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 ) ~, N* h* g2 n* o$ kprotocol. Unlike TCP, these

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traffic do not respond to congestion signal; i.e., a packet loss. As a # r3 f* e" e* K* L* P2 X J9 uresult, audio/video

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applications may take an unfair share of the network bandwidth and ; X2 ~+ t& V/ T$ aalso cause persistent

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congestion. To avoid congestion collapse, the IETF has proposed that ' P7 s; m9 a" G; B+ Y' laudio/video applications

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 7 c, ^) i$ q* Tequation based congestion control to

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

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congestion 3 P- Y; f4 W6 p) Q$ Z0 J2 @control 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.

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

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 ' R9 C9 m; d6 z& n' xenqueue 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 7 ^$ i" e& V4 a$ O8 _# M, t/ c% m, Rpacket. Otherwise,

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discard the packet.

3. Determine whether any packet loss rate messages are generated by % `& H. D, I' r+ O1 f# k6 \receivers. 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 . |) E5 z& Z* K% Vuntil 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) 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 ; [5 {, u: s) [" o! w6 V* Mvalues, (iii) different packet loss

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reporting periods, (iv) loss calculation methods, (v) load p, (vi) & i9 k3 ^; V3 G" U- ^1 |9 Yrouter’s transmission rate;

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instead of one packet per‐tic, try k packets, and (vii) z ( K4 w* e1 f, l/ gnumber of new flows arriving at time t .

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8 l7 I- D0 Y2 i2 C Do with sources 4 h2 p/ a; [# h" Y' g$ Ausing 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

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

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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:

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.

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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.

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d. If state equals ON, generate a packet.

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 experiment with

different k $ W) Q# c" V+ n9 qand z & J/ ?1 W. E0 H! g( }) u: jvalues and determine their impact on congestion.

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Reference

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

Applications, ACM SIGCOMM, May, 2000.