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 ; a- e3 r; t, d2 M; E7 Hgiven the increasing number

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of audio/video applications that use UDP as their main transport 3 B% P- o3 s2 Q* C( }protocol. Unlike TCP, these

traffic do not respond to congestion signal; i.e., a packet loss. As a 2 _; L, W0 D% Q$ C" @9 g. w/ P' W) ~' oresult, audio/video

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applications may take an unfair share of the network bandwidth and - b& u1 U& z, d$ f salso cause persistent

congestion. To avoid congestion collapse, the IETF has proposed that # n o, X( o- j, V5 p7 v" H# r% |audio/video applications

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use equation based congestion control (see Lecture‐7 and the reference % y% d6 m# b2 z6 U7 p) ]9 |given on the next

page).

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In this assignment, you will simulate n * U8 S6 y' n% T. v6 r3 S# tsources that uses equation based congestion control to

set their transmission rate. From your simulation, you will determine % S" u0 u! @7 |) `6 V( x+ lwhether equation based

congestion - S* V6 _7 f/ k( ?, Pcontrol 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.

For each sender, set an initial transmission rate, and determine the & U# W% D! |0 x+ p) |time when the first packet is

to be generated.

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Body

FOR t=1 to SIM_TIME DO

{

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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 0 V7 R( [6 b/ r: Bpacket. Otherwise,

discard the packet.

3. Determine whether any packet loss rate messages are generated by : d. F. }1 T+ p; m; P: U2 Rreceivers. 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 ' [0 W# g3 L/ I, J6 [% E; funtil the next packet

arrives.

4. Collect all required statistics.

}

In your simulation, collect the (a) queue length over time, (b) |6 y" v$ s4 _average 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 5 B: P. C" ]% w! [* ]arriving at time t .

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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 2 C* v, }2 e1 Q& \8 F# xgenerates bursty traffic, where

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multiple packets arrive in consecutive time intervals.

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 4 F- N7 Z8 p6 y, ]1 y* B4 ]. mthe ON state. With

probability k, it will transition to the OFF state where it will remain idle. In ; O& ?2 U9 d( i t6 W! ythis state, it has

probability z of moving back to the ON state.

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 AND R>=k, set state=OFF.

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

d. If state equals ON, generate a packet.

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Design an algorithm to control the token/leaky‐bucket rate of each ' T' M5 [. N, q v& s/ k# \source (or all sources

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

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

Reference

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

Applications, ACM SIGCOMM, May, . F1 q% A5 e4 E/ H, S/ d8 j2000.