Comparative Analysis of Link State and Hybrid Routing Protocols

cloutedcoughNetworking and Communications

Oct 28, 2013 (3 years and 7 months ago)

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Comparative Analysis
o
f Link State
a
nd Hybrid
Routing Protocols

Muhammad Irf
an

Ashraf
1
, Mrs
.

Saman Iftikhar
2
,
M. Umer Sarwar
3
,
Aatzaz Latif
4

College of Compute
r Science & Information Studies
,

Govt
. College University Faisalabad
, Pakistan
.



1
irfan
-
ashraf@hotmail.com


2
iftikhar.saman@gmail.com


3
sarwaromer@gmail.com



4
mianaatzaz@yahoo.com


Ab
s
tract

Routing Protocol

is playing a

key role in

modern
communication

networks
.
Routing

Protocol

is a protocol that

is
responsible for determining

how the

router

to communicate with

each packet

travels

from source to

destination node

through the

best route to follow
. Among the routing protocols, Enhanced
Interi
or Gateway Routing Protocol (EIGRP) and Open Shortest
Path First (OSPF) are the pre
-
eminent routing protocols. EIGRP
is a Cisco proprietary distance
-
vector protocol based on
Diffusing Update Algorithm (DUAL). On the other hand, OSPF
is a link
-
state interio
r gateway protocol based on Dijkstra’s
algorithm (Shortest Path First Algorithm).

In the context of

the
performance of

routing protocols
, each
of which

has a

different

architecture
, adaptive,
root

processing delay
,
and

the

convergence

function
.

This Research

presents a

simulation
-
based
performance analysis

comparison

between

OSPF

and

EIGRP

in

enterprise environments

using

OPNET
Modeler. The main
objective of this report is to evaluate OSPF and EIGRP’s
performance on the basis of quantitative met
rics such as
Convergence Time, Scalability, and Resources Utilization
through the simulated network models. This report offers a
guideline for the design of the EIGRP, OSPF Single Area, and
OSPF Multi Area routing protocols, and provide
recommendations for

each routing protocols for certain
circumstances.

Keywords:

OSPF Single Area, OSPF Multi Area, EIGRP.

I.

I
NTRODUCTION

Before

computer networks

have been introduced

in data
communications
, computer users
in businesses

face

many
complications,

cost

and

frustration

to the

data

and

share
resources
.
Companies that

use

computers

have spent

a large
amount

of resources and

time to fully

equip each

computer

with

its own

hardware and

accessories

under

storage

devices
,
printers, modems,
scanners

and copiers
.
Furt
hermore, each

computer

must

manually set the

software

to configure,

and

it

is

time
-
consuming

problem
.
Operating system

and

application

programmers

must be installed on

each

computer
, resulting in

decreased
speed and

flow
,
use of space and

capacity
, the
impact on
security
,
and

information sharing

problem
.



A

difficult problem

arises when the

computer

is

not

an
effective

data

and information sharing

possible.

Only

medium

diskette

partnership
.
Another problem

in the enterprise

increases when

more

than one copy of

the same dat
a

in

different

computer

disk
.
Floppy disks

are not able

to handle

large amounts of data

to be transferred
,
so that

data

consistency

problems

result

when

more

than

floppy disks

used

for

data
.

Network

created for

the problem.

Int
roduction

network

proved
to be

a very

good

communication

and

result

in

better
information

exchange

and user satisfaction.

However,

with

the
addition of

such

flexibility

and

ambiguity

of data
communications

and

data

flow control

is created
.

A.

C
OMPUTER
N
ETWORKS

N
etwork

is

simply a

combination

of hardware, software

and

cables

together

various

communication devices

to
communicate

with

one another.

Network

made

to

allocate
resources.

Agents

are divided into

hardware

such as printers

and

plotters,

backup

devices
, scanners
and

modems,

and

software resources
,
such as

application programs
, operating
systems
and databases.

[
1
]

Computer communication networks are growing speedily
during this modern era. Services such as file transferring, print
sharing, video s
treaming and voice conferencing are now
provided by communication technology to a user in a
convenient and friendly manner. The technical infrastructure
of the computer communication networks is based on routing
protocols. How routers exchange traffic with

each other and
transmit packets across the internetwork is standardized by a
routing protocol
.

[
10
]

B.

N
ETWORK
T
OPOLOGY

T
he term

topology

describes how the

network is designed

and

implemented
, either physical
or

logical.

It

shows how the

devices on the
network

are

organized
, regardless of
their
physical

management
.
Although the

relative positions of the

topology

selection

devices to

communicate with each

other

to
International Journal of Computer Science and Management Research Vol 2 Issue 4 April 2013
ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
2244




be considered.

