高酬matlab编程救助（能做的高手请与我联系QQ 346719984）

cherrielee18

在network 中 如何用token bucket to control packet transmission rate.
编程序后做图表分析
能做的高手请与我联系QQ 346719984

内容如下

The risk of congestion collapse on the Internet is becoming a reality ! ~- ~7 m% Y, }( S- d$ Bgiven the increasing number

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of audio/video applications that use UDP as their main transport & Y! _$ [) I! qprotocol. Unlike TCP, these

traffic do not respond to congestion signal; i.e., a packet loss. As a c; Y; D7 v, f7 [; j/ zresult, audio/video

applications may take an unfair share of the network bandwidth and also cause persistent

congestion. To avoid congestion collapse, the IETF has proposed that audio/video applications

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use equation based congestion control (see Lecture‐7 and the reference ( p$ w7 C+ R2 n6 s' \' X1 xgiven on the next

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page).

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In this assignment, you will simulate n sources that uses 8 q2 p" n1 t6 `( Oequation based congestion control to

set their transmission rate. From your simulation, you will determine + \- U" d- R0 y: |) C. qwhether equation based

congestion 2 a/ b* i% A' p% P* u: h- Qcontrol is effective in reducing packet loss, and hence congestion.

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The above network can then be simulated as follows:

Initialization

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Set the router’s queue size to N, meaning it can hold up to N packets.

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For each sender, set an initial transmission rate, and determine the time when the first packet is

to be generated.

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Body

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FOR t=1 to SIM_TIME DO

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{

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1. IF the router’s queue is not empty then dequeue a packet, and : R; ?. P, d; P* u0 Kenqueue that packet in

the corresponding receiver’s queue.

2. IF a sender has a packet to send THEN

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‐ Check if the router’s queue is full. If not, enqueue the sender’s 7 m) b3 x5 v1 Hpacket. Otherwise,

discard the packet.

3. Determine whether any packet loss rate messages are generated by & s" L2 {. y" E( N. mreceivers. If yes,

then re‐compute the sender’s transmission rate. Determine the new time when the

next packet will be generated. I.e, t+k, where k is the time interval until the next packet

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arrives.

4. Collect all required statistics.

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In your simulation, collect the (a) queue length over time, (b) ; {5 m1 u; |; W) ~: R* @- Baverage queue length, (c) average

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end‐to‐end packet delay, and (d) Jain’s fairness index. Determine the 4 ~% Y! E9 V4 H5 veffect of the following

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factors: (i) increasing source and receiver pairs, (ii) varying N + F( r+ ^& A2 \( P1 Cvalues, (iii) different packet loss

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reporting periods, (iv) loss calculation methods, (v) load p, (vi) router’s transmission rate;

instead of one packet per‐tic, try k packets, and (vii) z ' d" y u) F7 L' @" S) Cnumber of new flows arriving at time t .

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Do with sources 7 J6 i' q- f! R7 d3 q. jusing a token/leaky bucket to control their transmission rate.

Another difference is that each source has an application that / q# h2 p, ]! h% sgenerates bursty traffic, where

multiple packets arrive in consecutive time intervals.

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To generate bursty traffic, use the following method:

In the diagram above, an application generates a packet when it is in the ON state. With

probability k, it will transition to the OFF state where it will remain idle. In this state, it has

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probability z of moving back to the ON state.

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The pseudo‐code is as follows:

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1. Start at a random state: ON/OFF.

2. At every simulation tic, do

a. Select a random number R in 0<= R <=1.

b. If in state=ON AND R>=k, set state=OFF.

c. If in state=OFF AND R>z, set state=ON.

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d. If state equals ON, generate a packet.

Design an algorithm to control the token/leaky‐bucket rate of each J$ V% W/ D* d/ |' Y% Y* y/ fsource (or all sources

simultaneously) such that congestion does not happen. Note, you must experiment with

different k ) }- M6 z3 p$ H$ B* sand z # B4 k- L5 [8 _" w5 Dvalues and determine their impact on congestion.

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Reference

S. Floyd, M. Handley, J. Padhye, y2 L' |5 A$ Q6 X: T! Gand J. Widmer (2000) Equation-based Congestion Control for Unicast

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Applications, ACM SIGCOMM, May, ; u- i% R, x7 P ^8 D% i2000.

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