Ph.D. Dissertation presented by Xiuduan Fang Department of Computer Science University of Virginia...

Ph.D. Dissertation presented by

Xiuduan FangDepartment of Computer Science

University of VirginiaSeptember 19, 2008

On Using Circuit-switched Networks for File Transfers

Outline

• Overview Hypothesis Contributions & Publications

• Motivation• Theoretical component:

Design and evaluate algorithms to support file transfers on circuit-switched networks

• Experimental component: Implement and demonstrate architecture for

internetworking circuit-switched networks with the Internet

• Conclusions & Future work2

Hypothesis

Circuit-switched networks, with dynamic call-by-call bandwidth sharing and support for heterogeneous-rate circuits, can be used efficiently to support file transfers, and can be evolved gradually into the existing Internet.

3

Yes

end-to-end circuits?

No

Theoretical component

Dissertation organization

Internetworking architectureCall-admission control (CAC):

rate allocation

minimum file size

Experimental component

Key Contributions

• File transfers on a hybrid architecture Constructed analytical models Provided insights on how to design admission control Proposed a novel heterogeneous rate-allocation

scheme to lower file-transfer delay

• Internetworking architecture Designed and implemented a gateway to interconnect

circuit networks with the Internet Characterized the gateway performance

4

Publications

• Ph.D. dissertation: X. Fang and M. Veeraraghavan, On using circuit-switched

networks for file transfers,” accepted to IEEE Globecom, New Orleans, LA, Nov. 2008.

X. Fang, M. Veeraraghavan, M. E. McGinley, and R. W. Gisiger, “An overlay approach for enabling access to dynamically shared backbone GMPLS networks,” in Proc. of IEEE ICCCN2007, Honolulu, Hawaii, Aug. 2007.

X. Fang and M. Veeraraghavan, “On using a hybrid architecture for file transfers,” Submitted to IEEE Transactions on Parallel and Distributed Systems, 2008.

• MS thesis: M. Veeraraghavan, X. Fang, and X. Zheng, “On the suitability

of applications for GMPLS networks,” in Proc. of IEEE Globecom, San Francisco, CA, Nov. 2006.

X. Fang, X. Zheng, and M. Veeraraghavan, “Improving web performance through new networking technologies,” IEEE ICIW'06, Guadeloupe, French Caribbean, February 23-25, 2006.

5

Outline

• Overview Hypothesis Contributions & Publications

Motivation• Theoretical component:

Design and evaluate algorithms to support file transfers on circuit-switched networks

• Experimental component: Implement and demonstrate architecture for

internetworking circuit-switched networks with the Internet

• Conclusions & Future work6

Motivation

• Why File Transfers on Circuit Networks? Packet switching is considered better than circuit

switching for file transfers Pros: high throughput under light loads Cons:

– Unpredictable delays– Proportional fairness but no temporal fairness

eScience community is using high-speed circuit-switched networks for very large file transfers

Predictable service time (admission control) Temporal fairness: give deference to job seniority

7

Experimental component:Interconnect circuit networks

with the Internet

Call blocking circuit network

Homogeneous Heterogeneous

rate allocation

Designed a gateway

Implemented software

Characterized performance

Analytical model

Analytical model

Simulation model

Analytical model

Simulation model

Fairness issue

Submitted to TPDS

Accepted by Globecom2008

Published in ICCCN2007

Yes


No

Dissertation Organization

Call blocking for circuit network?

Yes

homogeneous rate allocation

Theoretical component:File transfers on

a hybrid architecture

No

Call queueing circuit network

Blocked calls rerouted to the Internet path

For large files, waiting for high-speed circuit s is a better option than being immediately rerouted to Internet path

Hybrid Architecture - Example

9

Yellow nodes: Ciena CD-CI SONET switches

Blue nodes: Juniper T640 IP routers

Courtesy: Rick Summerhill (2006)

Internet2's new Dynamic Circuit (DC) network


with the Internet



rate allocation

Designed a gateway



Analytical model

Analytical model

Simulation model

Analytical model

Simulation model

Fairness issue

Submitted to TPDS



Yes


No


Call blocking for circuit network?

