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Task 1.1.evaluate-the-performance-of-communication-systems

Task 1.1
Performance of the Available Communication Technologies
Analog Telephone Lines/ Analog Modems.
These use the existing telephone infrastructure to link sites together. The
telephone cabling supports analogue frequencies in the range 300Hz to
3400KHz, and is primarily designed for speech. The available bandwidth of
the speech circuits provided by telecommunication companies (e.g. SLT,
Suntel) imposes limits on the available speed in bits per second that can be
The modems implement a dial-up connection. A connection is made between
the two modems by dialing the number assigned to the other modem, using the
existing dial up telephone network.
Generally modems fail to achieve the maximum speeds they depict. Errors
caused by noise on the telecommunication lines often cause modems to fall
back to a much lower speed, in order to reduce the number of errors. Thus a
high speed modem rated at 33600bps often achieves a throughput of 9600bps
due to the existing phone lines being too error prone to support the higher rate.
Another problem that occurs is with modems that utilize compression
techniques. Often, compression is measured on the transmission of
uncompressed files like text files. When these same compression modems are
asked to deal with the transfer of compressed files, they do not perform well,
and effectively either transfer at a much reduced rate or no compression at all.
In addition, modems utilizing the different compression schemes often fail to
communicate properly with compression enabled. This is due to variances in
manufacturers implementations of compression algorithms.
Advantages of implementing the analog lines at Aitken Spence
Widely available
Low cost
Most interoperate reliably
Disadvantages of implementing the analog lines at Aitken Spence
Low speed
Error Prone
ISDN – Integrated Service Digital Network
ISDN provides end-to-end digital connectivity between any two (or more)
communications devices. This can be thought of as an alternative to the
existing public switched telephone network (PSTN).
Information enters, passes through, and exits the network in a completely
digital fashion. Many aspects of telecommunications are improved with digital
technology. For example, digital technology lends itself to very large-scale
integration. Technology and its associated benefits of efficiency and cost
reduction. In addition, computers operate digitally. Digital transport provides
The ISDN is capable of transporting voice, data, graphics, text, and even video
information over the same equipment. The customer has access to a wide
spectrum of communications services by way of a single access link. This is in
contrast to existing methods of service access, which segregate services into
specialized lines.
Associated with integrated access and ISDN is the concept of a standard
interface. The objective of a standard interface is to allow any ISDN terminal
to be plugged into any ISDN interface, resulting in terminal portability,
flexibility, and ease in operation.
Ways in which ISDN can be connected
Fig 1.1
The above figure shows An ISDN terminal adapter with phone support (ISDN
modem) allows a telephone, fax machine and PC to communicate via the ISDN
Fig 1.2
The figure 1.2 depicts that LANs typically connect to ISDN via a router, which
enables multiple users to share the available channels. For Internet access, the router
supplies temporary IP addresses to each of the nodes. Routers may also provide
analog phone support.
Services that can be provided at Aitken Spence with ISDN
Fast file transfer - The user don't need to courier or post text, photographs,
drawings, video clips, etc. With ISDN this can be done between computers in
seconds. ISDN - Data interchange is made within seconds instead of hours
waiting at a normal dial-up connection terminal.
Fast internet access- Enables the user to search and download information
from the Internet at twice the speed of the fastest analogue modem and save
time and money on searching and downloading.
Network connectivity - With ISDN, the user can combine two local area
networks as one can allow data flow within these networks.
Call line identification - Displays the number of the person who calls before
the user answer a call and throughout the call.
Video conferencing - Enables the user to hold face to face meetings with
people around the world; discuss and amend documents, images in real time
without having to move from the desk. Moreover talk to customers,
businessmen, and other dignitaries face to face without having to travel
thousands of miles.
Remote network access - Allows the user to work from home and make
his/her work efficient and effective. With ISDN one can access information
held on the network and use the same applications.
E-mail - Transference of memos, letters, invoices, statements.
G4 faxes - Faxing becomes 7 times faster with ISDN. If an A4 size page takes
10 seconds to fax under normal circumstances, with ISDN it takes only 1.5
At present the ISDN service is available in Sri Lanka through Sri Lanka Telecom
(SLT). Refer appendix 1 for the current service areas and the charges for ISDN. The
details were taken from the SLT City Office – Kandy.
Advantages of Implementing ISDN at Aitken Spence
Low fixed cost
Fast call set up times
Based on digital technology and provides a very low ber (bit error rate)
Perfect clarity, reliability and speed.
