HowTo setup Link-based IPMP with VCS for Solaris 10.

Thanks Bret Sanders for the knowledge. Have used this to setup and like to share.

Original: http://www.runningunix.com/2009/01/link-based-ipmp-setup-with-vcs/

We know that Solaris 10 allows us to setup link-based IPMP. Though a nice feature which the OS determines NIC availability solely on the NIC driver reporting the physical link status - UP or DOWN, setting link-based IPMP in VCS is a little different.

Previous versions used “probe-based” IPMP, where connectivity is tested by pinging something on the network from each interface.

While probe-based is actually a more thorough test (tests network layer 3 as well as 2), it is much more cumbersome to configure, and you need an extra IP address for each interface for “test” addresses. usually Link-based IPMP is sufficient for most applications.

For some reason, configuring link-based IPMP in VCS is somewhat tricky, and the documentation doesn’t seem to help much. It seems all the default values for VCS are for probe-based IPMP only.

To achieve link-based IPMP, There are values you need to change from the defaults in the MultiNICB resource:

Tells VCS to use mpathd for network link status
UseMpathd: 1

The default, /usr/sbin/in.mpathd is just incorrect - it doesn’t live there.
MpathCommand: /usr/lib/inet/in.mpathd -a

If you leave this at 1, it will overwrite your /etc/hostname.xxx files with probe-based IPMP configuration
ConfigCheck: 0

The “interface alias” for each device is not needed, leave them blank.
Device: (your IPMP interfaces here)

You want VCS to NOT ignore link status, since this is how link-based IPMP works.
IgnoreStatus: 0

Do not use your IPMP group name here, it’s not needed. VCS is not monitoring the group, mpathd is.
GroupName:

Here’s how it looks in main.cf:

MultiNICB csgmultinic (
UseMpathd = 1
MpathdCommand = “/usr/lib/inet/in.mpathd -a”
ConfigCheck = 0
Device = { ce0 = “”, ce4 = “” }
IgnoreLinkStatus = 0
)