Networks and Protocols

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24 Οκτ 2013 (πριν από 3 χρόνια και 11 μήνες)

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STAFFORDSHIRE UNIVER
SITY

Networks and Protocols

Upgrade of a corporate network


Benoît Taine

20/11/2012







Networks and Protocols

Upgrade of a corporate network

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C
ONTENT

I.

Introduction

................................
................................
................................
................................
................................

2

II.

Network addresses assignment
................................
................................
................................
..........................

3

A.

Company

................................
................................
................................
................................
................................
..

3

B.

Sites

................................
................................
................................
................................
................................
............

4

a)

Stafford

................................
................................
................................
................................
................................

4

b)

Liverpool

................................
................................
................................
................................
.............................

4

c)

Birmingham

................................
................................
................................
................................
.......................

4

d)

Derby

................................
................................
................................
................................
................................
....

5

III.

Needs study

................................
................................
................................
................................
............................

6

A.

Costs and

their justification
................................
................................
................................
.............................

6

B.

Infrastructure overhaul
................................
................................
................................
................................
.....

8

IV.

Implementation of improvements
................................
................................
................................
................

9

A.

Office plans
................................
................................
................................
................................
..............................

9

a)

Headquarter
s

................................
................................
................................
................................
....................

9

b)

Subsidiaries

................................
................................
................................
................................
.....................
11

B.

Simulation

................................
................................
................................
................................
.............................
12

a)

Configuring

the network
................................
................................
................................
............................
12

b)

Results
................................
................................
................................
................................
................................
13

V.

Conclusion

................................
................................
................................
................................
................................
..
15




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I.

I
NTRODUCTION


In this project, we had to rethink the network of a multisite medical company. The
headquarters
are based in Stafford, and three others offices are in Birmingham, Derby and Liverpool.

This company currently runs a LAN mostly used for VoIP, which interconnections are done over
a slow Internet connectivity. The lag induced by this slow spe
ed made the company thinking
about upgrading its network infrastructure.


The web server of the company, where the intranet application is setup also suffers from a
heavy lag for users on the subsidiary sites.

This is why I was asked to improve the network

infrastructure.


The simulation files have been uploaded to BlackBoard with an electronic
version of this report.

The file needs to be extracted to
C:
\
Temp
\
op_models to run correctly.



Thank you
.

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II.

N
ETWORK ADDRESSES ASS
IGNMENT


We want to separate each
group of users into its own subnet. For this, we use VLSM.

My assigned address is
193.90.54.0
.

VLSM stands for Variable Length Subnet Mask, which is the local equivalent of CIDR (Classless
InterDomain Routing). It is used for
good subnetting with

minimal w
aste.

The major routing
protocols (OSPF, EIGRP, RIPv2, IS
-
IS) are compatible with VLSM.

Here is the number of hosts planning that includes workstations
, wireless devices, servers

and
printers.

Site

Admin

Reception

Printer

Doctor

Server

Wi
-
Fi

Stafford

4

1

2

7

2

10

Liverpool

2

1

2

5

0

10

Birmingham

2

1

2

5

0

10

Derby

2

1

2

5

0

7


A.

C
OMPANY


The company has an available /24 address space where each site has its own dedicated subnet.
When making the big subnets,
I

ha
d

to think that each sub
-
subnet will need an additional IP
address for the gateway, and that the big subnet itself needs an IP address for its gateway.

I looked on the Internet for conventions about the default gateway address, and I learned that
network administrators usually use either the first or the last usage IP address. I decided
use
the first usable address
,

and
I cared about not forgetting to cou
nt it as a host
.

The IP addresses attribution is handled by the router using either static or dynamic attribution.
For more security, we use static allocation for everything in the network but the wireless users
who will use DHCP. The router of a site acts

as the gateway of every of the subnets he manages.


