The rd NS v Sim ulator W orkshop br ought to you by - - PDF document

SLIDE 1 The rd NS v Sim ulator W

• rkshop

br

• ught

to you by Kevin F all La wrence Berk eley National Lab

• ratory

kfal le elblgov httpwwwnr ge elblgovkfal l AND Kannan V aradhan formerly at USCISI kannanc atarinausce du httpwwwisie dukannan August

SLIDE 2 Audience and Outline

• Audience
• net

w

• rk

researc hers

• educators
• dev

elop ers

• T
• pics

for to da y

• VINT

pro ject goals and status Kevin

• arc

hitecture plus some history KevinKannan

• v

erview

• f

ma jor comp

• nen

ts Kevin

• pro

jectco de status Kevin

• details
• f

ma jor comp

• nen

ts Kevin

• em

ulation facilit y Kevin

• COTcl

link age and sim ulation debugging Kannan

• scenario

generation and sessionlev el supp

• rt

Kannan

• m

ulticast and reliable m ulticast Kannan

• a

complex link CBQ Kevin

• p

erformance issues Kannan

• discussion

and futures Ev ery

• ne

rd NSv W

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SLIDE 3 NSv Arc hitecture

• Ob

jectorien ted structure

• ev
• lution

from NSv C with regular Tcl

• b

jects implemen ted in C and OTcl

• OTcl
• b

jectorien ted extension to Tcl from Da vid W etherall at MITLCS for V uSystem no w supp

• rted

b y UCB Mash group

• Con

trolData separation

• con

trol

• p

erations in OTcl

• data

pass through C

• b

jects for sp eed

• Mo

dular approac h

• negrain
• b

ject decomp

• sition
• p
• sitives

comp

• sible

reusable

• negatives

m ust plum b in OTcl dev elop er m ust b e comfortable with b

• th

en vironmen ts to

• ls

fairly steep learning curv e rd NSv W

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SLIDE 4 Dev elopmen t Status

• sim

ulator co de basis for VINT Pro ject

• ish

p eople activ ely con tributing to the co de base

• con

tributions from Xero x P AR C USCISI UCB LBNL

• Some

appro ximate n um b ers

• K

lines

• f

C co de

• K

lines

• f

OTcl supp

• rt

co de

• K

lines

• f

test suites examples

• K

lines

• f

do cumen tation

• Users

w e kno w ab

• ut
• univ

ersities

• companies
• US

go v ernmen t sites

• See

main VINT and NS w eb pages at httpnetwebusceduvint httpwwwmashcsberkeleyeduns nshtm l

• Op

en mailing lists

• nsusersmashcsb

erk eley edu

• nsannouncemashcsb

erk eley edu

• T
• subscrib

e

• ma

jordomomashcsb erk eley edu rd NSv W

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SLIDE 5 Directory Structure

• common

directory shared b et w een MASH UCB and VINT pro jects

Tcl

conf ... WORK common vint doc ns-2 nam lib test ex

bin

tcl www

rd NSv W

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SLIDE 6 Class Hierarc h y

• T
• plev

el classes implemen t simple abstractions

NewReno Replicator

AddrClassifier

Agent/Message/Prober

McastClassifier

Queue Classifier

Agent/Message

Delay Agent/TCP TclObject Connector

Shared with MASH Project:

NsObject Trace/Drop Trace/Hop Trace RED Agent Trace/Enq ... ... Trace/Deq Reno DropTail

rd NSv W

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SLIDE 7 Example a no de

• No

de a collection

• f

agents and classiers

• Agen

ts usually proto col endp

• in

ts and related

• b

jects

• Classiers

pac k et dem ultiplexers

Agent

Port Classifier Local Addr

Link Link

Classifier Addr

Node

Node.entry

Agent Agent

• Note

that the no de routes to itself

• r

to do wnstream links rd NSv W

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SLIDE 8 Example a link

• k

eeps trac k

• f

from and to No de

• b

jects

• generally

encapsulates a queue dela y and p

• ssibly

ttl c hec k er

Queue split classes (OTcl class) Link Delay

• Man

y more complex

• b

jects built from this base rd NSv W

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SLIDE 9 Example routers

• routers

unicast and m ulticast b y plum bing

Node ... ... Node

Node.entry

Link Link Link

• m

ulticast router adds additional classiers and replicators

• Replicators

dem uxers with m ultiple fanout

Addr Replicator Replicator Addr Classifier Classifier unicast? Mcast Classifier

MulticastNode

multicast?

... ...

(S1, G1) (S2, G2) (S3, G3)

Link Link

Node.entry

Link

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SLIDE 10 OTcl Basics

• See

the page at ftpftptnslcsmitedupubotcl

• b

ject

• rien

ted extension to tcl

• classes

are

• b

jects with supp

• rt

for inheritance

• Analogs

to C

• C

has single class decl

• OTcl

attac hes metho ds to

• b

ject

• r

class

• C

constructordestructor

• OTcl

initdestro y metho ds

• this
• self
• OTcl

metho ds alw a ys virtual

• C

shado w ed metho ds called explicitly with scop e

• p

erator

• OTcl

metho ds com bined implicitly with self next

• C

static v ariables

• OTcl

class v ariables

• m

ultiple inheritance is supp

• rted
• F
• r

use with tcl see httpwwwmashcsberkeleyedudist rd NSv W

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SLIDE 11 OTcl Basics con td

• use

instvar and instpr

• c

to deneaccess mem b er functions and v ariables

• Example

Class Counter Counter instproc init fg f self instvar cnt set cnt

• g

Counter instproc bump fg f self instvar cnt incr cnt g Counter instproc val fg f self instvar cnt return cnt g Counter c c val

• c

bump c val

• rd

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SLIDE 12 COTcl Split Ob jects

• Split
• b

jects implemen t metho ds in either language

• new

and delete set c new Counter c val

• c

bump c val

• delete

c

• Dene

instance v ariables in either C

• r

OTcl CounterCounter f bindcnt

• value
• value
• g

vs self set cnt

• bind

simply uses Tcl T r ac eV ar rd NSv W

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SLIDE 13 Example a simple sim ulation