Yes




No



For large files, waiting for high-speed circuits is a better option than being immediately rerouted to Internet path

Call-blocking Circuit Network• Goal: design efficient connection-admission control

(CAC) algorithms Metrics: file-transfer delay and utilization

• Block call if circuit is unavailable; reroute to Internet

• Our focus: What is an appropriate minimum file size?

Serve files sized x > minimum file size, Â, via the circuit network

What is an appropriate circuit rate, r, for a file transfer?

11

Analytical Model

Assumptions:• Single class

homogeneous rate allocation m circuits; per-circuit rate, r=C/m

• Call arrival process: Poisson with rate, ¸0 [Paxson95]

• Call holding times: Pareto distribution [Crovella97]

routing decisionrouting decision

x > Â¸0

¸0 … Link L

capacity C

NN

YY

nn

11

Circuit network

Internet

[Paxson95] V. Paxson and S. Floyd, "Wide area traffic: the failure of Poisson modeling," Networking, IEEE/ACM Transactions on , vol.3, no.3, pp.226-244, Jun 1995[Crovella97] M. E. Crovella and A. Bestavros, Self-Similarity in World Wide Web Traffic: Evidence and Possible Causes, IEEE/ACM Transactions on Networking, 5(6):835--846.

Key Insights Combine M/G/m/m loss model & TCP delay model

Erlang-B formula: input the number of channels, m, & traffic load; output: call blocking probability and utilization

TCP model: bottleneck link rate, round-trip time, packet loss rate [Padhye98]

Two criteria to select Â Delay-based (user-perspective): compare delay estimates across

two paths Utilization (service provider-perspective): make circuit-setup

overhead a small fraction (e.g., 10%) of circuit file-transfer delay Define a metric to quantify mean delay reduction

R = s-1 (E[Ttcp(x)]-E[Tcircuit(x)])¢fX(x)dx

Compute mopt (ropt = C/ mopt) & Âopt that maximize R

1

[Padhye98] J. Padhye, V. Firoiu, D. Towsley, and J. Kurose, “Modeling TCP throughput: A simple modeland its empirical validation,” in Proceedings of the ACM SIGCOMM, Aug. 1998, pp. 303–314.

Key Results

• To maximize R, ropt should be much higher than effective throughput on the Internet path e.g., Internet path: bottleneck link rate = 100 Mb/s,

RTT = 50 ms, packet loss rate = 1%) effective throughput = 1.9 Mb/s Circuit path: link capacity = 10 Gb/s, call-setup delay = 1 sec ) ropt = 63 Mb/s & Âopt = 75 MB

If r = 2 Mb/s ) Â = 4.5 MB) Files of size (4.5 MB, 75MB) will get lower delay on circuits

But, mean delay will increase; hence directed to Internet

• Load sensitive: under low loads, Larger per-call circuit rate, ropt

Larger ropt ) Larger minimum file size, Âopt

Relax utilization criterion to decrease Âopt

• RTT sensitive: Larger ropt & Âopt for short-RTT path 14


with the Internet



rate allocation

Designed a gateway



Analytical model

Analytical model

Simulation model

Analytical model

Simulation model

Fairness issue

Submitted to TPDS



Yes


No


Call blocking for circuit networks?

Yes




No


Blocked calls sent to the Internet path

For large files, waiting for high-speed circuits is a better option than being immediately rerouted to Internet path

Homogeneous Rate Allocation

16

• Key question: how much bandwidth should be allocated for each file transfer so that the system performance is optimized in terms of mean response time at a given effective utilization?

• Metrics: mean response time

• File size: bounded-Pareto distribution

• Call arrival: Poisson

M/G/m queueing model

• Goal: compute per-call circuit rate, ropt (i.e., C /mopt)

• Input: A set of m = {1, 10, 100, 1000} Link capacity C = 10 Gb/s

) r = {10Gb/s, 1Gb/s, 100Mb/s, 10Mb/s} Call setup delay = 1 sec Bounded-Pareto parameters

) the first two moments of service time Traffic load 2 (0, 1)

• Output: Effective utilization: call-setup delay overhead Mean waiting time

17

Numerical Results

Bandwidth allocation should be load sensitive18

19

• Heterogeneous scheme: divide calls into classes based on file size & allocate each class a different-rate circuit

A complete-partitioning system

Heterogeneous Rate Allocation

Analytical model• Multiple separate M/G/m subsystems

Basis for classifying calls: cutoff points, Â1,…, Ân-1?

