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OPNET Chapter 3 Description about Token Ring Topology and Simulation on OPNET
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OPNET IT Guru Academic Edition
Chapter 3 – Token Ring
N. Abedpoor
International Imam Reza University of Mashhad
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013
● Token Ring Model Description
• Model Scope and Limitations
• Process Models
• Model Interfaces
• Packet Formats
• ICI Formats
• Token Ring Addressing and Ring Identifiers
● Lab 2 – Token Ring
Chapter 3 Lab2- Token Ring
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 2
● The Token Ring Access Method (TR) provides general
purpose networking at 4 or 16 Mbits/sec transmission rates
for small or large numbers of communicating stations
configured in a ring or hub topology.
● Detailed information on the Token Ring protocol can be found
in the following documentation:
• IEEE Standard 802.5, 1985 Specification— Token Ring Access Method.
Token Ring Description
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 3
● Model Scope and Limitations
● The first important restriction is that the ring initialization and
recovery processes are not modeled explicitly. While the
model could be extended to address these areas (it is
provided in source code form), its primary usefulness is in
obtaining measurements of steady state performance.
● A second restriction has to do with the modeling of error
conditions and in general, the role of the NMT entity. In its
current form, the model makes no attempt to implement the
mechanisms related to the detection of damaged frames, or
the reporting of errors to NMT. The interface between MAC
and NMT is, in fact, not presently incorporated into the
implementation of MAC.
● The effects of station latency and propagation delay are also
incorporated into the model. The restack operation and the
THT are also explicitly modeled.
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 4
● Model Scope and Limitations
The parameters that may be easily controlled by the user,
without having to modify the internals of the provided models
include:
● The number of stations attached to the ring
● The address of the station that launches the token as the
simulation begins, the “active monitor”
● The delay incurred by frames and tokens as they traverse a
station’s ring interface
● The propagation delay separating stations on the ring
● The number of bits per second transmitted by the medium
● The duration of the THT, the amount of time a station may
transmit on the ring
● The amount of time it takes a station to modify its priority
stacks in a restack operation
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 5
● Model Scope and Limitations
Model features include:
● 24-bit assured minimum latency
● Token acceleration
● Modularity—there can be more than one ring in a network
model
● Token Ring link models allow you to simulate point-to-point
trunk links; a single trunk link can carry traffic for multiple
VLANs as specified by IEEE 802.1q.
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 6
● Model Scope and Limitations
Model features include:
● You can configure port-based VLANs on all generic bridge
and switch models, and on any vendor-specific models that
support this technology.
● To configure a VLAN, set the VLAN scheme attribute to
“Port-based VLAN” on the bridge or switch supporting the
VLAN. You can assign VLAN identifiers to specific port
numbers in the VLAN Port Configuration Table. (To find a
link’s port numbers, use Link Interfaces on the Edit Attributes
(Advanced) dialog box.) Note that you can assign only one
VLAN identifier to a specific port.
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 7
● Process Models
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 8
● Process Models
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 9
● Model Interfaces
Packet Formats
● The following table enumerates the packet formats used in
the Token Ring model suite.
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 10
● Model Interfaces
ICI Formats (Interface Control Information)
● The following table enumerates the interface control
information (ICI) formats used in the Token Ring model
suite.
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 11
● Model Interfaces
Token Ring Addressing and Ring Identifiers
● Each ring has a unique identifier, specified by the ring_id attribute of the tr_mac_op_v2 process model. All Token Ring MAC entities on the same ring must agree on the value of this identifier. The ring IDs can be specified to be automatically assigned to meet these requirements.
● Each MAC entity has a physical address, specified by the station_address attribute of the tr_mac_op_v2 process model. Token Ring addresses must be consecutive (no gaps in numbering) and increase in the direction of the point-to-point links along a ring. In addition, when using these models in conjunction with the Spanning Tree Bridge models, the addresses must be unique across the entire OPNET network to support correct bridge address learning. The addresses can be specified to be automatically assigned to meet these requirements.
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 12
● A token ring network consists of a set of nodes connected in
a ring.
● The ring is a single shared medium.
● The token ring technology involves a distributed algorithm
that controls when each node is allowed to transmit.