Subnet
Name

Hosts
needed

Net
work

address

Subnet
mask

IP address
start

IP address
end

B
road
cast
address

Default
g
ate
w
ay

STA

26

193.90.54.0

/26

193.90.54.1

193.90.54.62

193.90.54.63

193.90.54.1

LIV

20

193.90.54.64

/26

193.90.54.65

193.90.54.126

193.90.54.127

193.90.54.65

BIR

20

193.90.54.128

/26

193.90.54.129

193.90.54.190

193.90.54.191

193.90.54.129

DER

17

193.90.54.192

/27

193.90.54.193

193.90.54.222

193.90.54.223

193.90.54.193


We can’t use the
first and last addresses of a subnet because they are used as network and
broadcast addresses. The first usable address is also used for the gateway.

This means we have 2
n
-
3

usable addresses per mask bit.

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B.

S
ITES


a)

S
TAFFORD


This is our HQ. The main
difference with the other offices is the presence of the

two

company’s
HTTP+FTP and VoIP
servers.


There
are

4 admins, 1 receptionist, 2 printers, 7 doctors and nurses, 2 servers, and up to 10
wireless network users.

We have 4 subnets: one for the Wi
-
Fi us
ers, one for the doctors and
nurses, one for the administrators, and one for the servers.

We then have 4 gateways.


STA

Hosts
needed

Net
work
address

Subnet
mask

IP address
start

IP address
end

B
road
cast
address

Default
g
ate
w
ay

STA
-
WLAN

10

193.90.54.2

/28

193.90.54.3

193.90.54.16

193.90.54.17

193.90.54.3

STA
-
DOC

8

193.90.54.18

/28

193.90.54.19

193.90.54.32

193.90.54.32

193.90.54.19

STA
-
ADM

6

193.90.54.20

/28

193.90.54.21

193.90.54.34

193.90.54.35

193.90.54.21

STA
-
SERV

2

193.90.54.36

/29

193.90.54.37

193.90.54.42

193.90.54.43

193.90.54.37


b)

L
IVERPOOL


This is one of our subsidiaries. It is connected to the other offices over the Internet. Again, I had
to make sure that subnet cutting could support the required number of hosts, plus the gateways.


LIV

Hosts
needed

Network
address

Subnet
mask

IP address
start

IP address
end

Broadcast
address

Default
gateway

LIV
-
WLAN

10

193.90.54.66

/28

193.90.54.67

193.90.54.80

193.90.54.81

193.90.54.67

LIV
-
DOC

6

193.90.54.82

/28

193.90.54.83

193.90.54.96

193.90.54.97

193.90.54.83

LIV
-
ADM

4

193.90.54.98

/29

193.90.54.99

193.90.54.104

193.90.54.105

193.90.54.99


c)

B
IRMINGHAM


This is one of our subsidiaries. It is connected to the other offices over the Internet.

We can see
that even if I wanted to have a perfect result, there are always some addresses wasted in the
process. Theses addresses won’t be used because there are not enough hosts, and can’t be used
somewhere else.


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BIR

Hosts
needed

Network
address

Subnet

mask

IP address
start

IP address
end

Broadcast
address

Default
gateway

BIR
-
WLAN

10

193.90.54.130

/28

193.90.54.131

193.90.54.144

193.90.54.145

193.90.54.131

BIR
-
DOC

6

193.90.54.146

/28

193.90.54.147

193.90.54.160

193.90.54.161

193.90.54.147

BIR
-
ADM

4

193.90.54.162

/29

193.90.54.163

193.90.54.168

193.90.54.169

193.90.54.163


d)

D
ERBY


This is one of our subsidiaries. It is connected to the other offices over the Internet. Finally, we
stop the process at the address 233 of our /24. Our network is now efficiently VLSM’d.


