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 given the increasing number

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of audio/video applications that use UDP as their main transport $ q- M* f( k$ v$ jprotocol. Unlike TCP, these

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traffic do not respond to congestion signal; i.e., a packet loss. As a M/ c% m7 U$ P* y; b' vresult, 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

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

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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 9 c, W* y( }" G l9 ^whether equation based

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congestion 0 R! S" r* h% T- ~8 v! ycontrol 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.

For each sender, set an initial transmission rate, and determine the 8 g2 c; e, H) Z; x: r7 e; P( ztime when the first packet is

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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 , u* l0 j8 Y" _, P- a+ kenqueue that packet in

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the corresponding receiver’s queue.

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 1 }+ }/ V$ d& }7 ppacket. Otherwise,

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discard the packet.

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3. Determine whether any packet loss rate messages are generated by / P# R' e6 X- r; H1 o( Mreceivers. 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 ( ` Y; s& N+ zuntil 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 effect of the following

factors: (i) increasing source and receiver pairs, (ii) varying N ( J z/ c- P2 K: w: uvalues, (iii) different packet loss

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reporting periods, (iv) loss calculation methods, (v) load p, (vi) 4 T3 V8 O4 S1 i4 p8 w7 \7 brouter’s transmission rate;

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instead of one packet per‐tic, try k packets, and (vii) z ) F$ K$ }' p9 h9 Vnumber of new flows arriving at time t .

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# O8 P n3 K$ R1 u1 o7 P) q Do with sources A0 V( ?! D; }$ [' Fusing 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.

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 ) _6 K$ H+ R& D1 a& wthe ON state. With

probability k, it will transition to the OFF state where it will remain idle. In 3 q# y0 I3 \9 t8 X l2 m7 d* t3 l$ [this state, it has

probability z of moving back to the ON state.

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.

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b. If in state=ON " t( P5 b* K# g4 q1 Q6 GAND 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.

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 0 ^# V; L; s: D4 iexperiment with

different k and z values and determine & M: O1 @+ n% V! N$ J2 ftheir impact on congestion.

Reference

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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