Opnet

1
Opnet Lab Review

• ENTC 345
• Dr. Ana Goulart
• Assistant Professor

2
Lab1 Tutorial on M/M/1 Queue

• Review the main steps
• New project
• New node
• New network (with a single node)
• Statistics
• Configure Simulation
• Analyze the results

Run Simulation
View and Analyze Results
Create Network Models
Choose Statistics
3
Create Network Models

1. We had to create a New node model in Node Editor.
2. We had to create New network (with a single
   node) in Project Editor

4
Create Network Models
New node
Node Editor
Create Processor Source
Create Processor Queue
Create Processor Sink
Create Packet Streams
Verify Node Interfaces
Save
5
(No Transcript)
6
Create Network Models
Project Editor
Add the new node model to a Custom Palette
Create New Network With a single node
Save
7
(No Transcript)
8
Choose Statistics
Specify Network Model
Probe Editor
Set probes
Save
Create node statistic probe
Create node statistic probe
Choose object (queue)
Choose object (queue)
Statistic Queue delay
Statistic Queue size
9
(No Transcript)
10
Run Simulation
Simulation Sequence Editor
DES Configure DES (Advanced)
Set Duration, Seed
Create a Simulation Scenario
Outputs Statistical Collection (Probe File)
Save
11
(No Transcript)
12
View and Analyze Results
Analysis Tool
Analysis Configuration
Queue size
Choose network model And output statistics

• As Is
• Average
• Time Average

Queue delay
13
(No Transcript)
14
(No Transcript)
15
Create Network Models
Now, lets go back to the node editor
New node
Create Processor Source

• Generates packets
• The attributes are
• Name src
• Process model simple_source
• Packet Interarrival time
• exponential
• mean outcome 1
• Packet Size
• exponential
• mean outcome 9000 bits

Create Processor Queue
Create Processor Sink
Create Packet Streams
Verify Node Interfaces
Save
16

• For example, Packet inter-arrival time
• Exponential, mean outcome 1 means
• Poisson process, with rate ? 1 packet/sec

L
x
time
The exponential random variable X, with parameter
?. The PDF is given by
fX(x) ?e-?x
f(x)
x
0
1
2
17
Exponential PDF
fX(x) ?e-?x
f(x)
x
0
1
2
x1
x1
Probability (interarrival time x1) (
?e-?x dx
0
18

• Example of other PDF options
• Packet size constant
• Packet size uniform distribution
• Packet interarrival time constant
• Packet interarrival time normal distribution

f(x)
f(x)
x
x
1
1
There are several PDFs (probability density
function) to choose from. Then we would have a
different process (not necessarily an M/M/1 queue
model).
19
Create Network Models
New node
Create Processor Source

• Represent queue and service
• The attributes are
• Name queue
• Process model acb_fifo (first in / first out)
• Service rate 9600 bits/sec

Create Processor Queue
Create Processor Sink
Create Packet Streams
Verify Node Interfaces
Save
20
Create Network Models
New node
Create Processor Source

• To delete packets and save memory
• The attributes are
• Name sink

Create Processor Queue
Create Processor Sink
Create Packet Streams
Verify Node Interfaces
Save
21
Create Network Models
New node
Create Processor Source
To interconnect the modules
Create Processor Queue
Create Processor Sink
Create Packet Streams
Verify Node Interfaces
Save
22
Create Network Models
New node
Create Processor Source
Because of details of Opnet implementation
Create Processor Queue
Create Processor Sink
Create Packet Streams
Verify Node Interfaces
Save
23
Create Network Models
Now, lets review the Project Editor
Add the new node model to a Custom Palette
Create New Network With a single node
Save
24
Create Network Models
Now, lets review the Project Editor
Add the new node model to a Custom Palette
Create New Network With a single node
Save
25
For Lab2 (2nd part) An exercise to understand
the delays and collisions in Ethernet networks

• Consider a 100-m optical fiber link operating at
  1Gbps. The velocity of propagation of optical
  fiber is typically about 2 x 108 m/s.
• Assume a frame of 1000 octets (8000 bits).
• a) What is this frames transmission time?
• b) What is the propagation time?
• c) How many bits on the link when a stream of
  bits fully occupies the link?

26
Example
B
A
to
First bit of the frame
B
A
to tprop
.
Llink
B
A
to tx
.
Last bit of the frame
27
Example
And finally, all bits are transmitted and received
B
A
to tprop tx
last bit of the frame
28
One more example Now for 10Mbps Ethernet

• R 10Mbps
• D 100m
• V2x108m/s
• L 8000 bits (packet size)
• a) What is this frames transmission time?
• b) What is the propagation time?
• c) How many bits on the link when a stream of
  bits fully occupies the link?