Sun has a solid approach to security of IT that is independent of Sun's oprating systems and product lines. In fact, their approach, detailed in
TOWARD SYSTEMICALLY SECURE IT ARCHITECTURES lines up nicely with ITIL's Security Management process area because of Sun's focus on infrastructure aspects of security.
For Designing a Secure Architecture you need additional security options.
1. You can use physical (hardware) or software firewalls to restrict access to the resources in your environment. .
2. The network segments that connect the data, processing, and services domains are not physically secure from various network attacks , you still need to protect the data as it goes from one server to another. In this case, you can use Internet Protocol security (IPSec) or Secure Sockets Layer (SSL) to encrypt traffic from one server to another.