You use the ifconfig command to configure groups. This command uses a new group parameter that requires a group name and places both the IPv4 and IPv6 instance of the interface in that group. The group parameter has the following syntax:
ifconfig interface-name group group-name
Avoid using spaces in group names. The ifconfig status display does not show spaces. Consequently, if you have created two similar group names, but one of them contains a space, these group names look alike in the status display. However, they are different group names. This might be confusing.
Placing the IPv4 instance under a particular group automatically places the IPv6 instance under the same group. Also, you can place a second interface, connected to the same subnet, in the same group by using the same command (see "How to Configure a Multipathing Interface Group with Two Interfaces").
You can remove an interface from a multipathing group by using a null string with the group sub-command (see "How to Remove an Interface From a Group").
To place an interface in a new group when it is already part of some multipathing group, you do not need to remove it from any existing group. Placing the interface in a new group automatically removes it from any existing group (see "How to Move an Interface From an Existing Group to a Different Group").
You can have any number of network adaptors that you can configure in the same multipathing group. You cannot use the group parameter with logical interfaces. For example, you can use it with hme0, but not with hme0:1.
You must connect all the interfaces in the multipathing group to the same IP link, because when an interface fails, the failover operation moves all the IP addresses from the failed interface to an interface in the group that is functional. For routers to continue routing packets to the addresses that have been switched to the functional interface, the functional interface must be connected to the same IP link.