1. Modeling & Analysis Mathematical Modeling: Simulation:
probability theory
queuing theory
application to network models
Simulation:
topology models
traffic models
dynamic models/failure models
protocol models

2. Simulation tools VINT (Virtual InterNet Testbed) & NS-2:
[USC/ISI, UCB,LBL,Xerox]
network simulator (NS), network animator (NAM)
library of protocols:
TCP variants
multicast/unicast routing
routing in ad-hoc networks
real-time protocols (RTP)
…. Other channel/protocol
models & test-suites
extensible framework (Tcl/tk & C++)

3. GlomoSim (QualNet): UCLA, parsec simulator
OPNET:
commercial simulator
strength in wireless channel modeling
GlomoSim (QualNet): UCLA, parsec simulator
ONE (DTN sim), SUMO (vehicular mobility), OMNET++,... (more later)
Research resources:
ACM & IEEE journals and conferences
SIGCOMM, INFOCOM, Transactions on Networking (TON), MobiCom
IEEE Computer, ACM Communications magazine

4. Network Simulation (NS)
One tool to simulation network protocols for the Internet is the network simulator (NS)
The simulation environment needs to be set-up carefully to produce meaningful results
The simulation set-up is called ‘simulation scenario’

5. Simulation Scenarios
In general, a simulation scenario consists of three different main components (or dimensions)
Routed Topology
Connections, Traffic and Agents/end-host protocols
External events and Failures

6. Routed Topology Defines the number of nodes and their connectivity
Defines the links connecting the nodes, their bandwidth, delay, queuing discipline and other characteristics
Defines the routing protocols running in the nodes in terms of unicast and multicast routing
Can use topology generators (e.g., GT-ITM)

7. Connections, Traffic and Agents
Agents are end-host protocols, such as TCP, ftp, Telnet, UDP.. etc.
Traffic source can be: (uses a traffic model)
constant bit rate (CBR) at rate R
with distribution (Poisson or Pareto)
trace driven
Connection definition includes spatial distribution of connections (TCP sender/receiver, or group members)

8. External events and Failures
External events include the temporal distribution of connections:
start and end of TCP connections
join/leave patterns for multicast group members
Failures include link failures, packet loss patterns and congestion patterns and may follow a failure model or distribution
Events may also include movement patterns of mobile hosts

9. The network simulator (NS)
It is a packet-level discrete-event simulator
The simulation engine is written in C++ and mainly handles the event-queue and per packet processing (such as TCP and forwarding caches)
Most protocols (such as unicast/multicsat) routing protocols are implemented in Otcl (Object Tcl)
Check the vint project catarina.usc.edu/vint, and follow the on-line step-by-step tutorial

10. Getting Started Download the ns from: Install ns in your system
Tcl/tk, otcl, tclcl, ns
Install ns in your system
Binary release is provided for windows 9x/NT
NS-allinone package is strongly recommended
Download nam if visualization is needed
Included in ns-allinone package
Get help from
check the mailing lists on the ns web page

11. What is ns otcl: Object-oriented support tclcl: C++ and otcl linkage
Event
Scheduler
ns-2
tclcl
Network
Component
otcl
tcl8.0
otcl: Object-oriented support
tclcl: C++ and otcl linkage
Discrete event scheduler
Data network (the Internet) components

12. Internals Discrete Event Scheduler Network Topology Routing Transport
Application
Packet Flow

13. Discrete Event Scheduler
time_, uid_, next_, handler_
head_ ->
head_ ->
handler_ -> handle()
insert
time_, uid_, next_, handler_

14. Network Topology - Node
Addr Classifier
Port Classifier
classifier_
dmux_
entry_
Node entry
Unicast Node
Multicast Classifier
classifier_
dmux_
entry_
Node entry
Multicast Node
multiclassifier_

15. Network Topology - Link
enqT_
queue_
deqT_
drophead_
drpT_
link_
ttl_
n1 entry_
head_

16. Routing n0 n1 1 Addr Classifier Port Classifier classifier_ dmux_
entry_
Node entry
enqT_
queue_
deqT_
drophead_
drpT_
link_
ttl_
n1 entry_
head_ 1

17. Routing (cont.) n0 n1 1 1 Addr Classifier Port Classifier classifier_
dmux_
entry_
Addr Classifier
Port Classifier
classifier_
dmux_
entry_ 1 1
Link n0-n1
Link n1-n0