Disadvantages of Implementing ISDN at Aitken Spence
Not available in all cities ( e.g. Kandy, Kalutara)
Not suited to mobile users (users dialling in via remote access)
Digital Subscriber Line (xDSL)
xDSL is a high speed solution that allows megabit bandwidth from telecommunications to customers over existing copper cable, namely, the installed
telephone pair to the customers premises (called the local loop). xDSL offers
significant increases in connection speed and data transfers for access to
In many cases, the cost of relaying fiber optic cable to subscriber premises is
prohibitive. As access to the Internet and associated applications like multimedia, tele-conferencing and on demand video become persistent, the speed of
the local loop is a limiting factor.
xDSL is a number of different technologies that provide megabit speeds over
the local loop, without the use of amplifiers or repeaters. This technology
works over non-loaded local loops (loaded coils added by telephone
companies on copper cable pairs to improve voice quality). xDSL coexists
with existing voice over the same cable pair, the subscriber is still able to use
their telephone, at the same time. This technology is referred to seamless.
To implement xDSL, a terminating device is required at each end of the cable,
which accepts the digital data and converts it to analogue signals for
transmission over the copper cable. In this respect, it is very similar to modem
xDSL provides for both symmetric and asymmetric configurations.
Bandwidth is higher in one direction Bandwidth same in both directions
Suitable for Web Browsing
Suitable for video-conferencing
Variations of xDSL
There are currently six variations of xDSL.
xDSL Technology Meaning
2 x 64Kbps circuit switched
1 x 16Kbps packet switched
(similar to ISDN-BRI)
Digital Subscriber Line
High-bit-rate DSL
Single-pair or Symmetric
768Kbps over a single pair
High-bit-rate DSL
Asymmetric DSL
up to 6Mbps in one direction
Rate Adaptive DSL
An extension of ADSL which supports
a variety of data rates depending upon
the quality of the local loop
Very High-bit-rate
asymmetric DSL
Up to 52Mbps in one direction and
2Mbps in the other direction.
2.048Mbps over two pairs at
a distance up to 4.2Km
Considering Sri Lanka, the widely used is ADSL – Asymmetric Digital Subscriber
This technology takes advantage of the unused bandwidth that already exists
on the phone line.
Bandwidth refers to the amount of data that can be transmitted over a given
time period. Essentially, the more bandwidth, the faster information can be
delivered to the computer. The upstream (from the computer to the Internet)
and the downstream (from the Internet to the computer) speeds are different
hence the term 'asymmetric.'
ADSL is perfect for receiving multimedia, audio, video and animation files in
real time. ADSL technology gives users fast digital data transmission and does
not affect the analog telephone service that is currently used. That means the
user can enjoy a fast, permanent connection to the Internet, and still have full
use of the telephone.
At present the ADSL services are available in Sri Lanka through Sri Lanka Telecom
(SLT) and Suntel. Refer appendix 2 for the tariff rates. The details were taken from
the SLT City Office Kandy and Suntel City Office Kandy.
Additionally, Dialog Telekom provides a broadband high-speed internet access.
Given below are the details of dialog broadband.
Dialog Broad band’s wide range of high speed solutions are designed to meet
the needs of businesses of all sizes. All services offer full broadband speeds,
ultra-reliable connectivity, business-class features, and high speed broadband
internet access virtually anywhere in the Island.
Island-wide infrastructure and international gateway, continuous traffic
management and complete security are ensured both on the hosts as well as on
the network.
Adequate redundancy is provided for in the international circuit as well as in
equipment. The IP backbone makes internet delivery possible to the client’s
location without having to depend on a third party for access. The
distinguishing feature of high speed internet services is via a satellite gateway
and SEA-ME-WE fiber optic cable. Internet services give the equal measure
of performance, reliability and flexibility and cost-effectiveness.
Dialog Broadband Internet has in place rigorous traffic management and
monitoring procedures. All nodes services and equipment are monitored
online and online traffic graphs are guaranteed.
Connectivity and services are monitored round-the-clock. Bandwidth manager
software measures and allocates bandwidth to users for optimum usage. Real
time fault ensures minimum downtime in case of a failure.
Advantages of using ADSL at Aitken Spence
It is always-on - the connection is always available without needing to wait for
ages to 'dial up'. It also doesn't 'drop out'. It is 'just there' - when you need it,
It is dramatically faster than a dial modem or ISDN connection - up to 30-50
times faster. This makes an enormous difference to the effectiveness of the
internet experience, and as well for the company.
