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 3 J8 j; ?) l- n9 Ugiven the increasing number

of audio/video applications that use UDP as their main transport . @; z7 D- _. x/ {9 ]2 ?protocol. Unlike TCP, these

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

applications may take an unfair share of the network bandwidth and - q- h+ R; n: P/ O- M+ |" c5 Oalso cause persistent

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congestion. To avoid congestion collapse, the IETF has proposed that 8 ?6 N" u0 X2 ]2 C+ d! a+ ^6 naudio/video applications

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

page).

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In this assignment, you will simulate n sources that uses equation based congestion control to

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set their transmission rate. From your simulation, you will determine ( c5 F# Q u3 y7 e& ]+ I0 gwhether equation based

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congestion ( M0 ]5 _+ E6 y: J- O" 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.

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

to be generated.

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 5 g) s/ W- l9 \( n3 U Aenqueue 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 7 Y( b9 Y$ ~: r" c7 fpacket. Otherwise,

discard the packet.

3. Determine whether any packet loss rate messages are generated by 7 c* R3 K! G* A; s: Y1 Freceivers. If yes,

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then re‐compute the sender’s transmission rate. Determine the new time $ R3 o- K. r; ?) D' a, Bwhen 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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}

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In your simulation, collect the (a) queue length over time, (b) ' W1 _2 M3 C3 p8 gaverage queue length, (c) average

end‐to‐end packet delay, and (d) Jain’s fairness index. Determine the : A- N: x/ \0 I& q. Ceffect of the following

factors: (i) increasing source and receiver pairs, (ii) varying N 1 K0 w! R1 P c) K9 e% U8 {values, (iii) different packet loss

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reporting periods, (iv) loss calculation methods, (v) load p, (vi) 8 q- i8 m: {% Z0 o& l! ~router’s transmission rate;

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instead of one packet per‐tic, try k packets, and (vii) z number of new flows ( R0 G/ g* [* d6 Carriving at time t .

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

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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

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probability k, it will transition to the OFF state where it will remain idle. In , I9 j% ^7 j ]) wthis 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:

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.

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b. If in state=ON ) ^8 v# D# L3 Z. NAND 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.

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Design an algorithm to control the token/leaky‐bucket rate of each source (or all sources

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simultaneously) such that congestion does not happen. Note, you must " t U" V+ C7 nexperiment with

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different k and z $ @( L. f0 T8 U* H7 l1 a$ cvalues and determine * H B+ V @2 o$ B& otheir impact on congestion.

Reference

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S. Floyd, M. Handley, J. Padhye, R3 O) _! P+ V7 r2 n1 t. Cand J. Widmer (2000) Equation-based Congestion Control for Unicast

Applications, ACM SIGCOMM, May, 2000.

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