If

the two devices

share

a common bond

between them,

the relationship is a

peer
-
to
-
peer,
if the device

monitor

traffic and

other devices

must

go

through

it
,
this

relationship

is called the

primary
-
secondary education.
The
term

dedicated

means

that link

is only used

for

traffic between
the

two devices

it connects
, the connection i
s
peer
-
to
-
peer
is

a
compound

point
-
to
-
point.
Here

is

the network topology
:
Mesh
, Star,
Tree
,
Bus,

Ring
,
and

hybrid
.

[
4
]

Th
ese

topologies

used in this research project for the
performance evaluation of OSPF and EIGRP.

C.

C
ATEGORIES OF
N
ETWORKS

There are many
categories

of

the

network

as described

below.

L
OCAL
A
REA
N
ETWORK
(LAN)

This network is designed to link the communication devices in
a single office, building, or campus and is individually owned
by a company.
LAN

can

meet the

needs of an organization

and

the use of

LAN

topology

design

also depends on the

needs of an organization
.
LAN

size

is

limited to a few

kilometers
.

[
4
]

M
ETROPOLITAN
A
REA
N
ETWORK
(MAN)

[
4
]
MAN can be designed to expand over a couple of building
within same geographical region or an entir
e city. For
instance, a single network such as television cable network
can be a MAN, or it can be a medium of combining more than
one LANs into a larger network to share the resources among
LANs and devices.
The technology is similar

to

the

LAN
.

[
2
]


W
IDE

A
REA
N
ETWORK
(WAN)

WANs are used for long distance communication of
information, data, voice, image, and video. It is designed to
cover a
Large geographical area

may be

countries around the

world
,
or continent
. The difference between the LANs and
WANs is
that
LAN

hardware

only

own

their resources

and the
tools

used

for communication,

but

can also use the

WAN
,
leased,
public or private

communication

devices

and tools

can
also be

incorporated into the

WAN

design
.
This network

can
be extended

to

unlimited

mileage
.

[
4
]


D.


A
N
E
NTERPRISE
N
ETWORK

An enterprise can be describe as all types of organizations
,
businesses, government agencies
,
nonprofit

organizations
,
supply

chain
,
and

the company also

virtual
,
in

a company

is
used to

describe the part of

the
departments of

the company
,
such as departments

or programs
.
Company

network

is a
computer network

that is used

in

the company
.

[
5
]

E.

R
OUTING

Routing is a method of communicating data traffic within an
internetwork from one node to another node. It is an act

of
discovering all possible routes thorough computer networks
and using discovered routes to transfer data from a source
network to a destination network.
[
1
5
]

F.

R
OUTERS

Routers are the devices used to perform the process of routing.
These devices forward
and receive packets of data between
different networks and provide connectivity between two or
more networks. They are attached to the edges of networks to
control data traffic. Generically a router is a dedicated
machine with specialized hardware and soft
ware to carry out
the procedure of routing by discovering all achievable paths
from a source to a destination, and determining a suitable path
for data communication. Routers also exchange routing
information with each other about the networks they can or
cannot contact.

Many companies like Cisco, Juniper, Bay,
Nortel, and 3Com, Cabletron, among others are manufacturing
routers but the configuration and set up of each company‟s
product is different
.

[
1
5
]

G.

R
OUTED
P
ROTOCOLS

Routed protocols are the data being
transmitted through the
communication networks.
[
1
5
]

Examples of Routed

protocols
are IP (Internet Protocol), Telnet, RPC (Remote Procedure
Call), SNMP (Simple Network Management Protocol), SMTP
(Simple Mail Transfer Protocol), Novell IPX
,
Open Standards
Institute Networking Protocol
,

DEC net, AppleTalk, Banyan
Vines
,

and XNS (Xerox Network System).

H.

N
ON
-
R
OUTABLE
P
ROTOCOLS

A non
-
routable protocol is not capable to cross a router and
cannot be sent from one communication network to another
communication netw
orks. Generically these protocols are not
designed to survive for being routed. Theses protocols do not
accommodate addressing patterns in the data packets that
provide knowledge of multiple networks, and presume that all
communication devices are on the s
ame network. When a data
packet containing non
-
routable protocol reaches a router, it is
discarded because it cannot cross thorough a router.
[
3
]

Examples of non
-
routable protocols include

NetBEUI
(
NetBIOS Extended User Interface),
DLC (Data Link
Control)
,
LAT (Local Area Transport)
,
DRP (Directional
Routing Protocol)
, and
MOP (Maintenance Operational
Protocol).

I.

R
OUTING
P
ROTOCOLS

The two entities

will be unable to

communicate with each
other

without any

predefined rules

or conditions.