DER

Hosts
needed

Network
address

Subnet
mask

IP address
start

IP
address
end

Broadcast
address

Default
gateway

DER
-
WLAN

5

193.90.54.194

/29

193.90.54.195

193.90.54.208

193.90.54.209

193.90.54.195

DER
-
DOC

6

193.90.54.210

/28

193.90.54.211

193.90.54.224

193.90.54.225

193.90.54.211

DER
-
ADM

4

193.90.54.226

/29

193.90.54.227

193.90.54.232

193.90.54.233

193.90.54.227




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III.

N
EEDS STUDY


A.

C
OSTS

AND THEIR JUSTIFICAT
ION


For a smooth VoIP experience, we want a fast
,

stable
and reliable
network.

Neither of these
is

provided with the current 56

kb/s

line
,
which is

why we c
hose a fibre optic Internet provider.

Using the Asterisk
IPBX (IP Private Branch Exchange)

with 24 concurrent calls at 44 kHz using
the Speex codec and the SIP protocol, the bandwidth used for incoming and outgoing calls is 1.4
Mb/s, for a total of 2.8 Mb/
s.

For more flexibility, we won’t use dedicated IP phones but instead
softphones (telephony software) and a headset.

Accessing files from the file server using FTP should be responsive and fast, and our new
connection will allow this. But the network and t
he workstations need to be upgraded to use the
full speed.


Category 5e network cables are able to provide a bandwidth up to 1000

Mb/s. To use them at
their full potential, we chose to change the workstations for

a
more economical and less power
consuming
all
-
in
-
in
-
one solution
that embed a Gigabit Ethernet network card.


A tool to cut cable
s

and add RJ
-
45 connectors is needed, and cable testing will be done by the
switches.

As I said, workstations were changed for new and more powerful ones. The users will

be able to
use the resources way faster thanks to the upgraded network infrastructure.


The productivity suite the users will use daily is
LibreOffice
, the major open source office suite.
It provides a word processor, a spread sheet editor, a presentation

editor and a drawing tool. It
is free and frequently updated, thus making it the ideal software for a company.

Old black and white printers were changed for better and new ones, and colour printers were
added. Each printer
is

available on the network.


Th
e printers I chose use less than 1W in idle state, and less than 65W in waiting state, thus
making them very power
-
efficient devices.

Hubs have been thrown to be replaced by switches. The HQ has a 24 ports switch, and the other
offices have 16 ports switch
es.

These switches are fully manageable, this means they support a
large range of advance features and can be remotely administrated.
One of these useful features
is the

support

of

Quality of Service (QOS) which will be used to optimize VoIP traffic, and g
ive a
lower priority to
Wi
-
Fi

users.


Hubs don’t scale well and are bandwidth
-
limited, thus can’t support the expansion of the
company if a lot of new employees join.

This is because hubs are level 1 devices, so they don’t
manage a MAC addresses table in t
heir internal memory. Not knowing who on the network to
send the packets, the packets are broadcasted to every outgoing port of the hub. Moreover,
multiple devices can’t send information at the same time, thus making hubs only half
-
duplex
devices.
Having s
witches ensure that the network will go on even with hundreds of people
,
because it acts as a full
-
duplex layer 2 device working with a MAC

addresses table, handling
queuing
.

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The wireless access point will deliver to the users a 802.11g (up to 54

Mb/s) con
nectivity.

Security will be ensured
using the WPA2
-
PSK
encryption
algorithm.

The device I chose has
advanced feature, and its firmware can be changed for powerful dedicated open
-
source
solutions like
OpenWrt

or
dd
-
wrt
.

To connect LANs over WAN, we need
routers.

We chose a
Cisco

router that has a powerful
firewall and an efficient protection against intrusions.

Moreover, some available features can be
used for future improvements of the network
. Some elements of security can be introduced, like
IPsec/L2TP

VPN establishing secure tunnels at level

3 with encryption and authentication.

The servers used to have an old slow 10 Mb/s network card. The upgrade to a 100 Mb/s will
give them the performance boost needed to support our freshly upgraded network
infrast
ructure.


