debian wireless networking configuration

Question

When I issue the command

iwconfig wlan0 essid NAME

it sometimes takes a really long time to actually be able to view any webpages through a browser. I don't know why that is. Right now the /etc/network/interfaces file contains the following:

allow-hotplug wlan0
iface wlan0 inet dhcp
    # wireless-* options are implemented by the wireless-tools package
    wireless-mode managed
    wireless-essid NAME2

when I boot, there's never any issue like this. I never have to wait. So I tried changing NAME2 to NAME and the same problem remained. What can I do about this?

What I really want is for debian to just connect automatically to either NAME or NAME2 or any open wireless connection. I'm not sure whether this requires configuration in /etc/network/interfaces or /etc/NetworkManager/NetworkManager.conf. I'm currently trying to find examples of how to configure the files. So my questions are

1. how do I make the appropriate configuration?
2. do I even need the network-manager to do this?

Answer 1

Try this:

/etc/init.d/networking force-reload

This command reboot the network service when you changed any parameter of the current configuration.

Later the changes on the interface configuration can be applied whitout any waiting time.

Answer 2

See my answer here for details on how to configure multiple wireless networks. The delay you're seeing is DHCP, because there's no mechanism to trigger the DHCP client when the wireless connection is actually established. You probably just need to do ifdown wlan0 and ifup wlan0 when you want to connect.