These

entities

must

agree

on

a protocol for

reliable communication

that occurs
.
Routing Protocol

is a set of

rules

that

direct data

transmission
.
For example
,
what is

transmitted,

how it is
transmitted

and

when

it is sent
,
all

defined by the

protocol
.
It

is

impossible

without

protocol

two

devices are connected
,
but

they
cannot

communicate

without

protocol
.
[
4
]

Examples of Routing Protocols are IS
-
IS
(
Intermediate
System

Intermediate

System
), OSPF
(Open

Shortest

Path
First
),
RIP

(Routing

Information

Protocol),

IGRP

(
Interior
Gateway

Routing

Protocol)
,
EIGRP

(Enhanced

Interior

Gateway

Routing

Protocol)

and

v4

BGP

(
Border
Gateway

Protocol version

4).

International Journal of Computer Science and Management Research Vol 2 Issue 4 April 2013
ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
2245




J.

OSPF

AND
EIGRP

This research is on OSPF and EIGRP routing protocols to
conduct performance evaluation in a simulation based
enterprise network model. The performance of each routing
protocol is different from the other. OSPF is a robust link state
interior gateway protoc
ol based on Dijkstra‟s Algorithm; this
algorithm calculates the routes information within an
autonomous system based on the link cost. On other hand
EIGRP is an interior gateway distance vector routing protocol,
which is mainly based on DUAL (Diffusing Upd
ate
Algorithm), this algorithm calculates the routes without
creating routing table loops based on bandwidth and delay.

K.

A
IMS
&

O
BJECTIVES

Aim of this project is to compare, discuss, and simulate the
performance of OSPF and EIGRP in the context of
Convergence, Scalability, and Resources Utilization

within an
enterprise environment.
The outlined objective

of the
Research is to compare and analyze OSPF and EIGRP in the
context of Convergence Duration
.

L.

S
IMULATION OF
R
OUTING
P
ROTOCOLS

Computer commun
ication networks are growing speedily during this
modern era. Services such as file transferring, print sharing, video
streaming and voice conferencing are now provided by
communication technology to a user in a convenient and friendly
manner. The technica
l infrastructure of the computer communication
networks is based on routing protocols. How routers exchange traffic
with each other and transmit packets across the internetwork is
standardized by a routing protocol.

The
tactical

IP

networks

have special
requirements for

routing

protocol

selection
.
The most

important

is the

rapid convergence
,
short

end

to end

delay and

the ability to recover

from

emergencies

quickly
.

[
10
]

This research project is on EIGRP and OSPF routing protocols to
conduct performance e
valuation in an enterprise network model and
provides a simulation based study on EIGRP and OSPF routing
protocols. Optimized Network Engineering Tool (OPNET) is
employed as a simulator to analyze and measure the comparative
performance of these routing pr
otocols.

M.

M
OTIVATION

The motivation behind this research is to get better
performance in the case of selecting a routing protocol among
EIGRP and OSPF on the same network configuration. This
research will help the administrators to select a suitable
routing

protocol within an enterprise network and

provides a
deep understanding of the IGP routing protocols
(OSPF&EIGRP) and in
-
depth knowledge of routing in
computer networks. The analysis and conclusion will help t
o
understand how routing protocols can be applied to different
network environments that are usually solved using different
approaches.

II.

O
VERVIEW OF
R
OUTING
P
ROTOCOLS

In networks, routing protocols are configured to communicate
data packets from one node t
o another node by hoping one or
more hops. Implementation of routing protocols participates in
identifying possible paths for different pairs of source and
destination networks, and it also supports successful
communication of data traffic between them.


R
outing protocols illustrate how routers exchange data traffic
with each other,
find possible paths

to other

routers

maintain

routing table
,
routing

decide

to learn

an existing route
,
the
routing protocol
,
the

router connects

data traffic
,
routing
informati
on to

the

router

adjacent to each other,

shows

how to
propagate
.
By connecting

multiple networks

to provide
various types

of

packet forwarding

network
,
the

main

function

of

routing protocols

is to maintain

communication.

Describe
the process of

routing
,
routing algorithm
,
can be done

by
using

different metrics

in order to select

the optimal route

between the source and

destination networks
.

[
18
]


Convergence is process of
determining the

route

for the traffic
in

computer networks
, routers
agree

on

the
best

path

to send

packets

and

the

complete

update

their

routing

tables
.
Consolidation

is not

an immediate
,
thorough

routing
information

broadcast

network

takes time.

Time needed

for
passage

in the network has

to be

fast
,
so that

routing
information

can eas
ily be

distributed
.