ADSL seamlessly 'shares' a phone line along with normal 'voice' services. The
phone is not engaged when using the internet - in fact the user can freely use
the phone at the same time as access the internet.
No second phone line needed. You can easily offset the costs of ADSL by
Rs.3000 per month or more - this is the amount you might have otherwise
spent on a second phone line and on local calls to access the internet with a
modem, without interrupting the use of your primary telephone service.
You can save time and frustration by never having to wait for a modem to
connect, or suffering connection dropouts, in addition to the hugely increased
download speeds available
It is far more cost effective
Limitations of ADSL
ADSL is not available on all phone services
Aitken Spence may not be able to get ADSL for many reasons but the most
common are:
o The company is too far from the local telephone exchange.
o The local telephone exchange is not enabled.
ADSL is not a guaranteed bandwidth service
o For example the SLT network architecture, and the manner in which
ADSL data is moved around the city, mean that network congestion is
possible in the line at some times. The speeds quoted for ADSL
services are theoretical maximum rates.
o Performance of the network may vary by time of day or may decrease
over time due to increased network interference which is evident by
the SLT, Suntel line networks.
ADSL is only fast in one direction
o The asymmetric transfer rates provided by ADSL are designed to
optimise the speed of internet downloads. As a consequence, the
upload speed on ADSL is far slower.
o This means that ADSL is often unsuitable for situations where you
intend to upload (or serve) large quantities of data from a set location
back out into the internet.
Leased Line
A leased line is a private high-performance circuit leased by a common carrier
between a customer and a service provider’s network.
Leased lines are mostly used for either internet access or used privately
between two customer sites.
Unlike a dial-up connection, a leased line is always active. Similarly unlike
broadband, a leased line is not contended or shared and delivers dedicated
guaranteed bandwidth straight to the internet backbone.
Users pay a premium for a leased line and it is supported by a comprehensive
Service-Level Agreement (SLA) with a guaranteed fix time and a
compensation clause.
Otherwise referred to as a point to point, private circuit, private line or
dedicated access.
Bandwidth can be tailored to the company's exact requirements, ranging from
64 Kbps to 1000 Mbps. The required speed could depend upon the number of
employees accessing the internet or perhaps upon the applications used; some
being more bandwidth intensive than others.
Implementation of a Leased lines at Aitken Spence will cater for the following:
Provide a scalable access method, important particularly for organizations
with large user groups.
The quality of the connection is far superior to what is normally available
through dialup, thanks to digital signalling, less noise, fewer exchanges etc.
Provide permanent connectivity to the Internet.
Since the access is "always on", it is possible to associate a pool of permanent
IP addresses with a particular leased line.
Using these IP addresses it becomes possible to deploy a variety of services
such as mail, FTP, WWW, DNS, and proxy, to name the most common
requirements of Aitken Spence.
Starting typically with 64 Kbps, it is possible to deploy a scalable architecture,
with multiples of E1 (2 MBPS) pipes, providing the necessary bandwidth
Leased line can provide Aitken Spence with the following:
High availability and super fast access to web sites or mail servers hosted at
the premises.
Online transactions 24x7 to support the business.
Higher service level performance than available by alternative connections
(ADSL/SDSL etc.)
In excess of 2Mbps Internet access to the offices
Fast access to a secondary data centre site for business continuity applications.
High bandwidth at a later date with the option to scale bandwidth rapidly as
demand increases.
Currently SLT and Dialog Telekom provide the leased line facility, given below are
the details of the SLT leased lines and the Dialog leased lines.
Are dedicated digital circuits connecting two fixed points across a private
network. They are in fact the most secure and reliable type of voice and data
connections available today.
Totally dedicated thus its exclusive to the user.
Because no one else ever uses it, the core user has total access to it - 24 hours
a day - meaning there's never a delay in sending information.
SLT Leased Line is delivered on Copper or Faber optic transmission networks
and is monitored around the clock to provide you with a highly reliable
Dialog Leased Lines
Dialog provides Leased Line Internet connectivity to any organization located
in any part of the Island.
High speed connectivity.
Connected to the Internet backbone directly via Sea Me We 3 submarine
Redundancy Satellite link for emergency use.
Fig 1.3
The figure 1.3 shows a typical leased line connection.
