Software Defined Networking

1. Software Defined Networking Nick McKeown Stanford University

2. (part 1)

3. Why I love my job I work with people much smarter than me. I get to work on intellectually interesting ideas. … that might positively change the practice. Then, we try to actually change the practice.

4. Whatever it takes • Prove a theorem • Write a paper • Build a demo • Talk to lots of industry people • Write a standard • Give lots of talks • Write a blog • Start a company • Build an open source tool • …

5. Choosing research projects • Pick a problem that is intellectually interesting. • And improves the practice. • And industry doesn’t like (yet).

6. EthaneMartin Casadoet al [Sigcomm ‘07] Policy “Laptops can’t accept incoming connections” “A can’t talk to B” Network Control Plane Control Control Packet Forwarding Packet Forwarding Control Control Packet Forwarding Packet Forwarding Control Packet Forwarding

7. Microsoft: “Come on in….” Cisco: “It will never work…” Raw nerve. We must be onto something.

8. Checklist • Intellectually interesting. • And improves the practice. • And industry doesn’t like (yet).

9. Corollary: You can’t give stuff away Example 1: Order of magnitude faster router (1997) • Tried to give Tiny-Tera away for free. • Industry wasn’t ready. • Started Abrizio. Example 2: Network Memory (2001) • Tried to give it away for free, to save $500M per year. • Industry wasn’t ready. • Started Nemo. Example 3: Ethane (2007) • Tried to give it away for free; early stages of SDN. • Industry wasn’t ready. • Started Nicira.

10. I put everything in public domain Industry • Invests huge amounts to develop and sell products. • Patents protect ideas, giving the confidence to invest. University research • Serves society at large. • Stay ahead by running fast, not by protecting. • Makes it easier to work with industry. • If it’s good research, industry doesn’t see it yet. Everything in public domain since 1999.

11. (part 2)

12. If you are in any doubt about whether OpenFlow/SDN will be deployed in the WAN UrsHölzle (Google), ONS 2012

13. Software Defined Networks Martin Casado

14. What is SDN? (when we clear away all the hype)

15. SDN is the separation of the control plane from the forwarding plane.

16. Software Defined Network (SDN) Control Program Control Program Control Program Global Network Map Network OS Packet Forwarding Abstract Forwarding Model (e.g. OpenFlow) Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding

17. The Technical Benefits (1) Well-defined control abstraction • Control plane can run on modern servers • Can adopt software engineering best-practices • Easier to add new control programs • …or customize locally • Solve distributed systems problem once, rather than for every protocol

18. OSPF Dijkstra OSPF Dijkstra 5% Global Network Map Network Map Network OS 95% OS Packet Forwarding Specialized Hardware Packet Forwarding Packet Forwarding Packet Forwarding

19. The Technical Benefits (2) Well-defined forwarding abstraction • e.g. OpenFlow • Vendor-agnostic interface to forwarding plane • Simpler, lower-cost, lower-power hardware

20. Match-Action Forwarding Abstraction “Plumbing primitives” Action Primitives “Forward to ports 4 & 5” “Push header Y after bit 12” “Pop header bits 8-12” “Decrement bits 13-18” “Drop packet” … H H’

21. Multiple Table Match-Action Hn H’ H1

22. OpenFlow Philosophy Long-term, forwarding looking Match: Very general, not protocol specific. Action: Small instruction set, not protocol specific. • Make it easy to add new headers and actions. • Any network (packet, circuit, radio). Short-term, backward looking Match: include well-known header fields. Action: necessary set for existing protocols. • Support existing protocols on existing switch chips.

23. New switch chips emerging Match Table Match Table H Action Action Output Queues HEADER Out In Data H Recombine DATA Data H

24. The Technical Benefits (3) Well-defined forwarding behavior • The forwarding tables capture the entire forwarding behavior. • Control plane writes the forwarding state. • Therefore, we can verify its correctness.

