SDN Deep Dive Series – Part 2: Use Cases, Deployment, and Integration

July 2013   |   Reading Time: 12 minutes

In Part 1 of our Software Defined Networking (SDN) deep dive, we dissected the fundamentals and explored the architectural principles. Today, we explore practical SDN use cases, deployment realities, and integration with existing infrastructure.

Why SDN Matters Now

SDN enables unprecedented network agility, allowing administrators to reprogram data flows in real time. This flexibility is pivotal in data centers, service provider backbones, and enterprise WANs where dynamic traffic behavior demands rapid adjustment.

Use Case 1: Multi-Tenant Data Centers

Data center operators hosting cloud environments must ensure traffic segmentation, tenant isolation, and scalable routing. Traditional VLAN-based segmentation runs into scalability limits. SDN introduces programmatic overlay networks using tunneling protocols like VXLAN and NVGRE.

• Dynamic path computation using traffic policies
• Automated provisioning and teardown of tenant networks
• Improved visibility and security posturing

Use Case 2: Campus Networks

Enterprise campuses struggle with consistent policy enforcement across switches. SDN centralizes access control policies, allowing intent-driven networking where administrators define what should happen, not how to configure individual devices.

Use Case 3: WAN Optimization and Path Control

Branch connectivity often relies on MPLS or IPsec tunnels. SDN can dynamically reroute traffic based on cost, link quality, or congestion. By abstracting path decisions from hardware, operators gain control over application flows in hybrid WANs.

Integrating SDN into Existing Networks

Most organizations won’t rip and replace legacy infrastructure. SDN must interoperate with existing routing protocols, physical switches, and firewalls. This integration requires hybrid models:

• Overlay SDN: Using tunnels over IP to create virtual topologies
• Hybrid SDN: Coexistence of OpenFlow-controlled and traditional devices
• Service Chaining: Routing traffic through firewalls, IDS/IPS using SDN paths

Deployment Challenges

Despite the promise, SDN deployment faces practical hurdles in 2013:

• Controller Selection: No single OpenFlow controller has emerged as a clear winner
• Interoperability: Varying vendor support and OpenFlow versions hinder standardization
• Skill Gap: Network engineers must acquire programming and API knowledge
• Security: Centralized control plane creates new threat vectors

Tooling and Ecosystem Maturity

The SDN ecosystem is rapidly evolving. Notable players include:

• Floodlight: An open-source Java-based OpenFlow controller
• NOX and POX: Research-oriented Python frameworks
• Mininet: A powerful network emulator used for prototyping SDN topologies

Vendors like Cisco, HP, NEC, and Big Switch Networks offer hybrid switches and platforms, though interoperability varies widely.

Planning for SDN Adoption

Successful SDN adoption requires a phased approach:

1. Define target outcomes (e.g., improved visibility, traffic steering)
2. Select pilot environments (e.g., lab, edge switches, or isolated VLANs)
3. Train engineering teams on OpenFlow, controller APIs, and automation tools
4. Evaluate vendor support for hybrid SDN integration

Conclusion

SDN is no longer theoretical—it is evolving into a deployable technology. By aligning SDN use cases with real network needs, organizations can deploy incrementally while reducing operational complexity and improving responsiveness.

Eduardo Wnorowski
With over 18 years of experience in IT and consulting, he helps businesses simplify network complexity while improving visibility and control.
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VRF-Lite vs MPLS VPN in Enterprise Network Segmentation

July 2013 - Reading time: 7 min

As enterprise networks evolve, the demand for advanced segmentation strategies has become critical for scalability, compliance, and security. In 2013, many mid-sized to large enterprises are evaluating whether to adopt MPLS VPNs or stick with simpler alternatives such as VRF-Lite. While both approaches achieve logical network separation, their architectures, scalability, and operational complexity differ significantly.

Understanding the Basics

VRF-Lite (Virtual Routing and Forwarding Lite) is a lightweight solution primarily used within enterprise environments to segment Layer 3 routing tables without requiring a full MPLS backbone. On the other hand, MPLS VPNs (Multiprotocol Label Switching Virtual Private Networks) leverage provider edge (PE) and customer edge (CE) routers across a service provider’s backbone to offer scalable, secure VPN services using labels instead of IP routing alone.

Use Case Comparisons

Enterprises often debate the two when weighing their network expansion needs, data center segregation, and branch office integration. Let's explore where each shines:

• VRF-Lite: Ideal for internal segmentation — e.g., separating development, production, and management networks within a data center or large campus.
• MPLS VPN: Preferred for WAN scenarios where branches connect over service provider links, especially when managing different client or departmental routes.

Configuration Complexity

One of the major factors in this decision is operational overhead. VRF-Lite is simpler to deploy but lacks the auto-signaling and label-based forwarding advantages of MPLS. It often requires manual route leaking and redistribution if communication is needed between VRFs. Conversely, MPLS VPNs enable route target and route distinguisher mechanisms, making inter-VPN communications more scalable and policy-driven.

Control Plane Considerations

From a control plane perspective, VRF-Lite relies on traditional IP routing protocols (OSPF, EIGRP, BGP) instantiated per VRF instance. MPLS VPNs, however, are deeply tied to MP-BGP and LDP or RSVP for label distribution. This allows MPLS to scale across thousands of VPNs, which is why service providers favor it.

Security Implications

Both models offer traffic separation, but MPLS VPNs offer stronger separation due to enforced PE-CE policies and centralized route control. VRF-Lite still depends on engineers to ensure correct path enforcement and access controls between VRFs, increasing the chance for misconfigurations in large environments.

Performance and Forwarding

VRF-Lite forwarding is CPU-bound on traditional routers and doesn’t take advantage of MPLS's fast label switching. MPLS uses hardware-accelerated label switching paths (LSPs), which improves performance under scale. However, this comes at a higher operational cost and learning curve for enterprise teams unfamiliar with MPLS internals.

Cost and Vendor Support

VRF-Lite is supported across most enterprise-grade routers without licensing or additional hardware requirements. MPLS VPNs often require service provider partnerships or enterprise routers with advanced capabilities (e.g., ISR or ASR series with MPLS licenses). The Total Cost of Ownership (TCO) increases with MPLS, but so does control and scalability.

Example: VRF-Lite Configuration

interface GigabitEthernet0/0
 ip vrf forwarding PROD
 ip address 10.10.10.1 255.255.255.0

ip vrf PROD
 rd 100:1
 route-target export 100:1
 route-target import 100:1
  

Conclusion

For enterprises in 2013, the choice between VRF-Lite and MPLS VPN often hinges on the size and complexity of the network. VRF-Lite offers a quick and manageable way to segment routing domains without diving deep into service provider protocols. MPLS VPNs provide unmatched scalability and separation, but at the cost of complexity and operational expense.

Understanding your team's capabilities and your long-term network strategy is key in selecting the appropriate model.

Eduardo Wnorowski is a network infrastructure consultant and technologist.
With over 18 years of experience in IT and consulting, he brings deep expertise in networking, security, infrastructure, and transformation.
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