Andy T. Ogielski Dec 16 1999

ssfnetScalable Modeling & Simulations of Networks

DIMACSCenter for Discrete Mathematics & Computer Science

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ssf and ssfnet

ssf: a modern simulation platform

- scalable, parallel kernel, open API

- model configuration database framework

- random stream management & statistics

- pure Java (C++ version available)

design & performance demonstrated at earlier PI meetings

network modeling layers: ssfnet

---- core ssf & ssfnet completed

ssfnet - overview 1

modeling aids:

- network configuration verification and management

- total reproducibility: management of random number streams

- strongest random number generators, statistics package

- automated IP address generation (VLSM/CIDR)

- traffic pattern configuration

practical good news:

- parallel performance from a desktop PC to a supercomputer

- fast topology construction and protocol configuration

- no programming style restrictions

ssfnet - overview 2

walk-through example of multi-scale modeling:

- USA-scale multi-AS network

- full Internet protocol suite

- empirical model of the Web traffic

current research:

- networkers' IDE (integrated development environment)

- multiresolution analysis of spatio-temporal network dynamics

- wireless Internet problems

Java SSF performance 1

14 CPU SUN Enterprise, 200MHz

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events/second

outChannel inChannelEntity

process

Basic event spin-loop experiment

Event

JDK1.2 Solaris2.7

Java gets pretty fast by now!

Java ssfnet - parallel performance

OSPF in each AS (24 clients, 4 servers, 18 routers)

BGP between ASs

client-server TCP - large file transfer

server farmclient nets

each clnt to random AS server

each clnt to neighbor AS server

each clnt to local AS server

one AS per processor exec time

all AS on one processor exec time

parallel speedup

N networks (AS) connected as a ring

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JDK 1.2 SUN Enterprise 200MHz

Java ssfnet on a Windows PC

OSPF in each AS (24 clients, 4 servers, 18 routers)

BGP between ASs

each client-server TCP - 3MB file transfer

server farmclient nets

each client connects to a random AS server

typical dual-processor PC

6 networks (AS) connected as a ring

3,000 TCP packets

1.7 times faster for parallel simulation

Windows NT4.0 JDK1.2 PentiumPro 250 MHz

440 seconds

260 seconds

1 CPU 2 CPU

network modeling packages

SSF.Net

- host, router, queues, network interfaces

- links & LANs

- nested Net import, hierarchical component addressing

- IP address generation

SSF.OS

- ProtocolGraph - ProtocolSession - ProtocolMessage

x-kernel-like protocol design framework

- protocol and application models

ssfnet protocol validation

ssfnet distribution includes validation tests

- test network configurations, HTML docs, traces

- TCP, UDP, BGP4, OSPF in distribution

- validation against RFCs and other test suites

Example: ssfnet TCP validation

generic Tahoe, Reno, delayed ACK option

- BSD socket-like interface to app protocols

- validation against RFCs and ns-2 test suite (thanks!)

- full documentation and plots:

www.winlab.rutgers.edu/~ato/ssf/tcp/

TCP validation 2

binary tcpdump (standard)

fully instrumented

TCP implementation

(DML selectable)

matlab plotting

in ssfnet distribution

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Modeling aids: SSF.DML

Network configuration design/management database

- hierarchical object-oriented schemas: simple & powerful

- strong configuration reuse: substitution & multiple inheritance

- automatic verification of configuration correctness

- target for CAD and analysis tools

- separation of config database and executable code

reduces modeling errors

examples follow...

Modeling aids: SSF.Util.Random

Total reproducibility of parallel simulations

- control of seed distribution via cryptographic techniques (MD)

on random stream pathnames

- creation of random stream instances at multiple levels

(per distribution, protocol, host, timeline)

examples follow...

Strongest, fast random number generators & statistics

- Mersenne Twister, Ranlux, Ranmar, Ranecu, RandomShuffle,...