• A

small but complete sim ulation script

• set

up no de top

• logy

and

• ne

bulkdata transfer TCP

• arrange

to trace the queue

• n

the rk link

• place

trace

• utput

in the le simpouttr

• Create

a simple four node topology

• s
• Mbms
• Mbms
• r
• k
• Mbms
• s

set stoptime

• set

ns new Simulator set nodes ns node set nodes ns node set noder ns node set nodek ns node ns duplexlink nodes noder Mb ms DropTail ns duplexlink nodes noder Mb ms DropTail ns duplexlink noder nodek Kb ms DropTail ns queuelimit noder nodek

• ns

queuelimit nodek noder

• set

tcp ns createconnection TCP nodes TCPSink nodek

• tcp

set window

• tcp

set packetSize

• Set

up FTP source set ftp tcp attachsource FTP set tf

• pen

simpouttr w ns tracequeue noder nodek tf ns at

• ftp

start ns at stoptime close tf puts simulation complete ns halt ns run rd NSv W

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SLIDE 14 Example a simple sim ulation con t

• The

trace le pro duced lo

• ks

lik e this

• tcp
• tcp
• tcp
• tcp
• tcp
• tcp
• tcp
• tcp
• tcp
• tcp
• tcp
• tcp
• d
• tcp
• tcp
• tcp
• tcp
• d
• tcp
• tcp
• tcp
• tcp
• d
• tcp
• tcp
• tcp
• tcp
• rd

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SLIDE 15 The Sim ulator

• Sim

ulator API is a set

• f

metho ds b elonging to a simulator

• b

ject

• Create

a sim ulator with set ns new Simulator

• What

this do es

• initialize

the pac k et format calls create packetformat

• create

a sc heduler defaults to using a calendar queue

• Sc

heduler

• handles

time timers and ev en ts pac k ets deferred executions A Ts

• SchedulerList
• link

edlist sc heduler

• SchedulerHeap
• heapbased

sc heduler

• SchedulerCalendar
• calendarqueue

sc heduler

• SchedulerRealTime
• realtime

for em ulation

• see

Reev es Complexit y Analyses

• f

Ev en t Set Algorithms The Computer Journal

• rd

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SLIDE 16 Using the sc heduler

• Sc

heduler API is through Sim ulator

• b

ject Simulator instproc now

• r

eturn sche dulers notion

• f

curr ent time Simulator instproc at args

• sche

dule exe cution

• f

c

• de

at sp e ci e d time Simulator instproc run args

• start

sche duler Simulator instproc halt

• stop

p ause the sche duler Simulator instproc createtrace type files src dst

• cr

e ate tr ac e

• bje

ct Simulator instproc createpacket fo rm at

• set

up the simula tors p acket format

• Example

MySim instproc begin

• set

ns new Simulator ns usescheduler Heap ns at

• self

completesim

• MySim

instproc completesim

• rd

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SLIDE 17 Sim ulator Timing

• eac

h top

• logy
• b

ject has a generic receiv e metho d NsObjectrecvPacket Handler h

• most
• b

jects ha v e single neigh b

• r

Connectortarget

• cutthr
• ugh

transfers send pac k et directly to neigh b

• r

without in v

• lving

sc heduler ConnectorsendPacket p f target recvp g

• sche

duling b arriers

• an

y p

• in

t that adv ances time in to future ie dela y elemen t

• need

in terob ject proto col to decouple timing

• barrier

tak es nonn ull Handler

• sc

hedule dela y and in v

• k

e handler

• n

completion

• example

queuedela y

• b

jects later rd NSv W

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SLIDE 18 Mathematical Supp

• rt
• Random

n um b er generation

• RNG

implemen ted in sim ulator should pro duce same results

• n

v arious platforms

• based
• n

S P ark and K Miller CA CM

• Oct
• supp
• rt

for m ultiple streams

• dieren

t seeding

• ptions
• Random

v ariables

• distributions

applied to RNG streams

• distributions

uniform exp

• nen

tial pareto constan t h yp er exp

• nen

tial

• In

tegrals

• appro

ximation

• f

in tegral b y discrete sums

• used

for a v erage queue size computations

• Samples
• collect

samples

• pro

vides mean v ariance sum and coun t rd NSv W

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SLIDE 19 P ac k ets

• pac

k ets are events ma y b e sc heduled to arriv e

• con

tain header section and sometimes data

• header

section is a cascade

• f

all inuse headers

• all

pac k ets con tain a c

• mmon

he ader

• pac

k et size

• used

to compute transmission time

• timestamp

t yp e uid in terface lab el for debugging and m ulticast routing

• new

proto col agen ts ma y need to dene new headers rd NSv W

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SLIDE 20 P ac k et Header F

• rmat

hdrlen_ ip header body tcp header body rtp header body trace header body next_

Packet

at compile time at compile time size determined at compile time size determined at compile time size determined size determined points to next packet in either free list or in a PacketQueue bits() accessdata() packet data Size determined at simulator config time, stored in hdrlen_

Figure

• A

P ac k et Ob ject

• header

con ten ts are constructed at sim ulator initialization time

• p

erformed b y create packetformat rd NSv W

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SLIDE 21 Applications

timeout

Application Agent

idle (resume), recv data send, sendmsg, sendto, connect, close, listen, attachApp

• Applic

ation a mo del

• f

an application usually a trac source

• has

an asso ciated agent whic h usually corresp

• nds

to a trans p

• rt

en tit y

• in

terface is somewhat lik e so ckets rd NSv W

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SLIDE 22 Sources and T rac Generation

