Download - Network Traffic Control
Department of Computer & Electronic Engineering
“Network Traffic Control”
by
Ioannis Gallikas
MSc in Communication Network Planning and Management
Supervised by: Mr. Frank Margrave
2003-2004 “This report is submitted in partial submission for the degree of Master of Science”
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Abstract
The need for communication and data transfer was the reason that networking was
introduced. Only lately though networks provide us with real-time applications. Real-time
applications are the ones that we need to have the smallest possible end-to-end delay.
Such application are voice and video conferencing.
Unfortunately these applications are bandwidth demanding and most of the times,
a new higher capacity link is needed in order to provide the required delays, something
that it is not cost effective. Hence a new way was needed in order to run these
applications and still maintain the low end-to-end delay without having to spent more
money on upgrading the network.
This is done by implementing certain QoS techniques in the network which will
promise low latencies on the desired applications. The technique that we are most
interested in is Differentiated Services. There are several different ways to apply DiffServ
in a network. All these ways will be explained later on the background theory.
A network was chosen in order to apply DiffServ. This network was decided to be
the GUNET since it is a highly utilized network and such applications are under testing in
reality.
Instead of doing all the calculations by hand, computer software will be used,
something that is much faster and much more accurate. The simulation package that will
be used is called OPNET and is one of the best in the market for network simulation.
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ACKNOWLEDGEMENTS I would like to thank my Supervisor Mr Frank Margrave for providing me with
useful knowledge and directions on how to deal this project and Dr. Nick Savage for his
help and his notes provided on differentiated services.
I would also like to thank my parents and the rest of my family who supported me
and helped me reach this far with my studies. I would also like to thank my colleagues
who helped me by providing useful tips and support during the past few months here in
Portsmouth. Finally I would like to thank Mr. Vasileios Adamos, whose previous
experience of OPNET was very helpful.
….dedicated to my mother
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GLOSSARY
ATM Asynchronous Transfer Mode
CoS Class of Service
CQ Custom Queuing
DIFFSERV Differentiated Services
DLSw Data-Link Switching
DWRR Deficit Weighted Round Robin
FIFO First In – First Out
FTP File Transfer Protocol
GRNET Greek Network
GUNET Greek Universities Network
INTSERV Integrated Services
IP Internet Protocol
IPX Internetwork Packet Exchange
ISP Internet Service Provider
MDRR Modified Deficit Round Robin
MPLS Multi Protocols Labeling Switching
PPP Point to Point
PQ Priority Queuing
QoS Quality of Service
PBR Policy-Based Routing
RSVP ReSerVation Protocol
SAP Service Advertising Protocol
SMB Subnet Bandwidth Management
SNA Systems Network Architecture
TCP Transmission Control Protocol
ToS Type of Service
UDP User Datagram Protocol
VOIP Voice Over IP
WFQ Weighted Fair Queuing
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CHAPTER 1
1. INTRODUCTION
The demand for constant and instant data communication between companies,
organizations and universities which are spread in different locations has developed the need
of networking. As these networks become larger, much faster, more complex and more
bandwidth demanding, their design and management becomes an ever more challenging task.
Cost is a significant factor in a networks capacity. The increased demand on
bandwidth when new applications are introduced in a network makes a network to be cost
defective since better links are needed to keep the utilization levels and end-to-end delay in
minimal levels. Hence new ways should be introduced in a network that would cope with the
extra loading and still produce good results. This was succeeded by applying a new method
of traffic control called QoS. There are different approaches of QoS. The one of most interest
is differentiated services which work with real-time applications such as voice and video.
No matter what the nature of the network to be implemented is, before building
anything it is best to design it and, if possible, test it. This is the most cost efficient way as
potential errors are easier to be identified and corrected in an early stage. Problems can be
solved through, by running a computer simulation program since that would be more time
effectual than actually performing the calculations by hand.
OPNET is a graphically based package which allows the performance of
communication networks ranging from simple links to complex enterprise-wide systems to
be analyzed and predicted. It supports a building-block approach where the blocks are
familiar objects in the real world. The design tool has a library of these network objects, each
one representing one or more real-world objects. The object parameters are easily adjusted to
match the real world objects. It is capable for performing analysis of both computer and
communication networks and based on a description of a network, its control algorithms and
workload, it simulates the operation of the network and provides measures of network
performance.
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1.1. PROJECT TITLE & DEFINITION
“Network Traffic Control”
“Differentiated Services is an architecture for providing different types or levels of
service for network traffic. One key characteristic of Diffserv is that flows are aggregated in
the network, so that core routers only need to distinguish a comparably small number of
aggregated flows, even if those flows contain thousands or millions of individual flows.
Support for Differentiated Services on Linux is part of the more general Traffic Control
architecture. This project will investigate the use of diffserv and its role in traffic
management. The project will include the use of OPNET for traffic modelling and
investigation of diffserv.”
1.2. THE OBJECTIVES OF THE PROJECT PROPOSAL
The objectives of this project are to study the implementation of Differentiated
Services in a network in order to decrease the end-to-end delay of real-time applications such
as voice and video conferencing. The simulations will be based on a powerful computer-
based simulation package called OPNET Modeller, where the implementation of a network
will be made in order to simulate and obtain results of a network once without any Quality-
of-Service and once after applying differentiated Services. By comparing the results obtained
on both case studies, we can investigate and understand the effect of Differentiated Services
in a congested network, evaluate Differentiated Services and illustrate advantages and
disadvantages over non Differentiated data flows.
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The network on which Differentiated Services are going to be applied is the Greek
Universities Network, which is known as GUNET. The network consists of sixteen
universities, eight of which are located in Athens, two are located in Thessaloniki and the rest
six are spreaded around Greece. The decision of choosing that specific network was based on
the fact that GUNET is my country’s network which makes it easier to me to find vital
information and on the fact that only lately the universities started exploring the option of
adding VOIP in the network and Video Conferencing will be another advantage.
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CHAPTER 2
2. BACKGROUND THEORY
The project consists of two parts. One is the theoretical background on Quality of
Service and specifically Differentiated services and the other is the practical part of the
OPNET simulation package which will be used to run the network simulation and with the
results obtained a comparison of the performance will be discussed.
A company’s network is the backbone of the company’s success. Such a network
carries vital applications and data. Real time applications such as voice and video which are
sensitive to delay variation are of huge importance in a company. These kinds of
applications are bandwidth demanding and sometimes these services need to have predictable
delays and generally guaranteed services.
Differentiated Services is one approach of applying QoS in a network QoS is used
for:
Applying different levels of service to groups, such as customers or
enterprises
Applying different priorities on services which are given to particular groups
or applications
Tracing and dissolving areas of network bottlenecks and other forms of
congestion by rerouting the application
Monitoring network performance
Regulates the incoming and outcoming Bandwidth of the network.
There are two ways that QoS can be applied in a network
Resource Reservation (integrated Services) where the network resources are
apportioned according to an application’s QoS request, and subject to
bandwidth management policy (internet reference 27)
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Prioritization (differentiated Services) where the network traffic is classified
and apportioned network resources according to bandwidth management
policy criteria. A network’s elements give preferential treatment to
classifications identified as having more demanding requirements, when QoS
is enabled. (internet reference 27)
There are two more types that can characterize QoS.
Per Flow : Flow is a unidirectional data-stream between two nodes, and
is identified by its transport protocol, source address, source port, and
destination address and destination port.
Per Aggregate: Aggregate is just more than one flows which have some
common parameters as the ones mentioned earlier.
2.1. QUALITY OF SERVICE ARCHITECTURES
Standard networks are configured by default to provide with best effort data delivery.
This makes the network to have the minimum complexity as possible. In a network that
continuously grows, the increased demand of bandwidth from the host does not make the
network to deny the services but as more applications are introduced in the network, the most
it degrades. This is not a problem when the only applications in a network are client server
type such as FTP, E-mail or Database. These applications can cope vary easily with delay
variations. Instead it is of great concern when multimedia applications such as voice and
video are present, applications which cannot cope with delay variations since they are
characterised as peer to peer applications and they are more bandwidth hungry.
By increasing the bandwidth does not solve the problem, since the smallest increased
traffic which can occur will be enough to affect multimedia applications. QoS doesn’t
increase bandwidth, instead it manages the existing bandwidth in a more effective way for
certain applications.
QoS is a networking term which determines that a specific amount of data will be
transferred from one point A to another point B in a predetermined amount of time. The
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biggest advantage of ATM over technologies such as Frame Relay and Fast Ethernet is that
ATM supports QoS which allows ISPs to guarantee to customers that a low end-to-end delay
will not exceed certain limits.
QoS is based in four Protocols:
ReSerVation Protocol (RSVP)
Is the one that provides the signalling to enable the resource
reservation Protocol on the network. Although RSVP is used mainly
on a Per-Flow basis, sometimes, it can be seen to be used also Per-
Aggregates.
Differentiated Services (DiffServ)
Is the simplest way to categorize and prioritise network traffic flows
and aggregates.
Multi Protocols Labeling Switching (MPLS)
Is the one that manages the bandwidth on a network by routing the
traffic according to the labels in the packet headers.
Subnet Bandwidth Management (SMB)
Is responsible of categorizing and prioritizing at the data link-layer on
wired networks.
2.1.1. INTEGRATED SERVICES (IntServ)
Integrated Services approach is based on the concept that a stream that is serviced at a
higher data rate than it requires will be guaranteed the delay bound of a flow-by-flow
resource reservation. When an application will make a request to the network, it signals its
required bandwidth and delay requirements along with its traffic profile. The network will
then assess this application along with any other applications that it is currently servicing and
then it may grant the request as long as the application honours its originally specified
characteristics (traffic profile).The network will maintain a service level commitment using
advanced queuing disciplines for link sharing. [1]
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Picture 1 Integrated services Approach to providing QoS [1]
2.1.1.1 RESERVATION PROTOCOL (RSVP)
This mechanism should reserve resources along a network link so that they can
deliver the required network performance. Weather a resource is granted or not depends very
much on the policy that the network has in place. The exact nature of resource depends on
the network performance requirements and the specific network approach to satisfying them.
Resource reservation must be chargeable so a protocol must be in place that allows the
authentication, authorisation and accounting and settlement between different network
providers and between network providers and users. The authentication and authorisation
procedure is very important otherwise the reservation policy that is in place could be abused
to block network service to other users. Resource reservation is typically done with a
purpose-designed protocol such as RSVP. [1]
2.1.2. DIFFERENTIATED SERVICES (Diffserv)
Differentiated Services provides a scalable means of service differentiation in the
internet. No per-flow state needs to be maintained in the routers, neither is there an explicit
connection setup phase. The Differentiated Services architecture offers a framework within
which service providers can offer each customer a range of network services which are
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differentiated on the basis of performance in addition to pricing tiers used in the past.
Diffserv provides a wide range of services through a combination of the following functions.
Setting bits in the TOS octet at network edges and administrative boundaries using
those bits to determine how packets are treated by the routers inside the network conditioning
the marked packets at network boundaries in accordance with the requirements of each
service.