Order

Number

Reference

Price

Subtotal

Workstations

36

Acer Aspire XC100
-
002


£ 320.
00


£ 11 520,00

B&W printer

4

Brother HL2250DN


£ 66.
00


£ 264.
00

Colour printer

4

Brother HL
-
3070CW


£ 125.
00


£ 500.
00

Network
cable

5

305m CAT 5e


£ 64.
00


£ 320.
00

RJ
-
45 connector

1

500 pieces, generic, 5e


£ 16.
00


£ 16.
00

Network card

2

D
-
Link DGE
-
528T


£
9
.00


£ 1
8
.00

Crimping tool

1

Generic


£ 16.00


£ 16.00

HQ switch

1

Netgear JFS524E


£ 64.00


£ 64.00

SQ switches

3

Netgear FS116E


£ 53.00


£ 159.00

Routers

4

Cisco Small Business RVS4000


£ 90.00


£ 360.00

WLAN APs

4

Linksys WRT54GL


£ 60.00


£ 240.00

Internet
connection

4

Virgin the Biz plus 100Mb/s


£ 28.00


£ 112.00

Total





£ 13

5
89
.00


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B.

I
NFRASTRUCTURE OVERHA
UL



The company had a slow network, where users complained about the latency and poor
performance of VoIP.

This is our main concern for our improvement scenario.

In this schema, the red cables are the fibre optic connections to the Internet, and the black
cables are the cat 5e network cables. This is the basic design of how we want to improve our
network.

We c
an see that the servers, the printers, the wireless access point and the users’ workstations
are connected to the switch, which is itself connected to the router. In the schemas, we won’t
represent the way subnets are designed because we are focus on the p
hysical infrastructure.
However, we can consider that the boxes represent either the big subnets or the physical
buildings.



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IV.

I
MPLEMENTATION OF IMP
ROVEMENTS


A.

O
FFICE PLANS


a)

H
EADQUARTERS



Here is the improved version of our
headquarters office.

Every cable is wired into the switch
and runs at the
wall, their end being a RJ
-
45 socket
.

Each room has the adequate number of RJ
-
45 sockets.

The admin staff room contains the servers, which are put in a rack. The administrators manag
e
the router and the switch with the security policy they are working on.

The storage room, where
the router and the switch are, is locked to prevent any direct attack against the network.

For our plans and simulations, we use T3 lines instead of the fibre

optic we chose on the cost
study because the simulations are faster with these lines.
Knowing that fibre optic is better than
T3, we are sure that the result will be better than our simulation results.

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The workstations are wired to the network using a cab
le plugged in the network socket.

The
users will be able to use the network resources with this, and use the softphone for the IP
telephony.

The printers are

connected to the network, and are remotely administered by the admins. They
can check the toner le
vel and the hardware faults using a monitoring program
using

SNMP.

This office will be the most bandwidth consuming, because it hosts all the core of the
infrastructure: the servers and the main router. Efficient rules of QOS will be needed to provide
the
best network efficiency.

The wireless router is set up to let guest connect to the network with credentials given by the
admins.
The standard use is 802.11g, in the 2.4 GHz band, and operates at a maximum
bandwidth of 54 Mbit/s without overhead, but in
real life has a 19 Mbit/s net throughput.

The
WPA2
-
PSK security
algorithm ensures

a secure communication channel.

To prioritise working
medical staff and preventing the wireless users from overloading the network, optimised
Quality of Service rules are use
d.


The access point is placed near of the waiting area, were the users of the wireless network will
stay. The range of the signal will cover most of the office.



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b)

S
UBSIDIARIES



Here is the improved version of our
subsidiary

of
fice
s
. Every cable is wired into the switch and
runs at the wall, their end being a RJ
-
45 socket. Each room has the adequate number of RJ
-
45
sockets.

The admin staff room contains the administrators’
workstations, from where the admins
manage the router an
d the switch. The storage room, where the router and the switch are, is
locked to prevent any direct attack against the network.

Again, the office connected to the Internet with T3 lines for the simulation.

