1. Felicián Németh Balázs Sonkoly, András Gulyás NemethF@tmit.bme.hu
Sharing Networking Research Results with OpenFlow and Mininet in a few Easy Steps
Felicián Németh
Balázs Sonkoly, András Gulyás
The OpenFlow protocol is becoming an important enabler of network innovation by decoupling the control and data planes. Researchers can experiment with new network capabilities and management functions on high performance OpenFlow switches in real operating conditions. OpenFlow, however, is also useful not just to those researchers that work in the field of Software Defined Networking but to anybody doing research on computer networks or telecommunication. On the one hand, this new paradigm brings us rapid prototyping. On the other hand, using Mininet for OpenFlow development results in ready-to-share implementations.
The presentation first gives a primer to OpenFlow basics, then as an example it walks through the implementation details of extending an OpenFlow software switch with a simple Network Coding forwarding mechanism. The work consists of three main parts: extending the OpenFlow protocol, extending the switch's forwarding mechanism, and extending Mininet. In the end we will see how these simple steps leads to a downloadable virtual machine disk image that fellow researchers an experiment with.

2. Reproducible science Mathematics: theorem-proof
Biology: methodology refinement / rebuttal papers
Nature Editorial If you want reproducible science, the software needs to be open source

3. Research paper with easily reproducible results
Pros
Better quality
 higher acceptance probability
Reproducibility
follow-up works, citations
Cons
Fear of being surpassed
You have at least couples of months advantage

4. Part One: Primer to OpenFlow
Slide Credits
Rob Sherwood
“GENI Engineering Workshop June 2010”
Guido Appenzeller
Nick McKeown
Guru Parulkar
Brandon Heller
Lots of others
(this slide was also stolen) (with the previous note)

5. Why?
“Google is using OpenFlow on custom-designed hardware for all the internal networks it runs connecting its global data centers, said Urs Holzle, senior vice president of technology infrastructure at Google”
“How Google is using OpenFlow to lower its network costs? Google is checking out a new form of networking protocol known as OpenFlow, in the communications networks that run between its data centers. The search giant is testing the use of software defined networks in order to lower the cost of delivering a bit of information.” (gigaom.com)
“Virtualization and cloud infrastructure provider VMware (NYSE: VMW), announced this week that it will pay $1.05 billion in cash plus approximately $210 million in assumed unvested equity awards to acquire Nicira, a software-defined networking (SDN) specialist and provider of network virtualization for open source initiatives.“ (RCR Wireless News – Americas)

6. Current Internet Closed to Innovations in the Infrastructure Closed 6
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 6

7. “Software Defined Networking” approach to open it
Network Operating System
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

8. The “Software-defined Network”
App
App
App
Network Operating System
1. Open interface to hardware (e.g., OpenFlow)
Simple Packet Forwarding Hardware
Simple Packet Forwarding Hardware
Simple Packet Forwarding Hardware
Simple Packet Forwarding Hardware
Simple Packet Forwarding Hardware

9. What is OpenFlow? OpenFlow is an open interface to hardware
Control how packets are forwarded
Implementable on COTS hardware
Make deployed networks programmable
not just configurable
Vendors don’t need to expose implementation
Makes innovation easier
Goal (experimenter’s perspective):
No more special purpose testbeds
Validate your experiments on deployed hardware with real traffic at full line speed
Simulation is not enough

10. Ethernet Switch

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

12. OpenFlow Controller Control Path OpenFlow Data Path (Hardware)
OpenFlow Protocol (SSL/TCP)
Control Path
OpenFlow
Data Path (Hardware)

13. OpenFlow Usage Controller OpenFlow Switch OpenFlow Switch OpenFlowPC
OpenFlow
Switch
Rule
Action
OpenFlow
Protocol
OpenFlow
Switch
OpenFlow
Switch
Rule
Action
Rule
Action
OpenFlowSwitch.org 13 13

14. OpenFlow Firmware Controller PC OpenFlow Flow Table Abstraction
Software
Layer
Flow Table
MAC
src
dst IP
Src
Dst
TCP
sport
dport
Action
Possible actions
Forward packet to port(s)
Encapsulate and forward to controller
Drop packet
Send to normal processing pipeline
Modify Fields
Hardware
Layer *
port 1
port 1
port 2
port 3
port 4

15. OF Controller is King Write your own controllerPC
Write your own controller
handle ~20 OpenFlow messages
Download, configure existing controller
Extend existing controller
many frameworks to choose from (NOX, POX, Beacon, Maestro, Helios, …)
event-driven
module-based extensibility