Bandwidth allocation per subsystem, C1, …, Cn?

Ideal per-call circuit rate for each class, r1, …, rn?

• To compute optimal operating point that minimizes mean response time: Mathematica optimization package e.g., for a 2-class system

Start with an initial value for Â1

Determine C1, C2 & r1, r2

Vary Â1 to study its impact

• Fairness: Fairness ratio: ratio of mean slowdown of 2 classes Slowdown: ratio of waiting time to service requirement

20

21

File-size distribution parameters: Smallest file size: l = 1 MB Largest file size: u = 1 TB Cutoff point: Â = 1000 MB

Homogeneous system is virtually divided into 2 subsystems by Â

Fairness Ratio (small-file to large-file)

• A complete-partitioning heterogeneous scheme treats small files more fairly when compared with a complete-sharing homogeneous scheme

22

Heterogeneous system

Homogeneous system (at all utilization levels)

Simulation Study

• Single-link: simulation results are consistent with analytical results

• Multi-link: fairness study Short-path vs. long-path calls

Work-conserving scheme: unfair to long-path callsProposed conditional-priority scheme: give priority

to long-path calls based on queue occupancy

Small-file vs. large-file callsComplete-partitioning heterogeneous scheme

23

Key Results

• Complete-partitioning heterogeneous rate allocation Large files allocated high-rate circuits Lowers mean response time Treats small files more fairly when compared with

complete-sharing Requires a network management system to monitor

traffic load & dynamically update partitions

• Conditional priority scheme improves the fair treatment between long-path and short-path calls

24


with the Internet



rate allocation

Designed a gateway



Analytical model

Analytical model

Simulation model

Analytical model

Simulation model

Fairness issue

Submitted to TPDS



Yes


No


Call blocking for circuit networks?

Yes




No



For large files, waiting for high-speed circuit s is a better option than being immediately rerouted to Internet path

Experimental Component• Motivation:

It is expensive to deploy a new networking technology on an end-to-end basis

As link speeds increase, high-capacity circuit switches are cheaper than packet switches

Circuit-switched (CS) networks operated in shared mode ) admission control (AC) phase

Connectionless (CL) networks have no admission control phase

So internetworking CL + shared CS is a challenge

• Our solution: gateway that implements all sub-layers of the network layer with data-plane and control-plane (AC)

• Metrics: reliable file transfer, circuit utilization, forwarding rate26

Related Work

• State-of-the-art: IP routers Original purpose: interconnect connectionless networks [Cerf74,

RFC791, Clark88] Connection-oriented networks when used in the Internet are

used only in leased-line mode

• Proposed but not deployed: IP-over-ATM internetworking: Ipsilon's IP switching

Routers have to "guess" which flows are long-lived TCP switching: IP switching with protocol classifier

27[Cerf74] V. G. Cerf and R. E. Kahn, “A protocol for packet network intercommunication,” IEEE Transactions on Communications, vol. 22, no. 5, pp. 637–648, May 1974.[Clark88] D. D. Clark, “The design philosophy of the DARPA Internet protocols,” in SIGCOMM. Stanford, CA: ACM, Aug. 1988, pp. 106–114.

Internetworking Architecture

Circuitsubnetwork

IP-router core subnetwork

R

RRR

CAG CAG

regional network

R

regional network

R

R

R

CAG

Web client Web server

R IP router circuit/VC switchEthernet switch

enterprisenetwork

S

enterprise network

S

S

S R

R

S

CAG Circuit-aware application gateway

RR

Connectionless Connectionless

28

Internetworking Architecture

29

Circuit/subnetwork

IP-router core subnetwork

R

RRR

CAG CAG

regional network

R

regional network

R

R

R

CAG

Web client Web server

R IP router circuit/VC switchEthernet switch

enterprisenetwork

S

enterprise network

S

S

S R

R

S

CAG Circuit-aware application gateway

HTTP/TCP/connectionless IP HTTP/CTCP/circuit

RR

Gateway Design

• Start with an open-source Web proxy software package called Squid

• Data-plane: Base functionality provided by Squid Integrated Circut-TCP (removes Slow Start, receive-side

autotuning)

• Control-plane: Integrated RSVP-TE signaling client module into Squid to initiate circuit setup/release

30

Gateway Design contd.