The diffserv architecture is composed of a number of small functional units
implemented in the network nodes. This includes the definition of a set of Per-Hop Behaviors
(PHBs), packet classification and traffic conditioning functions like metering, marking,
shaping and policing. The resource allocation for each service type adds a new dimension to
the problem, for which the Bandwidth Brokers are being considered. (Internet reference 3)
The diffserv model is scalable because of a few reasons that are listed below:
Diffserv suggests that the more expensive tasks like multi-flow classification,
policing, shaping and marking be done at the border routers of the ISP networks. This is
because the border routers deal with the customer links that are slow as a result of which it
has time to do the costly functions like MFC and traffic conditioning. The core routers, on
the other hand simply does the forwarding based on the diffserv code point (DSCP), which is
the first six bits in the TOS byte in the IP header. Since the core routers need not maintain
any per-flow state, this model is more scalable. The granularity of service provisioning is a
class in diffserv, as opposed to being a flow in IntServ. Multiple flows may be mapped on to
a single per-hop behaviour (PHB), which is indicated by the value in the DSCP. This too,
ensures the scalability of the diffserv model. (Internet reference 3)
When implementing Diffserv, it can be seen that:
Diffserv codepoints (DSCPs) redefine the Type-of-Service (ToS) in the IPv4
field
Precedence bits are preserved
Type-of-Service bits are NOT
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Figure 1 IPv4Ffield [25]
IP precedence utilizes the 3 precedence bits in the IPv4 header's Type of Service
(ToS) field to specify class of service for each packet. Traffic can be partitioned in up to six
classes of service using IP precedence (two others are reserved for internal network use). The
queuing technologies throughout the network can then use this signal to provide the
appropriate expedited handling. (Internet reference 25)
The service provider establishes a Service Level Agreement (SLA or service level
specification) with each user. A user can then only generate a certain amount of traffic of a
specific class. The traffic is policed at the border of the service provider network. This
method differs to the integrated services approach by treating each packet individually rather
than trying to specify a set route that the packet must take. The overall network must set-up
to meet all of the SLA’s. [1]
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Picture 2 Differentiated services approach to providing QoS [1]
2.1.2.1. SERVICE LEVEL AGREEMENTS (SLA)
The SLA is and agreement between a user and a network provider to state the level of
availability, serviceability, performance, operation or other attributes of the service. The SLA
will define the parameters used and their associated values. It may contain general
parameters or may be technology specific. In the table below, the quality service parameters
can be seen and also the different service levels. [1]
QUALITY OF SERVICE PARAMETERS
Service Level Application Priority Mapping
1 • Non-critical data • Similar to Internet today • No minimum information
rate guaranteed
• Best-effort delivery • Unmanaged performance
2 • Mission-critical data • VPN outsourcing, e-
commerce • Similar to ATM VBR
• Low loss rate • Controlled delay and delay
variation
3 • Real time applications • Video streaming, voice,
videoconferencing
• Low loss rate • Low delay and delay
variation
Table 1. Quality service parameters (Internet reference 25)
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2.1.2.2. IP PRECEDENCE
Use of IP Precedence allows specifying the class of service for a packet. The three
precedence bits in the IPv4 header’s type of service (ToS) field is used for this purpose.
Figure 2 shows the ToS field. (internet reference 28)
Figure 2 IPv4 Packet Type of Service Field
Using the ToS bits, we can define up to six classes of service. Other features
configured throughout the network can then use these bits to determine how to treat the
packet in regard to the type of service to grant it. These other QoS features can assign
appropriate traffic-handling policies including congestion management strategy and
bandwidth allocation. For example, although IP Precedence is not a queueing method,
queueing methods such as weighted fair queueing (WFQ) and Weighted Random Early
Detection (WRED) can use the IP Precedence setting of the packet to prioritize traffic.
(internet reference 28)
By setting precedence levels on incoming traffic and using them in combination with
the Cisco IOS QoS queueing features, we can create differentiated services. We can use
features such as policy-based routing (PBR) and CAR to set precedence based on extended
access list classification. These features afford considerable flexibility for precedence
assignment. For example, we can assign precedence based on application or user, or by
destination and source subnetwork. (internet reference 28)
So that each subsequent network element can provide service based on the
determined policy, IP Precedence is usually deployed as close to the edge of the network or
the administrative domain as possible. We can think of IP Precedence as an edge function
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that allows core, or backbone, QoS features, such as WRED, to forward traffic based on CoS.
IP Precedence can also be set in the host or network client, but this setting can be overridden
by policy within the network. (internet reference 28)
We can use the three IP Precedence bits in the ToS field of the IP header to specify
CoS assignment for each packet. We can partition traffic into up to six classes, the remaining
two are reserved for internal network use and then use policy maps and extended ACLs to
define network policies in terms of congestion handling and bandwidth allocation for each
class. (internet reference 28)
However, the IP Precedence feature allows considerable flexibility for precedence
assignment. That means we can define your own classification mechanism. For example, we
might want to assign precedence based on application or access router. (internet reference 28)
2.1.2.3. QUEUEING DISCIPLINES
Queuing methods define the packet scheduling mechanism or the order in which
packets are dequeued to the interface for transmission on the physical wire. Based on the
order and number of times that a queue is serviced by a scheduler function, queuing methods
also support minimum bandwidth guarantees and low latencies.
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2.1.2.3.1. First In – First Out QUEUEING DISCIPLINE (FIFO)
FIFO is the mostly used queuing discipline which is set as the default queuing
mechanism for routers around the world. As a result, nothing needs to be configured, the only
thing is to implement it and it’s ready to be used. On Cisco routers, when no other queuing
disciplines are configured, all interfaces, except serial interfaces at E1 (2.048 Mbps) and
below, use FIFO queuing discipline by default.
From its name it is obvious its simple behavior. FIFO stands for First In – First Out
which means that packets arriving from different flows are treated accordingly to their
arriving order. This means that the first packet that got in the queue will be the first that will
go out.
The figure above represents a FIFO queue. As it can be seen, different packet flows
are represented by different colors. The queue acts as a barrier for temporary burst of packets
avoiding unnecessary dropping by storing them, hoping that congestion will improve and
they can be dispatched. When congestion is heavy and the queue overflows new arriving
packets will be dropped since the router doesn’t have any other choice for them.
1
2
3
4
5
6
Flow 1
Flow 2
Flow 3
Flow 4
Flow 5
Flow 6
Flow 7
Flow 8
Multiplexer 1 2 3 4 5 6
FIFO Queue
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2.1.2.3.2. WEIGHTED FAIR QUEUEING DISCIPLINE (WFQ)
There are two types of WFQ disciplines:
Flow-Based: Flow-based WFQ is responsible to allocate the ratio of the
transmission bandwidth between different traffic flows in periods of network
congestion
Class-Based: Class-based WFQ is responsible to allocate the transmission
bandwidth between different traffic flows during periods of congestion.
WFQ packets are classified by flow. Packets having the same source and destination
of IP address, same source and destination of TCP or UDP port, and packets with type of
service (ToS) field belong to the same flow.
In flow-based WFQ each flow corresponds to a separate output queue. When a packet
is assigned to a flow, it is placed in the queue for that flow. During periods of congestion,
WFQ allocates an equal share of the bandwidth to each active queue.
In class-based WFQ, packets are assigned to different queues based on their QoS
group or the IP precedence in the ToS field.
QoS groups allow the customization of a wanted QoS policy. A QoS group is an
internal classification of packets used by the router to determine how packets will be treated
by certain QoS features such as WFQ.
This can be implemented by applying a different weight for each class. During
periods of congestion, each group will be allocated a percentage of the output bandwidth
depending on the weight of the class. As an example, when a class is assigned a weight of 50,
all packets from this class will be allocated at least 50 percent of the outgoing bandwidth
when there is network congestion. When there is no congestion on the network, queues can
use any of the available bandwidth.
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2.1.2.3.3. PRIORITY QUEUEING DISCIPLINE (PQ)
Priority queuing allows network administrators to define how they wish traffic to be
prioritized in the network. This is done by defining a series of filters based on packet
characteristics. Traffic is placed into different queues. The queue having the highest priority
will be the first to be serviced, while lower priority queues will be serviced in a priority
sequence. If the queue with the highest priority is always full, then this queue is constantly
serviced and all the packets from other queues are dropped. When using the Priority Queuing
algorithm the highest priority traffic will dominate all others kinds of traffic. Priority queuing
assigns all the traffic to one of the following four queues: high, medium, normal, and low.
In the above Figure, the priority-group command assigns priority list 1 to Serial1. The
priority-list command defines the queuing algorithm to be used by queue list 1 and maps the
traffic into various queues. Priority queuing is useful when you want to guarantee that the
DLSw+ traffic will get through even if it delays other types of traffic. It works best if the
DLSw+ traffic is low volume (for example, a small branch with a transaction rate of five to
ten transactions per minute), and the number of queues is kept to a minimum (two or three).
In this configuration, DLSw+ is in the highest-priority queue, Telnet (TCP port 23) is in the
medium queue, IPX is in the normal queue, and FTP (TCP port 21) is in the lowest-priority
queue.
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2.1.2.3.4. CUSTOM QUEUEING DISCIPLINE (CQ)
Custom queuing, or bandwidth allocation, reserves a portion of the bandwidth of a
link for each selected traffic type. To configure custom queuing, the network manager must
determine how much bandwidth to reserve for each traffic type. If a particular type of traffic
is not using the bandwidth reserved for it, then other traffic types may use the unused
bandwidth.
Custom queuing works by cycling through the series of queues in round-robin order
and sending the portion of allocated bandwidth for each queue before moving to the next
queue. If one queue is empty, the router sends packets from the next queue that has packets
ready to send. Queuing of packets is still first in, first out in nature in each classification but
bandwidth sharing can be achieved between the different classes of traffic.
In the Figure below, custom queuing is configured to take 4000 bytes from the SNA
queue, 2000 bytes from the Telnet queue, and 2000 bytes from the default queue. This
allocates bandwidth in the proportions of 50, 25, and 25 percent. If SNA is not using all its
allocated 50 percent of bandwidth, the other queues can utilize this bandwidth until SNA
requires it again.
Custom queuing is commonly used when deploying DLSw+ networks because it
allows the network manager to ensure that a guaranteed percentage of the link can be used
for SNA, Telnet, and FTP. However, unless the DLSw+ traffic is broken into separate TCP
conversations (using SAP or LOCADDR prioritization described earlier), batch SNA transfer
or NetBIOS traffic shares the same output queue and may negatively impact interactive SNA
response times.
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2.1.2.3.5. MODIFIED DEFICIT ROUND ROBIN QUEUEING DISCIPLINE (MDRR)
With MDRR configured as the queuing strategy, non-empty queues are served one
after the other, in a round-robin fashion. Each time a queue is served, a fixed amount of data
is dequeued. The algorithm then services the next queue. When a queue is served, MDRR
keeps track of the number of bytes of data that was dequeued in excess of the configured
value. In the next pass, when the queue is served again, less data will be dequeued to
compensate for the excess data that was served previously. As a result, the average amount of
data dequeued per queue will be close to the configured value. In addition, MDRR maintains
a priority queue that gets served on a preferential basis. MDRR is explained in greater detail
below.
Each queue within MDRR is defined by two variables:
Quantum value - Average number of bytes served in each round.
Deficit counter - This counter is used to track how many bytes a queue has
transmitted in each round. It is initialized to the quantum value.
Packets in a queue are served as long as the deficit counter is greater than zero. Each
packet served decreases the deficit counter by a value equal to its length in bytes. A queue
can no longer be served after the deficit counter becomes zero or negative. In each new
round, each non-empty queue's deficit counter is incremented by its quantum value.
Each MDRR queue can be given a relative weight, with one of the queues in the
group defined as a priority queue. The weights assign relative bandwidth for each queue
when the interface is congested. The MDRR algorithm dequeues data from each queue in a
round-robin fashion if there is data in the queue to be sent.
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2.1.2.3.6. DEFICIT WEIGHTED ROUND ROBIN QUEUEING DISCIPLINE (DWRR)
Deficit Weighted Round Robin is the basis for a class of queue scheduling disciplines
that are designed to address the limitations of the WRR and WFQ models.
