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 2 H; s8 Y; X) @5 J* \' J; ggiven the increasing number

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of audio/video applications that use UDP as their main transport % [$ D5 }; W/ s2 x1 B# wprotocol. Unlike TCP, these

traffic do not respond to congestion signal; i.e., a packet loss. As a result, audio/video

applications may take an unfair share of the network bandwidth and 8 ~7 L, H8 ^2 V% d5 H i3 Y' [also cause persistent

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congestion. To avoid congestion collapse, the IETF has proposed that 9 N- E' e2 W# @+ }% g1 e2 I1 z+ Faudio/video applications

use equation based congestion control (see Lecture‐7 and the reference / w2 X" `8 F5 B* W, b5 T p3 Zgiven on the next

page).

In this assignment, you will simulate n 2 I3 Z2 R7 Z" K, w+ U% psources that uses equation based congestion control to

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set their transmission rate. From your simulation, you will determine / X' q3 ]* c. [5 Ewhether equation based

congestion 8 r8 V+ I* ~6 H$ u" Bcontrol 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.

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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

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1. IF the router’s queue is not empty then dequeue a packet, and enqueue that packet in

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 packet. Otherwise,

discard the packet.

3. Determine whether any packet loss rate messages are generated by 6 w( N! M' V7 n( g! Ureceivers. If yes,

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then re‐compute the sender’s transmission rate. Determine the new time # F o3 O3 G- E% g cwhen the

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next packet will be generated. I.e, t+k, where k is the time interval ! Y+ h# d( |( `! n: zuntil 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) . @& `/ }; T0 saverage queue length, (c) average

end‐to‐end packet delay, and (d) Jain’s fairness index. Determine the , r0 W6 F3 ~) [7 leffect of the following

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factors: (i) increasing source and receiver pairs, (ii) varying N * _/ n" A. u; d! i7 m. Jvalues, (iii) different packet loss

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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 4 z. s0 w4 w; Z* b/ e; p; ?number of new flows arriving at time t .

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; x8 Z: {% n* o) ` Do with sources using 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 ( v l# b: ]" J& K& R" pthe ON state. With

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probability k, it will transition to the OFF state where it will remain idle. In 3 s4 a7 e" J- ^- ]6 ^& T8 Nthis 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.

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 : {' I: }7 W0 w: W% D% yAND 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.

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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 : E, R6 y( U! z: Q6 Iexperiment with

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different k ' J# C; V4 H! }/ L5 g6 c6 s2 I# Iand z values and determine 1 o2 K1 A# N7 P+ T: ^* v5 D; `7 ltheir impact on congestion.

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Reference

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S. Floyd, M. Handley, J. Padhye, * T' W, S# K+ v4 C& f- g/ gand J. Widmer (2000) Equation-based Congestion Control for Unicast

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Applications, ACM SIGCOMM, May, 2000.

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