IF_MPADM(8) Maintenance Procedures IF_MPADM(8)


if_mpadm - administer interfaces in an IP multipathing group


if_mpadm -d | -r ifname


The if_mpadm utility administers IP interfaces that are part of an IP
Multipathing (IPMP) group. Currently, administration is limited to
offlining IP interfaces and undoing previous offline operations.

When an IP interface is taken offline, all IP data traffic that was
flowing over the IP interface is moved to another IP interface in the
IPMP group. In addition, all UP IP addresses hosted on the IP interface
are brought down, causing in.mpathd(8) to stop probe-based failure
detection on the IP interface. As a result, an offline IP interface will
not be used for any inbound or outbound IP traffic. Only IP interfaces
that are in an IPMP group may be brought offline. If the IP interface is
the last functioning interface in the IPMP group, the offline operation
will fail.

When an offline operation is undone, any IP addresses hosted on that IP
interface are brought UP and will be considered by in.mpathd for probe-
based failure detection. In addition, provided the IP interface is
otherwise active (see in.mpathd(8)), it will again be used to send and
receive IP data traffic for the IPMP group. Note that not all offline
operations can be undone. For instance, in.mpathd may have offlined an IP
interface because its hardware address was not unique within its IPMP
group. The ipmpstat utility can be used to determine why an IP interface
is offline, identify which IP interfaces in a group are being used for
inbound and outbound IP traffic, and more; see ipmpstat(8).


The if_mpadm utility supports the following options:

-d ifname
Offline the IP interface specified by ifname. If ifname is
not in an IPMP group, or the offline would cause the IPMP
group to lose network connectivity, the operation will fail.

-r ifname
Undo a previous offline of the IP interface specified by
ifname. If ifname is not offline, the operation will fail.


Example 1: Offlining an IP Interface

The following command offlines the IP interface under0, causing any IP
packets that were being sent and received through it to be handled by
another IP interface in its group.

example% if_mpadm -d under0

Example 2: Undoing a Previous Offline Operation

Use the following command to undo the operation in the previous example:

example% if_mpadm -r under0


See attributes(7) for descriptions of the following attributes:

|Interface Stability | Unstable |


attributes(7), ifconfig(8), in.mpathd(8), ipmpstat(8)


cannot offline: no other functioning interfaces are in its IPMP group.

This message means that offlining the IP interface would leave the
IPMP group without network connectivity.

cannot offline: not a physical interface or not in an IPMP group

This means that the IP interface is not an underlying interface in an
IPMP group, and therefore is not eligible to be offlined.

September 2, 2015 IF_MPADM(8)