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https://github.com/cncf/cnf-wg/blob/main/doc/whitepaper/Accelerating_Cloud_Native_in_Telco.md
Figure 2-1 from "Cloud Native Infrastructure" by Justin Garrison and Kris Nova (ISBN: 9781491984307)
Pre-Validation. Historically, Network Functions have been developed and pre-integrated with well-defined infrastructure, which was known in advance. That pre-validation was done by a Network Function vendor and the system was delivered as a validated/certified bundle together with performance and stability guarantees. In the cloud native world, there are too many permutations which makes it impractical to follow the traditional certification path. However, Cloud Native Network Function (CNF) vendors are still sticking to it by picking a small number of opinionated infrastructure flavors (different from vendor to vendor!) to pre-validate against, making any infrastructure outside this selection too complicated, too costly, and too slow to deliver for CSPs. This creates problems in the adoption of those CNFs as CSPs generally prefer to each have a unified cloud native infrastructure layer, which they are free to choose and often it can differ from the opinionated infrastructure already validated by the CNF vendors.
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