Software-Defined Networking
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This document introduces software-defined networking (SDN) and why it is important. It discusses how SDN separates the network control plane from the forwarding plane, allowing for more programmable networks. This benefits researchers developing new network architectures and cloud computing environments seeking scalable, cost-effective data center networks. The document also covers how network functions can be virtualized and run on general hardware rather than dedicated devices, and outlines some key SDN concepts including the "dumb fabric, smart edge" architecture and opportunities for new performance measurement tools.
Software-Defined Networking
- 1. © SWITCH 2013 Software-Defined Networking Simon Leinen Team Leader, Peta Solutions simon.leinen@switch.ch eduPERT Performance U! 2013-03-07
- 2. © SWITCH 2013 What is SDN and why should I care? 2
- 3. © SWITCH 2013 Why SDN? • Networking software-defined anyway? • Well yes, but… (is that of any use to us?) – Vertical integration dominates: Hardware, OS, “applications” all in a (closed) box – Network-wide functions defined by protocols Results: • Resistance to innovation (“fossilization”) • Cost/performance issues 3
- 4. © SWITCH 2013 Drivers towards SDN • Researchers who want to “innovate” – Future Internet/”Clean Slate” initiatives • “Warehouse-scale computing” (Cloud) – Need to build scalable, cost-effective fabrics – Research shows it can be done (VL2, Portland etc.) using fat trees/leaf+spine and multipath load balancing (e.g. Valiant) at edge 4
- 5. © SWITCH 2013 Data Center Networks 5Source: “A simpler data center fabric emerges”, Lippis White Paper
- 6. © SWITCH 2013 Data Center Networks 6 Source: A simpler data center fabric emerges, Lippis White Paper
- 7. © SWITCH 2013 Leaf-spine traffic flow (multipath) 7 Source: Interop 2012 talk by Brad Hedlund Architecting Data Center Networks…
- 8. © SWITCH 2013 “Mainframe business model” 8J. Hamilton, “Data Center Networks Are In My Way”, October 2010
- 9. © SWITCH 2013 Possible Approaches • Separate forwarding/packet processing logic (data plane) and control plane – OpenFlow (Kurt’s talk) • Improve onboard programmability – SDKs, better access to embedded OS • Use general-purpose hardware – E.g. Linux/Intel servers (Luke’s talk) 9
- 10. © SWITCH 2013 Dumb Fabric/Smart Edge Some SDN proponents suggest this architecture for future (DC) networks: • Use a simple fabric for bottleneck-free bw. – Could be IP, MPLS, or OpenFlow net… • Implement functionality at edge – E.g. isolation, load distribution over multipath – E.g. in the CPU-based hypervisor 10
- 11. © SWITCH 2013 NFV (Network Function Virtualization) • Telco buzzword for something natural… • “Network functions” can be run in VMs • This is already happening: – Cisco Nexus 1000V – Cisco Cloud Services Router 1000V – Juniper vGW (Virtual Gateway) firewall • Note how “hardware-based” firewalls are superseded by Xeon-based ones 11
- 12. © SWITCH 2013 Industry taking SDN seriously? • 2012-04-17: U. Hölzle gives talk @ONS about production Google OpenFlow WAN • 2012-07-23: VMware acquires Nicira for USD 1.05 billion 12
- 13. © SWITCH 2013 Do we have to take it seriously? • If you’re an SDN researcher, yes • If you’re a backbone operator… not yet(?) • If you have to do with campus networks and edge network devices (firewalls etc.): yes 13
- 14. © SWITCH 2013 What about Performance? • New approaches to fast networks: massive multipath, stupid core, edge functions on CPUs • New requirements and new opportunities for instrumentation (measurements) • New opportunities for things to go wrong, e.g. OpenFlow table-update bottlenecks 14
- 15. © SWITCH 2013 Further Reading • Gentle Introduction to SDN, S. Shenker, 2012 http://www.youtube.com/watch?v=eXsCQdshMr4 • Datacenter Networks Are In My Way, J. Hamilton, 2010 (read the slides!)http://perspectives.mvdirona.com/2010/10/31/Datacenter NetworksAreInMyWay.aspx • OpenFlow @Google, U. Hölzle, 2012 http://www.youtube.com/watch?v=VLHJUfgxEO4 • The Future of Networking, and the Past of Protocols, S. Shenker, 2011 http://www.youtube.com/watch?v=YHeyuD89n1Y http://www.slideshare.net/martin_casado/sdn-abstractions 15
- 16. © SWITCH 2013 Further Further Reading • Open Networking Summit (industry) – Each April in Silicon Valley • HotSDN workshop (research) – Each Summer wherever SIGCOMM is held • SDN MOOC by Nick Feamster (Georgia Tech.) – 6 weeks starting on 27 May https://www.coursera.org/course/sdn?goback=.gde_4359316_memb er_207551682 • Meta-list: http://www.nec-labs.com/~lume/sdn-reading-list.html 16