VPN’s PROS :

Virtual Private Networks

VPN differ from ordinary networks in three ways:

1. Virtual Private Networks allow any valid remote user to become part of a corporate central network, using the same network scheme and addressing as users on this central network.
2. Each Corporate’s central network can also be responsible for validating their own users, despite the fact that they are actually dialling into a public network.
3. The Internet Service Provider can give each of their customer’s a unique dial-up telephone number which will distinguish their service from any otherBenefits:

VPN lets remote users connect to your LAN over the Internet, which greatly reduces the cost and complexity of the remote connection. The savings begin with the fact that most small businesses will no longer require a dedicated remote-access server. Businesses with a large number of remote users, say more than 75, might still require a remote server to handle such a high volume of traffic, but these companies still save money because nobody has to dial directly into the server. Instead, users only make a local call to their ISPs. In fact, lower long-distance charges are one of the biggest benefits for all companies using a VPN.

Another benefit is that, unlike in a traditional remote-network setup, VPNs do not require similar hardware at both ends of the connection. For example, an employee on a business trip can connect to an ISDN modem in your office using a 33.6Kbps PC Card modem at the same time that a remote workgroup dials in with a 56Kbps serial modem.

In addition to these benefits, a VPN also lets small businesses reap the cost savings that come from using telecommuters and freelancers. Paying three Java programmers in South Carolina, a documentation specialist in upstate New York, and a project manager in Wisconsin, for example, is undoubtedly cheaper than hiring them all full-time locally.

Pros::
1. Cost Savings - By leveraging third party networks, with VPN, organizations no longer have to use expensive leased or frame relay
lines and are able to connect remote users to their corporate networks via a local Internet service provider (ISP) instead of via expensive 800-numberor long distance calls to resource-consuming modem banks.

2.Security - VPNs provide the highest level of security using advanced encryption and authentication protocols that protect data from unauthorized access.

3.Scalability - VPNs allow corporations to utilize remote access infrastructure within ISPs. Therefore, corporations
are able to add a virtually unlimited amount of capacity without adding significant infrastructure.

4.Compatibility with Broadband Technology - VPNs allow mobile workers, telecommuters and day extenders to take advantage of high-speed, broadband connectivity, such as DSL and Cable, when gaining access to their corporate networks, providing workers significant flexibility and efficiency.

5.VPNs enble you to create secure, business-critical communication links over the Internet.

6. Give telecommuters and mobile workers secure access to your LAN

7. Share resources with partners


Virtual Private Networks : advantages

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.

The biggest advantage to using VPNs is the cost savings. Traditional T1 and T3-based corporate networks must deal with tariffs that are structured to include an installation fee, a monthly fixed cost, and a

mileage chare, adding up to monthly fees that are greater than typical fees for leased Internet connections of the same speed. In comparison, an ISP-based private network only requires shorter leased-line circuits

from each remote location to the ISPs closest POP. VPNs are able to connect two computers over long distances yielding substantial savings over dedicated leased line options. With the VPN,

remote users make local connections to an ISP, which in turn "tunnels" the connection to a VPN device on the destination network.

There are also considerable savings to be realized with a reduced IT department due to the ease of the VPNs administration. In-house technical resources are no longer needed to install, configure, and

VPNs also allow organization to forego the costs associated with WAN equipment installation and maintenance as a single WAN interface can serve multiple purposes.

Another feature of a VPN is its scalability. Organizations can expand their capacity and extend the reach of their network by setting up more accounts to handle the increased flow. This ease of scalability allows

more quick and timely responses to market demands or organizational challenges. VPNs can also allow larger organizations to link international locations into the network while avoiding the complexities,

delays and high costs associated with setting up other connections across borders.

Another factor in the VPNs favor is its ease of scalability. Organizations using a VPN can expand their capacity and reach of their network by simply opening more accounts with their ISP. This

ease of scalability means quicker responses to both organizational changes and market demands.

VPNs can also reduce the demand for technical support resources. Much of this stems from standardization on one type of connection Internet protocol (IP) from mobile users to an ISP's POP and

standardized security requirements. Outsourcing the VPN to a service provider can also reduce your internal technical-support requirements, because the service providers take over many of the support tasks for the network.

VPNs offer network managers a way to reduce the overall operational cost of wide area networking through reduced telecom costs. In the case of a managed VPN service the savings can be even greater, as

the ISP or service provider manages the WAN equipment, so that fewer networking experts are needed to manage the security aspects of the VPN. In many cases, implementing a VPN also means that

better use is made of existing dedicated Internet connections.

VPN’s CONS:

Unfortunately, VPNs put IP at a disadvantage. The additional overhead of a VPN increases the size of IP packets. This causes packet fragmentation, which means that network resources are used inefficiently. Encryption also increases latency, which reduces overall throughput. Our performance numbers in multistream tests represent the best throughput available in a low-latency, zero-loss Internet with real-world software at both ends

We take interoperability for granted with most products, but VPNs are another story. As enterprises build huge VPNs, they'll quickly discover that no one vendor has a good solution for all environments and that multivendor interoperability is key to a successful deployment. Vendors who come to this realization as well will prosper; those who don't will wither.

Support of the equipment and services at the enterprise - the question
of who owns the VPN equipment and services--the corporate customer or
the public network service provider

According to industry experts, one major impediment is that a VPN
requires a great deal of pre-installation planning and careful
consideration of its impact on IP addressing and traffic loads.

We've got private IP addresses that need to be taken into consideration
when we move to a VPN," said Ronald Brendon, IS director at the
accounting firm Randall, Kline and Browner. "And we're probably typical
[in that] we're not really sure where is the best place to put a VPN
gateway." He noted, for instance, that he is not certain how network
traffic will be impacted if the gateway is put between a WAN router and
a LAN as opposed to making the gateway a node on the network.

The high cost of connecting to sites overseas.

A 128-kbit/s link between the United States and Europe typically costs
about $3,800 per month. A comparable VPN connection could cost much
less, on the order of $400 to $800 per month.

Hidden costs associated with distribution of VPN client software.

Some adopters are finding that simple tasks not unique to VPNs, such as
distributing and installing client software to remote users, pose a
bigger challenge than ever imagined.

Managing security and authentication systems, require realizing that
complex skill sets not available in-house.