To properly support traffic across the interconnect must be sequestered on a private vlan (non-routeable). What this means is that 1.1.1.1 (commonly used for interconnects) on one node cannot see 1.1.1.1 on a different node/cluster. I have seen, this very week when it is not quite right, the first node could ping/ssh to 1.1.1.2 on the second node, but when the second node tried to ssh back to 1.1.1.1 the login session went to an entirely different server. No wonder the install threw a hissy fit!

One way to check is to run ifconfig (or similar tool on other platforms) for the NIC running the interconnect, there will be a broadcast ip associated with it. Usually something like 1.1.1.255. Take that IP and run the following:

ping -b 1.1.1.255

If the result is similar to:

/home/oracle:(+ASM2)$ ping -b 1.1.1.255
WARNING: pinging broadcast address
PING 1.1.1.255 (1.1.1.255) 56(84) bytes of data.
64 bytes from 1.1.1.3: icmp_seq=0 ttl=64 time=0.040 ms
64 bytes from 1.1.1.1: icmp_seq=0 ttl=64 time=0.101 ms (DUP!)
64 bytes from 1.1.1.2: icmp_seq=0 ttl=64 time=0.244 ms (DUP!)

and .1-.3 are nodes in your cluster, then it is a good bet that they are on a private vlan. However (Caveat warning!), it does not guarantee it, it may be the case that that network is currently only used for those three hosts above and that others could be added later. If you see other subnets as well as the interconnect subnet, then you are assured that it is NOT a private vlan.

One final tip, don’t put the interconnect IP/name in DNS, it should only be able to be seen from the hosts involved in the cluster.