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
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内容如下

The risk of congestion collapse on the Internet is becoming a reality * i1 A3 C4 v4 Q9 }given the increasing number

of audio/video applications that use UDP as their main transport ( }; f8 m/ z4 \protocol. Unlike TCP, these

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

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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 audio/video applications

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use equation based congestion control (see Lecture‐7 and the reference . h2 g: I. d8 v; ]; [5 Dgiven on the next

page).

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In this assignment, you will simulate n sources that uses . I' i& s9 l7 E# S+ ]4 dequation based congestion control to

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set their transmission rate. From your simulation, you will determine 5 w+ D0 B( r0 Swhether equation based

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

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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 3 ?/ Y( g# Q* I" N, [1 q8 ~enqueue that packet in

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 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,

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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 + L/ `& D: \* U$ \' u3 iuntil 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

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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 $ |& \. k- `' z& H4 r- }3 Rvalues, (iii) different packet loss

reporting periods, (iv) loss calculation methods, (v) load p, (vi) 6 \2 T1 } f& s1 ~' T# H3 G7 Jrouter’s transmission rate;

instead of one packet per‐tic, try k packets, and (vii) z ) F( `0 [6 I; W! |' H( k) X7 N+ tnumber of new flows # S( R# L& d8 N0 i8 v( U" ~arriving at time t .

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Do with sources " N4 M I# m2 L' \0 e9 M% b( r1 R7 Y" Z( ^using a token/leaky bucket to control their transmission rate.

Another difference is that each source has an application that 9 k( z) @( Q9 n' fgenerates 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 the ON state. With

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probability k, it will transition to the OFF state where it will remain idle. In / \0 Q4 Z2 k' }, s$ e6 _$ p7 Cthis state, it has

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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.

2. At every simulation tic, do

a. Select a random number R in 0<= R <=1.

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b. If in state=ON : f5 E( Q2 _' |. b% B7 C/ E9 pAND 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.

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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 experiment with

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different k ' e( L* v+ W- q5 `6 z/ P* xand z values and determine their impact on congestion.

Reference

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S. Floyd, M. Handley, J. Padhye, a [0 ~6 J4 q" N& t) ~and J. Widmer (2000) Equation-based Congestion Control for Unicast

Applications, ACM SIGCOMM, May, 2000.

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