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 protocol. Unlike TCP, these

traffic do not respond to congestion signal; i.e., a packet loss. As a * f% ?# F8 U& A$ L% L) T' _result, audio/video

applications may take an unfair share of the network bandwidth and 9 E" F( r7 @. f5 j* r; D9 Nalso cause persistent

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congestion. To avoid congestion collapse, the IETF has proposed that ( i9 S" j. Z* f7 z0 n! P0 Faudio/video applications

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 sources that uses 7 q2 X% E$ q& lequation 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.

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 4 N6 U1 ` z# k" F4 A: N' F7 Vtime 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

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{

1. IF the router’s queue is not empty then dequeue a packet, and & m# j! o2 S7 T4 [2 b0 e3 Nenqueue 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 packet. Otherwise,

discard the packet.

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 1 l; E5 C" t; l9 pwhen the

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next packet will be generated. I.e, t+k, where k is the time interval until 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) ! Y" v8 r& p) W: D2 u' l4 W, vaverage queue length, (c) average

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 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 % u' Y7 h% q( o \6 f; ]9 ynumber of new flows 5 g* C* m$ N- {7 garriving at time t .

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Do with sources using a token/leaky bucket to control their transmission rate.

Another difference is that each source has an application that & L! g, V0 L# k- R8 M0 |- Sgenerates bursty traffic, where

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multiple packets arrive in consecutive time intervals.

To generate bursty traffic, use the following method:

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

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probability z of moving back to the ON state.

The pseudo‐code is as follows:

1. Start at a random state: ON/OFF.

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 5 H. T; z$ n, X( b# hAND 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

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simultaneously) such that congestion does not happen. Note, you must 9 M. M* m2 U" E5 m$ r4 Qexperiment with

different k 1 B: q# T, h- j/ oand z values and determine their impact on congestion.

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Reference

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S. Floyd, M. Handley, J. Padhye, 1 X1 b3 L% Z% y9 cand J. Widmer (2000) Equation-based Congestion Control for Unicast

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Applications, ACM SIGCOMM, May, 2000.

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