• Applications

are

• f

t w

• t

yp es sour c es and tr ac gener ators

• Sources

are used to driv e stream transp

• rts

eg TCP

• T

rac generators are used to driv e connectionless transp

• rts

eg UDP

• Sources
• T

elnet

• sim

ulates c haracters t yp ed b y a user

• FTP
• bulk

data transfer

• T

rac Generators

• EXPOO
• exp
• nen

tial

• no

times sen t at xed rate

• POO
• pareto
• no

times sen t at xed rate

• CBR
• deterministic

rate

• T

racT race

• use

trace le con taining timelen pairs rd NSv W

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SLIDE 23 Sources

• class

ApplicationTelnet

• ma

y sp ecify interval parameter

• if

zero pic ks randomly among

• measured

in terarriv als TCPLIB

• if

nonzero uses scaled exp

• nen

tial for in terarriv als

• pac

k et size constan t but a v ailable via bind call

• Metho

ds

• start
• con

tin uous send

• stop
• stop

sending

• send

n

• send

n b ytes

• class

ApplicationFTP

• bulk

data sender used to driv e TCP

• implemen

ted en tirely in OTcl

• Metho

ds

• start
• con

tin uous send

• stop
• stop

sending

• send

n

• send

n b ytes

• produce

n

• send

n pac k ets

• producemore

n

• send

n more pac k ets rd NSv W

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SLIDE 24 T rac Generation

• generate

trac according to distributions

• r

traces

• generally

used to driv e CBR

• r

UDP transp

• rt

agen ts

• Exp
• nen

tial class ApplicationTrafficExponential

• exp
• nen

tially distributed

• no

times

• parameters
• n

time

• time

rate pac k et size

• what

these mean

• burst

for exp

• time

with mean

• n

time

• b

e silen t for exp

• time

with mean

• time
• while

bursting send at rate rate

• use

appropriate in terdeparture time giv en ratesize

• P

areto class ApplicationTrafficPareto

• pareto

distributed

• no

times

• man

y aggregated together can b e LRD

• parameters
• n

time

• time

rate shap e pac k et size

• what

these mean

• lik

e exp

• except

pareto using shap e parameter rd NSv W

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SLIDE 25 T raceBased T rac Generator

• generate

trac according to trace le

• t

w

• classes

Tracefile and ApplicationTrafficTrace

• trace

le uses small binary format

• rst

bit eld in terpac k et time microsecs

• second

bit eld pac k et size b ytes rd NSv W

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SLIDE 26 Agen ts

• A

gents usually a transp

• rt

proto col endp

• in

ten tit y but ma y also b e used for implemen ting routing proto cols

• Where

they t in

Agent

Port Classifier Local Addr

Link Link

Classifier Addr

Node

Node.entry

Agent Agent

• What

they pro vide

• a

lo cal and destination p

• rt

address

• functions

for helping to generatellin in pac k et elds

• a

base class supp

• rting

the application in terface rd NSv W

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SLIDE 27 Creating a new Agen t

• The

Agent class class Agent

• public

Connector

• public

Agentint pktType virtual Agent virtual void timeoutint tno virtual void sendmsgint nbytes const char flags

• virtual

void sendint nbytes

• sendmsgnbytes

virtual void sendtoint nbytes const char flags nsaddrt dst virtual void connectnsaddrt dst virtual void close virtual void listen virtual void attachAppApplication app virtual int! size

• return

size inline nsaddrt! addr

• return

addr protected int commandint argc const charconst argv void recvPacket Handler

• basic

tasks to create a new agen t

• decide

its inheritance structure

• create

the class and ll in the API virtual functions

• dene

OTcl link age functions later

• write

the necessary OTcl co de to access y

• ur

agen t

• hardest

part ma y b e understanding the OTclC in teraction fortunately

• m

uc h

• f

this is shielded from y

• u

if y

• u

so c ho

• se

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SLIDE 28 Example the Message Agen t

• pro

vides a v ery simple place to store a message

• P

ac k et header from messageh struct hdrmsg

• char

msg

• perfield

member functions

• char

msg

• return

msg

• int

maxmsg

• return

sizeofmsg

• OTcl

link age for class creation from messagecc static class MessageHeaderC la ss

• public

PacketHeaderC la ss

• public

MessageHeaderCl as s

• PacketHeaderCl

as s P ac ke tH ead er M es sa ge

• sizeofhdrmsg
• classmsghdr

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SLIDE 29 Example the Message Agen t con t

• The

class denition constructor and v ariable link age static class MessageClass

• public

TclClass

• public

MessageClass

• TclClassAgent

M es sa ge

• TclObject

createint const charconst

• return

new MessageAgent

• classmessage

class MessageAgent

• public

Agent

• public

MessageAgent int commandint argc const charconst argv void recvPacket Handler protected int

• ffmsg
• MessageAgentM

es sa ge Ag en t

• AgentPTMESSAG

E

• bindpacketSiz

e

• size

bindoffmsg

• ffmsg
• rd

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SLIDE 30 Example the Message Agen t con t

