Configuring a virtual interface in Solaris

In this short article, we will see the steps to configure a virtual interface on Solaris, a virtual interface can be created for assigning multiple addresses to a physical interface and has several applications, the steps to create a virtual interface for a given physical interface is shown below.

1. Consider a physical interface

$ uname -a
SunOS qe9-proxy 5.10 Generic_139556-08 i86pc i386 i86pc
$ ifconfig -a
lo0: flags=2001000849 mtu 8232 index 1
        inet 127.0.0.1 netmask ff000000
e1000g0: flags=201000843 mtu 1500 index 2
        inet 10.1.150.151 netmask ffffff00 broadcast 10.1.150.255
        ether 0:14:4f:28:29:34

2. If we want to create a virtual interface e1000g0:1 for the physical interface e1000g0 and assign an address 10.1.150.152 to the virtual interface, the command would be as follows.

2.1 Plumb the virtual interface e1000g0:1

$ ifconfig e1000g0:1 plumb
$ ifconfig -a
lo0: flags=2001000849 mtu 8232 index 1
        inet 127.0.0.1 netmask ff000000
e1000g0: flags=201000843 mtu 1500 index 2
        inet 10.1.150.151 netmask ffffff00 broadcast 10.1.150.255
        ether 0:14:4f:28:29:34
e1000g0:1: flags=201000842 mtu 1500 index 2
        inet 0.0.0.0 netmask 0

2.2 Assign the IP address (10.1.150.152) to the virtual interface e1000g0:1

$ ifconfig e1000g0:1 10.1.150.152 netmask 255.255.255.0 broadcast + up
$ ifconfig -a
lo0: flags=2001000849 mtu 8232 index 1
        inet 127.0.0.1 netmask ff000000
e1000g0: flags=201000843 mtu 1500 index 2
        inet 10.1.150.151 netmask ffffff00 broadcast 10.1.150.255
        ether 0:14:4f:28:29:34
e1000g0:1: flags=201000843 mtu 1500 index 2
        inet 10.1.150.152 netmask ffffff00 broadcast 10.1.150.255

Note: There is no Ethernet address displayed for the virtual interface as shown above (obviously)

2.3 Test the reachability of the IP address served by the virtual interface

$ ping -s 10.1.150.152
PING 10.1.150.152: 56 data bytes
64 bytes from 10.1.150.152: icmp_seq=0. time=0.113 ms
64 bytes from 10.1.150.152: icmp_seq=1. time=0.101 ms
^C
----10.1.150.152 PING Statistics----
2 packets transmitted, 2 packets received, 0% packet loss
round-trip (ms)  min/avg/max/stddev = 0.101/0.107/0.113/0.0085
$

Using the above procedure, one can create several virtual interfaces (like e1000g0:2, e1000g0:3 and so on for the physical interface e1000g0), to disable a virtual interface, use the unplumb command (like ifconfig  e1000g0:1 unplumb), similar to the we used to unplumb a physical interface.