25. Software Defined Network (SDN) firewall.c … if( TCP_port == SMTP) dropPacket(); … Control Program Control Program Control Program Global Network Map Network OS Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding

26. Software Defined Network (SDN) 1 firewall.c … if( TCP_port == SMTP) dropPacket(); … Control Program Control Program Control Program Global Network Map 2 Network OS Packet Forwarding Packet Forwarding Packet Forwarding 3 Packet Forwarding Packet Forwarding

27. Software Defined Network (SDN) Policy Control Program Control Program Control Program “A can talk to B” “Guests can’t reach PatientRecords” “No loops” Global Network Map Network OS Packet Forwarding Packet Forwarding Forwarding Behavior Packet Forwarding Packet Forwarding Packet Forwarding

28. Networks notoriously hard to debug Today, even simple questions hard to answer: • Can host A talk to host B? • What are all the packet headers from A that can reach B? • Are there any loops in the network? • Is Group X provably isolated from Group Y? • What happens if I remove a line in the config file?

29. Header Space Analysis A B L Header Header Data Data 01110011…1 111..100000

30. Header Space Analysis 1 2

31. The set of packets from A that can reach B A B

32. All packets from A that can reach B A B

33. Header Space Analysis[Kazemian NSDI ‘12] Consequences • Abstract forwarding model; protocol independent • Finds all packets from A that can reach B • Find loops, regardless of protocol or layer • Can prove that two groups are isolated Can verify if network adheres to policy

34. HSA as a “foundation” HSA enables many tools and methods • Independent static checking • In-line in-controller invariance checking • Dynamic testing: Automatic test packet generation • Dynamic testing: Automatic performance monitoring Analogy to Boolean algebra for logic design

35. SDN: Business Consequences

36. The Business Consequences • Vertical integration will finally be replaced by a more competitive industry with a level playing field. • Large growth in software industry for networking. Faster innovation. • Hardware switches will focus on capacity, fan-out and power. (Think Intel for networking). • Multi $Bn tools industry will emerge.

37. Corollary The customer and end-user will be better served • Networks will be cheaper. • Networks will be faster. • Networks will be (much) more reliable. • Networks will improve faster. • Networks will be in service of the owner, the operator, the customer and the application rather than just the high-margin vendor. SDN is in the best interest of society at large. To resist is to be protectionist and self-serving.

38. App App App App App App App App App App App Specialized Applications Windows (OS) Linux Mac OS Specialized Operating System or or Open Interface Open Interface Specialized Hardware Microprocessor Horizontal Open interfaces Rapid innovation Huge industry Vertically integrated Closed, proprietary Slow innovation Small industry

39. App App App App App App App App App App App Specialized Features Control Plane Control Plane Control Plane or or Specialized Control Plane Open Interface Open Interface Specialized Hardware Merchant Switching Chips Horizontal Open interfaces Rapid innovation Vertically integrated Closed, proprietary Slow innovation

40. Hundreds of protocols 6,500 RFCs Specialized Features Specialized Control Plane Tens of millions of lines of code. Closed, proprietary, outdated. Specialized Hardware Billions of gates. Power hungry and bloated.

41. What SDN isn’t Ram in even more lines of code… “My box now has an OpenFlow interface too!”

42. (part 3)

43. What’s new? • Separation of control from forwarding. • Programmatic control of forwarding by writing entries into tables. Transport networks have done this for decades!

44. Natural Evolution: Converged Control Control Program Control Program Control Program Global Network Map Network OS Direct Control of Hardware, or Virtual transport network Control Data Center Data Center Transport Network MPLS MPLS New ONF Working Group: Optical Transport

45. Match-Action Forwarding Abstraction OpenFlow OpenFlow Packet flow Packet flow Packet flow Circuit/channel OpenFlow Circuit/channel Circuit/channel

46. Dynamic Circuit Switching Transport Network Packet Network Packet Network Transport Network UNI UNI

47. Why it was supposed to happen Technology: High capacity optical crossconnects. Aggregation: High capacity packet networks. Cost: Circuit switches cost less; use less power. Standard: GMPLS.

48. Why GMPLS failed • Router vendors prevented it. • GMPLS standard much too complicated.

49. Proprietary Interface Proprietary Interface Packet Network Transport Network GMPLS Control Plane OSPF-TE, RSVP-TE IP/MPLS Control Plane OSPF-TE, RSVP-TE + many more Vendor Islands EMS EMS EMS UNI We Didn’t Make it Easy! 49

50. Proprietary Interface Proprietary Interface Packet Network Transport Network GMPLS Control Plane OSPF-TE, RSVP-TE IP/MPLS Control Plane OSPF-TE, RSVP-TE + many more OSPF-TE, RSVP-TE OSPF-TE, RSVP-TE Vendor Islands EMS EMS EMS UNI GMPLS 175k OSPF RSVP Quagga 50k Linux 50