• Main

functions void MessageAgentr ec v Pa ck et

• pkt

Handler

• hdrmsg

mh

• hdrmsgpkt
• ac

ce ss

• f

f ms g

• process

packet

• int

MessageAgent co mm an d in t argc const charconst argv

• Tcl

tcl

• Tclinstance
• call

into interp if argc

• bj

send msgtext if strcmpargv

• send
• Packet

pkt

• allocpkt

hdrmsg mh

• hdrmsgpkt

a cc es s

• f

f ms g

• const

char s

• argv

int n

• strlens

if n

• mhmaxmsg
• tclresultm

es sa ge too big Packetfree pk t

• return

TCLERROR

• strcpymhmsg
• s

sendpkt

• return

TCLOK

• return

Agentcomman d ar gc

• argv
• for

inheritance

• rd

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SLIDE 31 CBR and UDP Agen t

• CBR

Agen t

• stands

for constan t bit rate not really used

• nly

this w a y

• nonconnectionorien

ted sending agen t

• sends

pac k ets at p erio dic in terv al

• r

quasip erio dically

• constan

tsize pac k ets

• UDP

Agen t

• deriv

ed from CBR agen t

• v

ery similar to CBR agen ts

• uses

TrafficGenerator class for pac k et sizestimes rd NSv W

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SLIDE 32 TCP Agen ts

• Tw
• categories
• new

a y and t w

• w

a y full TCP

• Onew

a y v arian ts

• f

TCP a v ailable

• Agen

tTCP

• a

taho e TCP sender

• Agen

tTCPReno

• a

Reno TCP sender

• Agen

tTCPNewReno

• Reno

with a mo dication

• Agen

tTCPSac k

• TCP

with selectiv e rep eat follo ws RF C

• Agen

tTCPV egas

• TCP

V egas

• Agen

tTCPF ac k

• Reno

TCP with forw ard ac kno wledge men t

• Agen

tTCPSession

• shared

congestion state wm ultiple connections

• Agen

tTCPIn t

• p

erconnection reliabilit y for use wSession

• Agen

tTCPRBP

• Reno

V egas with Rate Based P acing

• Agen

tTCPAsym

• TCP

mo ds for asymmetric c hannels

• Onew

a y TCP receiving agen ts curren tly supp

• rted

are

• Agen

tTCPSink

• ne

A CK p er pac k et

• Agen

tTCPSinkDelAc k

• congurable

dela y p er A CK

• Agen

tTCPSinkSac k

• selectiv

e A CK sink follo ws RF C

• Agen

tTCPSinkSac kDelAc k

• Sac

k with DelAc k

• Agen

tTCPSinkAsym

• sink

for Asym senders rd NSv W

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SLIDE 33 Tw

• W

a y TCP Agen ts

• Tw
• w

a y TCP agen ts b eta test

• Agen

tTCPF ullTcp

• pro

vides Reno functionalit y

• Agen

tTCPF ullTcpT aho e new

• Agen

tTCPF ullTcpSac k new

• Onew

a y and t w

• w

a y TCPs are not in terop erable rd NSv W

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SLIDE 34 Base TCP Agen ts

• TCP

T aho e TCPReno and TCPNewReno

• Common

features

• computations

all in pac k et units wcongurable pac k et size

• fast

retransmit

• slo

wstart and congestion a v

• idance
• dynamic

R TT estimation and R TX timeout assignmen t

• sim

ulated constan t receiv ers adv ertised windo w

• T

aho e TCP

• p

erform slo wstart

• n

an y loss R TO

• r

fast retransmit

• no

fast reco v ery

• Reno

TCP

• fast

r e c

• very

inate cw nd b y dup ac k coun t un til new A CK

• slo

wstart

• n

R TO

• n

fast retransmit cw nd

• cur

w in

• ssthr

esh

• cw

nd

• Newreno

TCP

• mo

dest mo dication to Reno TCP

• nly

exit fast reco v ery after A CK for highest segmen t arriv es

• helps

reduce stalling due to m ultiple pac k et drops in a windo w rd NSv W

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SLIDE 35 Other TCP Agen ts

• TCPSack

TCPFack and TCPVegas

• Selectiv

e A CK TCP

• SA

CK sim ulation based

• n

RF C

• A

CKs carry extra information indicating receiv ed segmen ts

• requires

SA CKa w are sink

• sender

a v

• ids

sending redundan t info

• default

to

• SA

CK blo c ks for using timestamps see RF C

• blo

c k con tains startend sequence n um b ers

• blo

c k con taining most recen tly receiv ed segmen t alw a ys presen t

• regular

A CK n um b er still giv es nal sa y

• F

ac k TCP

• forw

ard A CK TCP exp erimen tal see SIGCOMM

• use

SA CK info for estimate

• f

pac k ets in the net w

• rk
• v

erdamping algorithm to limit slo wstart

• v

ersho

• t
• ramp

do wn algorithm for transmission smo

• thing
• V

egas TCP

• con

tributed co de from T ed Kuo NC State Univ rd NSv W

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SLIDE 36 TCP Agen t P arameters