DWRR addresses the limitations of the WRR model by accurately
supporting the weighted fair distribution of bandwidth when servicing
queues that contain variable-length packets
DWRR addresses the limitations of the WFQ model by defining a
scheduling discipline that has lower computational complexity and that
can be implemented in hardware. This allows DWRR to support the
arbitration of output port bandwidth on high-speed interfaces in both the
core and at the edges of the network.
In the classic DWRR algorithm, the scheduler visits each non-empty queue and
determines the number of bytes in the packet in the head of the queue. The variable
DeficitCounter is incremented by the value quantum. If the size of the packet at the head of
the queue is greater that the variable DeficitCounter, then the scheduler moves on to service
the next queue. If the size of the packet at the head of the queue is less than or equal to the
variable DeficitCounter, then the variable DeficitCounter is reduced by the number of bytes
in the packet and the packet is transmitted on the output port. The scheduler continues to
dequeue packets and decrement the variable DeficitCounter by the size of the transmitted
packet until either the size of the packet at the head of the queue is greater than the variable
DeficitCounter or the queue is empty. If the queue is empty, the value of DeficitCounter is
set to zero. When this occurs, the scheduler moves on to service the next non-empty queue.
This can be seen in the figure below.
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2.1.3. MULTI PROTOCOL LABEL SWITSHING (MPLS)
MPLS is a hybrid technology that combines the best of ATM’s circuit switching and the
IP’s packet routing. This way it enables fast forwarding in the cores and in the conventional
routing.
MPLS can achieve substantial speed gains in packet forwarding by using short layer-
2 labels. When a packet enters a MPLS network it is assigned a forward equivalence class
(FEC), which is encoded as a fixed-length string (label). When the packet is forwarded to the
next hop, the label is transmitting with it. At the next hop, the label is used as an index into a
preconfigured table to identify the following hop and a new label. This process continues
until the packet reaches its destination. The increase in speed is achieved because all the
packets with the same FEC are forwarded in the same way. To provide explicit QoS support
MPLS makes use of certain elements in the integrated and differentiated services approaches.
The level distribution protocol can be used on RSVP. As the resource reservation protocol
transverses the path, it can reserve network resources to guarantee the QoS of the following
packets. [1]
Queue 1
Queue 2
Scheduler
Port
( 50% B/W, Quantum [1] = 1000 )
( 25% b/w, Quantum [2] = 500 )
( 25% b/w, Quantum [3] = 500 )
Q1
Q3Q2
Queue 3
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2.1.4. SUBNET BANDWIDTH MANAGEMENT (SBM)
SBM is a signalling scheme that provides a method for mapping an Internet-level
setup protocol such as RSVP onto IEEE 802-style networks. In particular, it describes the
operation of RSVP- enabled hosts/routers and link layer devices (switches and bridges) to
support reservation of LAN resources for RSVP-enabled data flows. For example, it can
signal 802.1p priorities between network switches or class of service information between
RSVP clients and RSVP networks. (Internet reference 24)
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CHAPTER 3
3. OPNET MODELLER
Problems can be effectively solved through, by running a computer simulation program
since that would be more time efficient than actually doing the calculations by hand. OpNet
is a graphically based package which allows the performance of communication networks
ranging from simple links to complex enterprise-wide systems to be analysed and predicted.
It supports a building-block approach where the blocks are familiar objects in the real world.
The design tool has a library of these network objects, each one representing one or more
real-world objects. The object parameters are easily adjusted to match the real world objects.
It is capable for performing analysis of both computer and communication networks and
based on a description of a network, its control algorithms and workload, it simulates the
operation of the network and provides measures of network performance. [5]
One of the first steps before the beginning of the Project is to register with the
OPNET simulation package. This will be done through the OPNET website. In order to learn
the capabilities of the OPNET simulation package, there are several online models which
were contributed by users, and also there are tutorials on the Program that will be very
helpful to succeed in a quick understanding on how the programs works and how to model
the required network for this project. [5]
3.1. OVERVIEW OF OPNET
OPNET is the industry’s leading network technology development environment,
allowing you to design and study communication networks, devices, protocols, and
applications with unmatched flexibility. OPNET Modeller is used by the world’s most
prestigious technology organizations to accelerate the R&D process. [5]
Modeller’s object-oriented modelling approach and graphical editors mirror the structure
of actual networks and network components, so your system intuitively maps to your model.
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Modeller supports all network types and technologies, allowing you to answer the most
difficult questions with confidence. Using OPNET Modeller, an organization will benefit by:
Boosting Network R&D Productivity: Leverage the specialized editors,
analysis tools, and off-the-shelf models provided with OPNET Modeller to
focus the time on the unique parts of a project. [5]
Improving Product Quality: Test product or service designs in realistic
customer scenarios before production. [5]
Reducing Time-to-Market: Develop and validate the designs ahead of the
competition. Use the models to demonstrate the value of the solutions to
customers and partners. [5]
Workflow: The workflow
Figure 1 for OPNET Modeller is the steps required to build a network model and run
simulations. It centres on the project editor. In this workspace you can create a network
model, collect statistics directly from each network object or from the network as a whole,
execute simulation and view results. [2]
Figure 1. Steps to build a network in OPNET Modeller [2]
Create Network Models
Choose Statistics
Run Simulations
View Analyze Results
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3.2. FEATURES OF OPNET MODELLER
Modeller Editors: OPNET Modeller has many editors in order to design and simulate
flexible networks. These editors, which are very easy to use with the helping tool providing
by the modeller, help the user observe and better understand a network. We will briefly
describe each editor so we can understand the purpose of each one in the OPNET Modeller:
The project editor: As we said before it is the main staging area for creating a
network simulation.
The node editor: The node editor lets you define the behaviour of each network
object. Figure 2.
The process model editor: The process model editor lets you create process
models, which control the underlying functionality of the node models created in
the node editor. Figure 2.
The link (network) model editor: The link model editor lets you create new
types of link objects. Figure 2.
The path editor: We use the path editor to create new path objects that define a
traffic value.
The packet format editor: The packet editor lets you define the internal
structure of a packet as a set of fields.
The Antenna pattern editor (Radio version only): In Modeller/Radio, the
Antenna pattern editor lets you model the direction-dependent gain properties of
antennas.
The ICI editor: The ICI (Interface Control Information) editor lets you define
the internal structure of ICIs.
ICI used to formalize interrupt-based inter-process communication.
The modulation curve editor (Radio version only): In Modeller/Radio, the
modulation curve editor lets you create modulation functions to characterize the
vulnerability of an information coding and modulation scheme to noise.
The PDF editor: The PDF (Probability Density Function) editor lets you
describe the spread of probability over a range of possible outcomes.
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The probe editor: The probe editor lets you specify the statistics to be collected
during simulation.
The simulation sequence editor: Although you can run simulations from within
the project editor, you may want to specify additional simulation constraints in
the simulation sequence editor.
The analysis tool: With analysis tool you can create scalar graphs, for parametric
studies, define templates to which you apply statistical data and create analysis
configurations that you can save and view later.
The filter editor: The filter editor lets you create additional filters.
Figure 2. The three primary editors of OPNET Modeller
The project editor will be explained below since is the one that will be used for the
design and simulation of the project’s network. [2]
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3.2.1. PROJECT EDITOR
OPNET network models are based on three types of objects: subnetworks, nodes, and
links. These objects are worked in the Project Editor. The Project Editor provides the
resources needed to model all high-level components of a real-world network. Project Editor
Operations can be used to:
Create and edit network models
Create derived models of nodes and links
Customize the network environment
Run simulations
Choose and analyze simulation results
The Project Editor contains a workspace for creating and editing network models.
Subnetworks and nodes are placed in the workspace as objects and depicted there as icons.
Other objects, depicted as connecting lines, represent communication links between the
nodes and subnetworks. Network objects are characterized by attributes that control how they
behave within the overall model. The Project Editor provides extensive operations for
viewing and editing these attributes.
The Project Editor provides many operations for creating and working with network
models. These operations can be accessed from the project editor menu bar, which contains
the following menus:
File: contains operations that relate to high-level functions such as opening and
closing projects, saving scenarios, importing models, and printing graphics and
reports.
Edit: contains operations that allow you to edit the environment attributes that
control program operation and to manipulate text and objects.
View: contains operations that affect the appearance of the editor window and its
contents
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Scenarios: contains operations that provide control over the scenarios included
in a project
Topology: contains operations related to network topology, including building a
network and creating network objects.
Traffic: contains operations related to specifying the traffic on a network,
including importing traffic files and specifying routing across the network.
Protocols: contains operations related to specific protocol models.
Simulation: contains operations for configuring and running simulations.
Results: contains operations that control the collection and viewing of statistics.
Windows: lists all open editor windows and allows the user to make one active.
Help: provides access to context-sensitive help, the online documentation and
tutorial, and information about the program.
Pop-Up Menus: In addition to the menu bar menus, several pop-up menus are available
within the Project Editor:
Workspace pop-up menu: contains operations related to setting the workspace
view, collecting results, and viewing results.
Object pop-up menu: contains operations related to setting object properties,
collecting results, and viewing results.
Statistic pop-up menu: contains operations related to a particular statistic.
Panel pop-up menu: contains operations related to the appearance and content
of an analysis panel.
Graph pop-up menu: contains operations related to the appearance and content
of a graph.
Miscellaneous Operations: There are also several operations available within the
Project Editor that do not appear on a menu:
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Display Subnet View: this operation moves the user down to the network
hierarchy by displaying the contents of a subnetwork when he/she double clicks
on the subnet’s icon.
Open Node Model: this operation automatically opens the corresponding node
model when the user double clicks on a network node.
Zoom Panel: The Zoom Panel operation lets the user magnify a selected part of
an analysis panel by dragging the cursor across it. After this operation, the
selected area fills the panel. The user also can use <Control>+z and
<Control>+u to zoom into and out for the centre of the panel.
Pan Panel: in an analysis panel, this operation shifts the display along the
horizontal axis when the left-arrow or right-arrow keys are pressed by the user.
(Not available when the full horizontal scale is displayed.)
Action Buttons: The Project Editor provides action buttons for several frequently used
operations. The button labels in figure 2.11 identify the operation invoked by the button. [3]
Figure 3. Action buttons of the Project Editor [3]
Features: Originally developed at MIT, and introduced in 1987 as the first commercial
network simulator, OPNET Modeller continues to define the state of the art with the
following features:
Topology: Verify Links
Topology: Mark object as failed
Topology: Mark object as recovered
View: Go to parent Subnetwork
View: Zoom in
View: Zoom out
Simulation: Run Simulation
Results: View Results
Results: View Web Reports
Results: Hide/or Show all panels Topology: Object Palette
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Hierarchical network models: Manage complex network topologies with
unlimited subnetwork nesting.
Object-oriented modelling: Nodes and protocols are modelled as classes with
inheritance and specialization.
Clear and simple modelling paradigm: Model the behaviour of individual
objects at the “Process Level” and interconnect them to form devices at the
“Node Level”. Interconnect devices using links to form networks at the
“Network Level”. Organize multiple network scenarios into “Projects” to
compare designs.
Finite state machine modelling of protocols and other processes. Simulate any
required behaviour with C/C++ logic in FSM’s states and transitions. We control
the level of detail.
Comprehensive support for protocol programming. Over 400 library functions
simplify writing protocol models.
Wireless, point-to-point, and multipoint links: Link behaviour is open and
programmable. Accurately account for delay, availability, bit errors and
throughput characteristics of links. Incorporate physical layer characteristics and
environmental effects.
