This document discusses developing SDN applications in Ryu. It provides an overview of OpenFlow, introduces Ryu application development, describes the OpenFlow API in Ryu, and demonstrates a hub application that floods ICMP packets and sends other protocols to the controller. The presenter is John-Lin from National Tsing Hua University researching network security in SDN using the Ryu controller.

1. For SDNDS-TW Sharing
Developing SDN apps in Ryu 林哲緯, John-Lin
http://linton.tw/

2. whoami
❖ 林哲緯 ( John-Lin )
❖ 清華⼤大學 通訊⼯工程所 HSNL LAB
❖ 背景是通訊⼯工程
• 原是寫 Python 當興趣，玩網路程式時接觸
SDN/OpenFlow
❖ ⽬目前研究使⽤用 Ryu 未來應該也會繼續⽤用 Ryu Controller
❖ Network Security in SDN
• Contribute Snort-Integrate patch in Ryu
• See more: http://linton.tw/2014/09/03/Ryu-with-Snort-Integration/

3. Outline
❖ OpenFlow Overview
❖ Introduction to Ryu application development
❖ The OpenFlow API in Ryu
❖ Demo

4. Outline
❖ OpenFlow Overview
❖ Introduction to Ryu application development
❖ The OpenFlow API in Ryu
❖ Demo

5. What is OpenFlow?
Controller Plane
OpenFlow Controller
OpenFlow Protocol (SSL/TCP)
Flow Table
Packet Packet
OpenFlow Switch
Data Plane
Forwarding
Drop
Forward to Controller

6. About Flow Entry
Rule Action Statistics
in_port
VLAN
ID
VLAN
pcp
1. Forward packet to ports
2. Forward to controller
3. Drop packet
4. Modify Field (set-field)
MAC
src
MAC
dst
Eth
type
1. Packet counter
2. Byte counter
IP src IP dst IP ToS sport dport
More match field: http://ryu.readthedocs.org/en/latest/ofproto_v1_3_ref.html?highlight=match#ryu.ofproto.ofproto_v1_3_parser.OFPMatch

7. Flow Table
Table id 0
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics

8. Multiple Flow Tables
Table id 0
Table id 1
Table id 2
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
Rule Action Statistics
SDN Controller
OpenFlow-enabled Network Device
OpenFlow Protocol

9. OpenFlow Controller and switch workflow
HANDSHAKE_DISPATCHER
CONFIG_DISPATCHER
MAIN_DISPATCHER
DEAD_DISPATCHER
如果發⽣生連線中斷
Ryu Controller 的4種狀態

10. The messages between Controller and switch
❖ Controller-to-Switch Messages (Controller->Switch)
❖ Features
❖ Modify-State
❖ Packet-out
❖ Configuration, Read-State, Barrier, Role-Request, Asynchronous-Configuration
❖ Asynchronous Messages (Switch->Controller)
❖ Packet-In
❖ Flow Removed
❖ Port Status
❖ Error
❖ Symmetric Messages (Switch<->Controller)
❖ Hello
❖ Echo Request / Reply
❖ Experimenter
OpenFlow Controller
OpenFlow Protocol
Flow Table
OpenFlow Switch

11. Outline
❖ OpenFlow Overview
❖ Introduction to Ryu application development
❖ The OpenFlow API in Ryu
❖ Demo

12. What is Ryu
❖ Ryu is a component-based software defined networking
framework.
❖ Fully written in Python
❖ Ryu supports various protocols for managing network
devices
• OpenFlow 1.0, 1.2, 1.3, 1.4, Netconf, OF-config
❖ License: Apache 2.0

13. Ryu Resources
❖ Official site:
• http://osrg.github.io/ryu/
❖ Mailing list:
• https://lists.sourceforge.net/lists/listinfo/ryu-devel
❖ API Documentation:
• http://ryu.readthedocs.org/en/latest/
❖ RyuBook Tutorial (Chinese):
• http://osrg.github.io/ryu-book/zh_tw/html/

14. Installation

15. Installation
❖ On Official site…
❖ Notice: Before you Install, check the dependencies first.

16. Automatic Installation Script
❖ On Ubuntu 12.04+, two-line command can install Ryu
3.14
❖ This helper script which should get all dependencies
and download, build, and install Ryu.
Fork me on: https://github.com/John-Lin/ryuInstallHelper

17. To install dependencies in Ubuntu

18. How to use
❖ Run your application
❖ Run your application with debug output

19. Application programming model
1. ⼀一個 OpenFlow message
可以視為⼀一個 event
2. 利⽤用 decorators 來接 event
3. 定義事件處理器(Event
Handler)
Custom library
事件
Come from OpenFlow switches:
• Asynchronous messages
• Switch reply messages

20. Outline
❖ OpenFlow Overview
❖ Introduction to Ryu application development
❖ The OpenFlow API in Ryu
❖ Demo

21. OpenFlow protocol API
Type Message Name Ryu OpenFlow API
Controller to
Switch
Messages
Features OFPFeaturesRequest / OFPSwitchFeatures
Configuration OFPSetConfig
Modify-State OFPFlowMod
Read-State
OFPFlowStatsRequest / OFPFlowStatsReply
OFPPortStatsRequest / OFPPortStatsReply
Packet-out OFPPacketOut
Barrier OFPBarrierRequest / OFPBarrierReply
Role-Request OFPRoleRequest / OFPRoleReply
Asynchronous-Configuration OFPSetAsync / OFPGetAsyncReply
Asynchronous
Messages
Packet-In OFPPacketIn
Flow Removed OFPFlowRemoved
Port Status OFPPortStatus
Error OFPErrorMsg
Symmetric
Messages
Hello OFPHello
Echo Request / Reply OFPEchoRequest / OFPEchoReply
Experimenter OFPExperimenter

22. OpenFlow Controller and switch workflow

23. Code Template in Ryu
❖ Usually in the
Class
❖ Inheritance
❖ Decorators: @
❖ 接取 OpenFlow
message event
❖ Event Handler
❖ 接到event 後要
做的事定義在
method裡
Initial method
Utility
Methods
Snort
Library Plugin
Controller to
Switch Messages
Asynchronous
Messages

24. Outline
❖ OpenFlow Overview
❖ Introduction to Ryu application development
❖ The OpenFlow API in Ryu
❖ Demo

25. DEMO
SDN
Controller
❖ Hub application
Flow table
1 2 3 4 priority=10, match=icmp, action=ALL
priority=0, actions=CONTROLLER:65535
Host A Host B
❖ 利⽤用 Flow Table match ICMP 封包將其 Flood，其他協定
封包導到Controller 做處理
❖ https://github.com/John-Lin/SDNDS-TW