As organizations increasingly adopt Software-Defined Networking (SDN) to improve network management, agility, and performance, a major challenge arises when attempting to integrate SDN with legacy network infrastructure. Many enterprises still rely on older hardware and software systems that were not designed with SDN in mind. These legacy systems often present compatibility issues, and the integration process can be complex and costly.
Despite many challenges, the benefits of integrating SDN make the process appealing to many businesses. SDN brings with it advantages such as centralized network control, enhanced automation, better scalability, and more efficient resource allocation. These factors make virtualization for networks an attractive option. This article explores the challenges of integrating SDN into networks that include legacy hardware and software and suggests strategies for overcoming these hurdles.
SDN Overview
Software-defined networking (SDN) is an innovative network architecture that separates the network control plane from the data plane. The term “control plane” refers to the functions that determine how traffic should be handled. The “data plane” implements traffic movement through forwarding. The SDN controller, a central software application, manages the control plane and can dynamically program the behavior of the network’s data plane devices, such as its switches and routers.
This separation of control and data planes allows for centralized management, greater automation, and more flexible network operations. SDN provides administrators with the ability to program and optimize network behavior using software-based tools, rather than relying on the physical configuration of individual devices.
How legacy networks typically work
Traditionally, a legacy network is an older networking infrastructure that relies on technologies that predate SDN. These networks often consist of hardware devices, such as routers, switches, and firewalls. These pieces of equipment are configured through manual processes and often use proprietary protocols and systems. Many legacy networks are built on traditional networking paradigms, such as static routing and centralized network management.
Integrating SDN with legacy networks can be challenging due to the differences in architecture, control mechanisms, and management practices between SDN and older networking systems. Legacy networks were not designed with the flexibility and programmability that SDN requires, making the transition or coexistence between the two more complex.
The challenges of integrating SDN into legacy networks
A new SDN system adds a coordinating software layer on top of a network. A traditional network is essentially a group of independent devices that are programmed to interact with each other when linked together by cables. The SDN centralizes those on-board processes. Effectively, your SDN is going to override the functions that are installed on your equipment and also interpret its own overview into individual settings and commands for each device.
You should expect that any SDN system that is on the market already has built-in automated discovery and management routines that simplify the complexity of running a network. However, it always pays to check on such capabilities before buying a specific SDN package. The points you should look for include:
- SDN system compatibility with existing equipment
- Protocol compatibility
- The ability to expand the network without disruption to service
- Failover and backup systems
- Cost and efficiency
- Usability
We’ll look at these issues in greater detail in the following sections.
System compatibility
One of the primary challenges of integrating SDN into legacy networks is hardware compatibility. SDN assumes a network that is capable of being dynamically reprogrammed, and traditional network devices like routers and switches often lack the capabilities needed to interface with an SDN controller. These devices may not support modern SDN protocols like OpenFlow, which allows SDN controllers to programmatically manage devices.
Older hardware is also often rigid in terms of configuration and lacks the necessary software interfaces (APIs) to be controlled by SDN systems. For example, many legacy devices may only support management via a command-line interface (CLI). Such configurations might rely on proprietary management protocols that do not align with SDN’s open standards.
Solution Strategies:
- SDN-Enabled Middleboxes: To address this issue, businesses can deploy SDN-enabled devices alongside legacy hardware, acting as “middleboxes” or intermediaries between the legacy infrastructure and the SDN controller. These devices can bridge the gap between old and new systems, allowing the SDN controller to exert influence over legacy devices indirectly.
- Overlay Networks: Another approach is to use overlay networking. An SDN controller can establish an overlay network, which is a virtualized network on top of existing physical infrastructure. You implement this by using software-defined switches that communicate with legacy hardware. This allows SDN to control traffic and policy management while still using the old infrastructure underneath.
Protocol compatibility
Many legacy networking devices and systems do not support open standards and protocols that SDN relies on, such as OpenFlow, NETCONF, or RESTful APIs. These protocols allow SDN controllers to communicate with devices in a standardized manner, enabling centralized management and automation. However, legacy devices may use proprietary protocols that cannot be easily integrated with modern SDN controllers.
