A good explanation of MULTINICA and MULTINICB in VCS

MULTINICA & MULTINICB IN VCS

( from http://unixtips.hpage.co.in/multinic_42103512.html )

The MultiNICA represents a set of network interfaces and provides failover capabilities between them.You can use one base IP address for all NICs, or you can specify a different IP address for use with each NIC. The MultiNICA agent configures one interface at a time. If it does not detect activity on the configured interface, it configures a new interface and migrates IP aliases to it.
Here is the example MulticnicA that i have configured. Here i'm going to use base IP for both the NIC.Here Linux641 is server1 and linux642 is server 2.

This is sample MutilnicA attribute. 192.168.0.101 is the base IP os linux 641 server and IP moves between eth0 and eth3 when there is failure.
Below is the sample main.cf output for multinica.

Below is the IPmulticnic that is confgiugred. This will point to MultinicA(nica) resource.

Here the ip 192.168.0.1 floats between eth0 and eth3 along with base IP.

MULTINICB (Link-based IPMP setup with VCS)
With Solaris 10 came a nice feature – Link-based IP Multipathing (IPMP). It determines NIC availability solely on the NIC driver reporting the physical link status – UP or DOWN. 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. IMO 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, here’s how I’ve configured my MultiNICB resource:

These are the values you must change from the defaults:
UseMpathd: 1
Tells VCS to use mpathd for network link status
MpathCommand: /usr/lib/inet/in.mpathd -a
The default, /usr/sbin/in.mpathd is just incorrect – it doesn’t live there.
ConfigCheck: 0
If you leave this at 1, it will overwrite your /etc/hostname.xxx files with probe-based IPMP configuration
Device: (your IPMP interfaces here)
The “interface alias” for each device is not needed, leave them blank.
IgnoreStatus: 0
You want VCS to NOT ignore link status, since this is how link-based IPMP works.
GroupName:
Do not use your IPMP group name here, it’s not needed. VCS is not monitoring the group, mpathd is.
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
)