use case: virtual private cloud

Operator provide virtual private cloud service for enterprises. A typical architecture is to allocate two zones in the VPC for security issue.

• DMZ provide http/email/video services for access from internet.
• Interior provide compute and storage resources for existing enterprise site.
• internet access cannot reach the interior.
  User can also describe connectivity to exterior, the internet and the existing site.
  The intent description should be topology indepentent with only business level sketch.