• Unpredictable rate across connectionless (CL) segments

• But fixed-rate across circuit-switched (CS) segments

• What if these are mismatched?

• Need buffering within gateways

• Buffers are finite: so possibility of losses?

• Squid implementation: back-pressure mechanism; Data not read from incoming TCP buffer if Squid buffer

(controlled by read_ahead_gap) is full Latter is full if outgoing TCP buffer is full

• Leads to circuit utilization problems

• Answer: main memory or disk buffering in gateways + multiplexing on circuits

31

Experimental Hypothesis

A modified version of Squid software can be used as a gateway to interconnect circuit-switched networks and connectionless packet-switched networks for reliable file transfers, and can support an effective throughput of 460 Mb/s when executed on a Linux 2.6.20 host with a 2.8GHz Xeon processor and 1 GB memory.

32

Experimental setup to test if there is buffer overflow

• NIC speeds: CHEETAH NIC (NIC2) = GbE, Internet NIC (NIC1) ¸ 100 Mb/s

• Circuit (zelda1 $ zelda4) rate=155Mb/s, link (zelda4 $ zelda5) rate=1Gb/s

• Control link rate on zelda1 ! zelda2 path to mismatch sending and receiving rates

• The parameter read_ahead_gap controls CAG’s application buffer for each flow, read_ahead_gap = 16 KB (default value)

33

34

CAG zelda1’s forwarding rate CAG zelda1’s CPU and memory usage

CAG zelda1’s receive window size for zelda1 $ zelda4 CTCP connection

• Key results: No packet loss in buffers within

CAGs due to a back-pressure mechanism

Drawback: low circuit utilizatione.g., only 1/155 < 1% for 1 Mb/s bottleneck link rate

Improving Circuit Utilization

• Configured read_ahead_gap: e.g., when read_ahead_gap (for CAG zelda1) = 1 GB, circuit

utilization = 90% for a 1-GB file transfer Problem: unscalable because Squid only uses main memory for

buffering in-transit data

• Disk buffering: used two instances of Squid on a CAG

35

Other Experiments & Analysis

• Measured maximum forwarding rate Stress test by using long flows: 460 ± 4.75 Mb/s

• Measured user-perceived throughput Throughput improvement when circuits replace

congested Internet paths.

• Related the internetworking architecture with the TCP/IP & OSI reference models Fits into the OSI model

36

Conclusions• File transfers on circuit-switched (CS) networks

Advantage relative to packet switching: predictable service time

• Packet switching (PS) better for small file transfers Call setup delay >> Transfer time (link rates ↑, transfer time ↓) Predictability not a concern when absolute delays are low

• Hence hybrid architecture: PS for small; CS for large

Call admission control algorithms designed to be fair across small-file, large-file & across short-path, long-path

37

Considered in routing decision

Not considered

Call blocking √ X

Call queueing X √

Internet path metricsCircuit

network operation

Conclusions contd.

• Designed a gateway called CAG to interconnect connectionless networks with circuit networks CAG implements all sub-layers of the network layer with

data-plane and control-plane (admission control) CAG supports reliable file transfers File transfers need high-speed links on whole path Gradually evolving circuit-switched networks for access

(current bottleneck) will lead to improved performance

38

Future Work

• More sophisticated bandwidth-sharing schemes Currently studied a complete partitioning scheme To avoid sensitivity to network management system

performance as is the case with partitioning

• Hardware-based implementation of CAG with the support of disk buffering for in-transit data Current software implementation could slow down

effective transmission rates

39

Questions from Form G111

41

Thank you!

Questions?

Questions from Form G111 -

Defining the problem

• Has the student stated the problem clearly, provided its motivation, and the requirements for a solution?

• In the context of new optical circuit-switched technologies and new application requirements, how do we support file transfers efficiently on a dynamically shared circuit-switched network and how can we interconnect a circuit network with a connectionless network?