[
18
]



If the link

is not available

or

are available
, resulting
in

a
change in

the

network topology
.
When running

the routing
algorithm

is independent

each

router

calculates

the metric

from these

changes
,
when

these changes

are to
create

a new

routing table
.
Convergence is

complete when the entire

routing table

is updated
.
Convergence duration

is the time
required

for

all

routers

until

agreement

on

a new

topology

and

to determine the route
.
Depends on many factors

such as

the
number

of routers

in a network

with

dynamic

routing
protocols
,
router

distance

to

location

changes

measured in

hops,

traffic

load

and bandwidth

communication

links,

and

routing protocols.
[
18
]

This feature is the most important criteria for the performance
of
EIGRP and OSPF to compare in this study.


Scalability means if the size of the network is large, it should
not affect the performance of network. Routing protocols
should provide appropriate scalability for large networks
.

[7
]



Do not rely on

any

central
node
.
If

a fault occurs

in the
central node
,
the disadvantage

of

this dependence

is that

the
routing process

is suspended.

Routing

process

should be on
the

basis

of multipath
.
If

one path fails

or is unavailable

because of congestion
, it can flow
the
other

available

routes

identified by the

comprehensive

data traffic

routing table
.
As
in

the case of multiple

paths

alternative

route path

to failure is

already known
,
to save time
.

[
11
]





International Journal of Computer Science and Management Research Vol 2 Issue 4 April 2013
ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
2246




OSPF (Open Shortest Path First)

OSPF was designed in 1987 and it
is a link state routing
protocol used for routing between routers belonging to a
single AS
.

[
1
7
]


The
first version of OSPFv1 was published in RFC 1131 in
1989; the second version OSPFv2 was released in 1991 in
RFC 1247, it was updated in 1998 in RFC 2328
and is the
current version in use; and the third version OSPFv3 for IPv6
was introduced in 1999.
[8
]


P
acket format of OSPF.

[6
]
E
ach packet servers a particular purpose and is defined
below.

Version:
Shows the version in use. Currently version 2 is in
use.

Type:
Identifies the type of the packet used. Followings are
the packet types.



Hello



Database Description (DBS)



Link state Request (LSR)



Link State Update (LSU)



Link State Acknowledgement (LSAck)

Packet Length:

This is the length of the packet measure
d in
bytes; it also includes the OSPF header.

Router ID:
Indicates the ID of the originating router thorough
the AS.

Area ID:
Identifies the area from which the packet originated.

Checksum:
It checks the packet whether they are damaged or
not.

Au Type:
Th
is field defines
three types of
authentication.



0

means the routing information exchanged
over the network is not authenticated.





1

Plain text or passwords are used for
simple authentication.



2
cryptography authentication using
message digest.

F
ollowi
ng
advantages and disadvantages of Open Shortest

Path First (OSPF)
.

[
1
2
]

Advantages:



Due to reliable flooding system to update
neighbouring routers of change in network
topology OSPF provides fast convergence.



Support for VLSM, super netting, and
summarizatio
n.



Support for large network diameters by
using VLSM.



Due to stub area routing the entries of
routing table are reduced.



Efficient and reliable transport of routing
updates.



Efficient use of media.



OSPF uses a cost metric, which may be
changed, to base the

routing decision on.



OSPF provides load

sharing across equal
-
cast paths, optimizing bandwidth and
multiple paths.



No vulnerability to split
-
horizon issues.



OSPF is fully classless and not a proprietary
protocol.



Support for route tagging of OSPF external

routes.

Disadvantages:



Complicated to configure and involves high
processor utilization.



Link state scaling problem.



More memory and CPU cycles are required
as compared to other routing protocols.

EIGRP (Enhanced Interior Gateway Routing Protocols)

EIGRP
is a classless and distance vector routing protocol and
was released in 1992 with IOS 9.21.EIGRP is an updated
version of IGRP and both are Cisco proprietary protocols but
EIGRP provides more scalability for medium and large
networks. EIGRP uses DUAL for t
he selection of routes.
Sometimes EIGRP is defined as a hybrid routing protocol
because it supports the features of a link state protocol for
building
neighbor

relationships and of a distance vector
routing protocol for the advertisement of routes. However

it is
not a hybrid routing protocol and Cisco no longer uses the
term hybrid to refer to EIGRP, it is only a distance vector
routing protocol
.

[
6
]

EIGRP is an evolution of IGRP. This advancement resulted
from developments in networks, and needs for varied and
large internetworks. Enhanced IGRP combines the properties
of a link state routing protocol into a distance vector routing
protocol. Moreover,
EIGRP has numerous considerable
features that significantly increase its working effectiveness as
compared to other protocols.
[
16
]

EIGRP protocol structure.
[
1
7
]

Version:

Identifies the version of EIGRP.

Opcode:

Specifies the message packet type. Followin
gs are
the packet types.