● With a ring topology, any link or node failure would render
the whole network useless. This problem can be solved by
using a star topology where nodes are connected to a token
ring hub.
● The hub acts as a relay, known as a multi station access unit
(MSAU)
Lab 2 – Token Ring
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 13
A Shared-Media Network with Media Access Control
● The “token,” which is just a special sequence of bits,
circulates around the ring;
● each node receives and then forwards the token.
● When a node that has a frame to transmit sees the token, it
takes the token off the ring and instead inserts its frame into
the ring. When the frame makes its way back around to the
sender, this node strips its frame off the ring and reinserts the
token.
● The token holding time (THT) is the time a given node is
allowed to hold the token.
● The THT has an effect on the utilization and fairness of the
network, where utilization is the measure of the bandwidth
used versus that available on the given ring.
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 14
● In this lab, you will set up a token ring network with 14 nodes
connected in a star topology. The links you will use operate
at a data rate of 4 Mbps.
● You will study how the utilization and delay of the network are
affected by the network load as well as the THT.
Pay Attention and Then Start …
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 15
NOTES:
Create Project:
● Name the project <your initials>_Token
● Name the scenario Balanced
● make sure that Create Empty Scenario
● Choose Office for Network Scale
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 16
NOTES:
Create the Network: ● Use Rapid Configuration.
● Star Topology
● Choose Token_ring from Model List
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 17
● Save Project
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 18
NOTES:
Configure Network Nodes
● configure the THT of the nodes
● Select Similar Nodes
● Edit Attributes.
● Set Value Shown in figure.
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 19
NOTES:
Configure the Simulation
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 20
NOTES:
Configure the Simulation
● Object Attributes Tab
● Office Network.*.Token Ring Parameters[0].THT Duration
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 21
NOTES:
Configure the Simulation
● Advanced Tab
● Set Scalar File Name to <your initials>_Token_Balanced
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 22
NOTES:
Choose the Statistics
● Choose Individual Statistics - Expand
the Global Statistics hierarchy
a) Traffic Sink – check the Traffic
Received (packets/sec) box
b) Traffic Source - check the Traffic Sent
(packets/sec) box
● Expand the Node Statistics hierarchy
a) Utilization
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 23
NOTES:
● to collect the average of the above statistics as a scalar value
by the end of each simulation run:
● Simulation menu - Statistics (Advanced)
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 24
NOTES:
● be sure Traffic Sent and Traffic Received appeared under
the Global Statistics Probes and Utilization appeared
under Node Statistics Probes
● Set the Values for both
Traffic Sent and traffic Rec
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 25
● we need to analyze the effect of THT on the network
performance:
● Objects menu Create Attribute Probe
● Right Click on new Attribute Probe Choose Attributed
Object expand Office Network select Node_0
● Right Click on new Attribute Probe Edit Attributes
● Save from File Menu
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 26
NOTES:
Duplicate Scenario
● The token ring network scenario we just implemented is
balanced: the distribution of the generated traffic in all nodes
is the same. To compare performance, you will create an
“unbalanced” scenario as follows:
● 1- Scenarios menu Duplicate Scenario name
Unbalanced OK
● 2- select Nod_0 and Nod_7 by shift-Clicking
Right click Edit Attributes
Set the Interarrival time Value show in this figure.
● 3- select all nodes except Nod_0 and Nod_7
Right click Edit Attributes
Set the Interarrival time Value show in this figure.
● 4- click anywhere in the workspace to unselect objects.
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 27
NOTES:
● 5- Click Configure/Run Simulation button:
● Name the scalar file <your initials>_Token_Unbalanced
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 28
NOTES:
Run the Simulation
● Scenarios menu Manage Scenario.
● Value under Results column to <collect>
● OK (to run Simulation)
● After simulation completes, click close
● Save your Project
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 29
NOTES:
View the Results
● Flow Steps in your source document to get the flowing
results.
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 30
NOTES:
View the Results
● Flow Steps in your source document to get the results.
● test your self in OPNET simulation now.
Start as professionals…
N. Abedpoor – International Imam Reza University of Mashhad Dec. 2013 31
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