Advantages of leased lines to Aitken Spence
Secure and private - dedicated exclusively to the company
Speed – symmetrical, un-contended and direct
Reliable – private circuit local loops are a premium product supported by fast
time to fix guarantees
Resilience – redundancy can be incorporated to reduce outages
Wide choice of speeds – bandwidth on demand, easily upgradeable
Dependable - leased lines are suitable for in-house office web hosting
Geographic reach - the performance you need across the globe
Total security - your own dedicated connection
Network Operations Centre (NOC) - 24x7x365 network monitoring, technical
and field support
Service guarantees - backed by comprehensive Service Level Agreements
Disadvantages of leased lines at Aitken Spence.
Leased lines can be expensive to install and rent
Lead times can be as long as 65 working days
Distance dependent to nearest point of presence.
Frame Relay
Consists of an efficient data transmission technique used to send digital
information quickly and cheaply in a relay of frames to one or many
destinations from one or many end-points. Typical Frame relay connections
range from 56Kbps to 2Mbps.
Frame relay puts data in variable-size units called "frames" and leaves any
necessary error-correction (such as re-transmission of data) up to the endpoints. This speeds up overall data transmission. For most services, the
network provides a permanent virtual circuit (PVC), which means that the
customer sees a continuous, dedicated connection without having to pay for a
full-time leased line, while the service-provider figures out the route each
frame travels to its destination and can charge based on usage.
Frame relay has its technical base in the packet-switching technology,
designed for transmitting analog data such as voice conversations. Frame relay
offers a fast packet technology, which means that the protocol does not
attempt to correct errors. When a frame relay network detects an error in a
frame, it simply drops that frame. The end points have the responsibility for
detecting and retransmitting dropped frames. (However, digital networks offer
an incidence of error extraordinarily small relative to that of analog networks.)
Frame relay often serves to connect local area networks (LANs) with major
backbones as well as on public wide-area networks (WANs) and also in
private network environments with leased lines over T-1 lines. It requires a
dedicated connection during the transmission period. Voice and video can be
sent over a frame relay network, often providing significant cost savings with
some sacrifice in voice or video quality, depending on network configuration.
Frame Relay has become one of the most extensively-used WAN protocols. Its
cheapness (compared to leased lines) provided one reason for its popularity.
The extreme simplicity of configuring user equipment in a Frame Relay
network offers another reason for Frame Relay's popularity.
Why Aitken Spence Needs a Frame Relay
Need for increased speed
Dynamic Bandwidth requirements
Smarter Attached Devices
Higher performance
Widespread Digital facilities
At present, the Frame Relay is offered by SLT, Suntel, LankaCom in Sri Lanka.
The above description about the frame relay comply with the SLT’s
LankaCom provides international Frame Relay services with its own Frame
Relay infrastructure using Cisco-Stratacom and New Bridge equipment.
The frame relay backbone network of Suntel provides extensive island-wide
coverage, which enables them to cost effectively deliver high quality, reliable
and secure wide area networks (WAN), to the customers.
Cost effective delivery of high quality, reliable and secure wide area networks
(WAN) for enterprise connectivity is provided through Suntel’s frame relay
switches, which are strategically located in order to facilitate island-wide
Switch to switch interconnection is through multiple E1 channel
configurations and every switch is connected to two other switches providing
redundant data paths in case of link failures. This will enable them to provide
the customer with enhanced bandwidth and efficient and reliable data
communication networks.
Advantages of Frame Relay to Aitken Spence.
Supports multicasting
Low cost compared to other technologies
Exploits recent advances in technology
The maximum burst permits data to transmit as fast as the circuit’s capacity.
Frame Relay is also widely deployed
Disadvantages of Frame Relay to Aitken Spence.
Because Frame Relay is a packet-switched technology, latency (delay) is
introduced in the processing of each packet at every Frame Relay switch.
Difficulty in ensuring Quality of Service, this is due to the fact that Frame
Relay uses variable-length packets.
IPTV – Internet Protocol Television
(Internet Protocol TV) also called "TV over IP," IPTV delivers scheduled TV
programs and video-on-demand (VOD) via the IP protocol and digital
streaming techniques used to watch video on the Internet. In order to receive
and decode the images in real-time, the user requires either an IPTV set-top
box or a computer and software-based media player.
IPTV enables a data-voice-video "triple play" service to be based entirely on
IP because Internet access, voice over IP (VoIP) and IPTV all use the same IP
packet format.