42


Analysis of previous and related work• Theoretical component: file transfers on circuit networks

Packet switching is considered better But circuit switching provides rate guarantees Very large file transfers on optical connection-oriented testbeds

e.g.: ESnet4, NSF DRAGON, CA*net4, UKLight, JGN2, etc. Focus: implementation & inter-domain usage Our work: how much bandwidth to allocate per file transfer

File transfers have not been considered on other circuit/virtual-circuit networks

e.g.: telephone networks, ATM

• Experimental component: interconnect circuit networks with connectionless networks State-of-the-art: IP routers

Original purpose: interconnect connectionless networks Used leased line modes to include circuit networks

Proposed but not deployed: IP switching & TCP switching Our work: gateway that handles service-type mismatch between

connectionless and circuit networks

43


Success criteria

• Has the student adequately defined the measure(s) of success to be used to evaluate the work? Is there a well defined metric with a goal? Does the metric adequately represent the desired success criteria?

• Success criteria Theoretical work: use a hybrid architecture for file transfers

Call blocking circuit network: optimal design parameters to maximize mean delay reduction

Call queueing circuit network: optimal design parameters to minimize mean response time at a given effective utilization

Experimental work: designed an internetworking gateway called CAG CAG supports reliable file transfers Improved circuit utilization Measured maximum forwarding rate of CAG

• Metrics Theoretical work: file-transfer delay, utilization, mean delay reduction,

fairness ratio Experimental work: reliable file transfer, circuit utilization, forwarding rate,

user-perceived throughput44


Solution

• Is the approach taken well executed? Does it appear to be correct? Is the work technically challenging? Does the student utilize appropriate professional standards?

• A combination of analytical, simulation, and experimental methods Call blocking circuit network for file transfers

Analytical model Call queueing circuit network for file transfers

Analytical model Simulation model

An internetworking gateway Software implementation Experimentation and measurements Architecture positioning

45


Innovation and risk

• To what extent is the work innovative? Has the student taken a risk in applying the chosen approach?

• Bandwidth sharing problem on using circuit networks for file transfers has not been studied before

• The problem of internetworking connectionless networks and dynamically shared circuit networks has not been addressed widely (only one previous solution – from the 90s which proved unviable)

46


Broader implications

• Has the student considered the broader implications of the work? Broader implication may include social, economic, political, technical, ethical, business, etc.

• Enable the deployment of high-speed circuit networks at low costs (sharing) to provide predictable-delay services New applications can be created with this type of service

• Integrated with Internet Avoids need for desert-start deployment

47

Background – High-Speed Circuit-Switching

• Data-plane technologies Switching: Time Division Multiplexing (TDM) &

Wavelength Division Multiplexing (WDM) Mapping: to carry Ethernet frames via SONET signals or

WDM lightpaths

• Control plane: Generalized MultiProtocol Label Switched (GMPLS) Three components: signaling, routing, & management Bandwidth sharing mode: immediate-request (IR)

• Equipment examples: SONET switches: Sycamore SN16000 WDM switches: Adva/Movaz RayExpress OADM

48

Layers in OSI reference modelAL: Application LayerTL: Transport Layer

Sublayers of network layer (NL)• SNICF: Subnetwork Independent Convergence Function• SNDCF: Subnetwork Dependent Convergence Function• SNACF: Subnetwork Access Function• SNSF: Subnetwork Switching Function

DLL or L: Data-Link LayerPHY or P: Physical Layer

[ITU X.200] http://www.itu.int/rec/T-REC-X.200-199407-I/en[Callon83] R. E. Callon, "Internetwork protocol,“ Proc of the IEEE, vol. 71, no. 12, pp. 1388-1393, Dec. 1983

Layers in the Internetworking Architecture

50

This internetworking architecture fits into OSI reference model

• File-size distribution: bounded-pareto, BP(®, l, u),

®: shape, l: minimum file size, u: largest file size

• Service time:

• Per-server traffic intensity:

• Effective utilization:

• Mean waiting time:

• Mean response time:

Analytical Model: Homogeneous Rate Allocation

• Each subsystem:

File-size distribution: bounded-pareto, BP(®, Âi-1, Âi),

®: shape, Âi-1 : minimum file size, Âi : largest file size

E[Y j ] = pi ¢ E[Yij]

Call arrival rate:

Capacity:

• Whole system:

Effective utilization:

Mean response time:

Analytical Model: Heterogeneous Rate Allocation

Simulation Results: Multiple-link

53

Model Validation & Verification

• Model validation Our models are for an initial design to support file transfers on circuit networks

No real-world measurements Model validation technique – peer/expert reviews

Real system measurements “available” for input parameters

E.g., real-system measurements for file transfer – Poisson call arrival process– Pareto distribution

• Model verification Compare analytical model results with simulation model results

54

[Jain91] R. Jain, The Art of Computer Systems Performance Analysis: Techniques for Experimental Design, Measurement, Simulation, and Modeling, New York, Wiley-Interscience, 1991.