The lag between 2
subsidiary users calling each o
ther will be higher here than 2 Stafford users calling, because all
the VoIP traffic goes through the se
r
ver located in the headquarters.

But the network has been
correctly dimensioned to ensure a minimal lag with the best available quality, thus making th
e
users totally forgot their old VoIP infrastructure.

The printers are connected to the network, and are remotely administered by the admins
, just
like in the HQ
.

The wireless router provides the same type of network as in the headquarters, with a 19 Mb/s
data rate and WPA2
-
PSK encryption. Its signal is available in the waiting area, and in some
rooms.

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B.

S
IMULATION


a)

C
ONFIGURING THE NETWO
RK


For the simulation, we used
Opnet Modeler 16
.

Each site is represented as a subnet which
is placed on the map of the
United
Kingdom using metric units.

We have our
four sites: the headquarters (Stafford),
and the three subsidiary sites (Liverpool,
Derby, Birmingham).

The map on the right represents the
connections between the sites.
The
routing was done using routers tha
t
communicate through the Internet.

We added the floor plans to the sites to
place the network devices where they
would be in real life to make the
simulations more adequate with the
physical reality.


This helps calculating the right values for the networ
k traffic, because the cables will have their
real length.

I put a 56 kb/s connection to the Internet for the current scenario, and basic routers and hubs.
They were changed to a T3 line, a good
Cisco

router and switches. Printers and Wi
-
Fi access
points a
nd clients were added.

LAN wires are cat 5e cables.


For the simulation, the Wi
-
Fi users can access the company’s network infrastructures like the
HTTP+FTP and VoIP servers.

SCHEMA_STAFFORD

The company headquarters in Stafford


I put the appConfig and prof
il
e
Config in the Stafford subnet, because this is where the server
is

located.

The simulated loads are: HTTP (Heavy), FTP (Heavy), VoIP (Heavy).

SCHEMA_SUBSIDIARIES

A subsidiary office in Liverpool, Birmingham or Derby


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Each one of the three subnets is the

same. The only differences are the name of the rou
ter, and
the network identifier for

the wireless router.

b)

R
ESULTS


The indices of the network improvements are:



HTTP page response time.


The time between a request to the webserver, and the response with t
he content of the
requested resource. The smaller, the better.



End
-
to
-
end packet delay.


The latency between the emission of a packet and its reception.

The smaller, the better.



Jitter
.


The voice signal fluctuation. The smaller, the better.

Our measures
and interpretations follow.



HTTP page response time

In this graph, we see that the page response time for
both scenarios is high.


For the current scenario, this is because the network
is slow and unreliable, and because the server can’t
handle a lot of r
equest with its poor network card.


For the improved scenario, this is because the server
handles lots of concurrent request, thus making its
load very high.

Furthermore, the WiFi clients have a high response
time, which is normal.




End
-
to
-
end packet dela
y

In this graph, we see that the delay is
getting higher in our current scenario.
This is caused by the hubs that can’t
manage a constant queuing and is not
full
-
duplex.

In the improved scenario, the delay is a
constant value near zero.



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Jitter

In this g
raph, w
e see that in the
current scenario, the jitter is not
constant and has a high value.


In the improved scenario, the
jitter is almost zero.

This means the packet on the
network are not coming late, are
no congestion phenomenon is
happening.



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V.

C
ONCLUS
ION


Even with a quick look at our simulation results, we can say that the upgrade was successful.
The VoIP experience is now totally smooth, the network has a way better overall speed, and the
users are happy with their new printers and wireless access po
ints. The administrators come to
work with a smiley face, because they love their job and their new network infrastructures.

To be more scalable and more easily manageable, we could have used VLANs which would have
greatly helped for subnetting. The sites
could also have been connected together using a
IPsec/L2TP VPN, which would guarantee security and data integrity.

We could also subscribe
for a symmetric gigabit connection, but it’s too expensive and too big for our needs.