IP television service allows Aitken Spence to have more control of television
services. This control ranges from instant service activation to real time
television on demand controls. Some of the advanced Internet television
features such as personal media channels, anywhere television extensions,
global television channels and multimedia programs are described.
Because each IP television viewer has a unique address, this allows
advertising messages to be sent to specific viewers (addressable advertising).
The ability to direct advertising messages to specific target audiences is more
valuable to companies than traditional broadcast advertising and this may
result in reduced viewing costs.
Advantages of using IPTV at Aitken Spence.
Includes the ability to integrate television with other IP-based services like
high speed Internet access and VoIP.
A switched IP network also allows for the delivery of significantly more
content and functionality.
A switched IP network works differently. Content remains in the network, and
only the content the customer selects is sent into the company/hotel. That frees
up bandwidth, this also implicates that the Aitken Spence’s privacy could be
compromised to a greater extent than is possible with traditional TV or
satellite networks.
Limitations of using IPTV at Aitken Spence
Because IPTV is based on the Internet Protocol, it is sensitive to packet loss
and delays if the IPTV connection is not fast enough.
At the moment IPTV is not available in Sri Lanka, but SLT is planning to
launch IPTV to broadcast video on demand in the future.
VoIP – Voice over Internet Protocol
VoIP is the routing of voice conversations over the Internet or through any
other IP-based network.
Companies providing VoIP service are commonly referred to as providers, and
protocols which are used to carry voice signals over the IP network are
commonly referred to as Voice over IP or VoIP protocols.
Advantages of using VoIP at Aitken Spence
VoIP services that use regular telephones can generally make calls to any
regular phone and receive calls from any phone.
VoIP saves money spent on long distance phone calls while promoting
bandwidth data capacity and telephony efficiency.
By using a phone adaptor (ATA), the VoIP technology can travel anywhere
where the user can connect to a broadband connection.
Disadvantages of using VoIP at Aitken Spence.
Because User Datagram Protocol does not provide a mechanism to ensure that
data packets are delivered in sequential order, or provide Quality of Service
guarantees, VoIP implementations face problems dealing with latency and
The support of sending faxes over VoIP is still limited. The existing voice
codecs are not designed for fax transmission.
The nature of IP makes it difficult to locate network users geographically.
Emergency calls, therefore, cannot easily be routed to a nearby call center, and
are impossible on some VoIP systems.
The majority of consumer VoIP solutions do not support encryption yet. As a
result, it is relatively easy to eavesdrop on VoIP calls and even change their
The figure below shows the overview of a VOIP
Fig 1.4
Some VOIP Providers in Sri Lanka
Omega Technologies (Pvt) Ltd.
TruConnect Technologies (Pvt) Ltd.
IP VPN – Internet Protocol Virtual Private Network
Virtual Private Network (VPN) delivers private network services over a public
An IP VPN is a partitioned private network constructed over a shared IP-based
backbone that utilizes technologies to ensure privacy of data. They offer
enterprise-class scalability and reach-ability across multiple IP-based
infrastructures, along with many of the performance and security
characteristics traditionally found only in dedicated private environments.
MPLS (Multi Protocol Label Switching) technology based VPNs combines
the intelligence of private IP routing with the added performance of label
switching to move packets between any locations on the network. With only
one access link to the MPLS “cloud” from each of the locations, full mesh
connectivity will improve the network scalability, reliability, and internal
network application performance.
IP VPN is provided by the SLT, Dialog Telekom and Suntel. Given below are the
descriptions of each IP VPN services provided by the aforementioned companies.
Suntel IP VPN
Suntel’s IP VPN network is powered by CISCO and built using MPLS (Multi
Protocol Label Switching) which can provide virtual networks for different
customers in such a manner that that external party cannot penetrate into the
VPN. Cisco is the world leader in supplying technology and their systems are
modular and scalable for small to very large enterprises.
Suntel customers will benefit by reduced cost of communication
infrastructure, increased reliability and security, easy connectivity to remote
workers, improved communication within groups, site to site connectivity for
branch offices and the opportunity to broaden their geographic presence.
With Suntel’s IP VPN facility, customers will no longer require skilled
technical staff to manage the network at their end. Suntel will provide that
service through IP VPN, making connectivity between branch offices far
better and smoother.