“Three validation techniques Expert intuition Real system measurements Theoretical results” [Jain91]

“Three aspects of model validation Assumptions Input parameter values and distributions Output values and conclusions” [Jain91]

Related Work – File Transfers on Other Testbeds

• Other testbeds: Large file transfers high per-circuit rate, long holding time Coarse-Grained Sharing (CGS)

• Our interest: Fine-Grained Sharing (FGS) for all files

55

Leased Line CGS FGS TCP/IP

Different bandwidth sharing modes

coarse fine

Circuit-switched networks: Signaling for call setup

Connection setup actions at each switch on the path:1. Parse message to extract parameter values2. Lookup routing table for next hop to reach destination3. Read and update CAC (Connection Admission

Control) table4. Select timeslots on output port5. Configure switch fabric: write entry into timeslot

mapping table6. Construct setup message to send to next hop

56

Host I-A Host

III-B

I

IV V

III

II

ab

c

a

b

c

d

d c

a

b

Connection setup (Dest: III-B; BW: OC1; Timeslot: a, 1)

Dest. Next hop

III-* IV

Routingtable

Connection-Admission Control (CAC)

57The procedure of CAC

Receive a file-transfer request with size x

x > ÂY

reject

N

allocate a circuit with rate rx

rejectaccept

Simple sum:rx < available bandwidth

NYSwitch model

Â: crossover file size rx: allocated bandwidth

CAC

12

N-1

N

¸ Simple sum

Â & rx

Network Management System

configures Â

Design and Implementation

• How does a CAG select the “best” parent? Static configuration based on geographic location of

Web servers using ARIN WHOIS database

• How does a user configure the Web client to use the Web proxy server? Configuring for every request is not user-friendly Instead, use Proxy Auto-Configuration (PAC)

58

File Transfers on Other Circuit/VC Networks

• Has ATM implemented file transfers with a guaranteed service? No.

59

Service classes on the ATM layer Hard QoS for multimedia applications

CBR: voice & VBR: audio No QoS at the ATM level for all other data traffic

ABR & UBR File transfers are served by UBR

No guaranteed bandwidth allocation Loss recovered with ARQ in TCP No effort to maintain flow rate to match VC rate

Analytical Model (cont.)

6060

M/G/m/m loss model Erlang-B: compute call blocking probability, Pb, and utilization, Ub,

given the number of channels, m, and traffic load, ½

The computation of ½:

¸: aggregate call arrival rate offered to the switch 1/¹: mean call holding time

…1

NLink L, capacity CRD

0

RD: routing decisionRD: routing decision

A switch model for file transfers

The Derivation of Offered Traffic Load, ½

6161

Serve files with size x > Â

Original call arrival rate, N¢¸0

Offered traffic load

File size: Pareto distribution

®: shape, k: scale

Mean file sizeCircuit file-transfer delay

Mean call holding time Aggregate offered call arrival rate

Tprop: propagation delay

C/m: per-circuit rate

The Selection of Crossover File Size, Â

6262

Utilization-based, Âu: the mean call-setup delay, E[Tsetup], is

a small fraction of circuit file-transfer delay, Ttransfer(x)

Choose

Delay-based, Âd: compare two delay values

where

e.g., ¯=10

Pb: call blocking probability

Numerical Results - Input Parameters

6363

File size distribution: shape, ®=1.0009, scale, k=1000bytes

Circuit: Link capacity C=10Gbps Original call arrival rate, N¢¸0=1100calls/second

Mean call setup delay, E[Tsetup]=1second Round trip time, RTT=50ms Utilization factor, ¯=10

Internet path Bottleneck link rate, r=100Mbps Packet loss rate, Ploss=1% Round trip time, RTT=50ms

