[PDF] - Audience and Outline The 3rd NS (v2) Sim ulator W orkshop PDF Document

SLIDE 1 The 3rd NS (v2) Sim ulator W

rkshop

br

ught

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

ratory

kfal l@e e.lbl.gov http://www-nr g.e e.lbl.gov/kfal l AND Kannan V aradhan (formerly at USC/ISI) kannan@c atarina.usc.e du http://www.isi.e du/~kannan August 7, 1998 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 (Kevin/Kannan) {

v

erview

f

ma jor comp

nen

ts (Kevin) { pro ject/co de status (Kevin) { details

f

ma jor comp

nen

ts (Kevin) { em ulation facilit y (Kevin) { C++/OTcl link age and sim ulation debugging (Kannan) { scenario generation and session-lev 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)

3rd NSv2 W

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kfal l@e e.lbl.gov Slide 2 NSv2 Arc hitecture

Ob

ject-orien ted structure { ev

lution

from NSv1 (C++ with regular Tcl) {

b

jects implemen ted in C++ and \OTcl" { OTcl:

b

ject-orien ted extension to Tcl (from Da vid W etherall at MIT/LCS for V uSystem) (no w supp

rted

b y UCB Mash group)

Con

trol/\Data" separation { con trol

p

erations in OTcl { data pass through C++

b

jects (for sp eed)

Mo

dular approac h { ne-grain

b

ject decomp

sition

{ p

sitives:

comp

sible,

re-usable { 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) 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 3 Dev elopmen t Status

sim

ulator co de basis for VINT Pro ject

5ish

p eople activ ely con tributing to the co de base

con

tributions from: Xero x P AR C, USC/ISI, UCB, LBNL

Some

appro ximate n um b ers: { 44K lines

f

C++ co de { 14K lines

f

OTcl supp

rt

co de { 40K lines

f

test suites, examples { 10K lines

f

do cumen tation!

Users

w e kno w ab

ut:

{ 82 univ ersities, 39 companies, 4 US go v ernmen t sites

See

main VINT and NS-2 w eb pages at: http://netweb.usc.edu/vint http://www-mash.cs.berkeley.edu/ns/ ns.htm l

Op

en mailing lists: { ns-users@mash.cs.b erk eley .edu { ns-announce@mash.cs.b erk eley .edu

T
subscrib

e: { ma jordomo@mash.cs.b erk eley .edu 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 4

SLIDE 2 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

3rd NSv2 W

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kfal l@e e.lbl.gov Slide 5 Class Hierarc h y

T
p-lev

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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 6 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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 7 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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 8

SLIDE 3 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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 9 OTcl Basics

See

the page at ftp://ftp.tns.lcs.mit.edu/pub/otcl/

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++ constructor/destructor ) OTcl init/destro 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 tcl8.0, see http://www-mash.cs.berkeley.edu/dist 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 10 OTcl Basics (con td)

use

instvar and instpr

c

to dene/access 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 ! 1 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 11 C++/OTcl 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

>

1 delete $c

Dene

instance v ariables in either C++

r

OTcl: Counter::Counter() f bind("cnt ", &value ); value = 10; ... g vs. $self set cnt 10 bind() simply uses Tcl T r ac eV ar 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 12

SLIDE 4 Example: a simple sim ulation

A

small but complete sim ulation script: { set up 4-no de top

logy

and

ne

bulk-data transfer TCP { arrange to trace the queue

n

the r1-k1 link { place trace

utput

in the le simp.out.tr

#

Create a simple four node topology: # s1 # \ # 8Mb,5ms \ 0.8Mb,50ms # r1

k1

# 8Mb,5ms / # / # s2 set stoptime 10.0 set ns [new Simulator] set node_(s1) [$ns node] set node_(s2) [$ns node] set node_(r1) [$ns node] set node_(k1) [$ns node] $ns duplex-link $node_(s1) $node_(r1) 8Mb 5ms DropTail $ns duplex-link $node_(s2) $node_(r1) 8Mb 5ms DropTail $ns duplex-link $node_(r1) $node_(k1) 800Kb 50ms DropTail $ns queue-limit $node_(r1) $node_(k1) 6 $ns queue-limit $node_(k1) $node_(r1) 6 set tcp1 [$ns create-connection TCP $node_(s1) TCPSink $node_(k1) 0] $tcp1 set window_ 50 $tcp1 set packetSize_ 1500 # Set up FTP source set ftp1 [$tcp1 attach-source FTP] set tf [open simp.out.tr w] $ns trace-queue $node_(r1) $node_(k1) $tf $ns at 0.0 "$ftp1 start" $ns at $stoptime "close $tf; puts \"simulation complete\"; $ns halt" $ns run 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 13 Example: a simple sim ulation (con t)

