The CSA Software Defined Perimeter Working Group has developed a model and specification that combines device and user authentication to dynamically provision network access to resources and enhance security. SDP includes three components:
An SDP client on the connecting asset (e.g. a laptop).
* The SDP controller for authenticating and authorizing SDP clients and configuring the connections to SDP gateways.
* The SDP gateway for terminating SDP client network traffic and enforcing policies in communication with the SDP controller. Reference: CSA Security GuidelinesV.4(reproduced here for the educational purpose)

Explanation/Reference:

All resources allocated to a particular tenant should be "isolated" and protected to avoid disclosure of information to other tenants For example, when allocated storage is no longer needed IIS Security Considerations for Cloud Computing by a client it can be freely reallocated to another enterprise. ln that case, sensitive data could be disclosed if the storage has not been scrubbed thoroughly(e.g, using forensic software).

Cloud service Provider is responsible for infrastructure in Software as a service(SaaS) service Model

Thats how Devops is referred