Geographical and mobility modelling: Model cellular and satellite networks or
any network with mobile nodes. Control each node’s position dynamically or
pre-define trajectories. Add maps and other background graphics for context and
visual enhancement.
Total openness: APIs for program-driven construction or inspection of all
models and result files. Easily integrates existing code libraries into your
simulations. Source code provided for all standard models.
Integrated analysis tools: Comprehensive tools to display simulation results.
Easily plot and analyze time series, histograms, probability functions, parametric
curves, and confidence intervals. Export to spreadsheets pr use XML.
Animation: Animate model behaviour, either during or after simulation.
Integrated debugger: Quickly validate simulation behaviour or track down
problems.
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Import data from text files, XML, and popular tools from HP, Concord,
Network Associates’ Sniffer, NetScout, Infovista, and others.
Financial cost attribute for devices: Export network costs to spreadsheets for a
financial bottom line.
Comprehensive library of detailed protocol and application models:
Including Multi-Tier Applications, Voice, HTTP, TCP, IP, OSPF, BGP, EIGRP,
RIP, RSVP, Frame Relay, FDDI, Ethernet, ATM, 802.11 Wireless LANs, MPLS,
PNNI, DOCSIS, UMTS, IP Multicast, Circuit Switch and many more. Provided
as FSMs with open source code.
Comprehensive library of detailed protocol and network devices: The
Standard Model Library includes hundreds of vendor specific and generic device
models including routers, switches, workstations, and packet generators. Quickly
assemble our own device models using the “Device Creator”. Aggregate traffic
from LANs or “Cloud” nodes.
Highly efficient simulation engine and memory management. Hybrid
simulations significantly improve performance by combining the accuracy of
discrete-event simulation with the speed of analytical modelling.
Runtime environment: Deliver proprietary protocol and device models to end-
users, running simulations and working at the network level only.
Windows NT, Windows 2000, and UNIX supported (transparent cross platform
usage).
Convenient licensing: Enhanced floating license system with automatic license
key downloads via the Internet and graphical license management.
What does OPNET Modeller Provide? OPNET Modeller provides:
An intuitive graphical environment that precisely models real networks, devices,
protocols, and applications.
The control over modelling detail needed to support our engineering decisions.
Built-in support for simulating all types of network technologies.
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The industry’s most comprehensive library of standards-based protocol models,
with completely open source code.
An environment designed to model proprietary protocols using Finite State
Models, C/C++ and extensive libraries.
Powerful analysis tools integrated directly into the GUI.
The industry’s most efficient simulation engine, with hybrid simulation
capability.
Outstanding support and services to ensure user success. [4]
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CHAPTER 4
4.1. NETWORK DECISION AND IMPLEMENTATION
The network that is to be implemented on the OPNET Modeler is the Greek
Universities Network (GUNET). This network is based on the existing Greek Network
(GRNET). In Picture 1 we can see the GRNET, the way it is connected between the Greek
cities and the available bandwidth of the network.
Picture 1 GRNET
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GUNET consists of sixteen Universities in total. Table 1 below displays the
Universities and their location in Greece.
Greek Universities Location
Agricultural University Athens
Pantion University Athens
Harokopio University Athens
University of Pireus Athens
National Metsovio University Athens
National Kapodistriako University Athens
University of Economics Athens
University of Good Arts Athens
Aristotelio University Thessaloniki
Macedonia University Thessaloniki
University of Patra Patra
University of Crete Heraklio
Ioannina University Ioannina
University of Thessaly Larissa
University of Thrace Xanthi
Aegean University Rhodes
Table 1 Greek Universities and their location
As it can be seen in Table 1, there are eight Universities in Athens, two Universities
in Thessaloniki and the rest are some on the mainland and some on the islands. Picture 2
displays the GUNET Network and the backbone links that connect the University Routers
and the cities where the Universities are located.
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Picture 2 GUNET Network
Table 2 below displays the capacity of the Backbone Network links between the
University Routers.
From Location To Location Capacity (Mbps)
Athens Thessaloniki 69 Mbps
Athens Patra 45 Mbps
Athens Heraklio 60 Mbps
Athens Rhodes 1000 Mbps
Athens Larissa 18 Mbps
Athens Ioannina 4.5 Mbps
Athens Xanthi 6 Mbps
Table 2 Capacity of the GUNET Backbone Network between the University Routers
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By looking extensively at Picture 1, we can see the capacity of the links that each
University is connected with the main Router of the city. The capacity of the links can be
seen in Table 3 below. In Athens, it can be seen that there are three Routers in which the
universities are connected with and these three Routers are the ones that connect to the main
Router of Athens. The capacity of the link between these Routers is 2.5 Gbps.
From City Router To University Capacity (Mbps)
Athens Agricultural University 1000 Mbps
Athens Pantion University 1000 Mbps
Athens Harokopio University 2 Mbps
Athens University of Pireus 1000 Mbps
Athens National Metsovio University 1000 Mbps
Athens National Kapodistriako University 1000 Mbps
Athens University of Economics 1000 Mbps
Athens University of Good Arts 2 Mbps
Thessaloniki Aristotelio University 34 Mbps
Thessaloniki Macedonia University 18 Mbps
Patra University of Patra 34 Mbps
Heraklio University of Crete 28 Mbps
Ioannina Ioannina University 24 Mbps
Larissa University of Thessaly 8 Mbps
Xanthi University of Thrace 21 Mbps
Rhodes Aegean University 1000 Mbps
Table 3 Capacity of the links Between Universities and City Router
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4.2. COMPONENTS USED
In this section of the report it can be seen the components that were used and the
configuration that was made to design the GUNET network in the OPNET Modeler
simulation package. All these components can be found inside the OPNET’s Model library
which is an advanced suite of real industry components.
When starting in designing a network, one of the first components to use is:
4.2.1. APPLICATION CONFIG
The "Application Config" node can be used for the following specifications:
1. "ACE Tier Information":
Specifies the different tier names used in the network model. This attribute will be
automatically populated when the model is created using the "Network->Import Topology-
>Create from ACE..." option.
The tier name and the corresponding ports at which the tier listens to incoming traffic
is cross-referenced by different nodes in the network.
2. "Application Specification":
Specifies applications using available application types. You can specify a name and
the corresponding description in the process of creating new applications.
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For example, "Web Browsing (Heavy HTTP 1.1)" indicates a web application performing
heavy browsing using HTTP 1.1.
The specified application name will be used while creating user profiles on the
"Profile Config" object.
3. "Voice Encoder Schemes":
Specifies encoder Parameters for each of the encoder schemes used for generating
Voice traffic in the network.
4.2.2. PROFILE CONFIG
The "Profile Config" node can be used o create user profiles. These user profiles can
then be specified on different nodes in the network to generate application layer traffic.
The application defined in the "Application Config" objects are used by this object to
configure profiles. Therefore, you must create applications using the "Application Config"
object before using this object.
You can specify the traffic patterns followed by the applications as well as the
configured profiles on this object.
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4.2.3. QoS CONFIG
Defines attribute configuration details for protocols supported at the IP layer. These
specifications can be refrenced by the individual nodes using symbolic names (character
strings.)
1. "Queuing Profiles": Defines different queuing profiles such as FIFO, WFQ, Priority
Queuing, Custom Queuing, MWRR, MDRR and DWRR.
2. "CAR Profiles": Defines different CAR profiles that can be used in the network.
4.2.4. SUBNET NODE
The Subnet node will be used to represent each city where the University will be
located. Inside each Subnet, there will be the nodes that will represent the University’s
Network configuration. In two cases though, the Subnet node will represent the University as
well since in these locations multiple Universities are located. These two locations are
Athens with 8 Universities and Thessaloniki with 2 Universities.
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4.2.5. 100BaseT_LAN NODE
Use 100BaseT_LAN object to represent a Fast Ethernet LAN in a switched topology.
The object contains any number of clients as well as one server. Client traffic can be directed
to the internal server as well as external servers.
Supported applications include: FTP, Email, Database, Custom, Rlogin, Video, X windows,
HTTP etc. These applications run over TCP or UDP. For each application, you can specify
traffic for group of clients, allowing you to quickly characterize the entire LAN.
You may also wish to set the following attributes:
Switching Speed: (default = 500,000pkts/sec)
Number of Workstations: (default = 10)
LAN Server Name: (default = Auto Assigned)
4.2.6. PPP_SERVER NODE
The PPP_Server model represents a server node with server applications running over
TCP/IP and UDP/IP. This node supports one underlying SLIP connection. The operational
speed is determined by the data rate of the connected link.
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Protocols: RIP, UDP, IP, TCP, OSPF
Interconnections:
One SLIP connection at a selectable data rate.
Attributes:
Server Configuration Table: This attribute allows for the specification of
application servers running on the node.
Transport Address: This attribute allows for the specification of the address of
the node.
"IP Forwarding Rate": specifies the rate (in packets/second) at which the node can
perform a routing decision for an arriving packet and transfer it to the appropriate
output interface.
"IP Gateway Function": specifies whether the local IP node is acting as a
gateway. Workstations should not act as gateways, as they only have one network
interface.
"RIP Process Mode": specifies whether the RIP process is silent or active. Silent
RIP processes do not send any routing updates but simply receive updates. All
RIP processes in a workstation should be silent RIP processes.
"TCP Connection Information": specifies whether diagnostic information about
CP connections from this node will be displayed at the end of the simulation.
"TCP Maximum Segment Size": determines the size of segments sent by TCP.
His value should be set to largest segment size that the underlying network can
carry unfragmented.
"TCP Receive Buffer Capacity": specifies the size of the buffer used to hold
received data before it is forwarded to the application.
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4.2.7. CISCO ROUTER CS_12016_16s_a10_fe8_ge3_sl24_adv NODE
The model CS_12016_16s_a10_fe8_ge3_sl24_adv represents the following device:
Vendor: Cisco Systems
Product: CISCO 12016
Device Class: Gigabit Switch Router
Configuration: This model represents a specific configuration of an IP-based router
switch model.
Interconnections:
1. 12-port serial DS3 interfaces (44.736Mbps).
2. 8-port Packet over SONET (PoS) OC3 interfaces (PPP over SONET)(155.52Mbps)
3. 2-port Packet over SONET (PoS) OC12 interfaces (PPP over SONET)(622.08Mbps)
4. 2-port Packet over SONET (PoS) OC48 interfaces (PPP over SONET)(2.48832Gbps)
5. 8-port ATM OC3 (155.52Mbps)
6. 2-port ATM OC12 (622.08Mbps)
7. 8-port 100BaseT Fast Ethernet (100Mbps).
8. 3-port 1000BaseT Gigabit Ethernet (1000 Mbps)
General Operation:
IP packets arriving on an IP interface are routed to the appropriate output interface
based on their destination IP address. The Routing Information Protocol (RIP), Open Shortest
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Path First (OSPF) protocol, Border Gateway Protocol (BGP), Interior Gateway Routing
Protocol (IGRP) or Enhanced Interior Gateway Routing Protocol (EIGRP) may be used to
automatically and dynamically create the routing tables and select routes in an adaptive
manner. The key model features are:
1. An IP forwarding rate of 60,000,000 packets/sec
2. The router model implements a "store and forward" type of switching methodology.
Implemented Protocols:
1. Ethernet (IEEE 802.3)
2. Internet Protocol (IP)
3. Routing Information Protocol (RIP)
4. User Datagram Protocol (UDP)
5. Open Shortest Path First (OSPF) Protocol
6. Border Gateway Protocol (BGP)
7. Interior Gateway Routing Protocol (IGRP)
8. Enhanced Interior Gateway Routing Protocol (EIGRP)
Slot Interface Technology
0 0-3 4 atmOC3
1 4-7 4 atmOC3
2 8 1 atmOC12
3 9 1 atmOC12
4 10-17 8 eth100T
5 18 1 eth1000T
6 19 1 eth1000T
7 20 1 eth1000T
8 21-32 12 SLIP DS3
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9 33-36 4 SLIP OC3
10 37-40 4 SLIP OC3
11 41 1 SLIP OC12
12 42 1 SLIP OC12
13 43 1 SLIP OC48
14 44 1 SLIP OC48
Note: This router has 16 slots of which 15 slots are used as interface card slots and
one route processor slot. It has an aggregate switching capacity of 80 Gbps.
