1

MaxNet and TCP Reno/RED on mice traffic

Khoa Truong Phan

Ho Chi Minh city University of Technology (HCMUT)

Faculty of Computer Science and Engineering – HCMUT 2

Outline

Introduction Overview of TCP Congestion Control TCP Reno/RED and MaxNet TCP Experiment and Evaluation

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Introduction

Figure 1. Traffic jam

→ Traffic on the Internet will be like this if we don’t have an efficient mechanism to avoid congestion.

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Overview of TCP Congestion ControlC

ongest

ion

co

llapse

TC

P V

egas

1986 1988

TC

P

Tahoe

1990 1993 1996 2003

TC

P

Reno

TC

P

New

Ren

o

FAST

TC

P

2006

Maxn

et

TC

P

Figure 2. History of TCP Congestion Control Algorithms

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ACK packets`

Data packets

TCP receiverTCP sender

P P

p1 p2

P’’ PP’

Router Router

Source compute rate to transmit

Link mark/drop packets

P’’=P’+ P1 P=P’’+ P2

P’ P’’

PPP

Ra

te

P= ∑Pi

Sink sends ACK to source

Overview of TCP Congestion Control (cont)

Figure 3. TCP Congestion Control model

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TCP Reno

Figure 4. Demand function of TCP Reno

AIMD (Additive Increase Multiplicative Decrease) mechanism:

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TCP Reno (cont)

Figure 5. Operation mode of TCP Reno

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RED router

(1) (2)(3)

bmin bmax

2bmax

RED router defines two thresholds in the buffer: bmin and bmax. The probability of marking/dropping (p) as follows:

min

min max

max

0 (1)

0 1 2 (2)

1 2 (3)

if b b

p x if b b b

if b b

Figure 6. Operation mode of RED router

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TCP Reno/RED

( )ix t

( )1( 1) ( ) ( ). 1 ( ) . ( ). ( ).

( ) 2i

i i i i i ii

w tw t w t x t p t x t p t

w t

Assuming that sending rate at source is and router drops the packets at the probability of . Every drop packet causes a negative ACK.

Based on AIMD, source increases window size by 1/w for each positive ACK and decreases window size by half for each negative ACK.

ip

At equilibrium, window size adjustment equal to zero

0 20

2( ) 0

2ii

p tw

From the dropping scheme of RED, each source always have backlog at least at one router.

Window size adjustment:

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TCP Reno/RED (cont)

Elephant traffic

Mice traffic

RED router RED router

Figure 7. Queuing delay of RED router

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MaxNet TCP

Source Destination Link 2 Link N Link 1

Si p2 p1 pN

Max

( ) /max( ) iq t Tx t x e

( )( 1) ( ) . l l

l ll

y t Cp t p t dt

C

Source:

Router:

Figure 8. Operation mode of TCP Reno

Demand function:

µ < 100%

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MaxNet TCP (cont)

Figure 9. Operation mode of MaxNet TCP

MaxStart

Figure 10. Queuing delay of RED router

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Experiment

Figure 11. Experiment test bed

Pentium IV PCs (CPU 1.8GHz, 512MB RAM) are used

Dummynet router is used to configured end-to-end delay at 20ms

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Experiment (cont)

Monitoring the queue at MaxNet router and Reno/RED router

Figure 13(a). Queue at MaxNet router Figure 13(b). Queue at Reno/RED router

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Experiment (cont)

Response time of HTTP connections in MaxNet and Reno/RED

00.10.20.30.40.50.60.70.80.9

1

0

45 90

135

180

225

270

315

360

response time

cum

ulat

ive

prob

abili

ty

Reno/REDMaxNet

Figure 14. Response time of HTTP in Reno/RED vs. MaxNet

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Experiment (cont)

Figure 12(a). 1 FTP and 50 HTTP connections

Figure 12(a). 1 FTP and 100 HTTP connections

Impact of new HTTP connections on throughput of elephant traffic Reno/RED and MaxNet

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Conclusions

MaxNet clears buffer while Reno/RED always keeps a backlog in routers. MaxNet has shorter response time for mice traffic than Reno/RED. Arrival mice flows cause packet loss which degrades the throughput

of elephant traffic. MaxStart mechanism of MaxNet, using multi-bit signaling, controls

mice flows to the target rate more quickly than TCP Reno.

For using MaxNet, source hosts, intermediate routers and destination hosts need to be upgraded.

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References

MaxNet homepage:

www.netlab.caltech.edu/maxnet Duc Nguyen, Jidong Wang, Lachlan L. H. Andrew and Sammy Chan,

“MaxNet: A More Efficient Max-min Fair Allocation Scheme”, in Proc. Intl. Teletraffic Congress-19, Beijing China, 2005.

Bartek Wydrowski, Lachlan L.H. Andrew, Moshe Zukerman, "MaxNet: A Congestion Control Architecture for Scalable Networks",IEEE Communications Letters, vol. 7, no. 10 , Oct. 2003, pp. 511 -513.

Bartek Wydrowski, Lachlan L.H. Andrew, Iven M. Y. Mareels, "MaxNet: Faster Flow Control Convergence", NETWORKING 2004: 588-599.

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THANK YOU!

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Demand function of MaxNet

i i i

i i

D x

q

( ) /max( ) iq t Tx t x e→

Achieve Max-min fairness

Stability

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MaxMin Fairness

MaxMin fairness allocation

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Fairness bandwidth of MaxNet vs. Reno

MaxNet TCP Reno

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Elephant traffic MaxNet vs. TCP Reno

MaxNet

Reno

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Throughput of MaxNet

Throughput of MaxNet

Throughput of Reno