Bringing down one virtual network interface also removes other virtual network interfaces in Red Hat Enterprise Linux 4 and 5

Issue

• Why do the other virtual network interfaces go down when I bring down eth0:0?
• A higher numbered virtual interface goes down if any of the lower numbered virtual interface is disabled. For example, suppose that the virtual interfaces eth0:0, eth0:1, eth0:2 are up. If eth0:0 is disabled with "ifdown eth0:0" then eth0:1 and eth0:2 are also disabled. The command ifconfig or ip addr will no longer show those virtual interfaces.
• Another example is when eth0:1 is disabled with "ifdown eth0:1" then eth0:2 will go down but eth0:0 remains up.
• Under IP alias configuration environment on RHEL 5, we found the interface with bigger number after “:” (e.g. bond0.901:2) is coincidentally brought down when smaller number one is brought down (e.g. bond0.901:2). It happens from both “ifdown bond0.901:1”, or “ifconfig bond0.901:1 down”, and can be reproducible.
• In the most general case, if you remove a virtual network interface (also called an IP alias) from a network device, one of two things may occur.  If you remove the lowest-numbered virual interface (usually "eth0:0"), then all the virtual interfaces for that network device will be removed.  Alternatively, if you remove a higher-numbered virtual interface ("eth0:x" where x > 0) then all higher-numbered interfaces (eth0:x+1, eth0:x+2, etc.) will be removed.  Although ethernet devices are used here as examples, this will most likely occur with any kind of network device