Dialog Telekom IP VPN
MPLS based IP VPN solution capitalizes on the investment in Dialog’s
Advance network and leverages the strengths of the metro area networking
capabilities to provide operational cost savings to the customers with legacy
Fast Packet or Private Line networks, while evolving into an IP infrastructure.
IP-VPN Service also provides the platform that customers need to add other
value added services over time such as IP Telephony, Network-based
Firewalls and Internet Offload capabilities.
Customers in and out of the traditional Dialog Broadband footprint that need a
high-performance, cost-effective network solution, which offers end-to-end,
fully meshed, any-to-any connectivity (via ATM, FR and Ethernet) on an
MPLS platform as shown in fig 1.5.
Multiprotocol Backbone of Dialog offer
Reduce network management cost and complexity while rapidly scaling to
deploy business applications to new locations.
Secure, scalable and shared facilities to reduce the investment of building
private enterprise networks.
Exceeds the Quality of Service and privacy of ATM and Frame networks.
Fig 1.5
Sri Lanka Telecom IP VPN
SLT IP VPN as shown in the figure below gives the user choices in the network
design of sophisticated VPN technologies, access, security and voice, with the
flexibility to add on options such as remote access and hosting in IDC (Internet Data
Fig 1.6
Ways in which IP VPN can benefit the Aitken Spence.
IP VPNs can create an intranet that links a corporate headquarters to remote
offices over a shared network allowing users to gain access to secured corporate
Extranets support business-to-business communications enabling an enterprise to
be connected with other enterprises, customers, suppliers or business partners.
Cost Effectiveness
Previously, network connections between sites required dedicated circuits or
private virtual circuits (PVCs). MPLS-based VPNs provide access to the entire IP
network with any-to-any connectivity. This will reduce connectivity charges due
to the sharing of infrastructure.
Network redundancy and fault-tolerance ensure service availability.
IP VPN provides seamless integration of voice and data networks under one IP
network infrastructure, with the ability to customize VPN services for each
business customer thereby increasing differentiation and adding value through
bundled services for data, voice, video, network security and other options.
Each VPN on a single physical infrastructure is treated as a logically independent
routing domain, allowing end-users to use private and unregistered IP addresses to
secure their data as it travels through your network.
MPLS-based network architecture easily adapts to growth in complexity and
volume. Since the VPN network is any-to-any by default, VPN network expansion
can be achieved with minimum additional expenses
VPNs can be developed with different applications such as Full-Mesh topology
for voice and Hub-and-Spoke for Internet access.
Class of service
IP VPNs incorporate the ability to provide advanced Class of Service (CoS)
features that ensures network priority for mission-critical traffic, allowing
businesses to choose the appropriate CoS for their specific traffic patterns and
business requirements.
IP VPN services offered by SLT
VPN with Classes of Service - SLT provides Classes of features for providing
prioritization for traffic.
VPN with Integrated Internet Access - VPN can be given integrated internet
access, rather than having a separate internet leased line.
Remote VPN Access - Provide remote workers or travelling users the same
level of connectivity as individuals who work in branch offices
VPN with ISDN Backup - ISDN Backup provides redundancy to the VPN
Advantages of IP VPN to Aitken Spence
Cost effectiveness - Cost savings are a great motivator for enterprises
adopting IP VPN's in today's economic environment. Previously, network
connections between sites required a dedicated circuit or private virtual circuit
(PVC). IP networks provide access to the entire IP network for one site for one
price - with reduced connectivity charges due to the sharing of infrastructure.
Mobile or remote users can be migrated to an IP network from private dial-up
networks that are otherwise cumbersome and costly to maintain.
Reduced total cost of ownership - With IP VPN's one can buy capacity on
the public Internet, and isolate the traffic using network-based security to
create the IP VPN. This reduces the costs because the user doesn’t need to
over specify the network to ensure capacity. Nor does the user have the capital
or revenue costs associated with maintaining and developing a private
network, as these costs are shared with all users of the public network.
Improved security - When the IP VPN is created, the user separates the
traffic by encrypting it. This secures the data against unauthorised third party
access or manipulation. Such intrusions are very difficult to detect even on a
private-circuit-based (rather than IP VPN) network. This level of security also
allows the user to control site access on a user-by-user basis.
Ease of extending private networks to remote locations - Using a VPN on a
mixture of networks may be the only feasible way to provision services,
particularly where budgets are limited.