Solution Strategies:
- Protocol Translation: Organizations can implement protocol translation solutions to convert proprietary protocols to open standards. For example, software or hardware devices can translate commands from SDN controllers into formats that legacy devices can understand, allowing SDN to communicate with these devices in a compatible way.
- Middleware Solutions: Middleware platforms can also be used to bridge the communication gap between SDN controllers and legacy systems. These solutions translate data and control messages between the different network layers and devices, helping integrate legacy hardware with SDN.
Network complexity and scale
Integrating SDN into a large, existing network can increase complexity. Traditional networks were designed with a decentralized, hierarchical structure in which devices and systems operate independently. Introducing SDN into this environment requires careful planning to ensure that all network segments, including legacy components, work together seamlessly.
The sheer scale of many legacy networks makes it difficult to implement SDN without causing disruptions. This is especially cogent for those in large enterprises or service providers. Legacy systems may have a deeply embedded role in network operations, and attempting to switch to SDN in a wholesale manner could lead to network instability, service outages, or poor performance.
Solution Strategies:
- Gradual Transition: To mitigate this risk, organizations should take a phased, gradual approach to SDN integration. This can involve initially deploying SDN in smaller segments or specific use cases, such as in data centers, before rolling it out more broadly across the entire network. This allows network administrators to test and refine the integration process without disrupting critical services.
- Hybrid Networking: Another strategy is to create a hybrid network where SDN and legacy networks coexist. This approach allows legacy systems to maintain their functions while new SDN solutions gradually take over network management. Hybrid networks can run parallel to existing infrastructure, ensuring that legacy systems continue operating until SDN can fully replace or integrate with them.
Failover and continuity
Software-defined networking (SDN) significantly enhances network failover and recovery by enabling dynamic, automated traffic rerouting in response to failures. Traditional networks often rely on manual reconfiguration and static routing to recover from outages, which can be slow and error-prone. The centralized SDN controller has real-time visibility into network health and can instantly detect failures in any part of the network.
Once a failure is detected, the controller can automatically reroute traffic to alternate paths or backup systems, minimizing downtime and maintaining service availability. This real-time adaptability ensures a more resilient and responsive network, which is critical for maintaining business continuity, particularly in environments where uptime is crucial.
SDN simplifies disaster recovery by allowing for rapid and consistent reconfiguration of network topologies. In the event of a major failure or disaster, SDN can quickly bring the network back online by redistributing traffic or redirecting workloads across different data centers or cloud resources.
Solution Strategies:
- Multi-Path Routing and Dynamic Rerouting: Failover systems are easier to implement with an SDN than on a legacy system and it isn’t too difficult to set up redundant paths without falling into the error of accidentally creating a routing loop. Centralized multi-path routing enhances failover and continuity in a hybrid network environment with little more than better planning implemented through automated activity tracking. SDN can also implement load balancing without the need for specialized equipment.
- Automate Recovery with Network Orchestration and Policy-Based Management: Automating recovery processes is essential for minimizing downtime and ensuring continuous service. SDN enables automation through network orchestration tools and policy-based management. In an SDN-enabled network, administrators can define policies that automatically execute recovery procedures in the event of a network failure. These policies can specify how to reroute traffic, which backup resources to use, and how to handle degraded performance scenarios.
Cost of integration
Integrating SDN into legacy networks can be expensive, particularly when legacy hardware needs to be replaced or retrofitted to support SDN capabilities. In many cases, businesses must invest in additional hardware, such as SDN-compatible switches and routers, or deploy middleware solutions to bridge the gap between old and new systems.
The cost of retraining staff and hiring experts to manage the new SDN system can also add to the total cost of integration. Many IT teams are accustomed to managing traditional network configurations and may lack experience with SDN controllers and network automation tools.
Solution Strategies:
- Cost-Benefit Analysis: Before embarking on SDN integration, businesses should conduct a thorough cost-benefit analysis to assess the long-term advantages of SDN versus the upfront costs of upgrading legacy systems. In many cases, SDN’s automation, flexibility, and scalability can deliver significant cost savings over time, making the investment worthwhile.
- Phased Implementation: As mentioned earlier, taking a gradual approach to SDN implementation can help mitigate the financial impact. By integrating SDN in stages, businesses can spread the costs over time and reduce the strain on resources.
