There were many stated requirements for the NFVi platform, but two requirements would determine the success or failure of the design: Scalability and Performance. These two key design requirements for building a large scale and geo-distributed NFV systems would be critical to the design.
Aptira’s analysis of the customer requirements zeroed in on one key factor: the number and distribution of VNF’s deployed and managed in the platform, combined with the frequency of configuration change. New VNF’s or changed orchestration models further increase the demand on the orchestration function.
Orchestration has been implemented in the customer’s NFVi platform using Cloudify to manage the VNF lifecycles. This increase in the number of VNF deployments may impact scalability and performance requirements in a non-linear manner. As such, these factors have impacted the design of the deployment architecture of the orchestration layer.
The key design considerations for the deployment architecture include (but are not limited to) the following:
Factoring all these design elements into our analysis, Aptira designed two deployment options for consideration by our customer:
Each model has its pros and cons:
Whilst the Flat model is simple to deploy and is able to handle most of the orchestration related transactions, it suffers when transactions are to be handled across multiple data centres thereby bringing in dependency on WAN latency.
The Hierarchical model requires careful consideration of resource allocation and deploying them in failure domains but has significant advantages while handling operational aspects of VNF’s such as Close Loop Automation Policy (CLAMP). Localizing such actions increases the uptime of VNFs.
Aptira presented two options mainly due to the absence of defined tenant workloads and use cases. Our intent was to demonstrate to the customer the full range of possibilities and to work with the customer on how to choose the appropriate deployment model depending on the emerging tenant requirements.