Effective platform for web-enabled back-office applications - Aitken
Spence is increasingly adopting applications that make heavy demands on
bandwidth, as they have been designed for Internet-like networks. IP
applications like dial-in for remote access, video-over-IP, IP telephony, and
audio- or videoconferencing can easily be bundled on top of basic IP VPN
Speed of implementation - In contrast to the establishment of the companies
own wide area network (WAN), most of the infrastructure for an IP VPN is
already in place. This enables rapid deployment and flexible development.
Disadvantages of IP VPN to Aitken Spence
Standards/Interoperability - although IPSEC is the IETF standard protocol for
IP VPNs, many companies (such as Microsoft) do not support it. As a result,
the same equipment must be used at both ends of the tunnel to ensure
IPSEC is difficult to set-up and manage - remote clients need to be configured
with the right security parameters.
All traffic over the VPN is encrypted, regardless of need. This can potentially
cause bottlenecks since encrypting data creates network overhead.
Provides no internal protection on the corporate network - the VPN endpoint is
typically at the edge of the network. Once employees are on the internal
corporate network, data is not longer encrypted.
IP VPNs cannot restrict employees from accessing any server on the internal
network freely.
Evaluation of the Communication Technologies.
Technology Performance
 Accessing Corporate
 Downloading large
Files and / or
512 kbps
 Online shopping and
 Web browsing at a
faster speed online
It is the Global
Standard for high
speed voice, data and
ISDN also equips for
faster Internet
surfing, G4 faxes
Provides a static
 Access to the Internet,
phone and fax on the
same line increases
 Un-metered Internet
access makes budgeting
 No extra telephone
 Bandwidth
 Not available
in all the
Provides a very low BER 
You get Instant Call
Connection, Perfect
Clarity, Reliability and
It is easy to use.
Fast internet access
throughput can be as
much as 128 Kbps
Fast file transfer
Video conferencing
Remote network access
Not ready
always Dialup access
Not available
in all the
Not suitable to
mobile users.
256kbps to
 Online transactions
24x7 to support the
business model
 In excess of 2Mbps
Internet access to their
 Fast access to a
secondary data centre
site for business
 continuity applications
 Permanent IP address
 Dedicated bandwidth
 Geographic reach - the
 Very expensive
performance you need
 Professional's
across the globe
 Flexibility - scalable
options from 2 Mbps to
 Total security - your
own dedicated
 Advanced
infrastructure optimum service
quality and reliability
64Kbps to
 Provides a permanent
virtual circuit (PVC).
 Use packet-switching
 Voice and video can
be sent over a frame
relay network
 Lower cost of ownership  Latency is
 Low overhead combined
with high reliability
 Difficulty in
ensuring Quality
 Network scalability,
of Service
flexibility and disaster
 Inter-working with other
new services and
 Reduces the necessity of
installing multiple
modems and other
MPLS (Multi
Protocol Label
technology based
VPNs combines the
intelligence of
private IP routing
with the added
performance of label
Cost Effectiveness
IP VPNs incorporate the
ability to provide
advanced Class of
Service (CoS) features
Provides no
protection on the
All traffic is
Difficult to set up
and maintain
Considering the above evaluation of the available telecommunication technologies in
Sri Lanka and the history of the providers, which are SLT, Suntel, Dialog Telekom
and LankaCom. I strongly recommend the usage of Frame Relay (2Mbps) network
from Sri Lanka Telecom to be implemented at Aitken Spence.
With the Frame Relay, data transfers among the Group’s various locations can take
place and also the same network can be used for corporate voice, which will result in
securing huge savings on toll by pass. With this technology the following operations
can be conducted successfully.
Stock and supplies
Human resource management
Customer relations management.
The reason for getting the service from SLT is because they are a renowned Telco and
thus will provide the best service. They will provide “around the clock” services
ensuring only the best to the customer.
Few reasons for choosing SLT Frame Relay
Lower cost of ownership
Well established and widely adopted standards that allow open architecture
and plug and play service implementation
Low overhead combined with high reliability
Network scalability, flexibility and disaster recovery
Inter-working with other new services and applications such as ATM
If Aitken Spence is to outsource its business entities outside Sri Lanka they can opt
for an IP VPN from SLT to connect to the international branches and use the existing
Frame Relay for the local ventures. This will be a big boost for the services
As a backup line, if the frame relay network fails, I recommend the usage of an ISDN.
The ISDN service can be taken from the SLT and this will run as a back up line in
alternate to the current frame relay.