SDN: Week 5: Programming SDNs: Module 6.1: Motivation for northbound APIs

[gdt]

OpenFlow programming is not easy
- difficult to perform multiple independent tasks
- low level of abstraction
- controller only sees packets for events it does not know how to handle
- race conditions, avoid incorrect installation of rules

Solution: northbound API
- programming interface which allows applications and orchestration systems to program the network (not just an individual switch)
- uses: path computation, loop avoidance, routing, security
- users: sophisticated network operators, service providers offering value-added services, vendors, researchers. In short: people wanting to offer services over OpenFlow
- benefits: vendor independence, ability to quickly modify or customise control
- eg: present network as one large virtual switch, security, TE, security, middlebox integration
- goals: orchestration of high-level services

Summary:
- OpenFlow is a southbound API which controls a switch
- it makes it possible to program a network, but doesn't make it easy
- northbound API offers: sophisticated events, composition of policies, error handling