• Common

conguration parameters and defaults for TCP agen ts AgentTCP set maxburst

• max

pkts emitte d due to

• r

e cvd AgentTCP set maxcwnd

• max

b

• und
• n

c

• ngestion

window AgentTCP set syn false

• do

SYN exchange prior to data xfer AgentTCP set tcpipbasehdrsize

• size
• f

TCPIP hdr no

• pts

AgentTCP set timestamps false

• due

RF Cstyle time stamps AgentTCP set window

• max

b

• und
• n

window size AgentTCP set windowInit

• initialr

eset value

• f

cwnd AgentTCP set windowOption

• c
• ng

avoid algorithm

• standar

d AgentTCP set windowConstant

• use

d

• nly

when windowOption

• AgentTCP

set windowThresh

• use

d in c

• mputing

aver age d window AgentTCP set

• verhead
• adds

r andom time b etwe en sends AgentTCP set ecn

• TCP

should r e act to e cn bit AgentTCP set packetSize

• p

acket size use d by sender bytes AgentTCP set bugFix true

• se

e do cumentation AgentTCP set slowstartrestart true

• do

slowstart after id le p erio d AgentTCP set tcpTick

• timer

gr anularity in se c

• is

NONST AND ARD AgentTCP set maxrto

• b
• und
• n

R TO se c

• nds

AgentTCP set srttinit

• initial

value for smo

• the

d rtt est AgentTCP set rttvarinit

• initial

value for rtt var est AgentTCP set rtxcurinit

• initial

value for curr ent rtx timer AgentTCP set TSRTTBITS

• bits

after binary p

• int

for SR TT AgentTCP set TRTTVARBITS

• bits

after binary p

• int

for R TTV AR AgentTCP set rttvarexp

• exp
• nent
• f
• which

multiples rttvar

• Dynamic

v alues

• f

in terest AgentTCP set dupacks

• duplic

ate A CK c

• unter

AgentTCP set ack

• highest

A CK r e c eive d AgentTCP set cwnd

• c
• ngestion

window p ackets AgentTCP set awnd

• aver

age d cwnd exp erimental AgentTCP set ssthresh

• slowstat

thr eshold p ackets AgentTCP set rtt

• rtt

sample AgentTCP set srtt

• smo
• the

d aver age d rtt AgentTCP set rttvar

• me

an deviation

• f

rtt samples AgentTCP set backoff

• curr

ent R TO b acko factor AgentTCP set maxseq

• max

p acket se q numb er sent rd NSv W

• rkshop

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SLIDE 37 TCP Sink Agen ts

• Sinks

for

• new

a y TCP senders

• T

yp es

• standard

sinks dela y edA CK sinks SA CK sinks

• Standard

sinks

• generate
• ne

A CK p er pac k et receiv ed

• A

CK n um b er

• v

erloaded in sequence n um b er pac k et eld

• Dela

y edA CK sinks

• same

as standard but with v ariable dela y added b et w een A CKs

• time

to dela y A CKs sp ecied in seconds

• SA

CK sinks

• generates

additional information for SA CK capable sender

• congurable

maxSackBlocks parameter

• Asym

sinks

• A

CK pacing rd NSv W

• rkshop

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SLIDE 38 Tw

• W

a y TCP F ullTCP

• most

TCP

• b

jects are

• new

a y and require a sourcesink pair

• real

TCP can b e bidirectional

• sim

ultaneous t w

• w

a y data transfer alters TCP dynamics con siderably

• considered

b eta at this p

• in

t requesting feedbac k

• the

TCPFullTcp agen t

• follo

ws closely to Reno TCP implemen tation in

• BSD
• b

yteorien ted transfers

• t

w

• w

a y data supp

• rted
• most
• f

the connection establishmen tteardo wn

• symmetric
• nly
• ne

agen t t yp e used for b

• th

sides

• Dierences

from the real thing

• no

receiv ers adv ertised windo wp ersist mo de

• no

urgen t p

• in

ter

• no

MSL w ait

• no

RST segmen ts

• No

w supp

• rts

T aho e NewReno and Sac k v arian ts rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 39 F ullTCP P arameters

• P

arameters and defaults AgentTCPFullTcp set segsperack

• se

gs r e c eive d b efor e gener ating A CK AgentTCPFullTcp set segsize

• se

gment size MSS size for bulk xfers AgentTCPFullTcp set tcprexmtthresh

• dupA

CKs thr esh to trigger fast r exmt AgentTCPFullTcp set iss

• initial

send se quenc e numb er AgentTCPFullTcp set nodelay false

• disable

senderside Nagle algorithm AgentTCPFullTcp set dataonsyn false

• send

data

• n

initial SYN AgentTCPFullTcp set dupsegfix true

• avoid

fast rxt due to dup se gsacks AgentTCPFullTcp set dupackreset false

• r

eset dupA CK ctr

• n
• len

data se g s c

• ntaining

dup A CKs AgentTCPFullTcp set interval

• delaye

d A CK interval AgentTCPFullTcp set closeonempty false

• close

c

• nn

after send al l data AgentTCPFullTcp set tsoptionsize

• size
• f

rfc ts

• ption

bytes AgentTCPFullTcp set renofastrecov true

• c
• ngestion

window ination AgentTCPFullTcp set pipectrl false

• use

pip e mo del c

• ngestion

ctrl AgentTCPFullTcp set

• pencwndonpack

true

• incr

e ase cwnd

• n

p artial acks AgentTCPFullTcpNewre no set recovmaxburst

• maxburst

during r e c

• very

AgentTCPFullTcpSack set sackblocksize

• bytes

in a SA CK blo ck AgentTCPFullTcpSack set sackoptionsize

• bytes

in

• pt

hdr AgentTCPFullTcpSack set maxsackblocks

• max
• f

sack blks rd NSv W

• rkshop

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SLIDE 40 R TP and R TCP Agen ts

• R

TP

• Realtime

transp

• rt

proto col RF C

• implemen

ted as AgentCBRRTP

• b

ject

• sp

ecial R TP header con tains seq n um b er and srcID

• sends

data p erio dically similar to CBR sources

• resets

faster when mo ving from high to lo w rate

• R

TCP

• con

trol proto col for R TP

• implemen

ted as SessionRTP

• b

ject

• sends

at rate based

• n

n um b er

• f
• ther

senders

• rep
• rts

kno wn sources and stats rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 41 Other Simple Agen ts

• the

LossMonitor agen t

• monitors

arriv als

• f

pac k ets

• lo
• ks

for sequence n um b er holes

• pro

vides coun ters for

• nlost
• n

um b er

• f

holes in n um b er space

• npkts
• pac

k et arriv als

• bytes
• b

yte arriv als

• lastPktTime
• time
• f

last arriv al

• expected
• next

seq n um b er exp ected

• the

Message agen t

• v

ery simple agen t

• allo

ws for including text messages in pac k ets

• curren

tly limited to at most

• b

yte short messages rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 42 Connectors

• Conne

ctor simple inout top

• logy
• b

ject with drop target

• An

NsObject with

• nly

a single neighbor

• class

Connector

• public

NsObject

• public

Connector inline NsObject target

• return

target

• virtual

void dropPacket p protected int commandint argc const charconst argv void recvPacket Handler callback

• inline

void sendPacket p Handler h

• targetrecv

p

• h
• NsObject

target NsObject drop

• dest

for drops

• if

drop target undened dropp ed pac k ets are freed rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 43 In tro ducing Errors

• P

ac k et errors ma y b e in tro duced in to the top

• logy
• Err
• r

Mo dule

• collection
• f

error mo dels

• Err
• r

Mo del

• determines

t yp es

• f

errors

• Error

Module capabilities

• insert

classier for p ero w error con trol

• insert

m ultiple error mo dels

• collects

dropp ed pac k ets from eac h error mo del

• default

en try indicates where nonmatc hing trac go es

• Example

set lossylink ns link noder nodek set em new ErrorModule Fid set errmodel new ErrorModelPer io di c errmodel unit pkt errmodel set

