1. Stanford University
Software Defined Networks and OpenFlow SDN CIO Summit Nick McKeown & Guru Parulkar
In collaboration with Martin Casado and Scott Shenker
And contributions by many others

2. Executive Summary The network industry is starting to restructure
The trend: “Software Defined Networks”
Separation of control from datapath
Faster evolution of the network
It has started in large data centers
It may spread to WAN, campus, enterprise, home and cellular networks
GENI is putting SDN into hands of researchers

3. What’s the problem?

4. Cellular industry Recently made transition to IP
Billions of mobile users
Need to securely extract payments and hold users accountable
IP sucks at both, yet hard to change
How can they fix IP to meet their needs?

5. Telco Operators Global IP traffic growing 40-50% per year
End-customer monthly bill remains unchanged
Therefore, CAPEX and OPEX need to reduce 40-50% per Gb/s per year
But in practice, reduces by ~20% per year
How can they stay in business?
How can they differentiate their service?

6. Trend #1 (Logical) centralization of control

7. Already happening Enterprise WiFi Telco backbone networks
Set power and channel centrally
Route flows centrally, cache decisions in APs
CAPWAP etc.
Telco backbone networks
Calculate routes centrally
Cache routes in routers

8. Experiment: Stanford campus How hard is it to centrally control all flows?
2006
35,000 users
10,000 new flows/sec
137 network policies
2,000 switches
2,000 switch CPUs

9. How many $400 PCs to centralize all routing and all 137 policies?
Controllers
Ethernet
Switch
Ethernet
Switch
Ethernet
Switch
Host A
Host B
Ethernet
Switch
[Ethane, Sigcomm ‘07]

10. Answer:
less than one

11. If you can centralize control, eventually you will
If you can centralize control, eventually you will. With replication for fault-tolerance and performance scaling.

12. How will the network be structured?

13. Specialized Packet Forwarding Hardware
The Current Network
Routing, management, mobility management, access control, VPNs, …
Feature
Feature
Million of lines of source code
5900 RFCs
Barrier to entry
Operating
System
Specialized Packet Forwarding Hardware
Billions of gates
Bloated
Power Hungry
Vertically integrated
Many complex functions baked into the infrastructure
OSPF, BGP, multicast, differentiated services, Traffic Engineering, NAT, firewalls, MPLS, redundant layers, …
Looks like the mainframe industry in the 1980s

14. Restructured Network Network OS Feature Operating System
Specialized Packet Forwarding Hardware
Operating
System
Feature
Specialized Packet Forwarding Hardware
Operating
System
Feature
Specialized Packet Forwarding Hardware
Operating
System
Specialized Packet Forwarding Hardware
Feature
Operating
System
Specialized Packet Forwarding Hardware

15. Trend #2 Software-Defined Network

16. The “Software-defined Network”
2. At least one Network OS probably many. Open- and closed-source
3. Well-defined open API
Feature
Feature
Network OS
1. Open interface to packet forwarding
OpenFlow
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding

17. OpenFlow Basics
Narrow, vendor-agnostic interface to control switches, routers, APs, basestations. 17

18. Step 1: Separate Control from Datapath
Network OS
OpenFlow
Switch
OpenFlow
Switch
OpenFlow
Switch
OpenFlow
Switch

19. Step 2: Cache flow decisions in datapath
“If header = x, send to port 4”
Network OS
“If header = y, overwrite header with z, send to ports 5,6”
“If header = ?, send to me”
Flow
Table
OpenFlow
Switch
OpenFlow
Switch
OpenFlow
Switch
OpenFlow
Switch

20. Plumbing Primitives Match arbitrary bits in headers: Actions:
Match on any header; or user-defined header
Allows any flow granularity
Actions:
Forward to port(s), drop, send to controller
Overwrite header with mask, push or pop
Forward at specific bit-rate
Data
Header
e.g. Match: 1000x01xx x

21. Ethernet Switch/Router

22. Control Path (Software)
Data Path (Hardware)

23. OpenFlow Controller Control Path OpenFlow Data Path (Hardware)
OpenFlow Protocol (SSL)
Control Path
OpenFlow
Data Path (Hardware)

24. The “Software Defined Network”
2. At least one Network OS probably many. Open- and closed-source
3. Well-defined open API
Feature
Feature
Network OS
1. Open interface to packet forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding

25. Network OS Several commercial Network OS in development Research
Commercial deployments late 2010
Research
Research community mostly uses NOX
Open-source available at:
Expect new research OS’s late 2010

26. Software Defined Networks in Data Centers

27. 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
Quickly improve and innovate
Enables “cloud networking”
Several large data centers will use SDN.

28. Data Center Networks Existing Solutions Software Defined Network
Tend to increase hardware complexity
Unable to cope with virtualization and multi-tenancy
Software Defined Network
OpenFlow-enabled vSwitch
Open vSwitch
Network optimized for data center owner
Several commercial products under development

29. Software Defined Networks on College Campuses

30. What we are doing at Stanford
Defining the OpenFlow Spec
Check out
Open weekly meetings at Stanford
Enabling researchers to innovate
Add OpenFlow to commercial switches, APs, …
Deploy on college campuses
“Slice” network to allow many experiments

31. Virtualization or “Slicing” Layer
Isolated “slices”
Network Operating System 1
Network Operating System 2
Network Operating System 3
Network Operating System 4
Feature
OpenFlow
Virtualization or “Slicing” Layer
OpenFlow
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding
Packet
Forwarding

32. Some research examples

33. FlowVisor Creates Virtual Networks
OpenFlow Wireless
Experiment
PlugNServe
Load-balancer
OpenPipes
Experiment
OpenFlow
Protocol
OpenFlow
Switch
OpenFlow
Protocol
FlowVisor
Policy #1
Multiple, isolated slices in the same physical network
OpenFlow
Switch
OpenFlow
Switch

34. Demo Infrastructure with Slicing

35. Application-specific Load-balancing
Goal: Minimize http response time over campus network
Approach: Route over path to jointly minimize <path latency, server latency>
Internet
Network OS
Load-Balancer
“Pick path & server”
OpenFlow
Switch
OpenFlow
Switch
OpenFlow
Switch
OpenFlow
Switch
OpenFlow
Switch

36. Intercontinental VM Migration
Moved a VM from Stanford to Japan without changing its IP.
VM hosted a video game server with active network connections.

37. Converging Packet and Circuit Networks
Goal: Common control plane for “Layer 3” and “Layer 1” networks
Approach: Add OpenFlow to all switches; use common network OS
Feature
Feature
NOX
OpenFlow
Protocol
OpenFlow
Protocol
WDM
Switch IP
Router IP
Router
TDM
Switch
WDM
Switch
[Supercomputing 2009 Demo]
[OFC 2010]

38. ElasticTree Goal: Reduce energy usage in data center networks
Approach:
Reroute traffic
Shut off links and switches to reduce power
Network OS DC
Manager
“Pick paths”
[NSDI 2010]

39. X ElasticTree Goal: Reduce energy usage in data center networks
Approach:
Reroute traffic
Shut off links and switches to reduce power X
Network OS DC
Manager
“Pick paths”
[NSDI 2010]

40. Executive Summary The network industry is starting to restructure
The trend: “Software Defined Networks”
Separation of control from datapath
Faster evolution of the network
It has started in large data centers
It may spread to WAN, campus, enterprise, home and cellular networks
GENI is putting SDN into hands of researchers

41. Thank you