Usability and skills availability
SDN introduces a new paradigm in network management, and the skills required to operate and maintain SDN systems differ from those needed for traditional networking. In many cases, SDN consoles present an animation of a system that looks exactly like a physical network. This representation of the virtual network can enable network specialists to relate their experience to the new SDN environment.
IT professionals familiar with legacy systems may lack experience with SDN controllers, network virtualization, and automated provisioning. This skill gap can hinder the successful integration of SDN, as there is a need for ongoing training and education.
Solution Strategies:
- Training and Education: Organizations should invest in training their network administrators and IT teams in SDN technologies. Offering workshops, certifications, and hands-on experience can help staff become proficient in SDN management and ensure that they are equipped to support the integration process.
- Hiring SDN Experts: In some cases, it may be beneficial to hire SDN experts or consultants who can guide the integration process, helping to design and implement the transition plan while transferring knowledge to existing staff. These experts can assist with selecting appropriate SDN solutions, implementing middleware, and optimizing network performance during the transition.
Tips on SDN integration with legacy networks
As SDN is a new concept, the systems that implement it are also new. This is a big advantage for the field because all packages were written with ease of use and high-quality graphics as design priorities. Thus, many of the problems that new users might encounter are going to be eased by guides and help screens.
Here are a few tips that will help you onboard an SDN over your legacy network.
1. Develop a clear integration roadmap
Before beginning the integration process, organizations should create a clear and detailed roadmap that outlines the goals, milestones, and timelines for integrating SDN into the existing network. This roadmap should consider the technical aspects of SDN integration, such as hardware and protocol compatibility. It should also address the operational aspects of SDN implementation: staff training, budget allocation, and risk management.
A clear roadmap ensures that all stakeholders are aligned and that the integration process proceeds smoothly without unexpected disruptions. It also provides a framework for evaluating the success of the integration and identifying areas for improvement.
2. Leverage SDN’s flexibility
SDN is highly flexible, and organizations can take advantage of this flexibility when integrating with legacy systems. For example, SDN’s programmability allows network administrators to create custom integrations that bridge the gap between legacy hardware and SDN controllers. This adaptability means that SDN can be tailored to fit the specific needs and requirements of the organization’s existing network infrastructure.
Organizations should consider using open-source SDN solutions or customizable SDN platforms that allow for the creation of bespoke integrations and feature sets. By leveraging SDN’s flexibility, businesses can build a network that evolves in line with their needs, while ensuring compatibility with legacy systems.
3. Continuous monitoring and feedback loops
Once SDN is integrated, continuous monitoring is essential to ensure that the network is functioning as expected. SDN provides extensive monitoring capabilities, allowing administrators to track network performance, identify issues, and make real-time adjustments. By implementing feedback loops and performance metrics, businesses can quickly detect problems and address them before they become critical.
In a hybrid network, monitoring tools should be configured to track both SDN and legacy systems, ensuring that traffic flows are optimized and that legacy devices continue to function as expected. Regular performance assessments and audits will help identify areas where SDN can be further integrated or where adjustments to the existing infrastructure are necessary.
4. Collaborate with vendors and experts
Working closely with SDN vendors, hardware providers, and third-party experts can facilitate a smoother integration process. Vendors may offer tools, plugins, or firmware updates to help legacy hardware communicate with SDN controllers. In some cases, vendors may also provide professional services to assist with the integration, ensuring that best practices are followed.
Involving external experts or consultants with experience in SDN integration can provide valuable insights and help troubleshoot any issues that arise during the implementation process. Their expertise can ensure that the integration is done efficiently and without unnecessary delays.
Conclusion
Integrating SDN into networks with legacy hardware and software presents several challenges, but with the right strategies, these challenges can be effectively managed. By addressing issues such as hardware compatibility, protocol limitations, network complexity, cost, and skill gaps, organizations can leverage SDN’s flexibility and automation to enhance their network infrastructure.
Successful integration of SDN with legacy systems requires careful planning, a phased approach, investment in training, and collaboration with vendors and experts. With these strategies in place, organizations can modernize their networks, reduce operational complexity, and take full advantage of the benefits SDN offers. Rather than replacing your existing network, an SDN will enable you to squeeze extra value from your legacy infrastructure.
