1. SDN
刘 驰

2. Software Defined Networking (SDN)
What is SDN?
Background
An OS for networks
What is OpenFlow?
How it helps SDN
The current status & the future of SDN
Conclusions 2 2

3. Limitations of Current Networks
Switches 3

4. Specialized Packet Forwarding Hardware
We have lost our way
Routing, management, mobility management, access control, VPNs, …
App
App
App
Million of lines of source code
5400 RFCs
Barrier to entry
Operating
System
Specialized Packet Forwarding Hardware
500M gates
10Gbytes RAM
Bloated
Power Hungry
Many complex functions baked into the infrastructure
OSPF, BGP, multicast, differentiated services, Traffic Engineering, NAT, firewalls, MPLS, redundant layers, …
An industry with a “mainframe-mentality” 4

5. Reality Lack of competition means glacial innovation
App
App
App
App
App
App
Operating
System
Operating System
Specialized Packet Forwarding Hardware
Specialized Packet Forwarding Hardware
缺少竞争意味着缺乏创新动力
封闭的架构意味着模糊的，封闭的接口
不适用于科研和实验网络和想法
Lack of competition means glacial innovation
Closed architecture means blurry, closed interfaces
Vertically integrated, complex, closed, proprietary
Not suitable for experimental ideas
Not good for network owners & users
Not good for researchers 5

6. Glacial process of innovation made worse by captive standards process
Deployment
Idea
Standardize
Wait 10 years
captive standards process：圈养的标准流程
由生产厂商决定
客户被排斥在创新过程以为
厂商间无公共部分
Driven by vendors
Consumers largely locked out
Lowest common denominator features
Glacial innovation

7. Old Ways to Configure a Network
App
Operating
System
App
Specialized Packet Forwarding Hardware
Operating
System
App
Specialized Packet Forwarding Hardware
Operating
System
App
Specialized Packet Forwarding Hardware
Operating
System
Specialized Packet Forwarding Hardware
App
Operating
System
Specialized Packet Forwarding Hardware 7

8. No control plane abstraction for the whole network!
It’s like old times – when there was no OS…
Packages travel inside the network…
Switches pass them along…
But the decisions are made individually by the switches.. such as where to pass them
Nobody is dynamically controlling the network flow 8
Wilkes with the EDSAC, 1949 8

9. Idea: An OS for Networks!!!
Closed
App
Operating
System
App
Specialized Packet Forwarding Hardware
Operating
System
App
Specialized Packet Forwarding Hardware
Operating
System
App
Specialized Packet Forwarding Hardware
Operating
System
Specialized Packet Forwarding Hardware
App
Operating
System 9
Specialized Packet Forwarding Hardware

10. Idea: An OS for Networks
Control Programs
Network Operating System
App
Operating
System
App
Specialized Packet Forwarding Hardware
Operating
System
App
Specialized Packet Forwarding Hardware
How do we redefine the architecture to open up networking infrastructure and the industry!
By bring to the networking industry what we did to the computing world
Operating
System
App
Specialized Packet Forwarding Hardware
Operating
System
Specialized Packet Forwarding Hardware
App
Operating
System
Specialized Packet Forwarding Hardware 10 10

11. Idea: An OS for Networks
Control Programs
Network Operating System
Simple Packet Forwarding Hardware
Simple Packet Forwarding Hardware
The key is to have a standardized control interface that speaks directly to hardware
A whole network is like a big machine
Simple Packet Forwarding Hardware
Simple Packet Forwarding Hardware
Simple Packet Forwarding Hardware 11 11

12. Idea: An OS for Networks
“NOX: Towards an Operating System for Networks”
Software-Defined Networking (SDN)
Control Programs
Global Network View
Network Operating System
A remote controller has control of a switch’s forwarding decisions
Control via forwarding
interface
Protocols 12 12

13. Virtualization or “Slicing”
Trend
Controller 1
App
Controller 2
Virtualization or “Slicing”
OpenFlow
NOX
(Network OS)
Network OS
App
App
App
Windows
(OS)
Linux
Mac OS
Windows
(OS)
Linux
Mac OS
Windows
(OS)
Linux
Mac OS
Virtualization layer
x86
(Computer)
Computer Industry
Network Industry 13