The

trace le pro duced lo

ks

lik e this: + 0.0065 2 3 tcp 1500

0.0

3.0

0.0065

2 3 tcp 1500

0.0

3.0 + 0.23344 2 3 tcp 1500

0.0

3.0 1 2

0.23344

2 3 tcp 1500

0.0

3.0 1 2 + 0.23494 2 3 tcp 1500

0.0

3.0 2 3

0.24844

2 3 tcp 1500

0.0

3.0 2 3 + 0.46038 2 3 tcp 1500

0.0

3.0 3 6

0.46038

2 3 tcp 1500

0.0

3.0 3 6 + 0.46188 2 3 tcp 1500

0.0

3.0 4 7 + 0.47538 2 3 tcp 1500

0.0

3.0 5 8 ... + 0.98926 2 3 tcp 1500

0.0

3.0 25 40 + 0.99076 2 3 tcp 1500

0.0

3.0 26 41 d 0.99076 2 3 tcp 1500

0.0

3.0 26 41

1.00426

2 3 tcp 1500

0.0

3.0 21 36 + 1.00426 2 3 tcp 1500

0.0

3.0 27 42 + 1.00576 2 3 tcp 1500

0.0

3.0 28 43 d 1.00576 2 3 tcp 1500

0.0

3.0 28 43

1.01926

2 3 tcp 1500

0.0

3.0 22 37 + 1.01926 2 3 tcp 1500

0.0

3.0 29 44 + 1.02076 2 3 tcp 1500

0.0

3.0 30 45 d 1.02076 2 3 tcp 1500

0.0

3.0 30 45

1.03426

2 3 tcp 1500

0.0

3.0 23 38

1.04926

2 3 tcp 1500

0.0

3.0 24 39

1.06426

2 3 tcp 1500

0.0

3.0 25 40 ... 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 14 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") { Scheduler/List

link

ed-list sc heduler { Scheduler/Heap

heap-based

sc heduler { Scheduler/Calendar

calendar-queue

sc heduler { Scheduler/RealTime

real-time

(for em ulation) { see Reev es, "Complexit y Analyses

f

Ev en t Set Algorithms", The Computer Journal, 27(1), 1984 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 15 Using the sc heduler

Sc

heduler API is through Sim ulator

b

ject: Simulator instproc now ;# r eturn sche duler's 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 create-trace type files src dst ;# cr e- ate tr ac e

bje

ct Simulator instproc create_packet fo rm at ;# set up the simulator's p acket format

Example:

MySim instproc begin {} { ... set ns_ [new Simulator] $ns_ use-scheduler Heap $ns_ at 300.5 "$self complete_sim" ... } MySim instproc complete_sim {} { ... } 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 16

SLIDE 5 Sim ulator Timing

eac

h top

logy
b

ject has a generic receiv e metho d NsObject::recv(Packet*, Handler* h = 0)

most
b

jects ha v e single neigh b

r

Connector::target

cut-thr
ugh

transfers: send pac k et directly to neigh b

r

without in v

lving

sc heduler Connector::send(Packet* p) f target

>recv(p);

g

sche

duling b arriers: { an y p

in

t that adv ances time in to future (i.e., dela y elemen t) { need in ter-ob ject \proto col" to decouple timing { barrier tak es non-n ull Handler { sc hedule dela y and in v

k

e handler

n

completion { example: queue/dela y

b

jects (later) 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 17 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 31:10, Oct. 1988 { 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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 18 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 in-use 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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 19 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 1: A P ac k et Ob ject

header

con ten ts are constructed at sim ulator initialization time

p

erformed b y create packetformat 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 20

SLIDE 6 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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 21 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

(e.g. TCP)