4.2.8. CISCO ROUTER CS_12008_8s_a5_fe8_ge1_sl9_adv NODE
The model CS_12008_8s_a5_fe8_ge1_sl9_adv represents the following device:
Vendor: Cisco Systems
Product: CISCO 12008
Device Class: Gigabit Switch Router
Configuration: This model represents a specific configuration of an IP-based router
switch model.
Interconnections:
1. 4-port Packet over SONET (PoS) OC3 interfaces (PPP over SONET)(155.52Mbps)
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2. 4-port Packet over SONET (PoS) OC12 interfaces (PPP over SONET)(622.08Mbps)
3. 1-port Packet over SONET (PoS) OC48 interfaces (PPP over SONET)(2.48832Gbps)
4. 4-port ATM OC3 (155.52Mbps).
5. 1-port ATM OC12 (622.08Mbps)
6. 8-port 100BaseT Fast Ethernet (100Mbps).
7. 1-port 1000BaseT Gigabit Ethernet (1000 Mbps)
General Operation:
IP packets arriving on an IP interface are routed to the appropriate output interface
based on their destination IP address. The Routing Information Protocol (RIP), Open Shortest
Path First (OSPF) protocol, Border Gateway Protocol (BGP), Interior Gateway Routing
Protocol (IGRP) or Enhanced Interior Gateway Routing Protocol (EIGRP) may be used to
automatically and dynamically create the routing tables and select routes in an adaptive
manner. The key model features are:
1. An IP forwarding rate of 28,000,000 packets/sec
2. The router model implements a "store and forward" type of switching methodology.
Implemented Protocols:
1. Ethernet (IEEE 802.3)
2. Internet Protocol (IP)
3. Routing Information Protocol (RIP)
4. User Datagram Protocol (UDP)
5. Open Shortest Path First (OSPF) Protocol
6. Border Gateway Protocol (BGP)
7. Interior Gateway Routing Protocol (IGRP)
8. Enhanced Interior Gateway Routing Protocol (EIGRP)
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Slot Interface Technology
0 0-3 4 atmOC3
1 4 1 atmOC12
2 5-12 8 eth100T
3 13 1 eth1000T
4 14-17 4 SLIP OC3
5 18-21 4 SLIP OC12
6 22 1 SLIP OC48
Note: This router has 8 slots of which 7 slots are used as interface card slots and one
route processor slot. It has an aggregate switching capacity of 40 Gbps.
4.2.9. CISCO ROUTER CS_7206_6s_a2_ae8_f4_tr4_slip16 NODE
The CS_7206_6s_a2_ae8_f4_tr4_slip16 model represents the following device:
Vendor: Cisco Systems
Product: CISCO7204
Device Class: Router
Configuration: This model was created using the device creator utility and contains
the following technologies:
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Technology IF/Port Count
ATM 2
Ethernet 8
FDDI 4
Token Ring 4
Slip 16
4.2.10. ETHERNET16_LAYER4_SWITCH NODE
The ethernet16_layer4_switch node model represents a layer-4 switch supporting up
to 16 Ethernet interfaces. The switch implements the Spanning Tree algorithm in order to
ensure a loop free network topology. Switches communicate with each other by sending
Bridge Protocol Data Units (BPDU's). Packets are received and processed by the switch
based on the current configuration of the layer-4 redirection information and the spanning
tree.
General Function: Switch
Supported Protocols: Spanning Tree Bridge, Ethernet
Protocols:
Spanning Tree Bridge Protocol (IEEE 802.1D), Ethernet (IEEE 802.3)
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Interconnections:
1) 16 Ethernet connections at the specified data rate (10, 100, 1000 Mbps)
Restrictions:
The switch can only connect LAN's of the same type (Ethernet to Ethernet, FDDI to
FDDI, or Token Ring to Token Ring).
Port Interface Description:
Combination of up to 16 Ethernet ports (10 Mbps, 100 Mbps, or 1000 Mbps)
4.2.11. 100BaseT DUPLEX LINK
The 100BaseT duplex link represents an Ethernet connection operating at 100 Mbps.
It can connect any combination of the following nodes (except Hub-to-Hub, which cannot be
connected):
1) Station
2) Hub
3) Bridge
4) Switch
5) LAN nodes
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Packet Formats:
Ethernet
Data Rate:
100 Mbps
Model Attributes:
"Propagation Speed": specifies the propagation speed (in meters/sec) for the medium.
If the "delay" attribute of the link is set to "Distance Based", this speed is used to calculate
the propagation delay based on the distance between two nodes.
Restrictions:
This link can not be used to connect two Ethernet hubs.
4.2.12. PPP_ADV POINT-TO-POINT LINK
The PPP_Adv point-to-point link connects two nodes with serial interfaces (e.g.,
routers with PPP ports) at a selectable data rate.
Packet Formats:
ip_dgram_v4, ipx_pkt
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Data Rates:
Selectable (e.g., DS0, DS1, DS3, T1, T3, OC3, OC12, OC36, OC48).
4.3. NETWORK DESIGN AND IMPLEMENTATION IN OPNET
One of the first things to do in order to design and simulate the network is to
familiarize with OPNET. This is a powerful Network Simulation Package that will help us
design and simulate the network instead doing all the calculations by hand. After retrieving
the OPNET Modeler shortcut under the CAD tools on the SUN workstations we are ready to
launch the application.
Picture 3 Initial OPNET Modeler Logo
After the initial OPNET logo is displayed Picture 3, then it is time to create a new
project. This is done under the File menu New Project
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By pressing ok, we were sent to the next window where we will put the name of the
Network that we want to build and also to name a scenario for it as well.
In our case, the name of the model was GUNET and the scenario position remained
as it was. Now, we are ready to insert the first attributes we want the program to have. This
mean, we created and empty scenario.
By pressing next, we are being sent to the next table, in which we can choose the
location where we want our network to be located in. In our case we choose World and in the
next table we choose Europe.
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By pressing next, we will continue to the next dialog, where we must insert all the
nodes we want our template to include. This means to specify all the components like
routers, switches, LAN, links and servers.
After pressing the next button, a screen of Europe displays and then we have to zoom
in several times to reach to the desired location where our network will be designed which is
in Greece. After that, we can open the Object Pallet and start dragging the desired nodes in
the OPNET window and start building the network.
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4.3.1. NETWORK CONFIGURATION
Since the network is an existing one and there can be no changes in the way it is
designed, the only thing that can be done is to specify the applications that will be supported
and different profile configurations for each university if needed
Since Differentiated Services is our main concern in this report, real-time applications
are the ones that we are mostly interested in. Hence videoconferencing and voip are
applications that will have to be included on the network, in addition to the HTTP services,
E-mail services, FTP services and Database access.
All the attributes of the nodes can be accessed by right click on the desired node and
then click on the attribute menu. By doing that, we can change the attributes in each node
separately, or we can choose the select similar nodes, do the required changes, press the
apply to all selected nodes tab and apply the new changes in all the selected nodes. By
applying this to all the desired nodes, the following changes where made:
4.3.1.1. APPLICATION CONFIGURATION
The Application Configuration Attributes can be seen in Picture 4 below:
Picture 4 Application Config for the Application Definitions
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Inside the application definitions, is the table, were we can define all the applications
that we want to use on the network and the description of each application. The applications
that we used are FTP, Http, Email, Database, Voice and Video Conferencing and this can be
seen in Picture 5.
Picture 5 Applications Definition Table
By clicking inside the application and definition table in the description menu, we can
choose by High, Medium or Low setting of each application. The application descriptions for
the FTP application can be seen in Picture 6.
Picture 6 FTP Description Table
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The FTP application was set to low load and the FTP table displays the values the
FTP low description has. This can be seen in Picture 7.
Picture 7 Ftp Table
The application descriptions for the Email application can be seen in Picture 6. Email
application was set to high load. This can be seen in Picture 8.
Picture 8 E-mail Description Table
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The Email table displays the values that Email High description has. This can be seen
in Picture 9.
Picture 9 Email Table
The application description for the Database application can be seen in Picture 10. As
it can be seen the (…) value means that there was a change in the Database Table.
Picture 10 Database Description Table
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The Database table displays the values that Email High application has. This can be
seen in Picture 9. Here we changes the Transaction Mix to 50% which means that half the
traffic will be the queries and the other half will be the response.
Picture 11 Database Table
The Http application was set to Heavy Browsing. The Http description table can be
seen in Picture 12.
Picture 12 HTTP Description Table
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The Http table displays the values that Http application has. This can be seen in
Picture 13.
Picture 13 Http Table
The application description for the Voice application can be seen in Picture 14. As it
can be seen the (…) value means that there was a change in the Voice Table.
Picture 14 Voice Description Table
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The change made in the Voice table was on the traffic mix, which means that the
voice application will be behave as background traffic, something that increased the
simulation speed and decreased the overall simulation time. Also the encoder scheme was
changed to GSM (silence) which is one of the best schemes because when there is no voice
detected in the network, no traffic will be transferred. This can be seen in Picture 15
Picture 15 Voice Table
The application description for the Video Conferencing application can be seen in
Picture 16. As it can be seen the (…) value means that there was a change in the Video
Conferencing Table.
Picture 16 Video Conferencing Description Table
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The change made in the Video Conferencing table was on the traffic mix as
mentioned earlier in the voice table, which means that the Video Conferencing application
will be behave as background traffic, something that increased the simulation speed and
decreased the overall simulation time. This can be displayed in Picture 17.
Picture 17 Video Conferencing Table
In order for Voice Application to work, we need to define the Voice encoder
Schemes. This is done by clicking in the voice encoder scheme value as displayed in Picture
18 below:
Picture 18 Application Config for the Voice Encoder Schemes
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In order to be sure that there will be no problems in specifying the correct Voice
Encoder Scheme, as it can be seen in Picture 19, all the supported schemes were inserted.
Picture 19 Voice Encoder Schemes
4.3.1.2. PROFILE CONFIGURATION
Now that the Application Config is configured, it is time to setup the Profile Config.
Picture 20 displays the Profile Config. It was decided that it would be better to use separate
profiles for each University even though all the profile configurations will be the same.
Hence there are sixteen profiles created as it can be seen in Picture 21 and a profile that is
only for Video Conferencing.
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Picture 20 Profile Config Attributes
Picture 21 Profile Configuration Table
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It can also be seen that the Operation mode is set to Simultaneous which means that
all profiles will run together instead of running in serial order which means that all profiles
would run one after another which wouldn’t be so realistic.
By clicking inside the application inside the Profile Configuration of each University,
we can set the different applications we want the profile to have. The following applications
can be seen as displayed in Picture 22 below:
Picture 22 Application Profile Configuration for each University
For the Video Conferencing profile the following Application table can be seen as
displayed in Picture 23 below:
Picture 23 Video Conferencing Application Profile
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4.3.1.3. 100BaseT_LAN CONFIGURATION
Since no information on the exact number of the workstations in each University can
be found and the traffic is already known from the GUNET network monitor program, it was
decided that instead of adding random number of workstations on the network trying to
create the same amount of traffic that the workstations produce in reality, all that traffic
would be implemented as background traffic on the links and only the workstations of the
lecturers would be the ones that the applications would be implemented on.
