Multiple logical network devices can be created for each physical
hardware device. For example, if you have one Ethernet card in your
system (eth0), you can create logical network devices with different
nicknames and different configuration options, all to be specifically
associated with eth0.
Logical network devices are different from device aliases. Logical
network devices associated with the same physical device must exist in
different profiles and cannot be activated simultaneously. Device
aliases are also associated with the same physical hardware device, but
device aliases associated with the same physical hardware can be
activated at the same time. Refer to Section 18.11 Device Aliases
for details about creating device aliases.
Profiles can be used to create multiple
configuration sets for different networks. A configuration set can
include logical devices as well as hosts and DNS settings. After
configuring the profiles, you can use the
Network Administration Tool to switch back and forth
between them.
By default, there is one profile called Common. To
create a new profile, select =>
from the pull-down menu, and enter a
unique name for the profile.
You are now modifying the new profile as indicated by the status bar at
the bottom of the main window.
Click on an existing device already in the list and click the
Copy button to copy the existing device to a
logical network device. If you use the New
button, a network alias is created, which is incorrect. To change
the properties of the logical device, select it from the list and click
Edit. For example, the nickname can be changed to
a more descriptive name, such as eth0_office, so
that it can be recognized more easily.
In the list of devices, there is a column of checkboxes labeled
Profile. For each profile, you can check or uncheck
devices. Only the checked devices are included for the currently
selected profile. For example, if you create a logical device named
eth0_office in a profile called
Office and want to activate the logical device if
the profile is selected, uncheck the
eth0 device and check the
eth0_office device.
For example, Figure 18-16 shows a profile
called Office with the logical device
eth0_office. It is configured to activate the first
Ethernet card using DHCP.
Notice that the Home profile as shown in Figure 18-17 activates the
eth0_home logical device, which is associated with
eth0.
You can also configure eth0 to activate
in the Office profile only and to activate a PPP
(modem) device in the Home profile only. Another
example is to have the Common profile activate
eth0 and an Away
profile activate a PPP device for use while traveling.
To activate a profile at boot time, modify the boot loader configuration
file to include the
netprofile=<profilename>
option. For example, if the system uses GRUB as the boot loader and
/boot/grub/grub.conf contains:
title Red Hat Enterprise Linux (2.6.9-5.EL)
root (hd0,0)
kernel /vmlinuz-2.6.9-5.EL ro root=/dev/VolGroup00/LogVol00 rhgb quiet
initrd /initrd-2.6.9-5.EL.img |
modify it to the following (where
<profilename> is the name of the
profile to be activated at boot time):
title Red Hat Enterprise Linux (2.6.9-5.EL)
root (hd0,0)
kernel /vmlinuz-2.6.9-5.EL ro root=/dev/VolGroup00/LogVol00 \
netprofile=<profilename> \
rhgb quiet
initrd /initrd-2.6.9-5.EL.img |
To switch profiles after the system has booted, go to (on the Panel) => =>
(or type the command
system-control-network) to select a profile and
activate it. The activate profile section only appears in the
Network Device Control interface if more than
the default Common interface exists.
Alternatively, execute the following command to enable a profile (replace
<profilename> with the name of the profile):
system-config-network-cmd --profile <profilename> --activate |
