高酬matlab编程救助（能做的高手请与我联系QQ 346719984）

cherrielee18 发表于 2008-5-6 07:42

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<op></op>
of audio/video applications that use UDP as their main transport
protocol. Unlike TCP, these<op></op>
traffic do not respond to congestion signal; i.e., a packet loss. As a
result, audio/video<op></op>
applications may take an unfair share of the network bandwidth and
also cause persistent<op></op>
congestion. To avoid congestion collapse, the IETF has proposed that
audio/video applications<op></op>
use equation based congestion control (see Lecture‐7 and the reference
given on the next<op></op>
page).<op></op>
In this assignment, you will simulate n
sources that uses
equation based congestion control to<op></op>
set their transmission rate. From your simulation, you will determine
whether equation based<op></op>
congestion
control is effective in reducing packet loss, and hence congestion.<op></op>
 
The above network can then be simulated as follows:<op></op>
Initialization<op></op>
Set the router’s queue size to N, meaning it can hold up to N packets.<op></op>
For each sender, set an initial transmission rate, and determine the
time when the first packet is<op></op>
to be generated.<op></op>
Body<op></op>
FOR t=1 to SIM_TIME DO<op></op>
{<op></op>
1. IF the router’s queue is not empty then dequeue a packet, and
enqueue that packet in<op></op>
the corresponding receiver’s queue.<op></op>
2. IF a sender has a packet to send THEN<op></op>
‐ Check if the router’s queue is full. If not, enqueue the sender’s
packet. Otherwise,<op></op>
discard the packet.<op></op>
3. Determine whether any packet loss rate messages are generated by
receivers. If yes,<op></op>
then re‐compute the sender’s transmission rate. Determine the new time
when the<op></op>
next packet will be generated. I.e, t+k, where k is the time interval
until the next packet<op></op>
arrives.<op></op>
4. Collect all required statistics.<op></op>
}<op></op>
In your simulation, collect the (a) queue length over time, (b)
average queue length, (c) average<op></op>
end‐to‐end packet delay, and (d) Jain’s fairness index. Determine the
effect of the following<op></op>
factors: (i) increasing source and receiver pairs, (ii) varying N
values, (iii) different packet loss<op></op>
reporting periods, (iv) loss calculation methods, (v) load p, (vi)
router’s transmission rate;<op></op>
instead of one packet per‐tic, try k packets, and (vii) z
number of new flows
arriving at time t .<op></op>
<op>
</op>

Do with sources
using a token/leaky bucket to control their transmission rate.<op></op>
Another difference is that each source has an application that
generates bursty traffic, where<op></op>
multiple packets arrive in consecutive time intervals.<op></op>
To generate bursty traffic, use the following method:<op></op>
<op>
</op>
In the diagram above, an application generates a packet when it is in
the ON state. With<op></op>
probability k, it will transition to the OFF state where it will remain idle. In
this state, it has<op></op>
probability z of moving back to the ON state.<op></op>
The pseudo‐code is as follows:<op></op>
1. Start at a random state: ON/OFF.<op></op>
2. At every simulation tic, do<op></op>
a. Select a random number R in 0<= R <=1.<op></op>
b. If in state=ON
AND R>=k, set state=OFF.<op></op>
c. If in state=OFF AND R>z, set state=ON.<op></op>
d. If state equals ON, generate a packet.<op></op>
Design an algorithm to control the token/leaky‐bucket rate of each
source (or all sources<op></op>
simultaneously) such that congestion does not happen. Note, you must
experiment with<op></op>
different k
and z
values and determine
their impact on congestion.<op></op>
Reference<op></op>
S. Floyd, M. Handley, J. Padhye,
and J. Widmer (2000) Equation-based Congestion Control for Unicast<op></op>
Applications, ACM SIGCOMM, May,
2000.<op></op>
<op>
</op>
 <op></op>

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高酬matlab编程救助（能做的高手请与我联系QQ 346719984）