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Ns Tutorial

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... old mom: How are you doing?' Class Kid -superclass Mom ... puts '$age_ years old kid: What's up, dude?' set mom [new Mom] $mom set age_ 45. set kid [new Kid] ... – PowerPoint PPT presentation

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Title: Ns Tutorial

1
Ns Tutorial

Alhussein A. Abouzeid
Elect. Eng. Dept./U. of Washington
hussein_at_ee.washington.edu
Parts of this educational presentation use
examples available from http//www.isi.edu/nsnam/n
s/ns-documentation.html

2
Tutorial Goals

Using NS (the Otcl world)
Complete examples of its usage
Wired
Wireless
Extending NS (the C world)
Implementing new functionality

3
Schedule

Day 1 Wired simulations
Fundamentals
Supporting tools
Day 2 Wireless version of Day 1
Day 3 Extending ns capability
ns internals
Extending ns
Lab Assignments

4
Overview

What is ns? (the evolution)
Status of the code
Resources
Documentation
Remark!

5
What is ns?

A discrete event, packet-level simulator
Targeted at networking research
Supports the simulation of
intserv/diffserv, Multicast, Transport,
Applications, Wireless (fixed, mobile, satellite)
REAL variant (1989)?DARPA (LBL, Xerox PARC, UCB,
and USC/ISI) (1995)
Currently DARPA NSF collaboration with
researchers ACIRI, UCB Daedelus, CMU, Sun
Microsystems, NORTEL, Cisco, Me!

6
Status

ns-2
100K lines of C
70K lines of OTcl
50K lines of test suite, examples, docs
Platforms
Most UNIX and UNIX-like systems (FreeBSD, Linux,
Sun Solaris)
Window 95/98/NT (rocky)
(Emulation only for FreeBSD for now)

7
Resources

http//www.isi.edu/nsnam/ns
Installed on all machines in High Throughput Lab
(EE/CSE 365)
add to .cshrc
setenv TCL_LIBRARY /condor/ns-allinone-2.1b7a/tcl8
.3.2
ns-users_at_isi.edu
ns-users-request_at_isi.edu
subscribe ns-users in body
Archive http//www.isi.edu/nsnam/ns

8
Documentation

Tcl (Tool Command Language)
http//dev.scriptics.com/scripting
OTcl (MIT Object Tcl)
otcl/doc/tutorial.html (in distribution)
ns manual
Included in distribution ns/doc
http//www.isi.edu/salehi/ns_doc.ps.gz

9
Remember!

A simulator model of a real-world system is
necessarily a simplification. For example, in
simulating TCP
No SYN/FIN
Equal size segments
No variable window advertisement
Bugs Users of ns are responsible for verifying
for themselves that their simulations are not
invalidated by bugs.

10
Day 1 Schedule

Architecture
Basic Tcl/Otcl commands
Elements of an ns-2 simulation
Create the event scheduler
Turn on tracing
Create network
Setup routing
Insert errors
Create transport connection
Create traffic
Transmit application-level data
Example Multicast routing
nam Visualization

11
Architecture Object-Oriented

C for data
Per packet action
OTcl for control
Periodic or triggered action
Modularity (), re-usability(), scalability()
Speed(-), memory(-)

12
OTcl and C The Duality
Pure OTcl objects
Pure C objects
C/OTcl split objects
C
OTcl
ns
13
Script in interactive mode

linux21 ns
set ns new Simulator
_o3
ns at 1 puts \Hello World!\
1
ns at 1.5 exit
2
ns run
Hello World!
linux21

14
A script in batch mode

simple.tcl
set ns new Simulator
ns at 1 puts \Hello World!\
ns at 1.5 exit
ns run
linux21 ns simple.tcl
Hello World!
linux21

15
Basic Tcl

set a 43
set b 27
proc test a b
set c expr a b
set d expr expr a - b c
for set k 0 k lt 10 incr k
if k lt 5
puts k lt 5, pow expr pow(d, k)
else
puts k gt 5, mod expr d k
test 43 27

16
Basic OTcl

Class Mom
Mom instproc greet
self instvar age_
puts age_ years old mom How are you doing?
Class Kid -superclass Mom
Kid instproc greet
self instvar age_
puts age_ years old kid Whats up, dude?

set mom new Mom
mom set age_ 45
set kid new Kid
kid set age_ 15
mom greet
kid greet

17
Elements of ns-2 Simulation

Create the event scheduler
Turn on tracing
Create network
Setup routing
Insert errors
Create transport connection
Create traffic
Transmit application-level data

18
Creating Event Scheduler

Create event scheduler
set ns new Simulator
Schedule events
ns at lttimegt lteventgt
lteventgt any legitimate ns/tcl commands
Start scheduler
ns run

19
Tracing

Trace packets on all links
ns trace-all open test.out w
lteventgt lttimegt ltfromgt lttogt ltpktgt ltsizegt -- ltfidgt
ltsrcgt ltdstgt ltseqgt ltattrgt
1 0 2 cbr 210 ------- 0 0.0 3.1 0 0
- 1 0 2 cbr 210 ------- 0 0.0 3.1 0 0
r 1.00234 0 2 cbr 210 ------- 0 0.0 3.1 0 0
Trace packets on all links in nam format
ns namtrace-all open test.nam w
Must appear immediately after creating scheduler

20
Tracing

Turn on tracing on specific links
ns trace-queue n0 n1
ns namtrace-queue n0 n1

21
Creating Network

Nodes
set n0 ns node
set n1 ns node
Links and queuing
ns duplex-link n0 n1 ltbandwidthgt ltdelaygt
ltqueue_typegt
ltqueue_typegt DropTail, RED, CBQ, FQ, SFQ, DRR

22
Creating Network LAN

LAN
ns make-lan ltnode_listgt ltbandwidthgt ltdelaygt
ltll_typegt ltifq_typegt ltmac_typegt ltchannel_typegt
ltll_typegt LL
ltifq_typegt Queue/DropTail,
ltmac_typegt MAC/802_3
ltchannel_typegt Channel

23
Inserting Packet Errors