Once again since the number of the actual workstations for the lectures could be
found, an assumption was made that in each university there will be two LANs. Each LAN
would support the appropriate Profile Configuration plus one of the two LANs would support
the Video Conference as well. Since Voice and Video Conferencing work better when they
are set-up with destination preferences, each LAN was renamed accordingly to the
University that they represent. The one that would support Video Conferencing would be
renamed as LAN_0 and the other would be LAN_1.
4.3.1.3.1. LAN_1 CONFIGURATION
For LAN_1 the following values were changed.
First change is to rename the name of the node and insert the initials of the
University it represents
Under the Application Supported Profiles we will insert the appropriate
profile for the university that the LAN represents. This can be seen in Picture
25
Under the Application Supported Services we will insert the appropriate
service which for LAN_1 is only Voice. This can be seen in Picture 26
Under LAN Server Name we insert the initials of the University it represents.
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Under the Application Destination Preferences we will insert all the
destinations we want the supported services to go. This is shown in Picture 27
Under the Number of workstation we changed the default value of 10 to 25
which is a more realistic value for a University.
Picture 24 LAN_1 Attributes
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The application Supported Profiles table can be seen in Picture 25 below:
Picture 25 LAN_1 Application Supported Profiles
The Application Supported Profiles of LAN_1 can be seen in Picture 26 below
Picture 26 LAN_1 Application Supported Services
Picture 27, displays the Application Destination Preferences table, where we can
specify the Actual Name destination of the voice application.
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Picture 27 LAN_1 Application Destination Preferences
Assuming that each workstation has the ability to call any workstation on the GUNET
Network even workstations in the same LAN, the following settings where inserted in the
Actual name Table as it can be seen in Picture 28. In the left column we can see the
destinations and in the right column we can see the Selection Weight of the application
where we can select the type of priority with respect to the rest applications.
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Picture 28 LAN_1 Actual Name Table
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4.3.1.3.1. LAN_0 CONFIGURATION
For LAN_0 the following values were changed.
First change is to rename the name of the node and insert the initials of the
University it represents
Under the Application Supported Profiles we will insert the appropriate
profile for the university that the LAN represents. For LAN_0 we have two
profiles. One is the University it represents and the other is the Video
Conferencing profile. This can be seen in Picture 30
Under the Application Supported Services we will insert the appropriate
service which for LAN_0 is not only Voice but Video Conferencing as well.
This can be seen in Picture 31
Under LAN Server Name we insert the initials of the University it represents.
Under the Application Destination Preferences we will insert all the
destinations we want the supported services to go. Since we have two
supported applications that need destination preferences, for the voice is the
same as mentioned earlier in Picture 27 and for the video conferencing the
applications destinations preferences can be seen in Picture 32
Under the Number of workstation we changed the default value of 10 to 25
which is a more realistic value for a University
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Picture 29 LAN_0 Attributes
The application Supported Profiles for LAN_0 can be seen in Picture 30
Picture 30 LAN_0 Application Supported Profiles
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Picture 31 displays the two Application Supported Profiles for LAN_0.
Picture 31 LAN_0 Application Supported Services
Since we want the LAN to communicate with all the other LANs, but since the Video
Conferencing is only supported by the LAN_0 LANs, then a new Actual Name Table was
crated for this application as it can be seen in Picture 33 with all the LAN_0 ones.
Picture 32 LAN_0 Application Destination Preferences
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Picture 33 LAN_0 Actual Name Table
4.3.1.4. ROUTERS CONFIGURATION
All the routers attributes remained at default settings. The only change made on the
routers was the name. The name of the router corresponds to the location it is in and in other
cases the initials of the university it represents.
4.3.1.5. SWITCH CONFIGURATION
The switches were used to connect the two LANs with the University router and the
only change that was made in the attributes was the name, where the initials of the University
it represents was inserted.
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4.3.1.6. PPP_SERVER CONFIGURATION
There are four PPP_Servers inside each University. These servers were inserted in
order to support some of the applications that would run across the network. Each server
would support one application only. Hence the four servers were used to run HTPP, FTP,
Email and Database services. The PPP_Servers are connected with the University router with
1Gbps links.
Picture 34 PPP_Server Attributes
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Under the application supported services, we inserted 1 row and choose to insert the
Http heavy application. All the other servers were done accordingly to the application they
would support
Picture 35 PPP_Server Application Supported Services
4.3.1.7. LINKS UTILISATION
As mentioned earlier, the traffic of the computers will be implemented as background
utilization on the links. This utilization is based on the two hours average traffic that was
found from the online GUNET networking monitor software. It was decided to get the two
hours average on the assumption that the simulation of the network would run for two hours,
something that couldn’t be done since in the end when running the simulations, a few
minutes would take days to finish.
The Utilization on the links was implemented in the Links attributes under the
Background load attribute. The way that the utilization was implemented can be seen in
Picture 36.
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Picture 36 Link Attributes
Under the background load, we changed the intensity of the traffic in bps both
incoming and outgoing. These changes were done by clicking to change the intensity (bps)
value. A new window appears where we can put the number of bits/sec we want to put and
the period that we want this utilization to have. This can be seen in Picture 37 and Picture 38.
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Picture 37 Incoming Background Loading Table
Picture 38 Outgoing Background Loading Table
The Background traffic was implemented in most of the links. Theses changes can be
seen in the following tables. Table 4 below displays the network activity on each link of the
backbone network.
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Links between Routers Data carried in (bits/sec) Data carried out (bits/sec)
Athens - Thessaloniki 34.100.000 (bits/sec) 37.600.000 (bits/sec)
Athens -Patra 29.700.000 (bits/sec) 29.500.000 (bits/sec)
Athens - Heraklio 29.800.000 (bits/sec) 46.500.000 (bits/sec)
Athens - Rhodes 14.600.000 (bits/sec) 16.700.000 (bits/sec)
Thessaloniki - Xanthi 2.321,2 (bits/sec) 2589,1 (bits/sec)
Thessaloniki - Larissa 8.896 (bits/sec) 7.683,2 (bits/sec)
Patra - Ioannina 1.112,2 (bits/sec) 1.395,6 (bits/sec)
Table 4 Background Utilization between the City Routers
In some cases, this utilization is also for the traffic between the city routers and the
university router. Table 5 and Table 6 display the network activity between the city routers
and the university router.
City Router to University
Router
Data carried in
(bits/sec)
Data carried out
(bits/sec)
Thessaloniki Router to
Aristotelio University
19.600.000 (bits/sec) 23.700.000 (bits/sec)
Thessaloniki Router to
Macedonia University
6.335,1 (bits/sec) 5.570,1 (bits/sec)
Patra Router to
Patra University
22.400.000 (bits/sec) 22.500.000 (bits/sec)
Table 5 Background Utilization between City Router and University Router
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City Router to University
Router
Data carried in
(bits/sec)
Data carried out
(bits/sec)
Xanthi Router to
Thrace University
2.321,2 (bits/sec) 2589,1 (bits/sec)
Larissa Router to
Thessaly University
8.896 (bits/sec) 7.683,2 (bits/sec)
Ioannina Router to
Ioannina University
1.112,2 (bits/sec) 1.395,6 (bits/sec)
Heraklio Router to
Creta University
16.900.000 (bits/sec) 23.000.000 (bits/sec)
Table 6 Background Utilization between City Router and University Router
Unfortunately, exact number of the loading between the Athens routers and the
universities couldn’t be found and the only traffic implemented is based only between the
Athens Routers. There are three routers in ring topology in Athens which are connected with
2.5Gbps links and one of the routers connects to Athens city router with 1GBps link. Table 7
displays the Background Utilization between the Athens Routers and Table 8 displays the
Background Utilization between Athens City router and Athens Router
Athens Router to
Athens Router
Data carried in
(bits/sec)
Data carried out
(bits/sec)
Athens Router to
Acropolis Router
8.863,4 (bits/sec) 20.500.000 (bits/sec)
Athens Router to
Ilissos Router
96.500.000 (bits/sec) 375.900.000 (bits/sec)
Acropolis Router to
Ilissos Router
4.944 (bits/sec) 4.920 (bits/sec)
Table 7 Background Utilization between Athens Routers
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City Router to
Router
Data carried in
(bits/sec)
Data carried out
(bits/sec)
Athens City Router to
Athens Router
85.000.000 (bits/sec) 75.900.000 (bits/sec)
Table 8 Background Utilization between Athens City Router and Athens Router
Unfortunately in most cases, the GUNET was a highly utilized network and by
getting voice and video conferencing in the network would certainly have a big impact on it.
Hence some of the links needed to be upgraded without of course exceeding the GRNET
links capacity available. In one case though the link was downgraded in order to get some
congestion later on the network during simulation time. Hence Table 9 displays the new
capacity of the backbone network.
Links between Routers Initial Capacity (Mbps) Upgraded Capacity (Mbps)
Athens - Thessaloniki 69 (Mbps) 100 (Mbps)
Athens -Patra 45 (Mbps) 60 (Mbps)
Thessaloniki - Xanthi 6 (Mbps) 12 (Mbps)
Thessaloniki - Larissa 18 (Mbps) 12 (Mbps)
Patra - Ioannina 4.5 (Mbps) 12 (Mbps)
Table 9 Capacity of the Upgraded Backbone Network
Some changes on the capacity of the links occurred from the City routers to the
University routers as well. These changes can be seen in Table 10 below. In two cases where
the universities are located in Athens, the capacity of the link was upgraded from 2 Mbps to
1000 Mbps since all the other universities of Athens use Gbit links.
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Links between City Router
and University Router
Initial Capacity (Mbps) Upgraded Capacity
(Mbps)
Thessaloniki Router to
Aristotelio University Router
34 (Mbps) 60 (Mbps)
Thessaloniki Router to
Macedonia University Router
18 (Mbps) 22 (Mbps)
Xanthi Router to Thrace
University Router
21 (Mbps) 22 (Mbps)
Larissa Router to
Thessaly University Router
8 (Mbps) 22 (Mbps)
Patra Router to
Patra University Router
34 (Mbps) 60 (Mbps)
Ioannina Router to
Ioannina University Router
22 (Mbps) 22 (Mbps)
Athens Acropolis Router to
Harokopio University
2 (Mbps) 1000 (Mbps)
Athens Ilissos Router to
University of Good Arts
2 (Mbps) 1000 (Mbps)
Table 10 Capacity of the Upgraded Links between City Routers and University Routers
4.3.2. APPLYING QoS ON GUNET
4.3.2.1. SETTING UP THE APPLICATION CONFIGURTION
By reading several times the tutorial of OPNET on applying QoS in a network, the
attempt on applying QoS on the GUNET network was made. Fortunately the tutorial was
very helpful and the beginning of the simulation stared immediately. In order to configure
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the network, we should first declare in the application configuration node the priority of the
applications we wanted to test under QoS. The two applications in which we changed the
priority settings was voice and video conferencing and on both we inserted the same setting
for priority. By default, both applications are set to best effort (0) as seen Picture 39 and in
Picture 40.
Picture 39 Voice Table
Picture 40 Video Conferencing Table
By clicking on the Type of Service value, a new window appears. This window can be seen
in Picture 41.
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Picture 41 ToS/DSCP Priority Table
The options that we have in order to change the priority of the application can be seen
in Picture 42.
