1. Introductions of SDN in NS-3
张庆安
19/5/2016

2. Motivations for ns-3 project
Develop an extensible simulation environment for networking research
1) a tool aligned with the experimentation needs of modern networking research
2) a tool that elevates the technical rigor of network simulation practice
3) an open-source project that encourages community contribution, peer review, and long-term maintenance and validation of the software

3. Network performance evaluation options
ns-3 enables researchers to more easily move between simulations, test beds, and experiments
ns-3 core
Direct Code
Execution
Emulation
modes
Test and evaluation options
Pure
simulation
Simulation
cradles
Virtual/Physical
test beds
Field
experiments
Live
networks
Increasing realism
Increasing complexity

4. ns history 1990 2000 2010 1988: REAL (Keshav) regular releases
1990s: ns-1
1996: ns-2
: DARPA VINT
: DARPA SAMAN, NSF CONSER
2006: NSF CISE CRI Awards
Inputs: yans,
GTNetS, ns-2
ns-3 core development ( )
June 2008: ns-3.1
May 2015: ns-3.23

5. Relationship to ns-2
ns-3 is a new simulator, without backward compatibility
Similarities to ns-2:
C++ software core
GNU GPLv2 licensing
ported ns-2 models: random variables, error models, OLSR, Calendar Queue scheduler
Differences:
Python scripting (or C++ programs) replaces OTcl
most of the core rewritten
new animators, configuration tools, etc. are in work
ns-2 is no longer actively maintained/supported

6. Acknowledgment of support

7. Software overview

8. ns-3 main website
Project home:

9. Software overview
ns-3 is written in C++, with bindings available for Python
simulation programs are C++ executables or Python programs
~350,000 lines of C++ (estimate based on cloc source code analysis)
ns-3 is a GNU GPLv2-licensed project
ns-3 is mainly supported for Linux, OS X, and FreeBSD
Windows Visual Studio port available
ns-3 is not backwards-compatible with ns-2

10. Discrete-event simulation basics
Simulation time moves in discrete jumps from event to event
C++ functions schedule events to occur at specific simulation times
A simulation scheduler orders the event execution
Simulation::Run() executes a single-threaded event list
Simulation stops at specific time or when events end

11. Simulator and Schedulers
The Simulator class holds a scheduler, and provides the API to schedule events, start, stop, and cleanup memory
Several scheduler data structures (calendar, heap, list, map) are possible
"RealTime" simulation implementation aligns the simulation time to wall-clock time
two policies (hard and soft limit) available when the simulation and real time diverge

12. Nodes and Devices
ns-3

13. Node basics
A Node is a shell of a computer to which applications, stacks, and NICs are added
Application
Application
Application
“DTN”
ns-3

14. NetDevices and Channels
NetDevices are strongly bound to Channels of a matching type
ns-3 Spectrum models relax this assumption
Nodes are architected for multiple interfaces
WifiChannel
WifiNetDevice
ns-3

15. The basic ns-3 architecture
Application
Application
Application
Application
Sockets-like
API
Protocol
stack
Protocol
stack
Packet(s)‏
Node
Node
NetDevice
NetDevice
NetDevice
Channel
NetDevice
Channel
ns-3

16. Current models flow-monitor BRITE topology- read utilities stats
config-
store
netanim
visualizer
bridge
csma
emu
point-to-
point
spectrum
tap-bridge
virtual-
net-device
wifi
lte
wimax
devices
uan
mesh
lr-wpan
nix-vector-
routing
aodv
dsdv
olsr
click
protocols
openflow
Node class
NetDevice ABC
Address types
(Ipv4, MAC, etc.)
Queues
Socket ABC
Ipv4 ABCs
Packet sockets
applications
internet
(IPv4/v6)
propagation
mobility
mpi
energy
Packets
Packet Tags
Packet Headers
Pcap/ascii file writing
Smart pointers
Dynamic types
Attributes
Callbacks
Tracing
Logging
Random Variables
Events
Scheduler
Time arithmetic
network
core 16