Type 1: Update, Type 2: Reserved, Type 3: Query, Type 4:
Reply, Type 5: Hello, and Type 6: IPX
-
SAP.

Checksum:
Shows IP Checksum that is calculated using the
same checksum algorithm as a UDP checksum.

Flag:
First bit (0x00000001) is

initialization bit and
establishes a new
neighbor

relationship. Second bit
(0x00000002) is used in proprietary multicast algorithm and
referred as conditional receive bit. Other remaining bits have
no function.

Sequence Number and Acknowledge Number:
Bot
h are
used to send messages securely and reliably.



Asystem:
It is the number of
AS in the EIGRP Domain. A
gateway can contribute in multiple AS, running their own
IGRP and having completely separate routing tables. This
number is used to identify which set of routing tables is to be
selected by the gateway.


Type:
Describes the valu
e in the type field.

0x0001
-

EIGRP general
parameters (
Hello/Hold time)



0x0002
-
Reserved.



0x0003
-
Sequence.

International Journal of Computer Science and Management Research Vol 2 Issue 4 April 2013
ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
2247






0x0004
-
EIGRP Software version.



0x0005
-
Next multicast sequence.

Length:
Identifies the length of frame.

Following are the features of EIGRP.



Protocol D
ependent Modules (PDM)



Reliable Transport Protocol (RTP)



Diffusing Update Algorithm (DUAL)



Neighbour Discovery/Recovery and
Establishing adjacencies



Bounded and Partial Updates

Followings are the advantages and disadvantages of EIGRP
.

[
14
]


Advantages:



Enables a loop
-
free environment.




Backward compatibility with the IGRP protocol.




Provides support for the multiple routed protocols
and network layer protocols.






Support for discontinuous network s, classless
routing, and VLSM.




Supports routing update verification.




Relays network changes in place of periodic
changes.




EIGRP can balance a load to maximum of six eq
ual
or unequal paths.





EIGRP metric provides the most favourable path to
a destination, this metric is a combination of
bandwidth, delay and Maximum Transmission Unit
(MTU) sizes.





EIGRP provides a fast convergence and reduces
bandwidth utilization.


Disadvantages:

It is a Cisco proprietary routing protocol and routers from
other manufactures do not support it
.

III.


NETWORK MODELLING AN
D SIMULATIONS

Simulation and network modelling have a central place in the
phases of planning and designing enterprise n
etworks. These
allow a very wide range of operating modes to be explored
and examined in detail. So, the question is that why network
modelling has become very important to network
administrators, the answer is knowledge; the knowledge is
about what is hap
pening, and what is going to happen.
Network modelling can give useful information to a network
administrator.

S
IMULAT
I
ON

Simulation is a technique which simulates a real world object,
and models it for some specific purpose. It is a technique to
create a
system model for observing the behavior of the real
system under consideration
.

[
9
]


N
ETWORK
S
IMULATORS

Network Simulators are the programs that run simulations and
provide all the benefits of network modeling to a user or
organization in the context of
checking the functionality,
efficiency, and reliability of the network. Four types of
simulators

are mostly used by developers and researchers;
these are OPNET (Optimized Network Engineering Tools),
NS
-
2(Network Simulator version 2), OMN
E
T++, and
GLASS.

O
ther network simulators are also available such as Cisco
Packet Tracer 5.3 and GNS3 (Graphical Network Simulator
version 3), these simulators also do not provide required
statistics to conduct performance analysis. The version 1
4.5

of
OPNET Modeler provide
s all the statistics and graphs to
perform a quantitative analysis of routing protocols
.

[
9
]

S
ELECTION OF
N
ETWORK
S
IMULATOR

In this research, network simulator, OPNET Modeler
14.5

is
used as a simulation environment. It is very powerful software
to simulat
e heterogeneous network with various protocols and
applications.
[
19
]

In OPNET modeling, three domains are
developed for a network model. These domains are: Network
Domain, Node Domain, and Process Domain.
[
1
3
]

N
ETWORK
D
OMAIN

This is an overview of the
physical or logical network model
and sub
-
networks on the graphical user interface of the
simulator. Figure 3.1 presents the network domain model of a
logical enterprise

network.
[
1
3
]












Figure 3.1: Network Domain

N
ODE
D
OMAIN

It is an internal
infrastructure of network domain model. All
the nodes in a network have an underlying node model that
illustrates the internal flow of traffic in the object. Node can
be routers, workstations or any communication device. Figure
3.2 show the Node domain
.

[
1
3
]


International Journal of Computer Science and Management Research Vol 2 Issue 4 April 2013
ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
2248














Figure 3.2: Node Domain

P
ROCESS
D
OMAIN

Every node module in turn contains a process domain. These
domain models are used to identify the attributes of the
processor and queue model by using source code C and C++
which is inside the node
model. Figure 3.3 shows a process
domain Model
.