18. Transport n0 n1 1 1 Port Classifier Port Classifier dst_=1.0 dst_=0.0
Addr Classifier
Agent/TCP
Addr Classifier
Agent/TCPSink
agents_
agents_ 1 1
dmux_
dmux_
Link n0-n1
entry_
entry_
classifier_
classifier_
Link n1-n0

19. Application n0 n1 1 1 Port Classifier Application/FTP Port Classifier
dst_=1.0
dst_=0.0
Addr Classifier
Agent/TCP
Addr Classifier
Agent/TCPSink
agents_
agents_ 1 1
dmux_
dmux_
Link n0-n1
entry_
entry_
classifier_
classifier_
Link n1-n0

20. Packet Flow n0 n1 1 1 Port Classifier Application/FTP Port Classifier
dst_=1.0
dst_=0.0
Addr Classifier
Agent/TCP
Addr Classifier
Agent/TCPSink 1 1
Link n0-n1
entry_
entry_
Link n1-n0

21. NS\VINT web pages\tutorial:

22. The ONE (Opportunistic Network Environment) Simulator

23. * Ari Keränen, Jörg Ott and Teemu Kärkkäinen: The ONE Simulator for DTN Protocol Evaluation. SIMUTools'09: 2nd
International Conference on Simulation Tools and Techniques. Rome, March 2009.

25. DTN Protocols Supported
Direct Delivery: single-copy routing protocol
a node carries messages until it meets its final destination
First Contact: single-copy routing protocol,
a node forwards the message to the first node they encounter, which results in a “random walk” search for the destination node
Spray-and-Wait: n-copy routing protocol, limits number of copies
distributes (“sprays”) copies to contacts until number of copies is exhausted.
Three routing protocols perform variants of flooding:
Epidemic replicates messages to all encountered peers
PRoPHET estimates the node with highest “likelihood” of delivering the message based on node encounter history.
MaxProp floods the messages but explicitly clears them once a copy gets delivered to the destination. Sends messages based on hop counts and message delivery probabilities based on previous encounters.
Routing capabilities of simulators such as ns-2 or dtnsim2 can also be used in conjunction with ONE.
Others: Social-based forwarding: bubble-rap, simbet, profile-cast, etc.

26. Mobility Models Supported
Random Walk (RW) and Random Waypoint (RWP)
these models are popular to their simplicity
they have various known shortcomings
To better model real-world mobility, map-based mobility (MBM) constrains node movement to predefined paths and routes derived from real map data
Further realism added by the Working Day Movement (WDM) model, that attempts to model typical human movement patterns during working days

29. CORSIM (Corridor Traffic Simulator)
Simulates vehicles on highways/streets
Micro-level traffic simulator
Simulates intersections, traffic lights, turns, etc.
Simulates various types of cars (trucks, regular)
Used mainly in transportation literature (and recently for vehicular networks)
Does not incorporate communication or protocols
Developed through FHWA (federal highway administration)
Need to buy license

30. CORSIM

31. SUMO: Simulation of Urban Mobility
Vehicular mobility simulation
Takes input from maps, including open street maps (OSM)
Output can interface to protocols through other simulators (e.g., OMNET++)
* Michael Behrisch, Laura Bieker, Jakob Erdmann, Daniel Krajzewicz, “SUMO – Simulation of Urban MObility
An Overview”, SIMUL 2011 : The Third International Conference on Advances in System Simulation, 2011

34. En Route Framework
Roozbeh Ketabi, Babak Alipour, Ahmed Helmy, “En Route: Towards Vehicular Mobility Scenario
Generation at Scale”, IEEE INFOCOM – SmartCity, May 2017 (to appear).

36. Simulation Experiment: Vehicular Simulation using SUMO
1- install SUMO and gett acquainted with it
Use provided links for installation and initial experimentation
Run Cologne scenario for 2 hours
2- Use Open Street Maps (OSM) to get the map of Gainesville. Use built-in tools to generate traffic (random).
3- Perform measurement and compile graphing code to analyze the outputs. This way you are involved more with the outputs. Compare Cologne vs random Gainesville or random Cologne on one or two metrics.
4- (open ended, bonus points!) Experiment with VEINS framework and Networking simulators that run on top of SUMO  (uses OMNet++). Share your experience!

37. SUMO Links and Resources
SUMO main page (link to download for windows is here too):
SUMO wiki: Tutorials page (very helpful):
scenarios:
Cologne scenario:
Cologne scenario dl link from sourceforge:
Documentation for SUMO program:
Doc. for NetConvert (used for converting OSM to SUMO maps):
Doc. for DuaRouter:
OSM Web wizard (optional use as we used both this and querying OSM with other means):