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 - U9 u* z7 H) Xgiven the increasing number

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of audio/video applications that use UDP as their main transport protocol. Unlike TCP, these

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traffic do not respond to congestion signal; i.e., a packet loss. As a ' ^( Y \+ Z8 A' I: m% v1 Sresult, audio/video

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 2 {# d$ q' m* N& M& U& a v9 ^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 # j; A0 ^7 P8 ~2 E3 Wsources 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 control 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

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 ' I& \% K- @3 k% etime when the first packet is

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to be generated.

Body

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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 5 o1 e4 e; z7 q' wenqueue that packet in

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the corresponding receiver’s queue.

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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 # y3 V* l" n# \6 P" u6 |* }packet. Otherwise,

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discard the packet.

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

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 / h; w) V! l' a. ?until the next packet

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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

end‐to‐end packet delay, and (d) Jain’s fairness index. Determine the 4 {9 l. A, \2 K4 o4 ueffect of the following

factors: (i) increasing source and receiver pairs, (ii) varying N ! c0 O6 R- R; ]4 bvalues, (iii) different packet loss

reporting periods, (iv) loss calculation methods, (v) load p, (vi) : @# A" X" p: [$ k2 g; E: ^+ K, O$ krouter’s transmission rate;

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instead of one packet per‐tic, try k packets, and (vii) z number of new flows 8 z7 b3 ?8 k' Aarriving at time t .

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b! L( V/ W1 b- v: e% u Do with sources : l! {+ k; b/ musing 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 * c4 i" {7 E: q) c% Tthe 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.

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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.

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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 2 @8 M& c: w/ Y3 @0 z6 r% Gsource (or all sources

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simultaneously) such that congestion does not happen. Note, you must , j0 }+ d: R% jexperiment with

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

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Applications, ACM SIGCOMM, May, 2000.

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