1. How SDN will shape networking
Nick McKeown
Stanford University
With: Martín Casado, Teemu Koponen, Scott Shenker … and many others
With thanks to: NSF, GPO, Stanford Clean Slate Program, Cisco, DoCoMo, DT, Ericsson, Google, HP, Huawei, NEC, Xilinx

2. SDN: An industry change How SDN will shape networking
Outline
SDN: An industry change
How SDN will shape networking
Empower network owners/operators
Increase the pace of innovation
Diversify the supply chain
Build a robust foundation

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

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

5. Software Defined Network (SDN)
2. At least one Network OS probably many. Open- and closed-source
Control Program
Control Program
Global Network View
Network OS
1. Open interface to packet forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding

6. Simple example

7. OSPF Distributed System Dijkstra’s Algorithm Why SDN? The Consequences
RFC 2328: 245 pages
Distributed System
Builds consistent, up-to-date map of the network: 101 pages
Dijkstra’s Algorithm
Operates on map: 4 pages
Why SDN?
The Consequences
For industry
For research
For standards and protocols

8. Example OSPF (Dijkstra) IS-IS Network OS New! OSPF IS-IS OS
Packet
Forwarding
Distributed System
New!
OSPF
IS-IS
Distributed
System
Distributed
System OS
Custom Hardware

9. OpenFlow Forwarding Abstraction
Control Program A
Control Program B
Network OS
“If header = p, send to port 4”
“If header = q, overwrite header with r, add header s, and send to ports 5,6”
Packet
Forwarding
“If header = ?, send to me”
Flow
Table(s)
Packet
Forwarding
Packet
Forwarding

10. OpenFlow Forwarding Abstraction <Match, Action>
Match on any header, or new header
Allows any flow granularity
Action
Forward to port(s), drop, send to controller
Overwrite header with mask, push or pop
Forward at specific bit-rate
Header
Data
Match: 1000x01xx x

11. OpenFlow Forwarding Abstraction
Protocol Independent
Construct Ethernet, IPv4, VLAN, MPLS, …
Construct new forwarding methods
Backward Compatible
Run in existing networks
Technology Independent
Switches, routers, WiFi APs
Cellular basestations
WDM/TDM circuits

12. SDN in development Domains Products Data centers Public clouds
Enterprise/campus
Cellular backhaul
Enterprise WiFi
WANs
Home networks
Products
Switches, routers: About 15 vendors
Software: 8-10 vendors and startups
New startups. Lots of hiring in networking.

13. SDN: An industry change How SDN will shape networking
Outline
SDN: An industry change
How SDN will shape networking
Empower network owners/operators
Increase the pace of innovation
Diversify the supply chain
Build a robust foundation

14. How SDN will shape networking
Empower network owners and operators
Customize networks to local needs
Eliminate unneeded features
Creation of virtual, isolated networks
Increase the pace of innovation
Innovation at software speed
Standards (if any) will follow software deployment
Technology exchange with partners
Technology transfer from universities
Example 1

15. Example 1. Customizing the network Add distributed load-balancing
Nikhil Handigol, Mario Flajslik, Srini Seetharaman

16. LOAD-BALANCER

18. Experimental Setup Load-balancer Network OS: NOX Packet Forwarding

21. Nikhil’s Experiment: <500 lines of code
Feature
Network OS: NOX

22. More videos openflow.org/videos

23. How SDN will shape networking
Empower network owners and operators
Customize networks to local needs
Eliminate unneeded features
Creation of virtual, isolated networks
Increase the pace of innovation
Innovation at software speed
Standards (if any) will follow software deployment
Technology exchange with partners
Technology transfer from universities
Example 2

24. Example 2. Innovation at software speed Mininet: Rapid prototyping
Brandon Heller, Bob Lantz, Nikhil Handigol, Vimal Jeyakumar

25. Mininet: Rapid Prototyping
user
kernel
Load-balancer
Network OS: NOX, Beacon, …
Processes with network namespace
Packet
Forwarding
veth
Network OS
OpenFlow
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Open vSwitch in kernel

26. Mininet: Rapid Prototyping
Fast
Emulate network with 10s of switches on one laptop
Processes easily mapped to cores and servers
Emulate network with 1000s of switches in server rack
Rapid transfer
Deploy unmodified code directly into live network
Code available
openflow.org/mininet

27. How SDN will shape networking
3. Diversify the supply chain
A variety of software suppliers
Vendors, homegrown, outsourced, open-source
Common hardware abstraction, with extensions
4. Build a robust foundation
Standardized forwarding abstraction
Provable network properties at every step
Example 3

28. Example 3. Provable network properties Header Space Analysis
Peyman Kazemian

29. Header Space Analysis: Static checking
In today’s networks, simple questions are hard
Can A talk to B?
What are all the packet headers from A that can reach B?
Are there any loops in the network?
Is VLAN X (or ‘slice’) isolated totally from VLAN Y?
Step 1: Model packet header as a point in {0,1}L
Step 2: Model all switches as transforms of {0,1}L
Step 3: Analyze reachability, loops, slice isolation, …
Protocol independent, general, and surprisingly fast
< Match, Action >

30. Basic Model Packet Forwarding Header Data L 0110101…01 Action
Send to port 1, and
Rewrite with: 100XX00..1X +
Match L
011XXX…X1

31. Network Transfer Function
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding

32. Properties Network transfer function: set of Boolean expressions
Only relies on <Match, Action>
Subsumes Ethernet, IPv4, firewalls, NAT, …
Can prove reachability, isolation and find loops
Used to find faults in real networks
e.g. Analyzed Stanford backbone in 10mins
Code publicly available

33. SDN: An industry change How SDN will shape networking
Outline
SDN: An industry change
How SDN will shape networking
Empower network owners/operators
Increase the pace of innovation
Diversify the supply chain
Build a robust foundation

34. Thank you!

35. Backup

36. Experimental Setup with Slicing
NOX
Experiment
NOX
Experiment
NOX
Experiment
Network OS: NOX
Slicing Layer: FlowVisor
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding

37. Software Defined Network (SDN)
Control
Programs
Control
Programs
Control
Programs
Abstract Network View
Network Virtualization
Control Program A
Control Program B
Global Network View
Network OS
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding

38. Example: New Data Center
Cost
200,000 servers
Fanout of 20  10,000 switches
$5k vendor switch = $50M
$1k commodity switch = $10M
Savings in 10 data centers = $400M
Control
More flexible control
Tailor network for services
Quickly improve and innovate

39. Consequences for research
Ease of trying new ideas
Existing tools: NOX, Beacon, switches, Mininet
More rapid technology transfer
GENI, Ofelia and many more
A stronger foundation to build upon
Provable properties of forwarding
New languages and specification tools

40. Consequences for standards
Standards will define the interfaces
The role of standards will change:
Network owners will define network behavior
Features will be adopted without standards
Programming world
Good software is adopted, not standardized

41. Summary Networks becoming Abstractions More programmatic
Defined by owners and operators, not vendors
Faster changing, to meet operator needs
Lower opex, capex and power
Abstractions
Will shield programmers from complexity
Make behavior more provable
Will take us places we can’t yet imagine