Gavin Worden

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Presented By
Leased Lines vs. Internet Based VPNs

• Gavin Worden

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Evolution of WAN Technologies
(1)  1837 Telegraph (2)  1876
Telephone (3)  1960s - T-carrier system
developed by ATT for internal use. (4) 1969 -
ARAPNET (later becomes Internet) - first packet
switching network (5) 1970s - Dataphone
Digital Service (DDS) started deployment in 1974,
bringing digital transmission facilities to the
customer's premise. (6) 1980s T-1 services
become commercially popular (7) 1990s Frame
Relay began Deployment
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Leased Lines

• T-Carrier System
• Synchronous Optical Network
• Leased Line Implementations
• Private Point-to-Point
• Frame Relay

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T-Carrier System
Originally developed by ATT in the 1960s for
internal use. Initially used for voice, T1 and
T3 lines are widely used to create point-to-point
private data networks. T-carrier lines use four
wire cables. One pair is used to transmit and the
other to receive
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T-Carrier System
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SONET
In contrast to the copper transmission lines used
for T-carrier systems, the synchronous optical
network, or SONET, uses fiber-optic transmission
technology. Employed by telephone companies and
common carriers, speeds range from 51 Mbps to 40
Gbps. SONET backbones are widely used to
aggregate T1 and T3 lines
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SONET
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Private Point-to-Point
A permanent telephone connection between two
points set up by a telecommunications common
carrier. Typically, leased lines are used by
businesses to connect geographically distant
offices.
ATT offers private digital transmission at
speeds ranging from 9.6 kbps, 56 Kbps, T1,
Channelized DS1, E1, DS3, OC3c, OC12c, OC48c,
OC192c, Ethernet and STM-1/STM-4. This the most
expensive option. A prime component of cost is
geographic distance of the line.
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Frame Relay
Frame relay is a telecommunication service
designed for cost-efficient data transmission for
intermittent traffic between local area networks
(LANs) and between end-points in a wide area
network (WAN).
Frame Relay networks in the U.S. support data
transfer rates at T-1 (1.544 Mbps) and T-3 (45
Mbps) speeds. Frame Relay is a way of utilizing
existing T-1 and T-3 lines owned by a service
provider. Most telephone companies now provide
Frame Relay service for customers who want
connections at 56 Kbps to T-1 speeds.
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Virtual Private Networks
To emulate a point-to-point link, data is
encapsulated, or wrapped, with a header that
provides routing information allowing it to
traverse the shared or public transit
internetwork to reach its endpoint. To emulate a
private link, the data being sent is encrypted
for confidentiality.
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Network to Network VPN
Rather than using an expensive long-haul
dedicated circuit between the branch office and
the corporate hub, both the branch office and the
corporate hub routers can use a local dedicated
circuit and local ISP to connect to the Internet.
The VPN software uses the local ISP connections
and the Internet to create a virtual private
network between the branch office router and
corporate hub router.
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Client to Server VPN
Client VPNs differ from network to network VPNs
in that the connection for a client VPN is made
directly from the client machine to the
organizations VPN concentrator/server instead of
from the clients local network to the
organizations primary network.
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Evaluation of Alternatives

• In order to adequately evaluate the various WAN
  alternatives explored in this report, three
  different WAN scenarios will be examined.
• All three scenarios will be outlined from the
  perspective of a single organization that has ten
  offices around the world. The organization needs
• secure internal e-mail
• files sharing
• intranet
• network management
• Internet access

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Scenario 1

• Private Point-to-Point to Each Site
• Provides stable centrally managed WAN.
• Will provide control of bandwidth / performance
• Single interface to Internet
• Higher degree of network security
• All requirements will be met for this scenario
• This option is the most expensive

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Scenario 2

• Frame Relay to Each Site
• Provides stable centrally managed WAN.
• Will provide control of bandwidth
• Single interface to Internet
• Good degree of network security
• All requirements will be met for this scenario
• This option is the next most expensive

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Scenario 3

• Internet based Network to Network VPN
• Enhanced transport security (encryption)
• Much lower connection costs
• More complex setup and maintenance
• Multiple interfaces with Internet increases
  security risks
• All requirements met with this scenario

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Conclusion

• Major Determining Factors Include
• Performance Requirements
• Security Requirements
• and Cost
• High Security / Performance requirements will
  typically require private point-to-point.
• Lower Security / Performance requirements will
  allow organizations to take advantage of the low
  costs and flexibility of VPNs.

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Questions?
?
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Presented By
Leased Lines vs. Internet Based VPNs

• Gavin Worden