T

rac generators are used to driv e connectionless transp

rts

(e.g. 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

n/o

times, sen t at xed rate { POO

pareto
n/o

times, sen t at xed rate { CBR

deterministic

rate { T racT race

use

trace le con taining time/len pairs 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 22 Sources

class

Application/Telnet { ma y sp ecify interval parameter { if zero, pic ks randomly among 10000 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

Application/FTP { 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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 23 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 Application/Traffic/Exponential) { exp

nen

tially distributed

n/o

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 ter-departure time giv en rate/size

P

areto (class Application/Traffic/Pareto) { pareto distributed

n/o

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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 24

SLIDE 7 T race-Based T rac Generator

generate

trac according to trace le

t

w

classes:

Tracefile and Application/Traffic/Trace

trace

le uses small binary format: { rst 32-bit eld: in ter-pac k et time (microsecs) { second 32-bit eld: pac k et size (b ytes) 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 25 Agen ts

A

gents: usually a transp

rt

proto col endp

in

t/en 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 generate/ll-in in pac k et elds { a base class supp

rting

the application in terface 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 26 Creating a new Agen t

The

Agent class: class Agent : public Connector { public: Agent(int pktType); virtual ~Agent(); virtual void timeout(int tno); virtual void sendmsg(int nbytes, const char *flags = 0); virtual void send(int nbytes) { sendmsg(nbytes); } virtual void sendto(int nbytes, const char* flags, nsaddr_t dst); virtual void connect(nsaddr_t dst); virtual void close(); virtual void listen(); virtual void attachApp(Application* app); virtual int& size() { return size_; } inline nsaddr_t& addr() { return addr_; } protected: int command(int argc, const char*const* argv); void recv(Packet*, Handler*); ...

basic

tasks to create a new agen t: 1. decide its inheritance structure 2. create the class and ll in the API virtual functions 3. dene OTcl link age functions (later) 4. write the necessary OTcl co de to access y

ur

agen t

hardest

part ma y b e understanding the OTcl/C++ in teraction (fortunately , m uc h

f

this is shielded from y

u

if y

u

so c ho

se)

3rd NSv2 W

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kfal l@e e.lbl.gov Slide 27 Example: the Message Agen t

pro

vides a v ery simple place to store a message

P

ac k et header (from message.h): struct hdr_msg { char msg_[64]; /* per-field member functions */ char* msg() { return (msg_); } int maxmsg() { return (sizeof(msg_)); } };

OTcl

link age (for class creation, from message.cc): 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 ", sizeof(hdr_msg )) {} } class_msghdr; 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 28

SLIDE 8 Example: the Message Agen t (con t)

The

class denition, constructor and v ariable link age: static class MessageClass : public TclClass { public: MessageClass() : TclClass("Agent /M es sa ge ") {} TclObject* create(int, const char*const*) { return (new MessageAgent() ); } } class_message; class MessageAgent : public Agent { public: MessageAgent(); int command(int argc, const char*const* argv); void recv(Packet*, Handler*); protected: int

ff_msg_;

}; MessageAgent::M es sa ge Ag en t( ) : Agent(PT_MESSAG E) { bind("packetSiz e_ ", &size_); bind("off_msg_" , &off_msg_); } 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 29 Example: the Message Agen t (con t)

Main

functions: void MessageAgent::r ec v( Pa ck et * pkt, Handler*) { hdr_msg* mh = (hdr_msg*)pkt

>

ac ce ss (of f_ ms g_ ); ... process packet ... } int MessageAgent:: co mm an d( in t argc, const char*const* argv) { Tcl& tcl = Tcl::instance( ); // call into interp if (argc == 3) { // $obj send msgtext if (strcmp(argv[1] , "send") == 0) { Packet* pkt = allocpkt(); hdr_msg* mh = (hdr_msg*)pkt- >a cc es s(

f

f_ ms g_ ); const char* s = argv[2]; int n = strlen(s); if (n >= mh->maxmsg()) { tcl.result("m es sa ge too big"); Packet::free( pk t) ; return (TCL_ERROR); } strcpy(mh->msg( ), s); send(pkt, 0); return (TCL_OK); } } return (Agent::comman d( ar gc , argv)); // for inheritance } 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 30 CBR and UDP Agen t

