02-04-2011, 03:35 PM
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ABSTRACT
The Virtual Private Network - VPN - has attracted the attention of many organizations looking to both expand their networking capabilities and reduce their costs.
The VPN can be found in workplaces and homes, where they allow employees to safely log into company networks. Telecommuters and those who travel often find a VPN a more convenient way to stay "plugged in" to the corporate intranet.
No matter your current involvement with VPNs, this is a good technology to know something about. A study of VPN involves many interesting aspects of network protocol design, Internet security, network service outsourcing, and technology standards.
What Exactly Is A VPN?
A VPN supplies network connectivity over a possibly long physical distance. In this respect, a VPN is a form of Wide Area Network (WAN).
The key feature of a VPN, however, is its ability to use public networks like the Internet rather than rely on private leased lines. VPN technologies implement restricted-access networks that utilize the same cabling and routers as a public network, and they do so without sacrificing features or basic security.
A VPN supports at least three different modes of use:
• Remote access client connections
• LAN-to-LAN internetworking
• Controlled access within an intranet
VPN Pros and Cons
Like many commercialized network technologies, a significant amount of sales and marketing "hype" surrounds VPN. In reality, VPNs provide just a simple few clear potential advantages over more traditional forms of wide-area networking. These advantages can be quite significant, but they do not come for free.
The potential problems with the VPN outnumber the advantages and are generally more difficult to understand. The disadvantages do not necessarily outweigh the advantages, however. From security and performance concerns, to coping with a wide range of sometimes incompatible vendor products, the decision of whether or not to use a VPN cannot be made without significant planning and preparation.
Technology Behind VPNs
Several network protocols have become popular as a result of VPN developments:
• PPTP
• L2TP
• IPsec
• SOCKS
These protocols emphasize authentication and encryption in VPNs. Authentication allows VPN clients and servers to correctly establish the identity of people on the network. Encryption allows potentially sensitive data to be hidden from the general public.
Many vendors have developed VPN hardware and/or software products. Unfortunately, immature VPN standards mean that some of these products remain incompatible with each other.
The Future of VPN
The success of VPNs in the future depends mainly on industry dynamics. Most of the value in VPNs lies in the potential for businesses to save money. Should the cost of long-distance telephone calls and leased lines continue to drop, fewer companies may feel the need to switch to VPNs for remote access. Conversely, if VPN standards solidify and vendor products interoperate fully with other, the appeal of VPNs should increase.
The success of VPNs also depends on the ability of intranets and extranets to deliver on their promises. Companies have had difficulty measuring the cost savings of their private networks, but if it can be demonstrated that these provide significant value, the use of VPN technology internally may also increase.
1. INTRODUCTION:
1.1.Definition
An Internet-based virtual private network (VPN) uses the open, distributed infrastructure of the Internet to transmit data between corporate sites.
1.2.Overview
Why to develop vpn ?
Businesses today are faced with supporting a broader variety of communications among a wider range of sites even as they seek to reduce the cost of their communications infrastructure.
Employees are looking to access the resources of their corporate intranets as they take to the road, telecommute, or dial in from customer sites.
Plus business partners are joining together in extranets to share business information, either for a joint project of a few months' duration or for long-term strategic advantage.
At the same time, businesses are finding that past solutions to wide-area networking between the main corporate network and branch offices, such as dedicated leased lines or frame-relay circuits, do not provide the flexibility required for quickly creating new partner links or supporting project teams in the field.
Meanwhile, the growth of the number of telecommuters and an increasingly mobile sales force is eating up resources as more money is spent on modem banks, remote-access servers, and phone charges.
The trend toward mobile connectivity shows no sign of abating; Forrester Research estimated that more than 80 percent of the corporate workforce would have at least one mobile computing device by 1999.
Comparison of vpn with exiting network:
First and foremost are the cost savings of Internet VPNs when compared to traditional VPNs. A traditional corporate network built using leased T1 (1.5 Mbps) links and T3 (45 Mbps) links must deal with tariffs that are structured to include an installation fee, a monthly fixed cost, and a mileage charge, adding up to monthly fees that are greater than typical fees for leased Internet connections of the same speed.
Leased Internet lines offer another cost advantage because many providers offer prices that are tiered according to usage. For businesses that require the use of a full T1 or T3 only during busy times of the day but do not need the full bandwidth most of the time, ISP services, such as burstable T1, are an excellent option. Burstable T1 provides on-demand bandwidth with flexible pricing. For example, a customer who signs up for a full T1 but whose traffic averages 512 kbps of usage on the T1 circuit will pay less than a T1 customer whose average monthly traffic is 768 kbps.
