Sdn Software Defined Networking

Software-Defined Networking (SDN)

Implementing software-defined networking — from SDN controllers and OpenFlow through network virtualization, intent-based networking, and network programmability.

When to Use

• Decoupling network control plane from data plane
• Implementing programmable network infrastructure
• Automating network provisioning and configuration
• Building virtual networks and network overlays
• Implementing intent-based networking

SDN Architecture

SDN_LAYERS = {
    'infrastructure': 'Physical/virtual switches, routers, middleboxes (data plane)',
    'control': 'SDN controller (ONOS, OpenDaylight, Ryu) — central control plane',
    'application': 'Network apps — routing, firewall, load balancing (business logic)',
}

# Mininet-style network topology definition
def create_topology():
    """Define a software-defined network topology."""
    return {
        'switches': ['s1', 's2', 's3'],
        'hosts': ['h1', 'h2', 'h3', 'h4'],
        'links': [
            ('h1', 's1'), ('h2', 's1'),
            ('h3', 's2'), ('h4', 's2'),
            ('s1', 's3'), ('s2', 's3'),
        ],
        'controller': 'ryu',
    }

Common Pitfalls

1. Controller bottleneck — centralized controller becomes single point of failure; cluster it
2. Flow table exhaustion — OpenFlow switches have limited flow table entries
3. Southbound latency — control-to-data plane latency can impact convergence
4. Security of controller — compromised controller compromises entire network
5. Vendor lock-in — proprietary extensions reduce SDN benefits

Verification Checklist

• SDN controller clustered for high availability
• Flow table size monitored on switches
• Southbound protocol secured (TLS for OpenFlow)
• Northbound API documented and versioned
• Network state synchronized across controller cluster