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
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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

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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 also cause persistent

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congestion. To avoid congestion collapse, the IETF has proposed that . m7 f: H$ h) ?7 ?audio/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 sources that uses equation based congestion control to

set their transmission rate. From your simulation, you will determine whether equation based

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congestion 4 }" c! U `* E+ N( mcontrol is effective in reducing packet loss, and hence congestion.

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The above network can then be simulated as follows:

Initialization

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 X& a0 v4 K3 C7 mtime 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 1 D2 I" n9 |# A9 @) d! A& Zenqueue that packet in

the corresponding receiver’s queue.

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2. IF a sender has a packet to send THEN

‐ Check if the router’s queue is full. If not, enqueue the sender’s & q$ [8 D& p7 T/ e8 M: Fpacket. Otherwise,

discard the packet.

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3. Determine whether any packet loss rate messages are generated by % Q1 U Z8 R: E6 mreceivers. If yes,

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then re‐compute the sender’s transmission rate. Determine the new time 6 Q0 j, {% D, ~4 j, `3 Swhen the

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next packet will be generated. I.e, t+k, where k is the time interval % P8 C1 _) e+ Puntil the next packet

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arrives.

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4. Collect all required statistics.

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}

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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 effect 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) 3 g7 T" F/ }0 @. [! q$ @router’s transmission rate;

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instead of one packet per‐tic, try k packets, and (vii) z number of new flows " d8 ^5 W( q& V! S' d7 c1 ~# jarriving at time t .

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: y: E1 w S& m3 N$ r3 o Do with sources ) d1 Y3 P5 d! ~9 busing a token/leaky bucket to control their transmission rate.

Another difference is that each source has an application that 3 M% Y6 M$ B* Vgenerates 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 W3 R9 `: a, _, ]3 z7 \3 \+ \the ON state. With

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probability k, it will transition to the OFF state where it will remain idle. In @1 l- P! ]) c0 tthis 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

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

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b. If in state=ON AND 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 9 @6 G2 q0 p# K0 i7 bsource (or all sources

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simultaneously) such that congestion does not happen. Note, you must ) k$ \0 n) M- _% }. h! nexperiment with

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different k ( @5 w) K- h( m6 L$ g/ zand z 5 J3 w7 x2 ~0 `1 g! i: gvalues and determine their impact on congestion.

Reference

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S. Floyd, M. Handley, J. Padhye, : S$ E2 p. E( ]# i9 V9 |1 G4 `and J. Widmer (2000) Equation-based Congestion Control for Unicast

Applications, ACM SIGCOMM, May, + w @$ |4 @2 x& o7 F2000.