CBR

Agen t: { stands for \constan t bit rate" (not really used

nly

this w a y) { non-connection-orien ted sending agen t { sends pac k ets at p erio dic in terv al

r

quasi-p erio dically { constan t-size 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 sizes/times 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 31 TCP Agen ts

Tw
categories:
ne-w

a y and t w

-w

a y (\full TCP")

One-w

a y v arian ts

f

TCP a v ailable: { Agen t/TCP

a

\taho e" TCP sender { Agen t/TCP/Reno

a

\Reno" TCP sender { Agen t/TCP/NewReno

Reno

with a mo dication { Agen t/TCP/Sac k1

TCP

with selectiv e rep eat (follo ws RF C2018) { Agen t/TCP/V egas

TCP

V egas { Agen t/TCP/F ac k

Reno

TCP with \forw ard ac kno wledge- men t" { Agen t/TCP/Session

shared

congestion state w/m ultiple connections { Agen t/TCP/In t

p

er-connection reliabilit y for use w/Session { Agen t/TCP/*/RBP

Reno,

V egas with Rate Based P acing { Agen t/TCP/Asym

TCP

mo ds for asymmetric c hannels

One-w

a y TCP receiving agen ts curren tly supp

rted

are: { Agen t/TCPSink

ne

A CK p er pac k et { Agen t/TCPSink/DelAc k

congurable

dela y p er A CK { Agen t/TCPSink/Sac k1

selectiv

e A CK sink (follo ws RF C2018) { Agen t/TCPSink/Sac k1/DelAc k

Sac

k1 with DelAc k { Agen t/TCPSink/Asym

sink

for Asym senders 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 32

SLIDE 9 Tw

-W

a y TCP Agen ts

Tw
-w

a y TCP agen ts (b eta test): { Agen t/TCP/F ullTcp

pro

vides Reno functionalit y { Agen t/TCP/F ullTcp/T aho e (new) { Agen t/TCP/F ullTcp/Sac k (new)

One-w

a y and t w

-w

a y TCPs are not in terop erable 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 33 Base TCP Agen ts

TCP

(T aho e), TCP/Reno, and TCP/NewReno

Common

features: { computations all in pac k et units w/congurable pac k et size { fast retransmit { slo w-start and congestion a v

idance

{ dynamic R TT estimation and R TX timeout assignmen t { sim ulated (constan t) receiv er's adv ertised windo w

T

aho e TCP: { p erform slo w-start

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 w-start

n

R TO {

n

fast retransmit: cw nd cur w in=2 , 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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 34 Other TCP Agen ts

TCP/Sack,

TCP/Fack, and TCP/Vegas

Selectiv

e A CK TCP: { SA CK sim ulation based

n

RF C2018 { A CKs carry extra information indicating receiv ed segmen ts { requires SA CK-a w are sink { sender a v

ids

sending redundan t info { default to 3 \SA CK blo c ks" (for using timestamps, see RF C2018)

blo

c k con tains start/end 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 '96) { use SA CK info for estimate

f

pac k ets in the net w

rk

{

v

erdamping algorithm (to limit slo w-start

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) 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 35 TCP Agen t P arameters

Common

conguration parameters and defaults for TCP agen ts: Agent/TCP set maxburst_ ;# max pkts emitte d due to 1 r e cvd Agent/TCP set maxcwnd_ ;# max b

und
n

c

ngestion

window Agent/TCP set syn_ false ;# do SYN exchange prior to data xfer Agent/TCP set tcpip_base_hdr_size_ 40 ;# size

f

TCP/IP hdr, no

pts

Agent/TCP set timestamps_ false ;# due RF C1323-style time stamps Agent/TCP set window_ 20 ;# max b

und
n

window size Agent/TCP set windowInit_ 1 ;# initial/r eset value

f

cwnd Agent/TCP set windowOption_ 1 ;# c

ng

avoid algorithm (1: standar d) Agent/TCP set windowConstant_ 4 ;# use d

nly

when windowOption != 1 Agent/TCP set windowThresh_ 0.002 ;# use d in c

mputing

aver age d window Agent/TCP set

verhead_

;# !=0 adds r andom time b etwe en sends Agent/TCP set ecn_ ;# TCP should r e act to e cn bit Agent/TCP set packetSize_ 1000 ;# p acket size use d by sender (bytes) Agent/TCP set bugFix_ true ;# se e do cumentation Agent/TCP set slow_start_restart_ true ;# do slow-start after id le p erio d Agent/TCP set tcpTick_ 0.1 ;# timer gr anularity in se c (.1 is NONST AND ARD) Agent/TCP set maxrto_ 100000 ;# b

und
n

R TO (se c

nds)

