Frame relay security: What about SVCs?

We have been talking about the inherent security of PVCs as a transport infrastructure for IP virtual private networks (VPNs). But if switched virtual circuits (SVCs) are used within the service provider's infrastructure, do you need to revert to tunneling?

Probably not. After all, unlike a connectionless network that allows anybody to put any address on each packet, SVCs do require that a call be set up slightly in advance. In fact, the only fundamental difference between SVCs and PVCs is that the network operations center defines calls in a PVC environment, while the user defines calls in a SVC environment.

The call setup procedure, which is dynamic in the case of SVCs, is the only function that could be slightly less secure than the PVC method, in that there is the remote possibility that an intruder might have the ability to perform dynamic SVC call setup. Once a call is set up, though, there is no difference between a SVC and PVC: They send frames in the same format, and they use the same DLCIs.

SVCs require that a call be requested and accepted. The call will only be accepted if it comes from a "known" source. If you are nervous about SVC security, however, it never hurts to discuss the ins and outs of the matter with your IP VPN service provider.

Sometimes it is easier to buy the tunneling than to convince your management that it's not a good use of money. Technically, the bottom line is that in most cases you don't really need tunneling in an IP VPN that runs over a frame relay/ATM infrastructure. We've discussed three levels of inherent security and have taken an initial look at SVC security strategies within the infrastructure.

As the old lady from the hills of North Carolina discovered when the flood came, you really can count on some things in life to be secure. See this woman got caught in a terrible storm, and....

Oops! Out of space for this newsletter. Send e-mail to oldlady@webtorials.com for the rest of that story.

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Steven Taylor, consultant and broadband packet evangelist, and Joanie Wexler, an independent networking technology editor and writer, team up to bring you this analysis and commentary. Taylor specializes in education and market analysis, and Wexler adds incisive reporting and research. For more detailed information on most of the topics discussed in this newsletter, connect to www.webtorials.com, the first Web site dedicated exclusively to market studies and technology tutorials in the Broadband Packet areas of Frame Relay, ATM, and IP. Feedback and additional topic ideas are welcome. Please contact taylor@webtorials.com or joanie_wexler@mindspring.com.

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