Picture 42 Options of different Priority Settings
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Unfortunately due to luck of time, only the best priority could be simulated. Hence,
the settings on this window was changed from best effort (0) to Reserved (7). And also, in
order to have the best priority of the application, we clicked added the three options below
the type of service window in order the application to work better also for delay, throughput
and reliability. The final settings can be seen in Picture 43.
Picture 43 Final ToS/DSCP Priority Table
Since from the first minute it was observed that the simulation would take ages to
finish, we had to build the same project seven times and run each different queuing scenario
in different workstations in order to finish within the time limit.
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4.3.2.2 SETTING UP QoS SCHEMES
In order to apply the different QoS schemes, we did the following steps: First of all
was to setup the FIFO profile. Although the routers have by default the FIFO queue, a
simulation was implemented to get the results. All the other scenarios with the different
queuing techniques ware based on FIFO queue and the desired queuing method. This was
done by pressing the Protocols tab in the program. This can be seen in Picture 44.
Picture 44 Setting Up QoS Schemes
By pressing the configure QoS menu, a new window appears. This window is where
we can change the different queues and can be seen in Picture 45.
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Picture 45 QoS Configuration Table
The different queuing techniques available at OPNET Modeller are displayed in
Picture 46
Picture 46 Available Queuing Techniques
By selecting the desired queuing technique and applying the changes on the QoS
configuration table, all the connected interfaces on the network will be automatically
configured to run the selected QoS scheme.
The way that the different projects were named was the following:
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Project Name Queuing Technique
GUNET 1 Lower Links FIFO
GUNET 2 Lower Links WFQ
GUNET 3 Lower Links Priority Queuing
GUNET 4 Lower Links Custom Queuing
GUNET 5 Lower Links MWRR
GUNET 6 Lower Links DWRR
GUNET 7 Lower Links MDRR
By changing the Type of Service from ToS to DSCP (252) which is the highest
priority settings and running a simulation, there wasn’t any change on the results and hence
only the ToS was the one that was used to change the priority.
These were the only changes made in order to run the simulation and applying QoS
respectively.
CHAPTER 4 --------------------------------------------------------------------------------------------31 4.1. NETWORK DECISION AND IMPLEMENTATION------------------------------------31 4.2. COMPONENTS USED -----------------------------------------------------------------------35
4.2.1. APPLICATION CONFIG .................................................................................... 35
4.2.2. PROFILE CONFIG .............................................................................................. 36
4.2.3. QoS CONFIG........................................................................................................ 37
4.2.4. SUBNET NODE................................................................................................... 37
4.2.5. 100BaseT_LAN NODE ........................................................................................ 38
4.2.6. PPP_SERVER NODE .......................................................................................... 38
4.2.7. CISCO ROUTER CS_12016_16s_a10_fe8_ge3_sl24_adv NODE ..................... 40
4.2.8. CISCO ROUTER CS_12008_8s_a5_fe8_ge1_sl9_adv NODE ........................... 42
4.2.9. CISCO ROUTER CS_7206_6s_a2_ae8_f4_tr4_slip16 NODE ........................... 44
4.2.10. ETHERNET16_LAYER4_SWITCH NODE ..................................................... 45
4.2.11. 100BaseT DUPLEX LINK ................................................................................. 46
4.2.12. PPP_ADV POINT-TO-POINT LINK ................................................................ 47
4.3. NETWORK DESIGN AND IMPLEMENTATION IN OPNET ------------------------48 4.3.1. NETWORK CONFIGURATION......................................................................... 51
4.3.1.1. APPLICATION CONFIGURATION---------------------------------------------51
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4.3.1.2. PROFILE CONFIGURATION ----------------------------------------------------59 4.3.1.3. 100BaseT_LAN CONFIGURATION --------------------------------------------62 4.3.1.4. ROUTERS CONFIGURATION---------------------------------------------------70 4.3.1.5. SWITCH CONFIGURATION-----------------------------------------------------70 4.3.1.6. PPP_SERVER CONFIGURATION ----------------------------------------------71 4.3.1.7. LINKS UTILISATION -------------------------------------------------------------72
4.3.2. APPLYING QoS ON GUNET ............................................................................. 78
4.3.2.1. SETTING UP THE APPLICATION CONFIGURTION ----------------------78 4.3.2.2 SETTING UP QoS SCHEMES-----------------------------------------------------82
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CHAPTER 5
5.1. GUNET_1 FIFO
5.1.1. VOICE
As a test to see if OPNET was working correctly, the simulation was run twice
with the FIFO queuing. From the picture below we can see only one graph for both
scenarios, which means that both graphs are 100% similar. This is because when in
OPNET results coincide with each other in overlay mode the program shows only the first
graph and does not multiplex the colours together. The End-to-End delay is the time taken
for a packet from the moment it leaves from the source to the moment it reaches the
destination. The smaller the End-to-End delays the better for the users.
Clearly in the picture we can see that the traffic is generated just after the second
minute of the simulation and increases vertically up to the third minute before it starts to
stabilize but still it continues to increase because the utilisation of the network is
increasing. This is due to the fact that the links of the network are setup to work on high
utilization in order to apply differentiated services. If the utilization of the links were low,
then by applying the differentiated services would actually give worst End-to-End delays
because it would take more time for the routers to apply the different queuing techniques
plus to send the data instead of sending the data directly.
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Picture 1 Voice Packet End-to-End Delay
We can see in the graph below that the delay variation increases up to a certain
point when the traffic starts and then stabilizes a little. Then it starts decreasing slowly.
This means that the delay of the network is high in the beginning of the simulation and
then drops down as the traffic of the network moves on and because the network can
handle the traffic adequately.
Picture 2 Voice Packet Delay Variation
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5.1.2. VIDEO CONFERENCING
In the graph below, we can see that the video conferencing, the end-to-end delay
is increasing in the beginning of the simulation up to a certain point and from that point
onwards it degrades rapidly. This is done because the utilization of the network gets to a
steady state after a while and the data throughput of the routers stabilizes to a certain
value dropping the end to end delay.
Picture 3 Video Conferencing Packet End-to-End Delay
We can see in the graph below that the delay variation increases up to a certain
point when the traffic starts. Then it starts decreasing rapidly. This means that the delay
of the network is high in the beginning of the simulation and then drops down as the
traffic of the network moves on and because the network can handle the traffic
adequately. As well we can see that the video had a smoother end-to-end delay and also a
better packet delay variation by comparing it with the voice. This is because, the video
conferencing application sent larger amounts of data and makes fewer transactions, where
the voice application is sending smaller amounts of data but has more transactions.
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Picture 4 Video Conferencing Packet Delay Variation
5.2. GUNET_2 WFQ
5.2.1 VOICE
In the graph below we can see that WFQ compared to FIFO behaves much worse.
The end-to-end delay has increased significantly. While the FIFO delay is around 0.075
seconds in average the network with WFQ not only has a much higher delay but also it
never stabilizes to a certain value but continues to increase for the entire time that the
simulation was run.
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Picture 5 Voice Packet End-to-End Delay
In the graph below, we can observe that the blue which is the Fifo queuing, from
the minute the end-to-end delay stabilized, the packet delay variation started to drop.
Same thing can be seen for the red graph as well. From the minute it starts to stabilize, the
packet delay variation starts to decrease which means that the end-to-end delay starts to
stabilize.
Picture 6 Voice Packet Delay Variation
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5.2.2. VIDEO CONFERENCING
In the graph below, we see that once again FIFO queuing works much better
compared to WFQ. Although the end-to-end delay is increased and is always more than
the Fifo end-to-end delay, we can see that while traffic goes on, the red which represents
the WFQ queuing is more smooth than the blue graph. We could say that while the WFQ
performs worst than Fifo, the WFQ queuing has smoother characteristics.
Picture 7 Video Conferencing Packet End-to-End Delay
The graph below displays the video conferencing packet delay variation. As
expected, the Fifo queuing has stabilized as soon as the traffic went along and have a
normal behavior. The WFQ queuing had a new pinch which means that the packet delay
variation is not stable up to the time that the simulation finished.
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Picture 8 Video Conferencing Packet Delay Variation
5.3. GUNET_3 PRIORITY QUEUING
5.3.1. VOICE
The graph below displays the voice end-to-end delay using the Priority Queuing
technique. This is displayed with the red graph and the blue represents the FIFO queuing.
As we can see, by comparing the two graphs, the difference between the red and blue
graph is quite large which means that Priority Queuing is much more efficient than the
Fifo queuing since it produces much better results. We can also see that while the blue
graph is still increasing, the red has almost stopped increasing and is much smoother.
Priority queuing could be one option for an Internet Service Provider who wants to
promise some specific SLAs.
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Picture 9 Voice Packet End-to-End Delay
The graph below displays the voice packet delay variation. As we can see, the
priority queuing is much smoother and much smaller than the Fifo queuing which is
expected since the end-to-end delay of priority queuing was quite smooth. From the blue
graph, we can see that from the minute that the end-to-end delay starts to stabilize, the
packet delay variation starts to decrease.
Picture 10 Voice Packet Delay Variation
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5.3.2. VIDEO CONFERENCING
The graph below, displays the end-to-end delay using the priority queuing and the
Fifo queuing. Although the blue graph which represents the Fifo queuing has a big spike
in the beginning of the simulation, in the end it has a smaller end-to-end delay which is
better than the red graph which represents the Priority queuing. By comparing the blue
graphs we can see that the red although in the end has an increased delay, the graph is
more stable than the blue. This is better again for Internet Service Providers when the
want to specify the SLAs because the delay didn’t have any major spikes.
Picture 11 Video Conferencing Packet End-to-End Delay
As expected, the video conferencing packet delay variation of the priority queuing
is much better than the Fifo queuing. From the beginning of the simulation the red graph
is almost a straight line which means that there is no delay variation and the blue has a big
spike in the beginning which means that there was delay variation in the beginning of the
simulation but it degraded immediately. But in the end, the priority queuing is still the
best option over Fifo queuing.
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Picture 12 Video Conferencing Packet Delay Variation
5.4. GUNET_4 CUSTOM QUEUING
5.4.1. VOICE The graph below displays the voice end-to-end delay using the Custom Queuing
technique. This is displayed with the red graph and the blue represents the FIFO queuing.
As we can see, by comparing the two graphs, the difference between the red and blue
graph is quite large which means that Custom Queuing is much more efficient than the
Fifo queuing since it produces much better results. Custom queuing even gave better
results from Priority queuing whish was the best so far up to that point. We can also see
that while the blue graph is still increasing, the red has stopped increasing and is much
smoother. Custom queuing could be the best option for an Internet Service Provider who
wants to promise some specific SLAs.
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Picture 13 Voice Packet End-to-End Delay
The graph bellow displays the voice packet delay variation. We can observe that
the red graph is a straight line just above the x axis which means that there is minimum
delay variation The blue graph which is the Fifo queuing has a big spike in the beginning
of the simulation and as soon as traffic goes on, it starts degrading but still far away from
the custom queuing technique.
Picture 14 Voice Packet Delay Variation
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5.4.2. VIDEO CONFERENCING
The graph below displays the video conferencing end-to-end delay. As we can
see, custom queuing once again performed much better than Fifo queuing. As we can see,
fifo although it started with a drop of the end-to-end delay, it increased rapidly and as the
traffic kept going, it started degrading again. The custom queuing which is represented by
the red graph, from the beginning of the simulation decreased and after a few minutes of
simulation, the line was a straight line. Once again, a very good option when specifying
SLAs is needed.
Picture 15 Video Conferencing Packet End-to-End Delay
The graph below displays the video conferencing packet delay variation. As we
can see, the Fifo queuing has a spike in the beginning of the simulation, and then it
degrades immediately and as the traffic goes on, we see that due to the high utilisation of
the network, the packet delay variation increases again. The custom queuing represented
by the red graph, from the beginning of the simulation is a straight line close to the x axis
which means that there is minimal delay variation.