Agent/TCP set srtt_init_ ;# initial value for smo

the

d rtt est Agent/TCP set rttvar_init_ 12 ;# initial value for rtt var est Agent/TCP set rtxcur_init 6.0 ;# initial value for curr ent rtx timer Agent/TCP set T_SRTT_BITS 3 ;# # bits after binary p

int

for SR TT Agent/TCP set T_RTTVAR_BITS 2 ;# # bits after binary p

int

for R TTV AR Agent/TCP set rttvar_exp_ 2 ;# exp

nent
f

2 which multiples rttvar

Dynamic

v alues

f

in terest: Agent/TCP set dupacks_ ;# duplic ate A CK c

unter

Agent/TCP set ack_ ;# highest A CK r e c eive d Agent/TCP set cwnd_ ;# c

ngestion

window (p ackets) Agent/TCP set awnd_ ;# aver age d cwnd (exp erimental) Agent/TCP set ssthresh_ ;# slow-stat thr eshold (p ackets) Agent/TCP set rtt_ ;# rtt sample Agent/TCP set srtt_ ;# smo

the

d (aver age d) rtt Agent/TCP set rttvar_ ;# me an deviation

f

rtt samples Agent/TCP set backoff_ ;# curr ent R TO b acko factor Agent/TCP set maxseq_ ;# max (p acket) se q numb er sent 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 36

SLIDE 10 TCP Sink Agen ts

Sinks

for

ne-w

a y TCP senders

T

yp es { standard sinks, dela y ed-A 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 ed-A 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 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 37 Tw

-W

a y TCP (\F ullTCP")

most

TCP

b

jects are

ne-w

a y (and require a source/sink pair)

real

TCP can b e bi-directional

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

TCP/FullTcp agen t: { follo ws closely to \Reno" TCP implemen tation in 4.4 BSD { b yte-orien ted transfers { t w

-w

a y data supp

rted

{ most

f

the connection establishmen t/teardo wn { symmetric:

nly
ne

agen t t yp e used for b

th

sides

Dierences

from the \real thing": { no receiv er's adv ertised windo w/p ersist mo de { no urgen t p

in

ter { no 2MSL w ait { no RST segmen ts

No

w supp

rts

T aho e, NewReno, and Sac k v arian ts 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 38 F ullTCP P arameters

P

arameters and defaults: Agent/TCP/FullTcp set segsperack_ 1 ;# se gs r e c eive d b efor e gener ating A CK Agent/TCP/FullTcp set segsize_ 536 ;# se gment size (MSS size for bulk xfers) Agent/TCP/FullTcp set tcprexmtthresh_ 3 ;# dupA CKs thr esh to trigger fast r exmt Agent/TCP/FullTcp set iss_ ;# initial send se quenc e numb er Agent/TCP/FullTcp set nodelay_ false ;# disable sender-side Nagle algorithm Agent/TCP/FullTcp set data_on_syn_ false ;# send data

n

initial SYN? Agent/TCP/FullTcp set dupseg_fix_ true ;# avoid fast rxt due to dup se gs+acks Agent/TCP/FullTcp set dupack_reset_ false ;# r eset dupA CK ctr

n

!0 len data se g s c

ntaining

dup A CKs Agent/TCP/FullTcp set interval_ 0.1 ;# delaye d A CK interval Agent/TCP/FullTcp set close_on_empty_ false ;# close c

nn

after send al l data Agent/TCP/FullTcp set ts_option_size_ 10 ;# size

f

rfc1323 ts

ption

(bytes) Agent/TCP/FullTcp set reno_fastrecov_ true ;# c

ngestion

window ination Agent/TCP/FullTcp set pipectrl_ false ;# use "pip e" mo del c

ngestion

ctrl Agent/TCP/FullTcp set

pen_cwnd_on_pack_

true ;# incr e ase cwnd

n

p artial acks Agent/TCP/FullTcp/Newre no set recov_maxburst_ 2 ;# maxburst during r e c

very

Agent/TCP/FullTcp/Sack set sack_block_size_ 8 ;# # bytes in a SA CK blo ck Agent/TCP/FullTcp/Sack set sack_option_size_ 2 ;# # bytes in

pt

hdr Agent/TCP/FullTcp/Sack set max_sack_blocks_ 3 ;# # max #

f

sack blks 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 39 R TP and R TCP Agen ts

