Differences between CFS and RFS

Further to yesterday’s post about Service and Resource Availability, I received some questions about how to discern between CFS (Customer Facing Services) and RFS (Resource Facing Services).

I thought the following description, sourced from TM Forum’s GB999 (Service overview sec 1.1.3), might help clarify the differences:

  • “This enables us to model a wide variety of services in a common class hierarchy while differentiating between Services that are obtained as a Product by a Customer versus those that aren’t. As we will see, a CustomerFacingService is one that is obtained as a Product by a Customer. Therefore, the Customer may have specific control over this Service via its associated Product. In contrast, the Customer never knows explicitly which ResourceFacingServices are being used to support a CustomerFacingService. More importantly, the Customer shouldn’t have to know which ResourceFacingServices are being used, since the Customer hasn’t explicitly obtained them.”
  • CFS are associated with resource technology neutral services i.e. they describe general capabilities and have attributes that are general across many technologies e.g. throughput, latency, SLA /loss rate, availability.
  • CFS and RFS typically have different lifecycles, CFS are related to customer and product changes and RFS to technology changes.
  • RFS are associated with resource technology specific services i.e. they have attributes that predominately relate to a specific technology.
  • RFS typically do some of the following:
    1. Map between the native protocols used to expose management of resources e.g. Netconf, YANG, SNMP, etc.
    2. Provide some integrated approach to provisioning and assuring RFS that span multiple technical domains e.g. slices across RAN and Core).
    3. They may be Operator, SP, ISV or Supplier provided.

Further important notes:

  • Composition of subordinate CFSs to support the CFSs exposed by Production capabilities (iterative composition pattern). These subordinate CFSs may be from other Operational Domains both within the same operator or acquired from third party operators as happens with wholesale interconnect.
  • Mapping of CFS to internal Resource Facing Services (RFS) that abstract into services the resource defined by Suppliers’ Technical Domains whose boundaries are defined by technology and supplier choices. This mapping links the boundary decisions of Operational Domains to the Technical Domain boundary decisions of suppliers.
  • RFSs can be atomic or composite to include other RFS (iterative composition pattern). This is a decision taken by the Operations / Integrator composing or creating RFSs based on deployment needs.
  • In a Service Oriented Architecture any exposed services can be consumed by any other service.
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