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 given the increasing number

of audio/video applications that use UDP as their main transport 3 a% a2 S. n) E* C9 p- M- s# p/ Zprotocol. Unlike TCP, these

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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 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 3 s8 r! Q/ d4 ~) F7 c8 Vgiven on the next

page).

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In this assignment, you will simulate n sources that uses # k2 R7 s* u& `7 ^equation based congestion control to

set their transmission rate. From your simulation, you will determine # ^# E0 W* _6 N4 k$ q) H+ U- bwhether equation based

congestion ! q4 o$ s; ^5 P6 P3 Vcontrol 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 a; ]$ l' z$ Ctime when the first packet is

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to be generated.

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Body

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FOR t=1 to SIM_TIME DO

{

1. IF the router’s queue is not empty then dequeue a packet, and # C4 Y: E1 j: w( A, }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 5 n( \: R( Z7 } |- D4 Q" jpacket. Otherwise,

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discard the packet.

3. Determine whether any packet loss rate messages are generated by ' Q! B- G: K: N" c. [& ]: Rreceivers. If yes,

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 : n+ I) i3 \, guntil 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) 6 M4 g" l+ J- v, e: Iaverage queue length, (c) average

end‐to‐end packet delay, and (d) Jain’s fairness index. Determine the 4 l: R) j# V/ [; G5 Aeffect 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;

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instead of one packet per‐tic, try k packets, and (vii) z " Y8 U2 Z9 ?: f) W5 a; L# ` xnumber of new flows arriving at time t .

% W4 C. m& b& v; v3 ?' S2 c Do with sources using a token/leaky bucket to control their transmission rate.

Another difference is that each source has an application that 8 K2 ]: L" d% W4 cgenerates bursty traffic, where

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 the ON state. With

probability k, it will transition to the OFF state where it will remain idle. In 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.

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2. At every simulation tic, do

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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 source (or all sources

simultaneously) such that congestion does not happen. Note, you must 0 K8 c' z8 k7 q' Qexperiment with

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

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Reference

S. Floyd, M. Handley, J. Padhye, ) Z" a3 J& i/ iand J. Widmer (2000) Equation-based Congestion Control for Unicast

Applications, ACM SIGCOMM, May, 2000.