15. Outline What is SDN? Limitations of current networks
The idea of Network OS
What is OpenFlow?
How it helps SDN
The current status & the future of SDN
Conclusions 15 15

16. OpenFlow “OpenFlow: Enabling Innovation in Campus Networks”
Like hardware drivers
– interface between switches and Network OS 16

17. Control Path (Software)
OpenFlow
Control Path (Software)
Data Path (Hardware) 17

18. OpenFlow Controller Control Path OpenFlow Data Path (Hardware)
OpenFlow Protocol (SSL/TCP)
Control Path
OpenFlow
Leverages hardware inside most switches today (ACL tables)
Data Path (Hardware) 18 18

19. OpenFlow Basics Network OS OpenFlow Protocol SSL-TCP Control Program A
Control Program B
Network OS
OpenFlow Protocol
SSL-TCP
IBM 10 gigabit ethernet OpenFlow switch G8264, which has 48×10 GbE SFP+ ports and 4 × 40 GbE QSFP+ ports 19

20. OpenFlow Switching OpenFlow Client Controller PC OpenFlow Table
Software
Layer
Controller
OpenFlow Table
Hardware
Layer
MAC
src
dst IP
Src
Dst
TCP
sport
dport
Action PC *
port 1
port 1
port 2
port 3
port 4 20 20

21. Flow Table Network OS Control Program A Control Program B
“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”
Packet forwarding 包转发
Flow
Table(s)
Packet
Forwarding
Packet
Forwarding

22. Flow Table Rule (exact & wildcard) Action Statistics Default Action
Flow N.
规则，动作，数据 22 22

23. Flow Entry Match fields Match against packets Action
Modify the action set or pipeline processing
Stats
Update the matching packets
Match Fields
Stats
Action
In Port
Src MAC
Dst MAC
Eth Type
Vlan Id
IP Tos
IP Proto
IP Src
IP Dst
TCP Src Port
TCP Dst Port
Layer 2
Layer 3
Layer 4
Forward packet to port(s)
Encapsulate and forward to controller
Drop packet
Send to normal processing pipeline
1. Packet
2. Byte counters

24. Examples Switching Flow Switching Firewall Switch Port MAC src dst Eth
type
VLAN ID IP
Src
Dst
Prot
TCP
sport
dport
Action * *
00:1f:.. * * * * * * *
port6
Flow Switching
Switch
Port
MAC
src
dst
Eth
type
VLAN ID IP
Src
Dst
Prot
TCP
sport
dport
Action
port3
00:20..
00:1f..
0800
vlan1 4
17264 80
port6
Firewall
Switch
Port
MAC
src
dst
Eth
type
VLAN ID IP
Src
Dst
Prot
TCP
sport
dport
Action * * * * * * * * * 22
drop 24

25. Examples Routing VLAN Switching Switch Port MAC src dst Eth type VLANID IP
Src
Dst
Prot
TCP
sport
dport
Action * * * * * * * * *
port6
VLAN Switching
Switch
Port
MAC
src
dst
Eth
type
VLAN ID IP
Src
Dst
Prot
TCP
sport
dport
Action
port6,
port7,
port9 * *
00:1f.. *
vlan1 * * * * * 25

26. OpenFlow Usage Controller Alice’s Rule Alice’s code PC OpenFlow Switch
Decision?
OpenFlow
Protocol
Table entries can be updated
OpenFlow Switch
OpenFlow Switch 26 26

27. OpenFlow Usage Alice’s code: Simple learning switch Per Flow switching
Controller
Alice’s code:
Simple learning switch
Per Flow switching
Network access control/firewall
Static “VLANs”
Her own new routing protocol: unicast, multicast, multipath
Home network manager
Packet processor (in controller)
IPvAlice PC
Alice’s code
Table entries can be updated 27 27

28. OpenFlow
Standard way to control flow-tables in commercial switches and routers
Just need to update firmware
Essential to the implementation of SDN 28