• ffset
• errmodel

set period

• lossylink

errormodule em em insert errmodel em bind errmodel

• rd

NSv W

• rkshop

kfal le elblgov Slide

SLIDE 44 Error Mo dels

• Err
• r

Mo del a parameterized lossy connector can b e used as a base class for

• ther

loss mo dels

• drops

pac k et sets error bit

• r

ECN indication

• error

units pac k ets bits time

• base

v ersion is asso ciated with random v ariable

• r

p erio dic pa rameters set errmodel new ErrorModel errmodel unit pkt errmodel set rate

• errmodel

ranvar new RandomVariable U nif

• r

m

• if

drop target undened sen t to mo dule drop target

• Sp

ecialized Mo dels

• TwoState
• error

and errorfree Mark

• v

mo del

• MultiState
• arbitrary

state transitions in Tcl

• Periodic
• sin

usoidal p erio d phase burst length

• List
• sp

ecies individual pac k etsb ytes

• Select
• lik

e P erio dic but uses pac k et uids

• SRM
• lik

e Select but for SRM data

• nly
• Trace
• lik

e List but uses a le

• Mroute
• aects

certain t yp es

• f

mcast prune messages rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 45 Queue Managemen t and P ac k et Sc heduling

• buer

management ho w to hold and toss mark pac k ets

• p

acket sche duling what pac k ets get to depart when

• Buer

managemen t

• Droptail

FIF O

• Random

Early Detection RED

• P

ac k et sc heduling

• FIF

O

• CBQ

includes priorit y

• roundrobin
• Roundrobin

DRR

• V

arian ts

• f

F Q WF Q SF Q rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 46 Queue Handlers

• Dequeued

pac k ets are

• ften

sen t do wnstream to delays

• dela

ys usually cause t w

• actions
• the

pac k et is sc heduled to arriv e do wnstream at time t

• d
• the

queue b ecomes un blo c k ed at time t

• t

is transmit time d is prop dela y time

• so

dela ys represen t a commonlyo ccurring sche duling b arrier

• Queue

parameters Queue set limit

• max

p acket c

• unt

in queue Queue set blocked false

• queue

starts

• blo

cke d Queue set unblockonres um e true

• queue

is unblo cke d af ter r esume

• con

trol

• f

blo c king can b e useful for queue banks eg CBQ rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 47 Drop T ail and RED Queues

• DropT

ail Queues QueueDropTail class

• simple

FIF O droptail queues

• drop

from tail when

• ccupancy

reac hes qlim

• RED

Random Early Detection Queues QueueRED class

• active

buer managemen t tec hnique

• t

w

• thresholds

minth and maxth

• also

a maxim um probabilit y maxpr

• b
• compute

aver age queue

• ccupancy
• v

er time

• if

a v erage exceeds maxth

• r

qlim

• drop

a pac k et

• if

a v erage is under min th allo w pac k et to en ter queue

• b

et w een scale drop probabilit y linearly

• n
• maxpr
• b

rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 48 RED Queue P arameters

• bytes

do computations in b ytes instead

• f

pac k ets requires assignmen t

• f

a mean pac k et size estimate

• thresh
• min

thresh

• maxthresh
• max

thresh

• mean

pktsize

• used

for computing estimated link utilizations during idle p erio ds

• q

weight

• w

eigh t giv en to instan taneous queue

• ccupancy

for EWMA

• wait
• RED

should force a w ait b et w een drops

• linterm
• recipro

cal

• f

maxprob

• setbit
• mark

instead

• f

drop

• droptail
• drop

new pkt instead

• f

random

• ne

rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 49 T race and Monitoring Supp

• rt
• Tw
• main

items tr ac es and monitors

• T

races

• write

an en try for some ev en t

• ften

pac k et arriv alsdeparturesdrops

• TraceEnque
• a

pac k et arriv al usually at a queue

• TraceDeque
• a

pac k et departure usually at a queue

• TraceDrop
• pac

k et drop pac k et deliv ered to droptarget

• Monitors
• k

eep statistics ab

• ut

arriv alsdeparturesdrops and

• ws
• SnoopQueueOut
• n
• utput

collect a timesize sample pass pac k et

• n
• SnoopQueueDrop
• n

drop collect a timesize sample pass pac k et

• n
• SnoopQueueEDrop
• n

an early drop collect a timesize sampl e pass pac k et

• n
• QueueMonitor
• receiv

e and aggregate collected samples from sno

• p

ers

• QueueMonitorED
• queuemonitor

capable

• f

distinguish ing b et w een early and standard pac k et drops

• QueueMonitorEDFlowmon
• p

ero w statistics monitor manager

• QueueMonitorEDFlow
• p

ero w statistics con tainer rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 50 T race File F

• rmat
• File

format for traces generally

• f

this form

• tcp
• tcp
• tcp
• tcp
• tcp
• d
• tcp
• tcp
• tcp
• tcp
• d
• tcp
• Fields

arriv aldeparturedrop time trace link endp

• in

ts pac k et t yp e size ags

• w

ID src addr dst addr sequence n um b er uid

• Man

y

• f

these elds are from the common pac k et header struct hdrcmn

• int

ptype

• packet

type see above int size

• simulated

packet size int uid

• unique

id int error

• error

flag double ts

• timestamp

for qdelay measurement int iface

• receiving

interface label int refcount

• free

the pkt until count to

• static

int

• ffset
• ffset

for this header inline static int!

