VIRTUAL PRIVATE NETWORKS
Our guidelines for choosing what type of connection to use for VPNs will tell you how DSL stacks up against alternatives.
If you need to connect 1,000 locations to a WAN and minimize your network access expenses in a secure, low-cost package, a VPN might be the ticket.
Because VPNs use the Internet backbone to establish high-speed, secure links between telecommuter or branch offices and a corporate network, they're thought to be less expensive than other remote access networks. However, the intangible management costs may cloud the real savings.
You can find managed VPN services from a variety of carriers and ISPs, including AT&T, Genuity, Qwest, Sprint, Verizon and WorldCom. Managed services pricing varies depending on the type of network access, security and performance guarantees you're looking for, so the only real way to get a solid estimate is to issue a request for proposal outlining your needs.
Making connections
Cost comparison
Most managed VPN services provide fairly consistent features, including:
- Access options ranging from 56K bit/sec to fractional/burstable T-1 and T-3 lines.
- Remote dial access.
- 24-7 VPN monitoring and management.
- Hardware-based encryption with full IP Security compliance.
- Data Encryption Standard and Triple-DES packet encryption.
- MD5 and SHA-1 authentication.
- Firewall.
- Service-level agreement.
- One integrated bill.
Putting it all together
DSL typically offers the lowest cost and most bandwidth for dedicated Internet connections, and is highly sought after for large VPNs.ISDN is another popular technology for VPNs. ISDN is usually slower than DSL, but the service offers higher availability and a shorter installation time frame - 15 business days compared with 40 business days for DSL.
As is the case for any large network dispersed across the country or the globe, you'll probably have to rely on a combination of carriers and providers to meet your VPN needs. Finding a single company that can put it all together and make the VPN appear as a single, fully integrated and seamless network is most desirable.
Fueled by the availability of DSL and the growing ranks of telecommuters, the market for large VPNs has heated up in the past year. A mix of carriers, systems integrators and ISPs offer managed VPN services, the access portion of the network, or both.
However, don't count on getting DSL connections everywhere. Telco Exchange has conducted several hundred thousand prequalifications around the country and found that only 40% of those requests for DSL service resulted in availability and installation.
If you need to connect every one of your users or offices across the U.S., you'd better get serious about flat-rate ISDN, frame relay or T-1 alternatives. And while broadband cable services such as @Home or RoadRunner has been aggressively rolled out in the residential market, corporate America still overwhelmingly depends on carriers and ISPs for voice and data network services.
To get an idea of costs and features of various access services, see the chart below. For comparison purposes, we bundled DSL alternatives with Internet access to create a single monthly cost.
As you'll see, DSL is the hands-down winner when it comes to costs of connecting a small LAN to a VPN. ISDN, which is widely available and offered at a flat-rate tariff in many areas, is likely the least expensive way to connect a single PC to a VPN. However, frame relay is tops when it comes to the likelihood that you'll actually receive the service you ordered.
In the everlasting struggle to reduce costs and increase reliability, many IT executives are considering replacing their private lines with an IP-based VPN.
Making
connections 1. Prepare a list of all locations with local telephone numbers and complete addresses. Include the ZIP code and contact person if possible. 2. Set the minimum bandwidth requirements to support the applications that will be running over the VPN — 128K to 1.544M bit/sec is common. 
3. Decide on static IP or dynamic IP. 4. Choose an access service such as DSL, ISDN, Frame Relay or T-1. 5. Determine availability and delivery timetable for each type of service. 6. Review the results of the prequalification with pricing options. 7. Pick the preferred mix of technologies and costs to meet your project implementation plan and budget. |
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| Cost
comparison Here’s how some popular network services for accessing a VPN compare. DSL is the least expensive option for a LAN, but you’re also least likely to get it. |
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| Data network service | Speed | Estimated chance of receiving the service | Line installation fee | Equipment costs | Equipment installation costs | Monthly cost (bundled with Internet access) |
| DSL |
144K – 384K bit/sec | 40% | Waived | Free | Waived | $130 – $200 |
| ISDN single PC bit/sec | 128K | 80% | $100 | $175 | $200 | $90 – $130 |
| ISDN LAN | 128K bit/sec | 80% | $100 | $500 | $300 | $260 – $500 |
| Frame Relay | 384K bit/sec | 90% | Waived | $1,500 | $500 | $800 – $1,100 |
| Source: Telco Exchange | ||||||
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RELATED LINKS
Dunetz is president of Telco Exchange, an online marketplace for high-bandwidth communications services. He can be reached at info@telco_exchange.com.
Security issues with a VPN and DSL?
What are the security issues when you set up a VPN on a DSL line? Does DSL support a VPN connection?
Network World, 03/12/01.
Preventing VPN-based break-ins
Questions about DSL VPN security.
Network World, 04/09/01.
WorldCom VPN package gives users more control
WorldCom, which already offers fully managed VPN services, last week launched a VPN service package that puts the management back in users' hands.
Network World, 05/21/01.