29. Centralized/Distributed Control
“Onix: A Distributed Control Platform for Large-scale Production Networks”, UNIX OSDI 2010.
Centralized Control
Distributed Control
Controller
Controller
OpenFlow
Switch
OpenFlow
Switch
Controller
Partition, aggregation, consistency, durability
Asynchronous but eventually consistent
OpenFlow
Switch
OpenFlow
Switch
OpenFlow
Switch
OpenFlow
Switch 29

30. Virtualizing OpenFlow
Network operators “Delegate” control of subsets of network hardware and/or traffic to other network operators or users
Multiple controllers can talk to the same set of switches
Imagine a hypervisor for network equipments
Allow experiments to be run on the network in isolation of each other and production traffic

31. Switch Based Virtualization
Controller
Research VLAN 2
Flow Table
Controller
Research VLAN 1
Flow Table
Production VLANs
Normal L2/L3 Processing
Experiments running on PRODUCTION infrastructure
Key to get scale, key to get traffic on the network
(e.g. can’t just do a reset...) 31

32. FlowVisor A network hypervisor developed by Stanford
A software proxy between the forwarding and control planes of network devices

33. FlowVisor-based Virtualization
Heidi’s
Controller
Craig’s
Controller
Aaron’s
Controller
Topology discovery is per slice
OpenFlow
Protocol
OpenFlow FlowVisor & Policy Control
OpenFlow
Switch
OpenFlow
Protocol
OpenFlow
Switch
OpenFlow
Switch 33

34. Outline What is SDN? Limitations of current networks
The idea of Network OS
What is OpenFlow?
How it helps SDN
The current status & the future of SDN
Conclusions 34 34

35. OpenFlow Building Blocks
Monitoring/ debugging tools
oftrace
oflops
openseer
Stanford Provided
ENVI (GUI)
LAVI
n-Casting
Expedient
Applications
NOX
Beacon
Trema
Maestro
ONIX
Controller
Slicing
Software
FlowVisor
Console
FlowVisor
There are components at different levels that work together in making it work
The commercial switch details will follow in next slide
There are a plethora of applications possible. I only list those available at Stanford
Commercial Switches
Stanford Provided
Software
Ref. Switch
NetFPGA
Broadcom
Ref. Switch
HP, NEC, Pronto, Juniper.. and many more
OpenFlow
Switches
OpenWRT
PCEngine WiFi AP
Open vSwitch 35

36. Current status of SDN Hardware support More coming soon...
Juniper MX-series
NEC IP8800
WiMax (NEC)
HP Procurve 5400
Netgear 7324
PC Engines
Not only switches but other network components
Pronto 3240/3290
Ciena Coredirector
More coming soon... 36 36

37. Current status of SDN Industry support
Google built hardware and software based on the OpenFlow protocol
VMware purchased Nicira for $1.26 billion in 2012
IBM, HP, NEC, Cisco and Juniper also are offering SDNs that may incorporate OpenFlow, but also have other elements that are specific to that vendor and their gear. 
Nicira offers a way to build scale out virtualized networks and uses OpenFlow, but only as a small aspect of its controller product.
100+ institutions around the world are using openflow 37

38. Future Focuses of SDN New policies for security Programmable WLANs
The placement of controllers (amount; location; centralized/distributed)
Debugger for SDN
Transparently changing host IP to avoid attack – SDN provides a namespace interface (a strong mapping mechanism)
2. access point (AP) association decisions are not made by the infrastructure, but by clients. Have no control to that part… state changes.. Virtual AP for management
4. Breakpoints and packet backtraces 38 38

39. Conclusions What is SDN? A system-layered abstraction
Programmable, flexible, and extensible
What is OpenFlow?
Interface between switches and controllers
Enabling SDN
Future SDN
Enabling innovation
SDN not about new mechanisms; can use current
Forwarding primitives (e.g., MPLS)
State distribution primitives (e.g., flooding as in OSPF)
Operator control programs (e.g., BGP on scale-out router) 39 39

40. Wireless Data Center Networking
60 GHz spectrum
7 GHz (57–64 GHz) waveband
data rate over 1 Gb/s
10 meters
Line-of-Sight (LoS)