Because point-to-point links are not a part of the Internet VPN, companies do not have to support one of each kind of connection, further reducing equipment and support costs. With traditional corporate networks, the media that serve smaller branch offices, telecommuters, and mobile works—digital subscriber line (xDSL), integrated services digital network (ISDN), and high-speed modems, for instance—must be supported by additional equipment at corporate headquarters. In a VPN, not only can T1 or T3 lines be used between the main office and the ISP, but many other media can be used to connect smaller offices and mobile workers to the ISP and, therefore, to the VPN without installing any added equipment at headquarters.
VPN resolves the limitations of ordinary networks:
VPNs using the Internet have the potential to solve many of these business networking problems.
VPNs allow network managers to connect remote branch offices and project teams to the main corporate network economically and provide remote access to employees while reducing the in-house requirements for equipment.
Rather than depend on dedicated leased lines or frame relay's permanent virtual circuits (PVCs), an Internet-based VPN uses the open, distributed infrastructure of the Internet to transmit data between corporate sites.
Companies using an Internet VPN set up connections to the local connection points (called points-of-presence [POPs]) of their Internet service provider (ISP) and let the ISP ensure that the data is transmitted to the appropriate destinations via the Internet, leaving the rest of the connectivity details to the ISP's network and the Internet infrastructure.
Because the Internet is a public network with open transmission of most data, Internet-based VPNs include measures for encrypting data passed between VPN sites, which protects the data against eavesdropping and tampering by unauthorized parties.
In addition, VPNs are not limited to corporate sites and branch offices. As an added advantage, a VPN can provide secure connectivity for mobile workers. These workers can connect to their company's VPN by dialing into the POP of a local ISP, which reduces the need for long-distance charges and outlays for installing and maintaining large banks of modems at corporate sites.
While VPNs offer direct cost savings over other communications methods (such as leased lines and long-distance calls), they can also offer other advantages, including indirect cost savings as a result of reduced training requirements and equipment, increased flexibility, and scalability.
ABSTRACT
The Virtual Private Network - VPN - has attracted the attention of many organizations looking to both expand their networking capabilities and reduce their costs.
The VPN can be found in workplaces and homes, where they allow employees to safely log into company networks. Telecommuters and those who travel often find a VPN a more convenient way to stay "plugged in" to the corporate intranet.
No matter your current involvement with VPNs, this is a good technology to know something about. A study of VPN involves many interesting aspects of network protocol design, Internet security, network service outsourcing, and technology standards.
What Exactly Is A VPN?
A VPN supplies network connectivity over a possibly long physical distance. In this respect, a VPN is a form of Wide Area Network (WAN).
The key feature of a VPN, however, is its ability to use public networks like the Internet rather than rely on private leased lines. VPN technologies implement restricted-access networks that utilize the same cabling and routers as a public network, and they do so without sacrificing features or basic security.
A VPN supports at least three different modes of use:
• Remote access client connections
• LAN-to-LAN internetworking
• Controlled access within an intranet
VPN Pros and Cons
Like many commercialized network technologies, a significant amount of sales and marketing "hype" surrounds VPN. In reality, VPNs provide just a simple few clear potential advantages over more traditional forms of wide-area networking. These advantages can be quite significant, but they do not come for free.
The potential problems with the VPN outnumber the advantages and are generally more difficult to understand. The disadvantages do not necessarily outweigh the advantages, however. From security and performance concerns, to coping with a wide range of sometimes incompatible vendor products, the decision of whether or not to use a VPN cannot be made without significant planning and preparation.
Technology Behind VPNs
Several network protocols have become popular as a result of VPN developments:
• PPTP
• L2TP
• IPsec
• SOCKS
These protocols emphasize authentication and encryption in VPNs. Authentication allows VPN clients and servers to correctly establish the identity of people on the network. Encryption allows potentially sensitive data to be hidden from the general public.
Many vendors have developed VPN hardware and/or software products. Unfortunately, immature VPN standards mean that some of these products remain incompatible with each other.
