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: ```python # 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