R

TP

\Real-time"

(transp

rt)

proto col (RF C 1889) { implemen ted as Agent/CBR/RTP

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 Session/RTP

b

ject { sends at rate based

n

n um b er

f
ther

senders { rep

rts

kno wn sources and stats 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 40

SLIDE 11 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 64 b yte (short) messages 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 41 Connectors

Conne

ctor: simple in/out 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 drop(Packet* p); protected: int command(int argc, const char*const* argv); void recv(Packet*, Handler* callback = 0); inline void send(Packet* p, Handler* h) { target_->recv (p , h); } NsObject* target_; NsObject* drop_; // dest for drops };

if

drop target undened, dropp ed pac k ets are freed 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 42 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 er-o 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 non-matc hing trac go es

Example:

set lossylink_ [$ns link $node_(r1) $node_(k1)] set em [new ErrorModule Fid] set errmodel [new ErrorModel/Per io di c] $errmodel unit pkt $errmodel set

ffset_

1.0 $errmodel set period_ 25.0 $lossylink_ errormodule $em $em insert $errmodel $em bind $errmodel 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 43 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 parameters: set errmodel [new ErrorModel] $errmodel unit pkt $errmodel set rate_ 0.01 $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 error-free 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 ets/b ytes { Select { lik e P erio dic, but uses pac k et uid's { 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 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 44

SLIDE 12 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: { Drop-tail (FIF O) { Random Early Detection (RED)

P

ac k et sc heduling: { FIF O { CBQ (includes priorit y + round-robin) { Round-robin (DRR) { V arian ts

f

F Q (WF Q, SF Q) 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 45 Queue Handlers

Dequeued

pac k ets are

ften

sen t do wnstream to delays

dela

ys (usually) cause t w

actions:

1. the pac k et is sc heduled to arriv e do wnstream at time t + d 2. the queue b ecomes un blo c k ed at time t 3. t is transmit time, d is prop dela y time

so,

dela ys represen t a commonly-o ccurring sche duling b arrier

Queue

parameters: Queue set limit_ 50 ;# max p acket c

unt

in queue Queue set blocked_ false ;# queue starts

blo

cke d Queue set unblock_on_res um e_ true ;# queue is unblo cke d after r esume

con

trol

f

blo c king can b e useful for queue banks (e.g. CBQ) 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 46 Drop T ail and RED Queues

Drop-T

ail Queues (Queue/DropTail class) { simple FIF O, drop-tail queues { drop from tail when

ccupancy

reac hes qlim

RED

(Random Early Detection) Queues (Queue/RED 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 (or 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

[0; maxpr

b]

3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 47 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

drop-tail
drop

new pkt instead

f

random

ne

3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 48

SLIDE 13 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 (often pac k et arriv als/departures/drops) { Trace/Enque

a

pac k et arriv al (usually at a queue) { Trace/Deque

a

pac k et departure (usually at a queue) { Trace/Drop

pac

k et drop (pac k et deliv ered to drop-target)

Monitors
k

eep statistics ab

ut

arriv als/departures/drops (and

ws)

{ SnoopQueue/Out

n
utput,

collect a time/size sample (pass pac k et

n)

{ SnoopQueue/Drop

n

drop, collect a time/size sample (pass pac k et

n)

{ SnoopQueue/EDrop

n

an "early" drop, collect a time/size sampl e (pass pac k et

n)

