This looks like a netmask mismatch error. The netmask is used by the MPI processes to limit what hosts they are willing to receive packets from. To fix this, you need to look at the addresses and open up the netmask so that it will let in the traffic from
your other MPI ranks.
You can change the CCP_MPI_NETMASK cluster environment variable to match your Azure nodes. This requires administrator credentials on the cluster. For example:
cluscf setenvs CCP_MPI_NETMASK=10.28.0.0/255.255.0.0
Or, you can override the default netmask with an mpiexec argument. No admin credentials required. For example:
mpiexec -env MPICH_NETMASK 10.28.0.0/255.255.0.0
Note: The
linpack on Azure guide now includes a step to check the netmask settings.