One of our customers was building a greenfield Network Functions Virtualisation Infrastructure (NFVi) and requires Orchestration capabilities, but lacked the skills to do this themselves. Designing an ideal deployment model of the Orchestration system using Cloudify is a major challenge, but this type of challenge is what the Aptira engineers relish.
This greenfield NFVi platform consists of a private Cloud with a high-fidelity full-stack configuration that includes a Cloud platform / Virtualised Infrastructure Manager (VIM), Orchestration, Software Defined Networking (SDN), and solution-wide alarming and monitoring spread across multiple data centres across multiple regions.
Their internal team did not have a deep skill base in the area of Network Function Virtualisation Orchestration (NVFO) and so turned to Aptira to augment their core team with these skills.
In this engagement Aptira was responsible for designing and building Orchestration layer using Cloudify in the NFVI platform. The requirements for the platform were world-class enterprise Telco standards, and presented multiple design challenges:
- National service level scalability
- High availability across geo-distributed NFV systems
- Lack of concrete use case (since it was still early NFV days), and
- The myriad technical and operational requirements associated with such a large-scale platform
The Aptira Solution
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:
- Number of VNFs to be managed
- Operational design of VNFs
- Number of NFVi PoPs across which VNFs are to be orchestrated
- Latency/delay between Cloudify and the VNFs
- Number of technology domains across which Cloudify has to orchestrate
- Envisioned roadmap of the expansion of NFVi deployments
Factoring all these design elements into our analysis, Aptira designed two deployment options for consideration by our customer:
- Flat model: in which only one instance of Cloudify will be deployed. This Cloudify instance manages VNF instances and orchestration across different NFVi Domains/PoPs as shown in figure 1.
- Hierarchical model: in which Cloudify is deployed in each of the NFVi domains managing VNFs and orchestrating resources across domain specific NFVi-PoPs. And then a Global orchestrator to handle the orchestration across multiple NFVi/technology domains as shown in figure 2.
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.
Aptira were able to validate both deployment models to the customer using a real telco use case, and also prepared a design paper for use by the solution architects working on the entire NFVi solution. This allowed customer to plan their deployments and talk to their tenants about the use cases that can be realized with such a model.