Configuring Virtual Interfaces

From Docupedia

Background

Lets assume you already have an interface call it vel0 and you need to add an alias to it. This could be for a number for reasons. For example I sometimes will enable a box with an ip on a private lan and an alias on the same nic that contains a public ip. This is just one example and works for both Solaris (including Nexenta) and Linux.

Two steps are required. First you must plumb the interface (Solaris/Nexenta Only):

sudo ifconfig vel0:1 plumb

Once the interface is plumbed you can then configure the ip on it:

sudo ifconfig vel0:1 192.168.1.100 netmask 255.255.255.0 up

That should be sufficient to be able to ping the alias. To make it permanent, consult the documentation for your distribtion. In Solaris, it's as easy as creating the appropriate interface file:

/etc/hostname.vel0:1

For Linux it varies widely by distribution. One common method requires creating a similar interface configuration file in either /etc/sysconfig/network/ or /etc/sysconfig/network-scripts/. Debian and Ubuntu do things a little differently with /etc/network/interfaces. Nexenta uses the Solaris method.