• ffset
• return
• ffset

inline static hdrcmn accessPacket p int

• ff
• return

hdrcmn paccessoff "

• #
• ffset
• ff
• perfield

member functions

• rd

NSv W

• rkshop

kfal le elblgov Slide

SLIDE 51 T race Callbac ks

• ma

y

• pt

to in v

• k

e a Tcl function in lieu

• f

writing to le

• see

the le tclexcallback demotcl MyTest instproc begin

• link

tracecallback ns self dofunc

• MyTest

instproc dofunc args

• process

args

• Args

passed to the callbac k are a string con taining a trace

• utput

line eg

• tcp
• rd

NSv W

• rkshop

kfal le elblgov Slide

SLIDE 52 Monitors

• Queue

monitors aggregation p

• in

ts for arriv aldepartdrop stats

• Flo

w monitors similar but

• n

a p ero w basis

• Sno
• p

queues part

• f

the top

• logy
• taps

pac k et

• w

deliv ers samples to asso ciated monitor

Queue Delay Agent/Null Link Link::entry SnoopQueue/In SnoopQueue/Out SnoopQueue/Drop QueueMonitor

Figure

• A

QueueMonitor and supp

• rting
• b

jects rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 53 Monitor Stats

• Simple

stats k ept b y monitors

• arriv

als b ytes and pac k ets

• departures

b ytes and pac k ets

• drops

b ytes and pac k ets

• Aggregate

stats

• ptional
• queue
• ccupancy

in tegral

• b

ytes

• r

pac k ets

• QueueMonitorED
• b

jects

• early

drops b ytes and pac k ets

• some

drops ha v e this distinction eg RED

• Flo

w monitors

• t

yp es QueueMonitorEDFlow and QueueMonitorEDFlowmon

• same

as queue monitors but also

• n

p ero w basis

• w

dened as com b

• s
• f

srcdsto wid

• w

mon aggregates and creates new

• w
• b

jects rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 54 Em ulation

• allo

ws the sim ulator to in teract with a real net w

• rk

curren tly exp erimen tal and under dev elopmen t

• Uses
• sub

ject realw

• rld

implemen tations to sim ulated top

• logies
• sub

ject sim ulated algorithms to realw

• rld

trac

• T

rac transducers

• real

pac k ets mapp ed tofrom sim ulated pac k ets via tap agent

• real

from either liv e wire

• r

tcp dumpformatted le via libp cap

• Realtime

sc heduler

• sp

ecial v ersion

• f

curren tly Listbased sc heduler

• ties

sim ulated time to realtime

• for

no w pun ts if sim ulation gets far b ehind

• can

still do in teresting things

• Other

helpful agen ts

• icmp

generation

• ping

resp

• nder
• arp

resp

• nder
• NA

T function rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 55 T ap Agen ts

• Maps

sim ulated pac k ets tofrom realw

• rld

pac k ets

• Asso

ciated Network

• b

ject pro vides pac k et sourcesink

• P

ac k ets are assumed to b e net w

• rk

la y er generally IP

• Real

trac is stored in sim ulated pac k ets data area void TapAgentrecvp kt

• netsimulator
• allocate

packet and a data payload Packet p

• allocpktmaxpk

t

• fill

up payload sockaddr addr

• not

really used yet double tstamp int cc

• netrecvpa

cc es sd at a

• maxpkt

addr tstamp

• inject

into simulator hdrcmn ch

• hdrcmnpa

cc es s

• ff

c mn

• chsize
• cc
• double

when

• tstamp
• now
• if

when

• chtimestamp
• when

Schedulerins ta nc e

• sc

he dul e ta rg et

• p

when

• else
• chtimestamp
• now

targetrecv p

• rd

NSv W

• rkshop

kfal le elblgov Slide

SLIDE 56 Net w

• rk

Ob ject

• abstraction
• f

a realw

• rld

trac sourcesink

• p

ened read write

• r

readwrite b y caller

• base

class for sp ecic net w

• rk

t yp es eg IP net w

• rk
• Net

w

• rk

class

• requires

so c k et system API UNIX

• r

WinSo c k

• supp
• rts

a basic sendrecv in terface

• separate

sendrecv c hannels ie so c k ets

• nonblo

c king

• ptional
• framew
• rk

supp

• rts

m ulticast addriface selection etc

• IP

Net w

• rk

NetworkIP class

• RA

W IP in terface requires privs for ra w readwrite

• m

ulticast group joinlea v e

• lo
• pbac

k

• no
• m

ulticast ttl

• UDPIP

Net w

• rk

NetworkIPUDP class

• access

to IPUDP through underlying so c k et la y er

• do

es not require privs for use

• F

rame Lev el P ac k et Filtering and Generation rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 57 P ac k et Capture Net w

• rk

Ob ject

• Use

LBNLs libpcap facilit y to access pac k et traces

• Pro

vides access to trace les and liv e net w

• rk

pac k ets

• common

capabilities

• stats

pac k ets captured and dropp ed

• pac

k et lter function using p cap bpf

• ptimizer
• Liv

e P ac k et CaptureGeneration class NetworkPcapLive

• promiscuous
• r
• rdinary

pac k et capture

• framelev

el pac k et generation

• sp

ecication

• f

net w

• rk

in terface name

• File

P ac k et Capture class NetworkPcapFile

• pac

k et capture and ltering

• nly

rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 58 ARP Mo dule

• not

really an agent not deriv ed from Agent class

• uses

attac hed Network

• b

ject for IO

• pro

vides ARP queryresp

• nse

pro cessing

• also

pro vides pro xy ARP

• nly

w

• rks

for ethernet no w

• resp
• nder

is curren tly under dev elopmen t

• useful

for generating linkla y er headers

• ARP

cac he size congurable b y user

• Metho

ds

• network
• set
• r

gets asso ciated Net w

• rk
• b

ject

• myether
• sets

lo cal ethernet address

• myip
• sets

lo cal IP address

• lookup
• lo
• ks

up mapping for IP address

• resolve
• sends

ARP request for IP address

• insert
• insert

an en try in to the ARP cac he rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 59 ICMP Agen t

• generates

realw

• rld

ICMP messages

• class

AgentIcmpAgent

• curren

tly supp

• rts
• nly

ICMP redirect generation

• In

terface set become "who should have sent the redirect set target "who to send redirect to set dest "redirect for what destination set gw "new gateway to use ia send redirect become target dest gw

• pro

vides abilit y to masquerade as curren t default gatew a y some systems c hec k and require this to pro cess a redirect

• generates

dumm y pac k et uses defunct GGP proto col insp ected b y victim host to determine whic h destination mo d ify rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 60 NA T Agen t

