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 ) V+ ^8 O: J7 mgiven the increasing number

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

traffic do not respond to congestion signal; i.e., a packet loss. As a result, audio/video

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applications may take an unfair share of the network bandwidth and / \) }$ e* k$ f' a3 ~4 f5 _also cause persistent

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

use equation based congestion control (see Lecture‐7 and the reference 1 V0 q" u9 O: J% V/ o/ Egiven on the next

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page).

In this assignment, you will simulate n 1 N, x" s2 o9 {1 Z$ n+ bsources that uses equation based congestion control to

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set their transmission rate. From your simulation, you will determine ) S* D+ C2 r( A) ?0 [" a, h( awhether equation based

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congestion ) L; w# p' `/ v9 O7 S5 ccontrol is effective in reducing packet loss, and hence congestion.

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The above network can then be simulated as follows:

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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.

Body

FOR t=1 to SIM_TIME DO

{

1. IF the router’s queue is not empty then dequeue a packet, and enqueue that packet in

the corresponding receiver’s queue.

2. IF a sender has a packet to send THEN

‐ Check if the router’s queue is full. If not, enqueue the sender’s packet. Otherwise,

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discard the packet.

3. Determine whether any packet loss rate messages are generated by receivers. If yes,

then re‐compute the sender’s transmission rate. Determine the new time 0 y7 ~6 m" K- H9 S3 Ywhen the

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

arrives.

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4. Collect all required statistics.

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}

In your simulation, collect the (a) queue length over time, (b) ; p }: @) \0 V/ _5 g6 b# Caverage queue length, (c) average

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end‐to‐end packet delay, and (d) Jain’s fairness index. Determine the effect of the following

factors: (i) increasing source and receiver pairs, (ii) varying N values, (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 ( u( h' O, I4 }/ g+ j- uarriving at time t .

{( K$ l; C+ r* a Do with sources using a token/leaky bucket to control their transmission rate.

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Another difference is that each source has an application that generates 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 5 L- k' H, }# q y' L0 E$ Kthis 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.

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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.

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Design an algorithm to control the token/leaky‐bucket rate of each 1 o p- n5 P) C/ e+ a) Nsource (or all sources

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

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different k : W) X% A9 {+ f% tand z ' T# W* t- K* b+ Yvalues 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, 8 o. {8 G0 ^8 M8 X* w: {2000.

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