6464

Numerical Results: Impact of Per-circuit Rate on Â

Low per-circuit rateHigh per-circuit rate

Link capacity expressed in channels

Del

ayed

-bas

ed c

ross

over

file

siz

e

Util

izat

ion-

base

d cr

osso

ver

file

size

6565

For m=10, 100, and 1000 (i.e, per-circuit rate is 1Gb/s, 100Mb/s, and 10Mb/s)Âu is the limiting factor Simplifies the computation of Â

Del

ayed

-bas

ed c

ross

over

file

siz

e

Util

izat

ion-

base

d cr

osso

ver

file

size

Numerical Results: Impact of Per-circuit Rate on Â

m=1000m=1000

m=100m=100

6666

Numerical Results: Impact of Per-circuit Rate on File-transfer Delay

File

tra

nsfe

r de

lay

over

circ

uits

or

the

Inte

rnet

m=10, 100, and 1000 $per-circuit rate is 1Gb/s 100Mb/s, & 10Mb/s

(1.2GB)(11.9MB) (118.9MB)

6767

Numerical Results: Impact of Per-circuit Rate on Mean Delay Reduction

68

Design and Implementation

• Gateway: Started with an open-

source Web proxy software package called Squid

Integrated RSVP-TE signaling client module into Squid to initiate circuit set up/release

Integrated Circut-TCP (removes Slow Start, receive-side autotuning)

Added monitoring module to watch circuit usage. Initiate circuit release if idle for time >T

Receive a Web request

Cache miss

Circuit toparent

Fork a process to attempt a circuit setup;

Meanwhile, serve the request via the IP-

router core subnetwork

Y

Serve the request

N

N

Serve the request via the circuit

Y

Experiments to Measure User-perceived Response Time

• Two sets Controllable experiments by loading specific-

size files on a Web server Operational Web sites

• For each set, two tests Direct without proxy CHEETAH proxy: via CAGs but without

caching

69

Experimental Results – 1st SetInternet

CHEETAHSN16000SN16000

NIC1

NIC2wuneng

NIC1

NIC2

zelda1

Web server: zelda2

CAGCAG

Raleigh, NC

Web client: unc-planetlab1

Chapel Hill, NC

Atlanta, GAcircuit

707046.40± 1.70

15.08± 0.55

1 MB 100 MB10 MB100 KB

58.59± 2.3064.64± 3.2113.61± 0.76CHEETAH proxy

16.71± 0.6617.25± 0.5210.70± 0.65Direct

File sizeTest(Mb/s)

direct CHEETAH proxy

unc-planetlab1 zelda2

unc-planetlab1 wuneng

wuneng zelda1 (circuit)

zelda1zelda2

10.77 ms 1.27 ms 8.87 ms 0.23 ms

Experimental Results – 2nd Set

Web server parameters RTT (ms) via the Internet

Bottleneck local RTT

(ms)

file size (MB)

Latencies (s)

direct CHEETAH Proxy

namelocation

kernel.org Carrollton, TX

86 61.6 48 70 33

sourceforge.net Atlanta, GA 32 14.6 113 520 140

Web client

CHEETAH wuneng zelda1

Web serverBallstein.cs.virginia.edu

7171

Background –High-Speed Circuit-Switched Networks

CHEETAH: Circuit-switched High-speed End-to-End Transport ArcHitecture

SN16000: circuit switch 7272

US: DOE’s UltraScience net, CHEETAH, Internet2 Dynamic Circuit network Europe: UKLight (UK), SURFnet (Netherland), VIOLA (Germany), MUPBED Canada: CA*net 4 Japan: JGN

Atlanta, GA

zelda1

zelda2

zelda3

Raleigh, NC

OC192card

ControlCard

GbE/10GbE

card

SN16000

H wukong

Oak Ridge, TN

To Cray X1

zelda4

zelda5

HH

OC192card

ControlCard

GbE/10GbE

card

SN16000

H

HH

OC192card

ControlCard

GbE/10GbE

card

SN16000OC-192 OC-192

Numerical Results for Fixed Per-call Circuit Rates

73

Under high loads (U > 73%), heterogeneous scheme lowers mean waiting time By partitioning, small files do not need to wait for large files to

complete ) small files are treated more fairly

Ph.D. Dissertation presented by Xiuduan Fang Department of Computer Science University of Virginia...

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Transcript of Ph.D. Dissertation presented by Xiuduan Fang Department of Computer Science University of Virginia...