• supp
• rts

Net w

• rk

Address T ranslation NA T for use wem ulation

• Curren

tly supp

• rts
• nly

TCP UDP is an easy extension

• Supp
• rted

mo des

• source

address rewrite

• destination

address rewrite

• source

and destination address rewrite

• do

es not rewrite p

• rt

n um b ers

• r

A CKsequence n um b ers rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 61 Break

• rd

NSv W

• rkshop

kfal le elblgov Slide

SLIDE 62 Lo cal Area Net w

• rks
• The

lanlink sub class

• f

Link

• b

ject con tains

• list
• f

no des

• c

hannel

• b

ject

• in

terface queues

• MA

C

• b

jects

• Channel
• b

ject

• abstraction
• f

ph ysical la y er PHY

• supp
• rts

con ten tion collisions and holdjam

• simplex
• r

duplex

• ho
• k

for a dem ux classier based

• n

MA C id

• Interfac

e Queues

• lo

cated b et w een the LL and MA C

• b

jects

• same

as Queue

• b

jects discussed elsewhere rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 63 MA C Media Access Con trol Proto cols

• MA

C supp

• rt
• MA

C addresses

• CSMACA
• CSMACD
• IEEE
• Multihop

eg Metricom wireless net w

• rk
• Addresses
• simple

in teger iden ties xmitrecv station

• m

ulticast supp

• rt

via c hannelclassier mo ds rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 64 CSMAbased MA C supp

• rt
• Common

items in CSMACA and CSMACD

• xed

dela yo v erhead timing

• in

ter frame spacing

• slot

time

• minmax

con ten tion windo w dela y range

• retransmission

coun ter and limit

• carrier

sense

• no
• endofcon

ten tion ev en t handler

• bac

k

• function
• Dierences
• CSMACA
• bac

k

• n

activit y sense

• CSMACD
• bac

k

• n

collision rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 65 IEEE

• Supp
• rt
• Mo

des supp

• rted
• DCF
• basic

CSMACA con ten tion access

• R

TSCTS

• w

con trol

• PCF
• p
• in

t co

• rdination
• P

arameters

• DIFS
• Distributed

Co

• rdination

IFS

• SIFS
• Short

IFS

• PIFS
• PCFIFS
• CSMACD
• bac

k

• n

collision

• See
• standard

for more details rd NSv W

• rkshop

kfal le elblgov Slide

SLIDE 66 Hash classier

• Map

pac k ets to asso ciated

• ws
• r

classes

• Curren

tly srcdst srcdstd d plus default

Hash Classifier

htab_ slot_ Hash Function Packet hnodes

Hash Functions: Source/Dest, Source/Dest/FID, FID Hnodes: active, slot, src, dst, fid

default

rd NSv W

• rkshop

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SLIDE 67 CBQ Class Based Queueing

• Flo

yd and Jacobson Linksharing and Resource Managemen t Mo dels for P ac k e t Net w

• rks

T

• N

Aug

• rewrite

from CBQ co de in ns

• pac

k ets are mem b ers

• f

classes

• classes

ma y con tain a priority and a b andwidth al lo c ation

• classes

ma y b

• rr
• w

un used bandwidth from

• ther

classes

• pac

k ets are sc heduled using a roundrobin sc heduler according to the classes they b elong to

• pac

k etb ypac k et RR

• w

eigh ted RR

• hightolo

w priorit y rd NSv W

• rkshop

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SLIDE 68 CBQ Implemen tation

Queue (arbitrary) Queue (arbitrary) SD SD Connector CBQClass CBQClass Classifier (e.g. hash) SI SI SO SO CBQ (scheduler) QMon QMon

CBQLink

head_ drophead_ classifier_ queue_

• Ma

jor comp

• nen

ts

• classier

maps pac k ets to classes

• classes

holds class state

• sc

heduler sc hedules pac k et departures

• Implemen

ted as a sub class

• f

link CBQ link rd NSv W

• rkshop

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SLIDE 69 In tegrated Services Supp

• rt
• Dev

elop ed b y Breslau and

• thers

at Xero x P AR C

• Mo

del

• applications

request QoS

• net

w

• rk

returns y esno decision

• trac
• btains

sp ecialized QoS pac k et sc heduling

• Purp
• se
• comparison
• f

admission con trol sc hemes

• eect
• n

trac

• ne

mo del

• f

IETF In tServ Con trolled Load CL

• Comp
• nen

ts

• signalling

proto col

• admission

con trol algorithms

• QoSsensitiv

e pac k et sc heduling rd NSv W

• rkshop

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SLIDE 70 In tServ Signalling

• v

ery simple signalling proto col

• not

robust against signalling proto col pac k et loss

• p

erations supp

• rted
• request

accept reject conrm teardo wn

• extensible

to

• ther

proto cols eg RSVP

• ne

mo del

• f

IETF In tServ Con trolled Load CL

• Request

includes tok en buc k et params rate plus depth

• Conrm

is lik e request but for existing

• w
• decisions

are based

• n

admission con trol algorithms rd NSv W

• rkshop

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SLIDE 71 In tServ Admission Con trol

• Measuremen

t Based Admission Con trol MBA C

• acceptreject

decision algorithms

• Measured

Sum Jamin

• Ho

eding Bounds Flo yd

• Acceptance

Region at Origin Kelly

• Acceptance

Region T angen t at P eak Kelly

• more

coming

• Estimation

Algorithms

• used

as input to decision algorithms

• Time

Windo w

• Exp
• nen

tial Av erage

• P
• in

t Sample rd NSv W

• rkshop

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SLIDE 72 Router Mec hanisms

• Flo

yd and F all Router Mec hanisms to Supp

• rt

EndtoEnd Congestion Con trol LBNL TR F eb

• p
• rt

from ns v ersion based

• n

new Flo wMon and CBQ

Connector RED Queue RED Queue SD CBQClass CBQClass Classifier SI SI SO SO CBQ (scheduler) FlowMon head_ drophead_ classifier_ queue_

CBQLink with Router Mechanisms

FlowMon w/default SD ESD ESD

• kboxfm_

pboxfm_

rd NSv W

• rkshop

kfal le elblgov Slide