Oct 7 12:40 Linux+IPv6-HOWTO

That version may be newer than what you've got, and using that search
engine for it's design purpose should find a recent copy.

Old guy
.