As a matter of convention, network elements and applications are managed independently and the absence of a real-time communication on making changes either to network elements or applications results in several challenges. SDN attempts to address many of these challenges by allowing independent innovations at control-data planes and providing a comprehensive view and programmability of the network.
NFV on the other hand, looks at alleviating the challenges of building and maintaining a “physical network” such as heavy Capex, proprietary hardware, long deployment cycles, fast obsolescence resulting in frequent hardware replacements by virtualizing network node functions to run on Commercial Off-The-Shelf (COTS) hardware platforms.
This paper discusses the synergies that SDN and NFV bring in and the problems affecting enterprises and service providers in their efforts towards the creation of an efficient SDN / NFV infrastructure. It also details the ideas, plans and processes behind a new Validation Approach necessary for a virtualized environment.
Introduction
Traditionally a “physical network” of interconnected nodes and applications presents a number of debilitating challenges to enterprise and network operators:
SDN and NFV are geared to tackle the challenges mentioned above. While SDN centralizes network control, NFV answers the problems of a physical network by virtualizing entire classes of network node functions.
SDN - NFV: A Synergistic Relationship
Despite the possibility of implementing NFV without a SDN and vice-versa, the effective combination of the two can potentially unlock significant value. By integrating SDN and NFV into a composite whole, control and data planes can be clearly segmented; operators can optimize performance, simplify compatibility challenges with current deployments and facilitate ease of operation and maintenance procedures. Figure 1.1 illustrates the SDN and NFV relationship.
Figure 1.1: SDN and NFV Relationship
Further NFV can also offer support to SDN by providing the essential infrastructure upon which the SDN software can be implemented. Additionally, NFV works in close alignment with SDN objectives to use commodity servers and switches
Key Challenges Affecting SDN - NFV Adoption
Before outlining the Validation Approach, let’s take a look at the major challenges that a robust SDN - NFV blueprint must overcome:
Openness and Standardization
Most traditional network equipment vendors’ approach to Open SDN does not reflect ideas like open code, architecture and adherence to standards like ONF, ETSI, etc.
Performance Management
Migration to generic COTS-based hardware involves the minimizing performance degradation on latency, throughput and processing overheads.
Co-Existence and Compatibility
For existing IT and SDN / NFV executions to converge, the SDN and NFV implementation must co-exist with the operator’s legacy equipments and be compatible with their OSS, BSS, Element and Network Management Systems.
Portability and Interoperability
Interoperability and portability between multiple vendor solutions and standards is crucial for a SDN/NFV orchestration. It establishes the ability of NFV to load and execute virtual appliances in different but standardized data center environments, provided by different vendors for different operations.
Tools
Absence of standard tools to measure SDN/NFV functionality and performance on reliability, stability and portability poses a challenge to the adoption of SDN and NFV.
Skill Sets
As the industry moves towards cloud deployment, the availability of skilled man power with the ability to design, build, support, validate and manage a new software-centric carrier network over a long time is a major challenge.
The shift from a hardware-focused implementation to a hardware and software based cloud-centric approach poses a major challenge for SDN and NFV validation. SDN and NFV mostly relies on COTS hardware platforms and this implies a fundamental revision of traditional testing methodologies.
Further, there are several new validation challenges which arise due to a plethora of factors - Multi-vendor software, protocols and API inter-operating in COTS environment.
While engineering the validation solutions for SDN and NFV, a number of qualitative and quantitative criteria and dependencies need to be evaluated:
Given the above environment, it is essential to introduce a robust and reliable validation approach for the smooth migration of network functions and programmable and scalable network to the cloud environment.
Integrated Approach to SDN - NFV Validation
As we move proven network functions such as routing, policy, firewall, DPI and many other from physical hardware-based appliances to running on unproven virtualized server platforms, it necessarily calls for the complete re-validation of previously deployed network functions along with Network Function Virtualization Infrastructure (NFVI) and network orchestration components.
The network orchestration may primarily consist of SDN controllers which deliver a complete view of the network and has the flexibility to provision, manage and de-provision network elements according to NFV orchestrator’s instructions.
Typically SDN controllers are connected to cloud orchestration frameworks via appropriate North Bound APIs (e.g. Neutron Module in OpenStack); hence an integrated validation approach is necessary to ensure end-to-end network services. Figure 1.2 depicts the integrated SDN & NFV framework.
Figure 1.2: NFV Blueprint
The Fundamental Pivots of a SDN - NFV Validation Approach
As we begin to appreciate the many factors influencing an effective SDN - NFV Validation Approach, let’s look at the focus test areas involved therein:
Cloud infra [NFVI] validation – hypervisors, compute, storage
Network layer validation – SDN control plane, data plane, SDN APISV
API validation across NFV layers
VNF security validation
Management and orchestration layer validation
Layer validation
The Way Forward
SDN and NFV have together created a new paradigm for network operations and services. New levels of innovation, which were not possible earlier with existing legacy systems, have come to the front. Many operators are now testing, demonstrating Proof of Concepts (PoCs), learning, and making the push towards commercialized services in contained domains.
Virtualization demands a complete overhaul in the validation approach - an integrated and layered approach for SDN - NFV is of immense importance for ensuring cost-effective and successful transition of box-based appliances and their functionalities into a virtualized network environment.
Jayaprakash Hariharan is a Lead Architect in Wireline Networking at Wipro Technologies EngineeringNXT Services – Telecom Solutions Group.
Mohan Kumar NG is a Senior Architect in Wireline Networking at Wipro Technologies EngineeringNXT Services – Telecom Solutions Group.
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