Sdn

What I do

• Design and implement SDN architectures
• Program network behavior through controllers
• Separate control plane from data plane
• Implement network virtualization
• Create dynamic network policies
• Manage network through software APIs
• Deploy network automation with SDN

When to use me

Use me when:

• Building programmable network infrastructure
• Implementing network virtualization
• Managing data center networks
• Creating dynamic network policies
• Requiring network-wide visibility
• Automating network operations at scale

Key Concepts

SDN Architecture

┌─────────────────────────────────────────────────────┐
│                  Application Layer                   │
│              (Network Apps & Orchestration)          │
└─────────────────────┬───────────────────────────────┘
                      │ Northbound API
┌─────────────────────▼───────────────────────────────┐
│               SDN Controller                          │
│           (OpenDaylight, ONOS, Ryu)                  │
│         - Network state                              │
│         - Topology discovery                         │
│         - Path computation                           │
└─────────────────────┬───────────────────────────────┘
                      │ Southbound API
┌─────────────────────▼───────────────────────────────┐
│                 Data Plane                            │
│            (Switches, Routers)                        │
│         - Forwarding                                 │
│         - Flow tables                                 │
└─────────────────────────────────────────────────────┘

OpenFlow Protocol

Standard southbound protocol for SDN:

# Ryu SDN Controller example
from ryu.controller import ofp_event
from ryu.controller.handler import MAIN_DISPATCHER, set_ev_cls
from ryu.lib.packet import packet, ethernet, ipv4

class SimpleSwitch(app_manager.RyuApp):
    def __init__(self, *args, **kwargs):
        super(SimpleSwitch, self).__init__(*args, **kwargs)
        
    @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
    def packet_in_handler(self, ev):
        msg = ev.msg
        dp = msg.datapath
        ofp = dp.ofproto_parser
        
        # Install flow rule
        actions = [ofp.OFPActionOutput(ofp.OFPP_FLOOD)]
        self.add_flow(dp, 1, actions)

SDN Use Cases

• Data Center: Network virtualization, tenant isolation
• WAN: SD-WAN for branch connectivity
• Campus: Centralized policy management
• Service Provider: Network slicing

Controllers

• OpenDaylight: Enterprise, feature-rich
• ONOS: Carrier-grade, performance
• Ryu: Python, lightweight
• ODL: Vendor-neutral