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
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The risk of congestion collapse on the Internet is becoming a reality 4 g8 u$ f5 X4 m# s* ~1 `9 `given the increasing number

of audio/video applications that use UDP as their main transport protocol. Unlike TCP, these

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traffic do not respond to congestion signal; i.e., a packet loss. As a 9 a" \8 }. T; U( `result, 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

use equation based congestion control (see Lecture‐7 and the reference given on the next

page).

In this assignment, you will simulate n 3 X% T1 I# J Z" p0 ysources that uses 2 R, \9 L% S" ]9 ^equation based congestion control to

set their transmission rate. From your simulation, you will determine 3 s5 ?- }2 @3 N% Swhether equation based

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congestion control is effective in reducing packet loss, and hence congestion.

The above network can then be simulated as follows:

Initialization

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 ' e# W, ~8 ]; ?; M% ?time when the first packet is

to be generated.

Body

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FOR t=1 to SIM_TIME DO

{

1. IF the router’s queue is not empty then dequeue a packet, and % `. k. z- q9 Y. A( Benqueue that packet in

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the corresponding receiver’s queue.

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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 ; S: c% q; {* F5 j' n/ ^packet. Otherwise,

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discard the packet.

3. Determine whether any packet loss rate messages are generated by # k7 j0 w. @! b5 v6 i$ G+ lreceivers. If yes,

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

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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) 2 L1 ^! i W+ x0 Q ^; e# o5 uaverage queue length, (c) average

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end‐to‐end packet delay, and (d) Jain’s fairness index. Determine the # P- x% e" S+ Beffect of the following

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factors: (i) increasing source and receiver pairs, (ii) varying N 8 ?. d: X( r+ a D* A) T( evalues, (iii) different packet loss

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 number of new flows 8 O- C; N5 a3 r& I3 T! Y3 darriving at time t .

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% {4 U0 K+ X# K Do with sources * P7 Y! R# `0 F4 G/ e: Eusing a token/leaky bucket to control their transmission rate.

Another difference is that each source has an application that 9 i% t) J* O# M2 x+ ngenerates bursty traffic, where

multiple packets arrive in consecutive time intervals.

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To generate bursty traffic, use the following method:

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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.

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2. At every simulation tic, do

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

b. If in state=ON , g* @$ q. x( Y# _. D4 tAND R>=k, set state=OFF.

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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 source (or all sources

simultaneously) such that congestion does not happen. Note, you must # K+ p. T7 U$ E5 i% Hexperiment with

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different k and z values and determine their impact on congestion.

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Reference

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S. Floyd, M. Handley, J. Padhye, and J. Widmer (2000) Equation-based Congestion Control for Unicast

Applications, ACM SIGCOMM, May, 2000.

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