[
1
3
]












Figure 3.3: Process Domain

D
ESIGN AND
A
NALYSIS IN
OPNET

Creation of a network model on the network domain editor is
the first task to design in the OPNET. Second task is to choose
the statistics that determines the performance of the network
model. Third task is to adjust the simulation duration time and
start
the simulation. Last task is to observe and analyze the
results. Figure 3.4 shows a flow chart of these tasks.
[
11
]



Figure 3.4: Design and
Analyze

process

N
ETWORK
T
OPOLOGY

This research project
is on OSPF and EIGRP protocols. These
proposed protocols are compared and evaluated on the basis
of three quantitative parameters such as convergence,
scalability and resources utilization. The network topology is
designed by comprising following communica
tion devices and
configuration utilities.



CS_7200 Cisco Routers



CS_3600 Cisco Routers



CS_2600 Routers



CS_3000 Switches



Ethernet LANs



Nine Subnets



IP traffic utility



Failure Recovery Utility



100 base T Links

To simulate the chosen routing protocols OSPF and

EIGRP
uses a three
-
tier topology consists of Core, Edge, and Access
tiers.

C
ORE
T
IER

This layer is responsible for fault isolation and backbone
connectivity.
The core tier consists of three Cisco 7200 series
routers connected in a ring.








Figure
3.5: Core Tier



E
DGE
T
IER

The edge tier performs as a connection between the access tier
and the core tier. This core is responsible for providing
routing, filtering, and to decide how packets can access the
core tier if required.
The edge tier consists of Cisco 3600
series router for each site and three Cisco 3000 series switches
connected to access devices in tree topology
.



International Journal of Computer Science and Management Research Vol 2 Issue 4 April 2013
ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
2249












Figure 3.6: Edge Tier

A
CCESS
T
IER

A
ccess layer is most featured rich layer of the Cisco
three
-
layered model and

this layer is also called
desktop layer.

Each site consists of Cisco 3000
series Switches with Cisco 2600 series routers
along LAN nodes having ten devices.











Figure 3.7: Access Tier

O
VERALL
N
ETWORK
T
OPOLOGY

Overall the
simulation topology diagram is shown below,
which consists of core, edge and access tiers devices in a
hybrid topology fashion, as the core is connected in ring
topology (Figure 3.8) and the edge is connected to access
devices in tree topology (Figure 3.9)
. All devices in overall
topology are connected on 100BaseT Ethernet links.







Figure 3.8: Overall Network Topology















Figure 3.9: Topology Insight

S
CENARIOS

There are three scenarios in this project named as Single Area
OSPF, Multi Area OSPF, and EIGRP with same topology
described above, and two utilities named as Failure Recovery
International Journal of Computer Science and Management Research Vol 2 Issue 4 April 2013
ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
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Utility and the IP Attribute Utility. Figure 3.10 show network
with utilities.







Figure 3.10: Network
with Utilities

L
INK
F
AILURE
U
TILITY

In the topology created for this research, the routers build their
routing tables, and then they do not need to update them if
nothing goes down. That‟s why in all scenarios the

researcher
simulated failures to compare the behavior of the routers and
implemented routing protocols.

To simulate failures, the researcher opened the Object Palette,
selected the
Utilities

palette from the dropdown menu,

and
added a Failure Recovery obj
ect to the project

workspace.
Then named it Link Failure

and

right clicked on the Failure
object„s
Edit Attributes.

In the next step
expanded the
Link
and node Failure/Recovery Specification
.

S
CENARIO
1

S
INGLE
A
REA
OSPF


This

scenario simulates the single

area OSPF routing protocol.
To carry out this task the researcher enabled OSPF on all the
routers in the topology as shown in the figure 3.11.









Figure 3.11: OSFP Single Area Scenario

S
CENARIO
2

M
ULTI
A
REA
OSPF

This scenario simulates the multi area

OSPF routing protocol.
Figure 3.12 illustrates multi areas in the network topology.











Figure 3.12: OSPF Multi Area Scenario

S
CENARIO
3

EIGRP

This scenario simulates EIGRP routing protocol. Figure 3.13
shows

EIGRP topology.









Figure 3.13: EIGRP Scenario

IV.

S
IMULATION RESULTS AN
D COMPARISONS


After configuring three network scenarios EIGRP, OSFP
Multi Area, and OSPF Single Area, the researcher ran the
simulated networks for 24 hours
simulation time duration to
obtain the statistics to compare the performance of EIGRP and
OSPF.

