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
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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
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