{ QueueMonitor

receiv

e and aggregate collected samples from sno

p

ers { QueueMonitor/ED

queue-monitor

capable

f

distinguish- ing b et w een \early" and standard pac k et drops { QueueMonitor/ED/Flowmon

p

er-o w statistics monitor (manager) { QueueMonitor/ED/Flow

p

er-o w statistics con tainer 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 49 T race File F

rmat
File

format for traces generally

f

this form: + 1.45176 2 3 tcp 1000

1

256 769 27 48 + 1.45276 2 3 tcp 1000

1

256 769 28 49

1.46176

2 3 tcp 1000

1

256 769 22 43 + 1.46176 2 3 tcp 1000

1

256 769 29 50 + 1.46276 2 3 tcp 1000

1

256 769 30 51 d 1.46276 2 3 tcp 1000

1

256 769 30 51

1.47176

2 3 tcp 1000

1

256 769 23 44 + 1.47176 2 3 tcp 1000

768

3 52 + 1.47276 2 3 tcp 1000

768

4 53 d 1.47276 2 3 tcp 1000

768

4 53

Fields:

arriv al/departure/drop, 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 hdr_cmn { int ptype_; // packet type (see above) int size_; // simulated packet size int uid_; // unique id int error_; // error flag double ts_; // timestamp: for q-delay measurement int iface_; // receiving interface (label) int ref_count_; // free the pkt until count to static int

ffset_;

//

ffset

for this header inline static int&

ffset()

{ return

ffset_;

} inline static hdr_cmn* access(Packet* p, int

ff=-1)

{ return (hdr_cmn*) p->access(off < ?

ffset_

:

ff);

} /* per-field member functions */ ... }; 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 50 T race Callbac ks

ma

y

pt

to in v

k

e a Tcl function in lieu

f

writing to le

see

the le tcl/ex/callback demo.tcl MyTest instproc begin {} { ... $link12_ trace-callback $ns_ "$self dofunc" ... } MyTest instproc dofunc args { ... process args ... }

Args

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

utput

line (e.g.):

0.80612

1 tcp 1000

0.0

1.0 9 13 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 51 Monitors

Queue

monitors: aggregation p

in

ts for arriv al/depart/drop stats

Flo

w monitors: similar, but

n

a p er-o 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 2: A QueueMonitor and supp

rting
b

jects 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 52

SLIDE 14 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 (optional): { queue

ccupancy

in tegral { (b ytes

r

pac k ets)

QueueMonitor/ED
b

jects { \early" drops (b ytes and pac k ets) { some drops ha v e this distinction (e.g. RED)

Flo

w monitors: { t yp es QueueMonitor/ED/Flow and QueueMonitor/ED/Flowmon { same as queue monitors, but also

n

p er-o w basis {

w

dened as com b

s
f

(src/dst/o wid) {

w

mon aggregates and creates new

w
b

jects 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 53 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 real-w

rld

implemen tations to sim ulated top

logies

{ sub ject sim ulated algorithms to real-w

rld

trac

T

rac transducers: { real pac k ets mapp ed to/from sim ulated pac k ets via tap agent { real from either liv e wire

r

tcp dump-formatted le via libpcap

Real-time

sc heduler { sp ecial v ersion

f

(curren tly List-based) sc heduler { ties sim ulated time to real-time { 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 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 54 T ap Agen ts

Maps

sim ulated pac k ets to/from real-w

rld

pac k ets

Asso

ciated Network

b

ject pro vides pac k et source/sink

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 et's data area: void TapAgent::recvp kt () // net->simulator { ... // allocate packet and a data payload Packet* p = allocpkt(maxpk t_ ); // fill up payload sockaddr addr; // not really used (yet) double tstamp; int cc = net_->recv(p->a cc es sd at a( ), maxpkt_, addr, tstamp); // inject into simulator hdr_cmn* ch = (hdr_cmn*)p->a cc es s(

ff

_c mn _) ; ch->size() = cc; ... double when = tstamp

now();

... if (when > 0.0) { ch->timestamp( ) = when; Scheduler::ins ta nc e( ). sc he dul e( ta rg et _, p, when); } else { ch->timestamp( ) = now(); target_->recv( p) ; } } 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 55 Net w

rk

Ob ject

abstraction
f

a real-w

rld

trac source/sink

p

ened read, write,

r

read/write b y caller

base

class for sp ecic net w

rk

t yp es (e.g. IP net w

rk)
Net

w

rk

class: { requires so c k et system API (UNIX

r

WinSo c k) { supp

rts

a basic send/recv in terface { separate send/recv \c hannels" (i.e. so c k ets) { non-blo c king

ptional

{ framew

rk

supp

rts

m ulticast, addr/iface selection, etc

IP

Net w

rk

(Network/IP class) { RA W IP in terface (requires privs for ra w read/write) { m ulticast group join/lea v e { lo

pbac

k

n/o

{ m ulticast ttl

UDP/IP

Net w

rk

(Network/IP/UDP class) { access to IP/UDP 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 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 56

