Permit Root SSH Login
SSH is disabled for root to connect from other clients on Solaris OS by default. Therefore, we need to enable it by ourselves. Here is the procedure.
Permit root remote logon
root@solaris11vm:~# vi /etc/ssh/sshd_config
...
#PermitRootLogin no
PermitRootLogin yes
Change the type of root to normal
This step seems to be optional for newer releases.
root@solaris11vm:~# vi /etc/user_attr
...
root::::type=normal
Restart ssh service
root@solaris11vm:~# svcadm restart ssh
It works now.