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

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of audio/video applications that use UDP as their main transport + U# h( N1 N- I; S M" w9 J/ rprotocol. Unlike TCP, these

traffic do not respond to congestion signal; i.e., a packet loss. As a 7 a% O6 M7 y! S! v- Eresult, audio/video

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applications may take an unfair share of the network bandwidth and " Q" R; m* x. h3 @( q: ialso cause persistent

congestion. To avoid congestion collapse, the IETF has proposed that . r& V$ N/ Z( haudio/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).

In this assignment, you will simulate n ; O; T) K9 k& v) ?# asources that uses equation based congestion control to

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set their transmission rate. From your simulation, you will determine * K, T; U; ~8 `6 g$ Lwhether 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:

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 time when the first packet is

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 2 V* \6 O F$ E. Penqueue that packet in

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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 packet. Otherwise,

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discard the packet.

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

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next packet will be generated. I.e, t+k, where k is the time interval until the next packet

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arrives.

4. Collect all required statistics.

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}

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In your simulation, collect the (a) queue length over time, (b) & o8 ?0 l# z7 P' X% K2 I8 Iaverage queue length, (c) average

end‐to‐end packet delay, and (d) Jain’s fairness index. Determine the ! y: n- E. u' ieffect of the following

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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;

instead of one packet per‐tic, try k packets, and (vii) z number of new flows arriving at time t .

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Do with sources 9 z D: z. H7 f2 S9 ?" D! Z, dusing a token/leaky bucket to control their transmission rate.

Another difference is that each source has an application that ( C$ _# e* X: y6 sgenerates bursty traffic, where

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 " ~! ?2 j3 K5 f* w4 B! A# vthe 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.

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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

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 9 r5 j$ T: d* \7 e. asource (or all sources

simultaneously) such that congestion does not happen. Note, you must % |: t" l0 ]5 _ lexperiment with

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different k and z . T9 @0 N5 }8 l; n9 B) ^ n2 bvalues 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

Applications, ACM SIGCOMM, May, 2000.

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