Re: strange wireless problem that I don't understand

On Jun 30, 6:16 am, Robert Heller <hel...@xxxxxxxxxxxx> wrote:
At Sun, 29 Jun 2008 21:53:54 -0700 (PDT) zhengquan <zhang.zhengq...@xxxxxxxxx> wrote:





Hello,
My interfaces file looks like this

auto
lo
iface lo inet loopback

auto eth0
iface eth0 inet static
address 192.168.2.4
netmask 255.255.255.0
gateway 192.168.2.1

auto wlan0
iface wlan0 inet dhcp

1 I connect the net cable and boot the computer,
I have network connection, I can ping 192.168.2.1 and I can connect to
the internet.

2 I disconnect the net cable and sudo /etc/init.d/networking restart
the system tells me that it receives a dhcp offer and got ip
192.168.2.5 for wlan0(the wireless card). After this, I try to ping
192.168.2.1(the router), I got unreachable
message. and it shows that my ip is still 192.168.2.4(static ip of
eth0).

3 I sudo ifdown eth0
and everything is ok, I can ping 192.168.2.1 and I can connect to the
internect.

What confuses me is that why do I have to ifdown eth0 to change the
computer ip to the wireless ip?

You don't *have* to take eth0 down, what you do have to do is change
your default route. When you take eth0 down, you remove the route that
uses it, leaving the route via wlan0.

Also *conputers* don't have IP addresses -- network interfaces have IP
addresses.



Thanks.
Zhengquan

--
Robert Heller -- Get the Deepwoods Software FireFox Toolbar!
Deepwoods Software -- Linux Installation and Administrationhttp://www.deepsoft.com/ -- Web Hosting, with CGI and Database
hel...@xxxxxxxxxxxx -- Contract Programming: C/C++, Tcl/Tk

Thanks, Bill and Robert, So is there any automatic way to switch from
wired to wireless?

Thanks.
Zhengquan
.

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