Networking :: How To Stop / Start Network In Ubuntu 10.04

This should not be this difficult. I have a plain install of Ubuntu 10.04 64 bit with a wired network card. It picks up a private IP address from my router. It has an app called NetworkManager Applet 0.8 in the notification area of the panel. If I right click on this app and select "Disconnect" it does. ifconfig shows that the IP address is gone. I can then right click on the app again and "Auto eht0 and I am connected again and ifconfig shows the IP address restored. So far, so good. I was testing a crossover cable to see how fast I could transfer files to/from my server - both machines have gigabit cards but my switch is only 100 Mb.

I unplugged the PC from the router, hooked up the crossover cable to the server and found that I had no connectivity - the IP address was gone. Not wanting to mess with hard configuring IP addresses for the moment I connected the PC back to the router. When I unplugged the cable the app showed the networking disconnected icon. I tried right clicking on the app and unchecking [ ] Enable Networking then rechecking it. This works on my netbook running Ubuntu 9.04. No luck on 10.04 (and I had not tried the Auto eht0 as described above - did not discover that until later). So then I tried to fix it from the command line.

ken@taylor12:~$ sudo /etc/init.d/networking start
Rather than invoking init scripts through /etc/init.d, use the service(8)
utility, e.g. service networking start

Since the script you are attempting to invoke has been converted to an Upstart job, you may also use the start(8) utility, e.g.
start networking
networking stop/waiting.

So I then tried
ken@taylor12:~$ sudo service networking start
networking stop/waiting
but still no connectivity. A reboot got things back in order.

Then I did a little more testing.
ken@taylor12:~$ sudo /etc/init.d/networking stop
* Deconfiguring network interfaces...
Ignoring unknown interface eth0=eth0.
and I am still connected.

Editing Connections within the NetworkManager Applet shows "Auto eth0 - last used never" even though I have used it. [Edit] Auto eth0 via the app appears to show information about my wired NIC.

ifconfig shows eht0 as active
ken@taylor12:~$ ifconfig
eth0 Link encap:Ethernet HWaddr 00:25:64:e8:18:2c
inet addr:192.168.0.112 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::225:64ff:fee8:182c/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2234 errors:0 dropped:0 overruns:0 frame:0
TX packets:2407 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
bytes:1824427 (1.8 MB) TX bytes:404086 (404.0 KB)
Interrupt:17