SLIDE 15 P ac k et Capture Net w

rk

Ob ject

Use

LBNL's 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 Capture/Generation (class Network/Pcap/Live) { promiscuous

r
rdinary

pac k et capture { frame-lev el pac k et generation { sp ecication

f

net w

rk

in terface name

File

P ac k et Capture (class Network/Pcap/File) { pac k et capture and ltering

nly

3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 57 ARP Mo dule

not

really an agent (not deriv ed from Agent class)

uses

attac hed Network

b

ject for I/O

pro

vides ARP query/resp

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 link-la 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 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 58 ICMP Agen t

generates

real-w

rld

ICMP messages

class

Agent/IcmpAgent

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) 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 59 NA T Agen t

supp
rts

Net w

rk

Address T ranslation (NA T) for use w/em 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 CK/sequence n um b ers 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 60

SLIDE 16 Break. . . 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 61 Lo cal Area Net w

rks
The

lan-link (sub class

f

Link)

b

ject con tains: { list

f

no des { c hannel

b

ject { in terface queue(s) { MA C

b

ject(s)

Channel
b

ject { abstraction

f

ph ysical la y er (PHY) { supp

rts

con ten tion, collisions and hold/jam { 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 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 62 MA C (Media Access Con trol) Proto cols

MA

C supp

rt:

{ MA C addresses { CSMA/CA { CSMA/CD { IEEE 802.11 { Multihop (e.g. Metricom wireless net w

rk)
Addresses

{ simple in teger iden ties xmit/recv station { m ulticast supp

rt

via c hannel/classier mo ds 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 63 CSMA-based MA C supp

rt
Common

items in CSMA/CA and CSMA/CD: { xed dela y/o v erhead timing { in ter frame spacing { slot time { min/max con ten tion windo w (dela y range) { retransmission coun ter and limit { carrier sense

n/o

{ end-of-con ten tion ev en t handler { bac k

function
Dierences

{ CSMA/CA

bac

k

n

activit y sense { CSMA/CD

bac

k

n

collision 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 64

SLIDE 17 IEEE 802.11 Supp

rt
Mo

des supp

rted:

{ DCF

basic

CSMA/CA con ten tion access { R TS/CTS

w

con trol { PCF

p
in

t co

rdination
P

arameters: { DIFS

Distributed

Co

rdination

IFS { SIFS

\Short"

IFS { PIFS

PCF-IFS

{ CSMA/CD

bac

k

n

collision

See

802.11 standard for more details 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 65 Hash classier

Map

pac k ets to asso ciated

ws
r

classes

Curren

tly: src/dst, src/dst/d, 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 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 66 CBQ: Class Based Queueing

Flo

yd and Jacobson, "Link-sharing and Resource Managemen t Mo dels for P ac k e t Net w

rks",

T

N,

Aug 1995

rewrite

from CBQ co de in ns-1

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 round-robin sc heduler according to the classes they b elong to: { pac k et-b y-pac k et RR { w eigh ted RR { high-to-lo w priorit y 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 67 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 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 68

SLIDE 18 In tegrated Services Supp

rt
Dev

elop ed b y Breslau and

thers

at Xero x P AR C

Mo

del: 1. applications request QoS 2. net w

rk

returns y es/no decision 3. 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 { QoS-sensitiv e pac k et sc heduling 3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 69 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, tear-do wn { extensible to

ther

proto cols (e.g. 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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 70 In tServ Admission Con trol

Measuremen

t Based Admission Con trol (MBA C) { accept/reject 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 3rd NSv2 W

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kfal l@e e.lbl.gov Slide 71 Router Mec hanisms

Flo

yd and F all, "Router Mec hanisms to Supp

rt

End-to-End Congestion Con trol", LBNL TR, F eb 1997

p
rt

from ns-1 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_

3rd NSv2 W

rkshop

kfal l@e e.lbl.gov Slide 72