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 ( T. f$ H# q* u% [given the increasing number

of audio/video applications that use UDP as their main transport 3 q2 ^- a ~$ p; s8 U# gprotocol. 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 & r% h9 ^& X0 L# j% T1 Ialso cause persistent

congestion. To avoid congestion collapse, the IETF has proposed that audio/video applications

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use equation based congestion control (see Lecture‐7 and the reference 6 p1 V. V7 z, Y7 @) q! U+ Fgiven on the next

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page).

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In this assignment, you will simulate n ) Y9 N, ?1 U/ [9 P8 w- A2 ~ j4 A1 Ksources that uses & F1 p4 s$ F; gequation 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 4 }$ `' g! T) T- U ?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

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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

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

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the corresponding receiver’s queue.

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 2 L+ {$ J! ]" K' R5 u. fpacket. 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 9 m8 u4 t1 A( V% s9 K1 i3 gwhen the

next packet will be generated. I.e, t+k, where k is the time interval 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 : i6 ?. x- R' V$ @! X% Ceffect of the following

factors: (i) increasing source and receiver pairs, (ii) varying N values, (iii) different packet loss

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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 # A4 t: [% y5 F$ Bnumber of new flows / z, ^- e8 Y+ K0 A4 E* h' Uarriving at time t .

Do with sources ; m4 N+ @ S4 C" C# L+ h* m& Lusing 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.

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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 ( z3 ^5 N+ X8 ?. F' nthe 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:

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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.

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.

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 ; {- z7 Z: T0 N: S* g) ]% Mexperiment with

different k and z / Q, h& s' c, p# p9 X6 _* ~values and determine their impact on congestion.

Reference

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S. Floyd, M. Handley, J. Padhye, 4 Y7 h0 g1 X- J6 {+ g9 Xand J. Widmer (2000) Equation-based Congestion Control for Unicast

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Applications, ACM SIGCOMM, May, 2000.

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