Attached is a conceptual 3 tier Dc design. From securiy perspective seems like everything has been taken care of in terms of provisioning of active equipments. Note that majority of employees are going to access the provisioned servcies off this Dc from WAN ( MPLS VPN) depicted as " Internal users".
Given the needs:
1. The DC will host variety of applications, both critical and non critical, holding cofidential data as well non confidential data with varying RPO / RTO needs.
2. Not all applications would be built around standard 3 tier architecture model.
3. Most applications will be maintained and supported by varying 3rd parties / vendors.
4. Service / apps hosted within will be accessed by users who are not trusted e.g. Customers, JV partners, Consultants etc.
What do you suggest in terms of design enhancements to cater for the above 4 needs given that we are starting as a green field?