The Future of VPN
The success of VPNs in the future depends mainly on industry dynamics. Most of the value in VPNs lies in the potential for businesses to save money. Should the cost of long-distance telephone calls and leased lines continue to drop, fewer companies may feel the need to switch to VPNs for remote access. Conversely, if VPN standards solidify and vendor products interoperate fully with other, the appeal of VPNs should increase.
The success of VPNs also depends on the ability of intranets and extranets to deliver on their promises. Companies have had difficulty measuring the cost savings of their private networks, but if it can be demonstrated that these provide significant value, the use of VPN technology internally may also increase.
1. INTRODUCTION:
1.1.Definition
An Internet-based virtual private network (VPN) uses the open, distributed infrastructure of the Internet to transmit data between corporate sites.
1.2.Overview
Why to develop vpn ?
Businesses today are faced with supporting a broader variety of communications among a wider range of sites even as they seek to reduce the cost of their communications infrastructure.
Employees are looking to access the resources of their corporate intranets as they take to the road, telecommute, or dial in from customer sites.
Plus business partners are joining together in extranets to share business information, either for a joint project of a few months' duration or for long-term strategic advantage.
At the same time, businesses are finding that past solutions to wide-area networking between the main corporate network and branch offices, such as dedicated leased lines or frame-relay circuits, do not provide the flexibility required for quickly creating new partner links or supporting project teams in the field.
Meanwhile, the growth of the number of telecommuters and an increasingly mobile sales force is eating up resources as more money is spent on modem banks, remote-access servers, and phone charges.
The trend toward mobile connectivity shows no sign of abating; Forrester Research estimated that more than 80 percent of the corporate workforce would have at least one mobile computing device by 1999.
Comparison of vpn with exiting network:
First and foremost are the cost savings of Internet VPNs when compared to traditional VPNs. A traditional corporate network built using leased T1 (1.5 Mbps) links and T3 (45 Mbps) links must deal with tariffs that are structured to include an installation fee, a monthly fixed cost, and a mileage charge, adding up to monthly fees that are greater than typical fees for leased Internet connections of the same speed.
Leased Internet lines offer another cost advantage because many providers offer prices that are tiered according to usage. For businesses that require the use of a full T1 or T3 only during busy times of the day but do not need the full bandwidth most of the time, ISP services, such as burstable T1, are an excellent option. Burstable T1 provides on-demand bandwidth with flexible pricing. For example, a customer who signs up for a full T1 but whose traffic averages 512 kbps of usage on the T1 circuit will pay less than a T1 customer whose average monthly traffic is 768 kbps.
Because point-to-point links are not a part of the Internet VPN, companies do not have to support one of each kind of connection, further reducing equipment and support costs. With traditional corporate networks, the media that serve smaller branch offices, telecommuters, and mobile works—digital subscriber line (xDSL), integrated services digital network (ISDN), and high-speed modems, for instance—must be supported by additional equipment at corporate headquarters. In a VPN, not only can T1 or T3 lines be used between the main office and the ISP, but many other media can be used to connect smaller offices and mobile workers to the ISP and, therefore, to the VPN without installing any added equipment at headquarters.
VPN resolves the limitations of ordinary networks:
VPNs using the Internet have the potential to solve many of these business networking problems.
VPNs allow network managers to connect remote branch offices and project teams to the main corporate network economically and provide remote access to employees while reducing the in-house requirements for equipment.
Rather than depend on dedicated leased lines or frame relay's permanent virtual circuits (PVCs), an Internet-based VPN uses the open, distributed infrastructure of the Internet to transmit data between corporate sites.
Companies using an Internet VPN set up connections to the local connection points (called points-of-presence [POPs]) of their Internet service provider (ISP) and let the ISP ensure that the data is transmitted to the appropriate destinations via the Internet, leaving the rest of the connectivity details to the ISP's network and the Internet infrastructure.
Because the Internet is a public network with open transmission of most data, Internet-based VPNs include measures for encrypting data passed between VPN sites, which protects the data against eavesdropping and tampering by unauthorized parties.
In addition, VPNs are not limited to corporate sites and branch offices. As an added advantage, a VPN can provide secure connectivity for mobile workers. These workers can connect to their company's VPN by dialing into the POP of a local ISP, which reduces the need for long-distance charges and outlays for installing and maintaining large banks of modems at corporate sites.
While VPNs offer direct cost savings over other communications methods (such as leased lines and long-distance calls), they can also offer other advantages, including indirect cost savings as a result of reduced training requirements and equipment, increased flexibility, and scalability.