Below are the simulation results and comparisons. In Average
Stacked Graphs, top graph is for

EIGRP, middle is for

OSPF
Multi Area and bottom is for OSPF Single

Area and in
Average Overlaid Graphs Blue
color

is for EIGRP, Red
color

International Journal of Computer Science and Management Research Vol 2 Issue 4 April 2013
ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
2251




is for OSPF Multi Area, and Green
color

is for OSPF Single
area.

COVERGENCE

In dynamic routing convergence is an important characteristic.
Routers are intelligent devices and collect a
ll available
topology information from each other through routing
protocols. If there is a change in network topology, the
process of convergence starts. During this process each router
recalculates the route metric and creates a new route table.
Convergen
ce is completed when all the routing tables have
been updated and all routers are agreed on what a network
topology look like.

C
ONVERGENCE
D
URATION
S
TATISTICS FOR
OSPF

S
INGLE
A
REA
,

OSPF

M
ULTI
A
REA
,

AND
EIGRP

Routers exchange information about the changes i
n network
topology during the process of routing and this exchange
depends on the routing protocols being used. Convergence is
completed when all routing information updates have been
advertised to all the routers participating in the process of
routing.

Convergence duration is the time that is needed for all
the routers to reach an agreement about new topology and
establish routes

In simulation performed the convergence activities being
recorded with the duration of convergence cycles for the
OSPF Single

Area, Multi Area, and EIGRP routing tables
across the whole network as global and node statistics.

G
LOBAL
S
TATISTICS

Appended are the Average Stacked and Overlaid graphs with
spread sheets data for OSPF Single Area, Multi Area and
EIGRP. All the obtained
results shows that the convergence
durations are more in OSPF Single Area as compare to Multi
Area and overall both OSPF Single and Multi Area took more
time to converge than EIGRP.

Global Analysis obtained from the simulation proved that the
EIGRP conver
ged faster than OSPF.

S
TACKED
G
RAPH


O
VERLAID GRAPH


O
BJECT
S
TATISTICS FOR
C
ORE
S
ITE
A

(R
OUTER
)


Appended are the Average Stacked and Overlaid graphs with
spread sheets data for OSPF Single Area, Multi Area and
EIGRP for the Core Site Router A. All the o
btained results
shows that the convergence durations are more in Core Site A
for OSPF Single Area as compare to Multi Area and overall
both OSPF Single and Multi Area Routing Protocols took
more time to converge than EIGRP.

Node or object Analysis obtained from the simulation for the
Core site A proved that the EIGRP converged faster than
OSPF.

S
TACKED
G
RAPH


International Journal of Computer Science and Management Research Vol 2 Issue 4 April 2013
ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
2252




O
VERLAID GRAPH


O
BJECT
S
TATISTICS FOR
C
ORE
S
ITE
B

(R
OUTER
)


Appended are the Average Stacked and Overlaid graphs wit
h
spread sheets data for OSPF Single Area, Multi Area and
EIGRP for the Core Site Router B. All the obtained results
shows that the convergence durations are more in Core Site B
for OSPF Single Area as compare to Multi Area and overall
both OSPF Single and

Multi Area Routing Protocols took
more time to converge than EIGRP.

Node or object Analysis obtained from the simulation for the
Core site B proved that the EIGRP converged faster than
OSPF.

S
TACKED
G
RAPH


O
VERLAID GRAPH


O
BJECT
S
TATISTICS FOR
C
ORE
S
ITE

C

(R
OUTER
)


Appended are the Average Stacked and Overlaid graphs with
spread sheets data for OSPF Single Area, Multi Area and
EIGRP for the Core Site Router C. All the obtained results
shows that the convergence durations are more in Core Site C
for OSPF
Single Area as compare to Multi Area and overall
both OSPF Single and Multi Area Routing Protocols took
more time to converge than EIGRP.

Node or object Analysis obtained from the simulation for the
Core site C proved that the EIGRP converged faster than
OSPF.

S
TACKED
G
RAPH



International Journal of Computer Science and Management Research Vol 2 Issue 4 April 2013
ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
2253




O
VERLAID GRAPH


V.

ANALYSIS

AND

CONCLUSION


Robustness, resiliency and flexibility are the key features that
an enterprise needs. These qualities must be provided into the
data structures that maintain the enterprise business. That‟s
why the enterprises spend huge resources on Internet
-
Protocol
-
only (IP) networks. The main feature of IP networks
is interior gateway routing.

The interior gateway routing protocols are used to perform the
path selection process between the source and dest
ination
devices. There are many famous interior gateway routing
protocols but the most important are OSPF and EIGRP. Each
protocol has its own characteristics and method to determine
the best route to the destination. Routing protocols have their
own disti
nguishable features such as scalability, convergence,
and the resource
utilization

with the bandwidth consumption
for routing updates. So a common question which is
repeatedly raised is “which is the better among the two
protocols, EIGRP and OSPF?” In fact

both are ideal and
outstanding technologies in the world of IP routing with
tremendous features and support for a scalable and robust
network design. Hence, the answer to the question is not only
difficult but also has different opinions. From the researc
her‟s
prospective neither is better than the other but it is the
topology and design which affects the efficiency of these
protocols.

