VPNs -redundancy and premium services

If you are using the Internet as the backbone for your virtual private network (VPN), you are willing to accept a little unpredictability.

After all, the Internet at large remains a best-effort environment where delay can vary widely depending on things such as the time of day or outages in segments of the Internet. The only link you have direct control over is the access line to your ISP.

You should evaluate the amount of downtime each site in your VPN can endure before the effectiveness of your VPN as a whole is compromised. For example, a central site being accessed by many individual remote users or satellite sites is key and needs to be accessible most of the time.

At such sites, install a redundant Internet connection. Use two different ISPs and two different access providers. That diversity should give you a backup if either access line fails or if one of your ISPs suffers outages in its own network.

Remote or mobile users whose access to the VPN is deemed critical might also warrant accounts with two ISPs. That will reduce the chance they get locked out of the VPN altogether.

For better reliability on the backbone of your VPN, you may want to consider a premium service from individual service providers. They can link all your sites to their privately owned IP network and offer service-level agreements across that network, as well. You pay more, but depending on your needs, it could be worth it.

Tim Greene is a senior editor at Network World, covering virtual private networking gear, remote access, core switching and local phone companies. You can reach him at tgreene@nww.com.

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