Report urges switch from SNA to IP nets

Corporations that stick with SNA networks as their primary access to legacy data will soon be spending more money and deriving fewer benefits than those using consolidated networks based on IP, according to a recent Gartner Group report.

And the longer the integration is put off, the greater the total cost of ownership of SNA networks will be, because of falling product support and skills availability, said Audrey Apfel, author of the Gartner report.

There's also a greater chance of missing Internet-related business opportunities that can be exploited only via IP networks, she added.

"Web-based features and functionality will continue to be built and centered around IP," said Steven Clemens, director of network technologies at American Family Mutual Insurance in Madison, Wisconsin.

Despite those reasons to switch, SNA-based shops have moved slowly to IP because of performance concerns and a reluctance to walk away from SNA-related investments in technical skills, business processes, applications and vendor relationships.

According to Gartner, fewer than 50 per cent of mainframe shops that had SNA networks in 1990 now have consolidated networks.

American Mutual is in the midst of an SNA-to-IP conversion involving more than 3200 sales offices, 8500 workstations and more than 6500 users in 70 corporate offices. Much of that migration is being driven by the greater vendor support and product choices -- both of which promise lower costs.

SNA networks, which grew out of mainframe technology, were until recently considered far more reliable and robust than client/server-based IP networks. SNA's low-bandwidth requirements and guaranteed service levels were ideal for transaction-intensive networks such as those for banking and reservation systems. Concerns that much of that would be lost in a switch to IP has delayed a mass migration -- as has the potential hassles involved.

A case in point: American Mutual's conversion forced the company to change all mainframe-access terminals and emulation technologies, Clemens said. All desktop 3270 emulation is being converted from Advanced-Peer-to-Peer Networking (APPN) technology to TN3270.

But new technologies are letting customers layer SNA-like capabilities -- such as traffic and bandwidth prioritisation -- on top of IP networks, said Gary Weaver, network communications manager at Smurfit-Stone Container in Chicago.

Vendors such as Cisco Systems and Nortel Networks subsidiary Bay Networks offer products that allow customers to run SNA on top of IP networks.

Other technologies, such as Frame Relay Access Services, APPN, Data Link Switching and TN3270, allow SNA traffic to be sent over IP networks both natively and in encapsulated form.

Those advances not only close the performance gap, but also provide many of the bandwidth reservation, traffic prioritisation and management capabilities of SNA, Apfel said.

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