On Fri, 6 Apr 2001, Alexey Marinichev wrote: > On Fri, Apr 06, 2001 at 02:10:00PM -0800, James A. Crippen wrote: > [...] > > DON'T USE IFCONFIG AND fooN:M ALIASES IF YOU CAN HELP IT. > [...] > > Why? What exactly is the difference between using aliases from ifconfig > and from ip? > Why? Just curious. BSD uses ifconfig and route just fine, so does > SunOS. Right, and the Linux version used to work perfectly well too. But there have been so many changes to the underlying network subsystem (under kernel 2.4 particularly) that ifconfig and route aren't totally in sync with the system. Aliases are a good example. They don't really exist anymore as network devices. Instead there's a clear separation now between the hardware device and its driver and the network stack and addresses assigned to a device. The old ifconfig way was to create fake devices like eth0:0 to hang other IP addresses on. The new way that the 'ip' tool works is to assign an arbitrary number of addresses to *one* real device. If you create an alias with ifconfig as an eth0:0 type of device then you can see it attached to the real device using 'ip'. However if you allocate a number of addresses and attach them to eth0, say, then you won't see any except the first with ifconfig. This is because ifconfig doesn't understand the new alias mechanism. Then you start to get out of sync, and you have the problem of your device going down when you try to remove an alias. It's just not good to use for anything more than the old single-address, single-device metaphor. Anything more complicated is better done with 'ip'. And if you've learned how to use 'ip' you'll find that it's so convenient that you want to just throw ifconfig and route away. 'james -- James A. Crippen <james@xxxxxxxxxxxx> ,-./-. Anchorage, Alaska, Lambda Unlimited: Recursion 'R' Us | |/ | USA, 61.2069 N, 149.766 W, Y = \f.(\x.f(xx)) (\x.f(xx)) | |\ | Earth, Sol System, Y(F) = F(Y(F)) \_,-_/ Milky Way.
