8/8/2019 Awadh Quest

http://slidepdf.com/reader/full/awadh-quest 1/4

 InternetWeek

TechWeb

Internet

Advanced Search

Sections

Home

Breaking News

In Depth

Reviews

Columns

Case Studies

E-Business

Applications

Net

Infrastructure

Net Results

E-Research

Net Effects

SoapBox

 Resources

About InternetWeek

Rules of Engagement:

Working With

InternetWeek

Resource Centers

VPN Source Page

Q&As

Supplements

Beat Coverage

Salary Survey

 Services

E-Mail Newsletter

Subscriptions

Marketing &

Advertising

2001 Editorial

Calendar

ShopMarketplace.com

 

Search

nmlkji

nmlkj

nmlkjFind

 

VPN Frequently Ask Questions

This page contains a list of frequently asked questions about VPNs. The list is

broken into three main categories.

General VPN Questions 

Performance Issues 

VPN Technology Questions 

General VPN Questions 

Q: What is a virtual private network?

A: A VPN gives users a secure way to access corporate network resources over

the Internet or other public or private networks.

Q: What are the elements to a VPN?

A: VPNs typically include a number of security features including encryption,

authentication, and tunneling.

Q: How do companies use VPNs?

A: A VPN can be used in place of traditional dial-up connections to provide

access to remote users and telecommuters; can be used to connect LANs in

different sites instead of using the public switched telephone network or

dedicated leased lines; and can be used to give customers, clients and

consultants access to corporate resources.

Q: Is a VPN the same thing as an extranet?

8/8/2019 Awadh Quest

http://slidepdf.com/reader/full/awadh-quest 2/4

 

IT Week Career Direct

Card Deck Online

Privacy Statement

Sponsored by: 

Bank Systems

& Technology

CMPmetrics

eBusiness ExpoFile Mine

InformationWeek

Insurance &

Technology

InternetWeek

Network Computing

PC Expo

Planet IT

TechCalendar

TechEncyclopedia

TechLearning

TechReviewsTechWeb News

TechWeb Today

Wall Street &

Technology

Ad Info

A: No. Most VPNs can be designed to work as an extranet. But not all extranets

are VPNs.

Q: Then what is an extranet?

A: Extranet is a general term than can mean many different things. The common

definition of an extranet is a type of network that gives outside users, such as

customers, clients and consultants, access to data residing on a corporation'snetwork. Users access the data through a Web browser over the Internet and

typically need to enter a user name and password before access to the data is

granted.

Q: How is this different from a VPN?

A: A VPN can be used in a similar manner, but typically a VPN has much higher

security associated with it. Specifically, a VPN typically requires the

establishment of a tunnel into the corporate network and the encryption of data

passed between the user's PC and corporate servers.

Q: Why bother with a VPN, aren't there other ways to give users secure access

to network resources?

A: There are different ways to control access and provide secure access to

network resources. A VPN is just one of those ways.

Q: What are some of the other methods for giving users access to network

resources over the Internet?

A: Depending on the level of security needed, a company could choose to use an

extranet approach or a customized approach that combines password protection

of network servers with third-party authentication systems.

Q: Why do companies use VPNs?

A: There are many reasons to use a VPN. The most common reasons are (1) to

save telecommunications costs by using the Internet to carry traffic (rather than

paying long distance phone charges), (2) to save telecommunications costs by

reducing the number of access lines into a corporate site, and (3) to save

operational costs by outsourcing the management of remote access equipment

to a service provider.

Q: How does a VPN cut long distance phone charges?

A: Long distance phone charges are reduced with a VPN because a user

typically dials a local call to an ISP rather than placing a long distance calldirectly to the company.

Q: How do VPNs help a company reduce the number of access lines they must

pay for.

A: Many companies pay monthly charges for two types access lines: (1) high-

speed links for their Internet access and (2) frame relay, ISDN Primary Rate

Interface or T1 lines to carry data. A VPN may allow a company to carry the data

traffic over its Internet access lines, thus reducing the need for some installed

8/8/2019 Awadh Quest

http://slidepdf.com/reader/full/awadh-quest 3/4

nes.

Q: How can a VPN save operational costs?

A: Some companies hope to save operational costs by outsourcing their remote

access to an ISP or other type of service provider. The idea is that by giving

users access to the network via a VPN, a company can get rid of its modem

pools and remote access servers. The operational cost savings come from not

having to manage those devices.

Performance Issues 

Q: What about VPN performance?

A: There are several issues to consider when exploring VPN performance. Some

are related to the Internet itself. Is if available? What is the latency for packets

traveling across the network? Other performance issues are related to the

specific VPN applications.

Q: What are the concerns about network availability?

A: The Internet occasionally experiences outages. For example, in 1997 there

was a system-wide availability problem when a corrupted master list of Domain

Names was distributed to the handful of root servers that are the heart of the

Internet. More frequently, a particular Internet service provider may experience

equipment problems leading to a service outage that can last from hours to days.

Q: What can be done to ease concerns about network availability?

A: Many service providers are trying to improve the reliability of their networks to

prevent outages. While they cannot guarantee 100 percent availability, many

providers are offering service level agreements that offer credits or refunds if

network availability falls below a certain level.

Q: How good are the network availability service level agreements (SLAs)?

A: Most of the service providers with nation-wide backbones guarantee the

network will be available at least 99.6 percent of the time. That translates into a

maximum outage time of about 6.5 minutes a day before the refund or credits

kick in. Some offer higher availability with refunds or credits kicking in for outages

of 3 minutes per day or longer.

Q: What are the short-comings of these SLAs?

A: All VPN SLAs offered today only apply to the specific service provider'snetwork. If the traffic crosses from one provider's network to another, the SLAs do

not apply.

Q: What about latency?

A: To date, there are no VPN SLAs that address latency. The service providers

say they will need a number of things, like the ability to offer quality of service

guarantees, to happen before latency SLAs will be offered.

8/8/2019 Awadh Quest

http://slidepdf.com/reader/full/awadh-quest 4/4

 

: re t ere ot er ssues t at w prevent atency-re ate s

A: Yes. IT managers will not see end-to-end latency SLAs for VPNs as they get

for other services such as a Frame Relay service that carriers time-sensitive SNA

terminal to host traffic. One of the reasons end-to-end latency SLAs will not be

practical for VPNs is that there are many variables, such as the type of

encryption used and the client's process power, that determine end-to-end

performance in VPN applications.

VPN Technology Questions 

Q: What are the common tunneling protocols?

A: There are currently three major tunneling protocols for VPNs. They include the

Point-to-Point Tunneling Protocol (PPTP), Internet Protocol Security (IPSec), and

Layer 2 Tunneling Protocol (L2TP).

Q: What types of encryption can be used in VPN applications.

A: Virtually all of the common encryption technologies can be used in a VPN.

Most VPN equipment vendors give the user a choice. IT managers can often

select anything from the 40-bit built-in encryption offered by Microsoft under

Windows 95 to more robust encryption technologies like triple-DES.

Q: How are VPN users authenticated?

A: VPN vendors support a number of different authentication methods. Many

vendors now support a wide range of authentication techniques and products

including such things as Kerberos, tokens, and software and hardware-based

dynamic passwords.

Q: Can user access and authentication be linked to existing access control

systems?

A: In some cases, yes. Some VPN vendors, notably Aventail, Novell, and New

Oak Communications, provide ways to link VPN access rights to defined access

rights such as those in Windows NT Workgroup lists, Novell Directory Services

or Binderies.

Back To Main VPN Source Page