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Picture 16 Video Conferencing Packet Delay Variation
5.5. GUNET_5 MWRR
5.5.1. VOICE
In the graph below we can see that MWRR compared to FIFO behaves much
worse. Similar results as the WFQ queuing were obtained. The end-to-end delay has
increased significantly. While the FIFO delay is around 0.075 seconds in average the
network with MWRR not only has a much higher delay but also it never stabilizes to a
certain value but continues to increase for the entire time that the simulation was run.
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Picture 17 Voice Packet End-to-End Delay
In the graph below, we can observe that the blue which is the Fifo queuing, from
the minute the end-to-end delay stabilized, the packet delay variation started to drop.
Same thing can be seen for the red graph as well. From the minute it starts to stabilize, the
packet delay variation starts to decrease which means that the end-to-end delay starts to
stabilize.
Picture 18 Voice Packet Delay Variation
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5.4.2. VIDEO CONFERENCING
In the graph below, we see that once again FIFO queuing works much better
compared to MWRR. Although the end-to-end delay is increased and is always more than
the Fifo end-to-end delay, we can see that while traffic goes on, the red which represents
the MWRR queuing is more smooth than the blue graph. We could say that while the
MWRR performs worst than Fifo, the MWRR queuing has smoother characteristics.
Picture 19 Video Conferencing Packet End-to-End Delay
The graph below displays the video conferencing packet delay variation. As
expected, the Fifo queuing has stabilized as soon as the traffic went along and have a
normal behavior. The MWRR queuing had a new pinch which means that the packet
delay variation is not stable up to the time that the simulation finished.
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Picture 20 Video Conferencing Packet Delay Variation
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6. CONCLUSION
The purpose of this project was to monitor the traffic on a network by implementing
Differentiated Services.
The GUNET network was proposed in order to implement DiffServ since it is a
slightly congested network and voice and video conferencing are applications that a technical
team is trying to insert to the network nowadays. The network uses as a backbone a part of
the GRNET links to transfer data between the universities. Due to the fact that GUNET
doesn’t use the whole capacity of the GRNET, some upgrades on the links were made in
order to get voice and video application a real possibility to be implemented.
The links although the network was setup in the beginning to provide with real-time
delays, when differentiated services were implemented, we had to downgrade the links in
order to increase the utilization on the links since DiffServ applies to congested networks.
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CHAPTER 7
7.1. PROBLEMS OCCURRED AND LIMITATIONS
During the project period, there were many problems that occurred in the design and
simulation of the network. These problems were mostly with the OPNET Modeler package
and its configuration.
First problem that was observed was that when designing the network, it was
impossible to have both PPP and FDDI links in the network. While running the simulation,
the error that was given was the IPRouting wasn’t configured and more than two nodes had
the same IP which confused the program.
Second problem observed was that once the Hard disk limit on the account was on its
limits, then the program would turn the links to default values which in the end of the
simulation gave too many errors because all the links returned to default values and the
utilization of the network increased to 100% and hence the network had to keep
retransmitting data.
Third problem and limitation was found as soon as QoS was implemented on the
network. As soon as the simulation was starting, the speed of the simulation degraded
something that affected the time taken to finish each simulation, or the program would stop
responding and no results were obtained. Also, this is the reason why I have all my project
scenarios in separate projects and not only one where it would be much easier to discuss on
the results since all the results would be in the same screenshot.
All these problems during the period of the project had as an affect on the time
needed to finish all the simulations on schedule and spend less time on writing the final
report.
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7.2. FUTURE IMPROVEMENTS Unfortunately due to the many problems and limitations observed during the period
of the project, time didn’t allow doing some more work on different architectures of QoS.
Hence as future work, Integrated services, RSVP could be implemented on the network and
hence we could observe and compare the two QoS architectures, in order to find the
capabilities of each one.
Another thing that could be done is to add some wireless networking inside the
University Subnets since more and more enterprises and organizations change from wired to
wireless networks.
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CHAPTER 8 ]
8.1. REFERENCES
[1] N. Savage. (2004). B351 Multimedia Networks Study Notes, Portsmouth
University
[2] OPNET Online Tutorial. University of Portsmouth Department of Computer &
Electronic Engineering
[3] OPNET Online Documentation. University of Portsmouth Department of
Computer & Electronic Engineering
[4] Gremont, Boris (Dr.) “Data Communications & Networks 1” Issue 3
University of Portsmouth 2000-2001 Department of Computer & Electronic
Engineering
[5] OPNET Modeller Manual v9
8.2. INTERNET REFERNCES - BIBLIOGRAPHY
1) http://docs.sun.com/db/doc/816-4094/6mab39ut0?a=view
2) http://kabru.eecs.umich.edu/qos_network/diffserv/DiffServ_links.html
3) http://qos.ittc.ukans.edu/DiffSpec/node5.html
4) http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/qos.htm#1020698
5) http://www.cisco.com/warp/public/732/Tech/qos/
6) http://www.ietf.org/html.charters/diffserv-charter.html
7) http://www.informit.com/articles/article.asp?p=26125&seqNum=3
8) http://www.informit.com/articles/article.asp?p=26125&seqNum=6
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9) http://www.objs.com/survey/QoS.htm
10) http://www.protocols.com/papers/diffserv.htm
11) http://www.sciencedaily.com/encyclopedia/differentiated_services
12) http://www.telecom.tuc.gr/networkcourse/1
13) http://www.webopedia.com/TERM/Q/QoS.html
14) http://www.gunet.gr/index.pl?id=3121
15) http://netmon.grnet.gr/traffic/
16) http://diffserv.sourceforge.net/
17) http://qos.ittc.ukans.edu/diffoverview/index.htm
18) http://qos.ittc.ukans.edu/ipqos/ip_qos.htm
19) http://docs.sun.com/db/doc/816-4094/6mab39ut0?a=view
20) http://www.ypes.gr/nomarxiakh_aut.htm
21) http://www.ellada.net/travelinfo/rhodes.html
22) http://www.webopedia.com/TERM/A/ATM.html
23) http://www.webopedia.com/TERM/T/throughput.html
24) http://www.linktionary.com/s/sbm.html
25) http://www.telecom.tuc.gr/networkcourse/qos.ppt
26) http://www.sciencedaily.com/encyclopedia/differentiated_services
27)http://66.102.9.104/search?q=cache:http%3A%2F%2Fwww.hep.ucl.ac.uk%2F~ytl%2
Fqos%2Findex.html
28)http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/qos_c/qcp
rt1/qcdclass.htm
29) http://www.opalsoft.net/qos/WhyQoS.htm
30)http://www.cisco.com/en/US/netsol/ns339/ns392/ns399/ns404/networking_solutions_
white_paper0900aecd800dd974.shtml
31)http://www.cisco.com/en/US/products/sw/iosswrel/ps1820/products_feature_guide09
186a00800f4891.html#29478
32)http://www.cisco.com/en/US/tech/tk331/tk336/technologies_design_guide09186a008
0237a48.shtml#wp16388
33) http://www.cisco.com/warp/public/63/mdrr_wred_overview.html
34) http://networking.ittoolbox.com/documents/document.asp?i=2528
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35) http://www.cisco.com/warp/public/732/Tech/qos/
36)http://www.cisco.com/warp/public/105/dscpvalues.html#dscpandassuredforwardingcl
asses
37) http://www.cse.ohio-state.edu/~jain/cis788-99/ftp/qos_protocols/
38)http://www.cisco.com/univercd/cc/td/doc/product/rtrmgmt/ciscoasu/class/qpm1_1/usi
ng_qo/c1plan.htm#xtocid321027
39) http://www.cse.ohio-state.edu/~jain/cis788-99/ftp/qos_protocols/index.html
Last accessed 20/09/04
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CHAPTER 8 ]
8.1. REFERENCES
[1] N. Savage. (2004). B351 Multimedia Networks Study Notes, Portsmouth
University
[2] OPNET Online Tutorial. University of Portsmouth Department of Computer &
Electronic Engineering
[3] OPNET Online Documentation. University of Portsmouth Department of
Computer & Electronic Engineering
[4] Gremont, Boris (Dr.) “Data Communications & Networks 1” Issue 3
University of Portsmouth 2000-2001 Department of Computer & Electronic
Engineering
[5] OPNET Modeller Manual v9
8.2. INTERNET REFERNCES - BIBLIOGRAPHY
1) http://docs.sun.com/db/doc/816-4094/6mab39ut0?a=view
2) http://kabru.eecs.umich.edu/qos_network/diffserv/DiffServ_links.html
3) http://qos.ittc.ukans.edu/DiffSpec/node5.html
4) http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/qos.htm#1020698
5) http://www.cisco.com/warp/public/732/Tech/qos/
6) http://www.ietf.org/html.charters/diffserv-charter.html
7) http://www.informit.com/articles/article.asp?p=26125&seqNum=3
8) http://www.informit.com/articles/article.asp?p=26125&seqNum=6
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9) http://www.objs.com/survey/QoS.htm
10) http://www.protocols.com/papers/diffserv.htm
11) http://www.sciencedaily.com/encyclopedia/differentiated_services
12) http://www.telecom.tuc.gr/networkcourse/1
13) http://www.webopedia.com/TERM/Q/QoS.html
14) http://www.gunet.gr/index.pl?id=3121
15) http://netmon.grnet.gr/traffic/
16) http://diffserv.sourceforge.net/
17) http://qos.ittc.ukans.edu/diffoverview/index.htm
18) http://qos.ittc.ukans.edu/ipqos/ip_qos.htm
19) http://docs.sun.com/db/doc/816-4094/6mab39ut0?a=view
20) http://www.ypes.gr/nomarxiakh_aut.htm
21) http://www.ellada.net/travelinfo/rhodes.html
22) http://www.webopedia.com/TERM/A/ATM.html
23) http://www.webopedia.com/TERM/T/throughput.html
24) http://www.linktionary.com/s/sbm.html
25) http://www.telecom.tuc.gr/networkcourse/qos.ppt
26) http://www.sciencedaily.com/encyclopedia/differentiated_services
27)http://66.102.9.104/search?q=cache:http%3A%2F%2Fwww.hep.ucl.ac.uk%2F~ytl%2
Fqos%2Findex.html
28)http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/qos_c/qcp
rt1/qcdclass.htm
29) http://www.opalsoft.net/qos/WhyQoS.htm
30)http://www.cisco.com/en/US/netsol/ns339/ns392/ns399/ns404/networking_solutions_
white_paper0900aecd800dd974.shtml
31)http://www.cisco.com/en/US/products/sw/iosswrel/ps1820/products_feature_guide09
186a00800f4891.html#29478
32)http://www.cisco.com/en/US/tech/tk331/tk336/technologies_design_guide09186a008
0237a48.shtml#wp16388
33) http://www.cisco.com/warp/public/63/mdrr_wred_overview.html
34) http://networking.ittoolbox.com/documents/document.asp?i=2528
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35) http://www.cisco.com/warp/public/732/Tech/qos/
36)http://www.cisco.com/warp/public/105/dscpvalues.html#dscpandassuredforwardingcl
asses
37) http://www.cse.ohio-state.edu/~jain/cis788-99/ftp/qos_protocols/
38)http://www.cisco.com/univercd/cc/td/doc/product/rtrmgmt/ciscoasu/class/qpm1_1/usi
ng_qo/c1plan.htm#xtocid321027
39) http://www.cse.ohio-state.edu/~jain/cis788-99/ftp/qos_protocols/index.html
Last accessed 20/09/04