This project evaluated EIGRP and OSPF according to
predefined criteria to compare the two protocols, and
concluded the app
ropriate protocol for the researcher‟s
designed network topology. The researcher didn‟t configure
any protocol for optimized condition to perform better than
the other. The design included the default behaviours for
OSPF Single Area, Multi Area and EIGRP w
ith default
configurations.

NETWORK PLANNING


OSPF offers a concept of areas, either a single area throughout
the topology or a hierarchical structure by dividing the
topology into different areas around the backbone area 0. An
OSPF hierarchal design repre
sents the real life infrastructure
requirement of an organization. However, there are some
limitations with OSPF hierarchical structure such as the
number of the areas configured on a single router or the
number of routers an area can support. But OSPF alw
ays
implements a hierarchal network design; this hierarchy also
exists in single area structure. This requirement of a
hierarchical network topology makes OSPF difficult to
implement and conceptually tedious, because different types
of rules and messages a
re used for different hierarchal levels
or areas.

EIGRP does not implement a hierarchal feature. Although it
provides flexibility from design perspective and can logically
divide the infrastructure into a hierarchy that is based on the
aggregation of the
interfaces. But it causes inappropriate
network design because EIGRP needs some advanced
configuration to support special features.

C
ONCLUSION

So, the researcher concluded that planning a network design
for OSPF network can be more difficult as compared to

EIGRP network, however OSPF design offers better
management to any organization‟s internal infrastructure and
levels hierarchy.

CONVERGENCE

Enabling a routing protocol on a router enables it to send and
receive the routing information about the overall to
pology of
the network between connected layer three devices. The
amount of this exchange information and the method it
chooses to send and receive is mainly based on the selected
routing protocol. A router or a network topology is converged
when this infor
mation is shared with the entire network and all
the layer three devices, and all the routers have the identical
information about the topology and all are agreed on that.

This convergence is not permanent if any change occurs in the
topology; it requires
every router in the network to converge
with the new topology information. This process needs time to
be completed. Thus the convergence duration is determined
by the time a router or overall topology takes to converge after
changes. This was the researche
r‟s one of the objective to find
out the convergence duration of the OSPF Single Area , OSPF
Multi Area and EIGRP , and to determine the best routing
protocol in term of convergence duration as it is an important
characteristic of the overall performanc
e of a routing protocol.

EIGRP uses the DUAL algorithm to converge in case of
changes, whereas the OSPF uses LSA‟s and the Dijkstra‟s
(SPF) algorithm. So, which routing protocol‟s algorithm is
better, is it EIGRP or OSPF? An ultimate answer to the
questio
n cannot be made generally; the convergence duration
is based on many aspects such as the network topology itself.

C
ONCLUSION

When changes in topology occur EIGRP uses DUAL
Algorithm for convergence, if there is a feasible successor the
convergence will
be fast, and OSPF recalculates the routes
using Dijkstra‟s or SPF algorithm. So, EIGRP should provide
better convergence as compared to OSPF. The researcher
International Journal of Computer Science and Management Research Vol 2 Issue 4 April 2013
ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
2254




simulated the designed network topology for OSPF and
EIGRP to find out the convergence duration. I
n the simulated
network topology the statistics showed that the EIGRP
converges faster than OSPF, and OSPF Multi Area converges
faster than the OSPF Single Area. Therefore, the simulation
recommends the use of EIGRP as a routing protocol if the
convergence

factor is the main priority. However if Cisco
devices (Routers) are not available then the use of OSPF is the
only option and the OSPF Multi Area would be better choice
as compared to OSPF Single Area.

CONCLUSION

AND

ANALYSIS

EIGRP is commonly regarded as

more scalable in terms of
routing domain size but OSPF is the most efficient in terms of
router
-
CPU
-
utilization, message processing, routing table size
and the traffic sent in bits per seconds. In the event of a
network failure, the network recovery time
is known as
convergence duration. And this research proves that EIGRP‟s
convergence duration is less than OSPF in the designed
topology. The researcher recommends using EIGRP as a
routing protocol if all the layer three devices are from Cisco as
the conver
gence factor is very important than the others, but
in case of different vendor products OSPF would be the
choice and the recommendation is for OSPF Multi Area.



R
R
E
E
F
F
E
E
R
R
E
E
N
N
C
C
E
E
S
S



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ISSN 2278-733X
Muhammad Irfan Ashraf et.al. www.ijcsmr.org
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