Frame relay security: Why PVCs preclude the need for tunneling
 
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In a recent newsletter, we informed you that buying an IP virtual private network (VPN) service provisioned using PVCs on a frame relay or ATM platform, means that you do not need to buy a special tunneling option to accompany it.
In connectionless Layer 3 router-based IP VPNs, on the other hand, a scrambled address (through error or intent) could result in traffic arriving at the wrong location-perhaps at a site not even on your company's VPN. That is why the use of special tunneling protocols, including Layer 2 Tunneling Protocol, Ascend Tunnel Management Protocol and Point-To-Point Tunneling Protocol, are important in these networks. For particularly mission-critical applications you might want to add to the security mix by including encryption in the end stations, so that only the intended recipient (not just the destination network device, shared by many users) can decode the communication.
One of the reasons why tunneling is not very critical in an IP VPN that is transported over a connection-oriented infrastructure (read frame relay or ATM) is that PVCs inherently provide a "tunnel" of sorts.
The data link connection identifiers, defined for use with a given router or frame relay access device, are predefined by the network operator - thus creating the "permanent" part of the virtual circuit. There is no option to set up PVCs on the fly by the end user, so there's no possibility of sending (or receiving) information from an unauthorized location. It's as if the routers were connected via private lines. Thus, the network allows traffic to travel only to the intended location on the VPN.
We will continue this frame relay security discussion in an upcoming newsletter.
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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