16. Cisco Catalyst 3750 (prototype)
OF switches: Software → Hardware
Stanford Reference Implementation v1.0
Ericsson implementation v1.1 & v1.2
Linux-based Software Switch running in User Space
Limited by host PC, typically 4x 1Gb/s
Useful for development & testing
Starting point for other implementations
Open vSwitch
Linux-based Software Switch running in Kernel Space
Not just an OF switch, widely used by virtual machines (VirtualBox, XEN)
Firmware of some devices based on Open vSwitch
NetFPGA-based implementation
Requires PC and NetFPGA card
Hardware accelerated
4 x 1 Gb/s OR
4 x 10 Gb/s throughput
1G: $500 for academics
10G: $1,675 for academics
Prototype
Product
Core
Router
Cisco Catalyst 6k
(prototype)
Juniper MX-series
(prototype)
HP ProCurve 5400 and others
Pronto
Enterprise
Campus
Data Center
Cisco Catalyst (prototype)
Arista 7100 series (Q4 2010)
NEC IP8800
Circuit
Switch
Ciena CoreDirector
WiMAX (NEC)
more to follow...
Wireless

17. MiniNet: “Network in a Laptop”
Machine-local emulated network
great dev/testing tool
Uses linux virtual network features
lightweight virtualization: cheaper than VMs
one switch is one small linux process
Arbitrary topologies, nodes
Rapid prototyping, scalable, shareable, path to hardware

18. Part Two: Adding a new forwarding mechanism to OpenFlow
Implementations highlights to show how easy it is

19. Multicast with MPLS
sudo -E mn --custom ~/nox11oflib/src/nox/coreapps/butterfly_app/butterfly.py
controller mpls; vlc start; bottleneck 0.26; controller nc;

20. Network Coding

21. Network Coding = XOR-based NC in the butterfly topology Packet format
MPLS label:
Flow id
MPLS label: Seq. no 1
Seq. no 2.
data
Impossible in OpenFlow
Create seq. numbers at s5 & s6
Encode at s7
Decode at s9 and s10

22. Network Coding in OpenFlow: Implementation Steps
Extending the OpenFlow protocol
by defining new experimenter actions to encode and decode packets
Writing a controller application
that proactively fills up the flow tables
Extending the software switch's forwarding mechanism
to handle the newly defined actions
Extending Mininet by
creating the topology, and
adding new CLI commands for the demo
Sharing the virtual machine

23. Extending the OpenFlow protocol
/display/PUBLIC/ONF+Registry
Protocol is designed for extendibility
New message types can be added as experimenter messages
Get an Experimenter ID
create from an IEEE OUI (if you have one)
request one from ONF
Define the wire format
experimenter action:
type = experimenter
length
Experimenter ID
vendor specific data

24. Network Coding in OpenFlow: Implementation Steps
Extending the OpenFlow protocol
by defining new experimenter actions to encode and decode packets
Writing a controller application
that proactively fills up the flow tables
Extending the software switch's forwarding mechanism
to handle the newly defined actions
Extending Mininet by
creating the topology, and
adding new CLI commands for the demo
Sharing the virtual machine

25. Flow tables at s5 MPLS Paths Network Coding data data MPLS label:
Flow id
data
MPLS label:
Flow id
MPLS label: Seq. no 1
Seq. no 2.
data

26. Experimenter Action: Set MPLS label from a counter
action parameters
packet being processed in the pipeline
reuse existing actions

27. Flow table at Node s9 decode action next action, e.g., output
Match: flow id
actions
red
decode, output
blue
red  blue
decode, drop
red’
output
blue’
Packet
next action, e.g., output
re-process packet
decode action
Duplicate
Decode
Re-label decoded packet to red’ or blue’
Decoded packet is re-processed: Flexibility
New actions support other scenarios too

28. Network Coding in OpenFlow: Implementation Steps
Extending the OpenFlow protocol
by defining new experimenter actions to encode and decode packets
Writing a controller application
that proactively fills up the flow tables
Extending the software switch's forwarding mechanism
to handle the newly defined actions
Extending Mininet by
creating the topology, and
adding new CLI commands for the demo
Sharing the virtual machine

29. Extending Mininet 1. mn --custom=topo.py
custom topology and node parameters from a python file …

30. Extending Mininet 2. Mininet isn’t designed for general extendibility
Source can be enhanced
open-source, object-oriented
small modifications spread everywhere
leads to maintenance problems
 alter Mininet’s behavior by monkey patches
modify a class by overriding its method form another file
can lead to upgrade problems as well

31. Network Coding in OpenFlow: Implementation Steps
Extending the OpenFlow protocol
by defining new experimenter actions to encode and decode packets
Writing a controller application
that proactively fills up the flow tables
Extending the software switch's forwarding mechanism
to handle the newly defined actions
Extending Mininet by
creating the topology, and
adding new CLI commands for the demo
Sharing the virtual machine

32. Sharing the VM Just upload the disk image somewhere
Put the sources up, e.g., to github

33. Summary Software Defined Networking
is about to change the equipment market
by the commoditization of routers and switches,
reshapes the active research areas
from distributed computing towards centralization
Reproducible research results
Articles have no room for experiments’ details
Sharing a proof-of-concept, prototype implementation is enough
usually a Mininet script will do
“runnable papers”