Network management using DHCPCD

Abstract
It is possible to have a working network stack without resorting to Gentoo net.* scripts at all on simple configuration.

only hardware interfaces are needed, i.e. no virtual interfaces; IP addresses delivered through DHCP (eventually APIPA)

In such conditions all hardware interfaces can be configured, even the loopback interface, lo.

Basic configuration
Install dhcpcd

When you need wireless support also install wpa_supplicant

In case you're migrating from the old network setup make sure you have wext compatibility enabled in your kernel

Remove all network scripts from all runlevels

Add dhcpcd to the default runlevel:

There is no need for having wpa_supplicant in the runlevel as dhcpcd will detect the interface, whatever it is called and set its IP address automatically. Also note a nice thing Linux does when having wired and wireless interfaces together on the same network is that the one with the lowest metric takes precedence over existing connections.

Suppose for instance you have an ongoing transfer of a very large file over your wireless interface to an existing network mountpoint. Plug the cable and wait for dhcpcd to set the IP address of the ethernet interface and you'll see the network activity switch to the fastest interface. You don't even need to interrupt and restart the transfer. That feature comes handy when you cannot bond interfaces, especially with wireless.

Cleanup
When the net setup is working well you might want to remove the old net.* setup. So disable the netifrc useflag and reemerge openrc.

Now you can remove netifrc.

Also the old config files and symlinks can be removed