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

of audio/video applications that use UDP as their main transport ( g$ v; A" ^) B& rprotocol. Unlike TCP, these

* R( j0 \5 F Y' L0 p; g

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 ) {1 f/ ~& l; falso cause persistent

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

use equation based congestion control (see Lecture‐7 and the reference ( V( [/ a8 | O, t% I3 }# Hgiven on the next

4 G! O9 O) P* d7 r8 a; p6 S

page).

In this assignment, you will simulate n sources that uses . g. G; ~( R7 A4 Sequation based congestion control to

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

4 g) g/ {7 P( }% L4 u" i }- G. B5 [

congestion & ~2 E: ^. E9 X) [& i& hcontrol is effective in reducing packet loss, and hence congestion.

% D/ D; O8 I, }7 @: [

The above network can then be simulated as follows:

Initialization

4 g$ Q$ v2 I% {9 y3 A% b& Z

Set the router’s queue size to N, meaning it can hold up to N packets.

+ V. Q" X" R% a

For each sender, set an initial transmission rate, and determine the time when the first packet is

to be generated.

; |3 I( H) D/ H

Body

FOR t=1 to SIM_TIME DO

% ]) ]7 z+ U' |- a% c$ J

{

- R$ A! R, |( a0 }/ Y

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

the corresponding receiver’s queue.

2. IF a sender has a packet to send THEN

1 N3 I& _5 D/ }; C1 h1 l

‐ Check if the router’s queue is full. If not, enqueue the sender’s ) t5 U* Y! [- U2 q6 e Z0 ^- q0 Tpacket. Otherwise,

discard the packet.

$ i! P* w# k& E2 S

3. Determine whether any packet loss rate messages are generated by $ S6 y5 J" Y, o2 Zreceivers. If yes,

then re‐compute the sender’s transmission rate. Determine the new time when the

next packet will be generated. I.e, t+k, where k is the time interval until the next packet

& F# v% e" [! `- H# w4 T

arrives.

4. Collect all required statistics.

" r7 S6 P- [1 \# q8 K" [, r

}

9 d1 o/ v! }' y+ y2 f

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 . L8 {/ S6 F1 x; W- e1 Ueffect of the following

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

, |! _+ F. ^* E4 m

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 number of new flows arriving at time t .

* f8 B% {0 `# z- n$ ]

' z1 d. q6 h& e( V/ |& b/ d: @ Do with sources 8 H1 B4 x6 O2 ` ousing a token/leaky bucket to control their transmission rate.

6 _6 p8 H* u9 C: V' A: G3 e: H' U) c$ s/ `

Another difference is that each source has an application that # E# U+ @. a; _; N5 F r, @generates bursty traffic, where

2 t- a% g' {) F8 X; D1 |

multiple packets arrive in consecutive time intervals.

& `6 p" F) b1 O# s* N6 ]

To generate bursty traffic, use the following method:

# w$ `: }9 J, O. P0 Q

a/ T" z9 F3 t; O2 I: b) O/ _

$ c' W e3 i( {) X4 \& ~

In the diagram above, an application generates a packet when it is in the ON state. With

. ^' A8 [; ^9 V! h# T, J" {: M, r

probability k, it will transition to the OFF state where it will remain idle. In this state, it has

0 s6 p, l* G$ s" x

probability z of moving back to the ON state.

( E1 v& M" j/ j& V- V0 l

The pseudo‐code is as follows:

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

P B) J& T" q4 L

2. At every simulation tic, do

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

b. If in state=ON * ]8 }5 o/ I% kAND R>=k, set state=OFF.

6 Z! G' a& b0 x# P8 J- U

c. If in state=OFF AND R>z, set state=ON.

* u6 V5 P9 w6 a" J" X b5 o

d. If state equals ON, generate a packet.

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 experiment with

different k and z values and determine their impact on congestion.

Reference

& ]' w6 p( F) N% R% j

S. Floyd, M. Handley, J. Padhye, / Y1 G1 w' r# L/ N% Jand J. Widmer (2000) Equation-based Congestion Control for Unicast

Applications, ACM SIGCOMM, May, 2000.

5 k2 H" O. t, {4 z& L" |: n) R

2 ~4 O( z2 }$ G- P9 \0 G