17. The ns-3 build tool, called 'waf', can be used to run programs
ns-3 programs
ns-3 programs are C++ executables that link the needed shared libraries
or Python programs that import the needed modules
The ns-3 build tool, called 'waf', can be used to run programs
waf will place headers, object files, libraries, and executables in a 'build' directory

18. Structure of an ns-3 program
int main (int argc, char *argv[]) { // Set default attribute values // Parse command-line arguments // Configure the topology; nodes, channels, devices, mobility // Add (Internet) stack to nodes // Configure IP addressing and routing // Add and configure applications // Configure tracing // Run simulation }
ns-3

19. Visualization

20. Pyviz screenshot (Graphviz layout)

21. Pyviz and FlowMonitor
src/flow-monitor/examples/wifi-olsr-flowmon.py

22. NetAnim
"NetAnim" by George Riley and John Abraham
pyviz

23. SDN Overview
作为网络核心的路由器,承载功能不断扩展,如分组过滤、区分服务、多播、服务质量(QoS)、流量工程等,路由器最初定义的“哑的、简单的”数据转发单元已经变得臃肿不堪.

24. Top Five Ethernet Switch Vendors

25. SDS, SDDC, SDCar… Software Defined X, SDX
频带、空中接口协议和功能可通过软件下载和更新来升级，而不用完全更换硬件。
用普通话说就是软件独立于硬件，让硬件标准化，软件平台化，信息中心化。
SDS, SDDC, SDCar…

26. SDN (Software Defined Network)
SDN originates from OpenFlow
OpenFlow is a fish in the sea of SDN
SDN is an architecture, ideology.
当前各种SDN的标准化组织

27. From device supplier programmable turn to user programmable
Three Targets by SDN
From device supplier programmable turn to user programmable
From device programmable turn to network programmable
Integrated network with IT applications

28. OpenFlow User Controller Switch Applications Control software Openflow
Protocol
OpenFlow仅仅是SDN中控制器控制转发面设备的协议而已，控制器本身的架构、网络拓扑算法、运行环境、编程工具，以及和上层应用的集成技术都是SDN的一部分，并且是架构上更为核心的部分。
Controller
Switch

29. OpenFlow

30. SDN in NS-3 Circuit/Packet Hybrid Data Center Network Simulator
Topology aware
Circuit Schedule Algorithms
Routing …
RYU Controller
RYU由日本NTT公司负责设计研发的一款开源SDN控制器，同POX一样，也是完全由Python语言实现，使用者可以在Python语言的基础上实现自己的应用，采用Apache License开源协议标准，目前支持协议OpenFlow1.0、1.2、1.3，同时支持在OpenStack上的部署应用。提供逻辑上的集中化管理，通过提供API使网络管理更加方便。
POX是由斯坦福使用Python语言开发的基于OpenFlow的一种控制器，是NOX的兄弟，它具有能将交换机送上来的协议包交给指定软件模块的功能。
Data Plane
Circuit/Packet Hybrid Data Center Network Simulator

31. Realize and simulate the delay of different circuits’ switch
Data Plane
Realize and simulate the delay of different circuits’ switch
Layer2P2MPChannel Class
m_delay传输延时
m_reconfigureDalay 链路切换延时
m_src源节点， m_dst目的端网卡集合
如果m_mask包含多个数据，则表示有多个网卡接收该channel发送的数据，即表示物理层的组播

32. Control Plane Support Openflow 1.0 set_topology() get_topology()
update_topology()
set_flowtable()
get_flowstatus()
为应用提供编程接口

33. Application Plane
Topology Aware
Route Computing
Traffic Demand Estimation
Circuit Schedule Algorithms
Reconfigure Circuit/Flow Table

34. NS3 is discrete-event simulator and written by C++ SDN≠Openflow
Summary
NS3≠NS2
NS3 is discrete-event simulator and written by C++
SDN≠Openflow
Architecture of Openflow
Application plane
Control plane
Data plane
Hybrid Data Center Network Simulator

35. Questions？