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 6 R3 {( w+ E s. B4 s2 [given the increasing number

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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 ! V; T. P1 c+ aresult, audio/video

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

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congestion. To avoid congestion collapse, the IETF has proposed that 4 s: o2 [- ?# d* ?# R' Kaudio/video applications

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use equation based congestion control (see Lecture‐7 and the reference . L" T6 k! J$ W8 E5 j Q" dgiven on the next

page).

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

set their transmission rate. From your simulation, you will determine whether equation based

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congestion + u/ \- X" {' scontrol is effective in reducing packet loss, and hence congestion.

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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 time when the first packet is

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to be generated.

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.

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2. IF a sender has a packet to send THEN

‐ Check if the router’s queue is full. If not, enqueue the sender’s $ C2 h! A5 P* _2 l+ Vpacket. Otherwise,

discard the packet.

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

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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

arrives.

4. Collect all required statistics.

}

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In your simulation, collect the (a) queue length over time, (b) average queue length, (c) average

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end‐to‐end packet delay, and (d) Jain’s fairness index. Determine the 2 o) e8 U" N1 teffect of the following

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factors: (i) increasing source and receiver pairs, (ii) varying N values, (iii) different packet loss

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reporting periods, (iv) loss calculation methods, (v) load p, (vi) 7 o$ r6 R( ^! _" b p2 ^( Wrouter’s transmission rate;

instead of one packet per‐tic, try k packets, and (vii) z 3 t+ Q. r; J% s+ z( ^number of new flows # x1 Z% y$ y6 _% [arriving at time t .

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Do with sources using a token/leaky bucket to control their transmission rate.

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 * H% l: h) k- @/ j( g! V0 o; nthe ON state. With

probability k, it will transition to the OFF state where it will remain idle. In - R. I9 }4 M* G$ T4 rthis 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.

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b. If in state=ON 4 K+ b7 Z8 Z# U( X( [, {AND R>=k, set state=OFF.

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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 ; s+ x- p0 X# t( @- N7 \4 z$ tsource (or all sources

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

different k 9 l, }8 z: M: f+ e9 S+ S% sand z values and determine their impact on congestion.

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Reference

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

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Applications, ACM SIGCOMM, May, - D$ v2 G$ R. v" A& g! |6 {' i( r' a2000.

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