Software-Defined Networking
Software-Defined Networking separates decisions about network behavior from the devices that forward traffic. Software controllers program that behavior through defined interfaces, giving applications and operators a network-wide control point.
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Don't Panic
Don't Panic - Software-Defined Networking
Software-Defined Networking is the subject of this course. Software-Defined Networking, or SDN, separates network control from packet forwarding. The forwarding plane still moves, drops, or changes packets.
The useful unit of work is a closed loop: clarify the goal and boundaries, gather the inputs the practice requires, make the decision or change, record evidence, and return with owners for the next cycle. Skipping any link leaves teams busy without durable results.
Tooling supports the loop; it does not replace it. Choose tools after the boundary and evidence model are clear. Comparing products without that model produces feature matrices that do not change how the work runs.
Common failure modes include undefined ownership, metrics that count activity instead of outcomes, and irreversible steps taken without a review path. Treat those as design defects in the practice, not as individual heroics to compensate later.
Operators should be able to explain which signals would change a decision this week. If no signal can change the plan, the practice has become ritual. Keep the feedback path short enough that evidence still influences the next cycle.
Name the owners for each stage of the loop before the work scales. Unowned stages become permanent exceptions. Record decisions with enough context that a future operator can tell why a tradeoff was accepted. Prefer fewer, sharper metrics that change behavior over broad dashboards that only describe activity after the fact.
Read the Intro for the core model. Use the Cheatsheet when you need the operating map. Updates tracks official guidance when this course configures an update source; otherwise the practice is settled without a live feed.
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Sources
- https://www.rfc-editor.org/rfc/rfc7426.html
Supports
- SDN as dynamic network programmability through interfaces
- Separation between controller and controlled entities
- Application, control, management, operational, and forwarding planes
- DAL, CAL, MAL, NSAL, and plane interfaces
- Forwarding, topology, path-selection, failover, monitoring, and configuration responsibilities
- OpenFlow, ForCES, NETCONF with YANG, PCEP, and other SDN model views
- Physical or virtual resources and local or remote plane placement
- Distributed-state and security considerations in SDN design
- https://opennetworking.org/sdn-definition/
Supports
- Physical separation of network control from forwarding
- Direct programmability and infrastructure abstraction
- Logically centralized controllers with a network-wide view
- Dynamic programmatic configuration and open-standards implementations
- https://www.opennetworking.org/wp-content/uploads/2014/10/openflow-switch-v1.5.1.pdf
Supports
- OpenFlow logical-switch components and controller channels
- Flow tables, flow entries, priority matching, instructions, actions, counters, and timeouts
- Pipeline processing and configured table-miss behavior
- Controller-to-switch message and connection model
- https://github.com/sindresorhus/awesome
Supports
- The Awesome catalog identifies Software-Defined Networking as a networking list
- https://github.com/sdnds-tw/awesome-sdn
Supports
- The Software-Defined Networking list includes Mininet, Open vSwitch, OpenDaylight, and P4
- The list organizes SDN network operating systems, switches, protocols, controllers, emulators, languages, libraries, and testing tools
- https://mininet.org/overview/
Supports
- Mininet creates virtual hosts, switches, controllers, and links
- Mininet supports SDN learning, prototyping, testing, and debugging on one machine
- Mininet switches support OpenFlow and its hosts run standard Linux network software
- https://mininet.org/walkthrough/
Supports
- The walkthrough covers topology creation, connectivity testing, the command line, switches, and controllers
- https://docs.openvswitch.org/en/stable/intro/what-is-ovs/
Supports
- Open vSwitch is a production multilayer software switch
- It exposes forwarding functions to programmatic extension and control
- It supports virtualized server environments and standard management interfaces
- https://opendaylight.org/
Supports
- OpenDaylight is an open-source SDN controller platform
- It supports programmatic network control and device management through standard protocols
- https://docs.opendaylight.org/en/latest/
Supports
- OpenDaylight documentation covers controller services, plugins, models, and operational use
- https://p4.org/specifications/
Supports
- The P4 project publishes specifications for the P4 language, P4Runtime, target architectures, and telemetry