- 24 common prob. distributions...statistics (CERN packages)

walk-through a large model

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router + 4 LANs,LAN = 25 hosts, = 100 hosts add a router

and connect together

walk through a large model 2

networks [ network100 [ Net [ router [ id 0 interface [ id 0 _extends .dictionary.100Mb ] # LAN interface [ id 1 _extends .dictionary.100Mb ] # LAN ...... interface [ id 5 _extends .dictionary.1Gb ] # to be attached interface [ id 6 _extends .dictionary.1Gb ] # to be attached _find .dictionary.routerGraph.graph ]

# all hosts are identical. 4 lans @ 25 hosts per lan = 100 hosts host [ idrange [from 1 to 25] _find .dictionary.client100Mb.interface _find .dictionary.client100Mb.graph nhi_route [dest default interface 0 next_hop 0(0 )] ] # LAN 0 link [ delay 0.001 attach 0(0) attach 1(0) attach 2(0) attach 3(0) attach 4(0) attach 5(0) ...... attach 21(0) attach 22(0) attach 23(0) attach 24 (0) attach 25(0) ]

DML database entry

4 5 6

from database of network cards....... inheritance

from database of protocol graphs...... substitution

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BGP4

combine submodels together

... make a small Autonomous System:

1,300 client hosts, 4 big servers,

26 internal routers (OSPF),

1 AS boundary router (OSPF + BGP)

as2 [ Net [ AS_status boundary ospf_area 0

Net [id 0 _extends .networks.network1.Net] # backbone Net [id 1 _extends .networks.network4.Net] # server farm Net [id 2 _extends .networks.network33.Net] Net [id 3 _extends .networks.network21.Net] Net [id 4 _extends .networks.network34.Net]

walk through a large model 3

DML database entry:

......Net import from a database - a powerful concept

2133

34

1

walk-through a large model 4

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now connect 25 copies of an as2 network ...and we have 33,325 hosts & routers ... do you recognize the ISP ?

walk through a large model 5

client100Mb [ graph [ ProtocolSession [ name client use SSF.OS.WWW.httpClient # HTTP session empirical model. inter_session_time [ distribution [ name "Exponential" lambda 0.01 ] ] inter_page_time [ distribution [ name "Pareto" k 25.0 alpha 2.0 ] ] ........ more

Traffic pattern databases

randomstream [ generator "MersenneTwister" stream "seedstarter4" reproducibility_level "host" ]

traffic [ pattern [ client 10 servers [ port 80 nhi_range [ from 10:1:2(0) to 10:1:5(0) ] ] ] .......... more

local global

Current research: net dynamics

AT&T Research - DIMACS - Princeton

- collaboration on multiresolution analysis of spatio-temporal

behavior of large networks (Willinger, Feldmann, Daubechies,

Ogielski and others)

- towards "new theory of networks"

- very challenging - drives ideas for new methodologies & tools

- simulated & real traffic studies

examples follow...

Scalable Simulation Framework

Hongbo Liu

R 2R 0S R 1

C

C

C

C

Challenge:

manipulate & visualize

1000s of flows

Current research: wireless Internet

WINLAB & affiliated corporations

(Motorola, Lucent, Cisco,...)

- SSF is the platform for various wireless Internet and 3G projects

- TCP over adaptive radio link protocols (like cdma2000)

- ad-hoc Bluetooth-based IP networks

- signal level multicell 3G systems: waveform to IP

examples follow...

Scale and Details matter!

ssfnet2 - integration of Internet & Wireless models

wireless access + wired global net

scalable design & analysis tools

Internet software radios,

inter-protocol interactions,

traffic, service design,...

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Research on TCP - RLP interactions:towards better protocols for wireless Internet

phase 1: correlated fading losses

1 wireless host, 1 TCP connection,

RLP, fading, simplified IP cloud

phase 2: add multiaccess

N wireless hosts, many connections,

MAC + RLP, fading, interference,

simplified IP cloud

phase 3: add wired congestion

phase 2 plus realistic IP cloud:

correlated wireline delays/losses

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Current research: network IDE

Integrated Design Environment for networking research

- graphical DML-based network editor

topology generation, protocol configuration, database generation,

validation (prototype exists, needs some more work)

- High-volume stream data collection (~ 1000s of tcpdumps)

and multiscale analysis package

(challenging...)

dual-use for model & real networks

ssfnet '99 development team

DARPA ITO project administered by DIMACS, Rutgers U.

Andy Ogielski DIMACS & WINLABJames Cowie Cooperating SystemDavid Nicol Dartmouth College

Students (wired Internet)

Myongsu ChoePhilip KwokHongbo LiuBrian Premore

Students (wireless Internet)

Yong BaiVikram KaulWenfeng Zhang

ssfnet web site

www.ssfnet.org

ssfnet software distribution

Open source modeling packages, protocols, networks.