Road map critical to guide open system; Owens-Corning searched for more openness, became test-site for HP's OSE service - Open Software Environment - Owens-Corning Fiberglass

Software Magazine, Jan, 1992 by Jerry Cashin

Network planners and implementors generally identify the following transition schemes between TCP/IP and OSI as offering the best options for success:

* Build separate networks: S simplistic but expensive approach. A big advantage of this pan is the ability to isolate OSI experimentation from the TCP/IP or other network that is doing current work. Interoperability between the two systems will be nil, at least in its early stages.

* Convert applications: This alternative focuses on translating data streams from TCP/IP vehicles such as FTP and SMTP to their counterparts in the OSI world of Ftam and X.400, then back again. Thus, file transfer and electronic mail applications can migrate back and forth between different networks. Companies such as Retix, Santa Monica, Calif., and Touch Communications, Campbell, Calif., are prominent in this arena. While system performance may suffer in this arrangement, depending on conversion complexity, it does preserve the integral nature of each configuration via an arms-lenght conversion.

* Dual protocol stacks: By installing the complete set of TCP/IP and OSI protocols on all hosts in a network, users can avail themselves of either approach. This requires an inordinate amount of additional memory and management capability, but does retain acceptable performance levels. Retix, Touch and The Wollongong Group, Palo Alto, Calif., offer products that support this scheme.

* Dual routers: This approach places multiple protocol sets within the network, but they are physically external to host sytems. Router boxes direct traffic within and without the network, depending on whether it is OSI, TCP/IP or something else. Some of the vendors active in this market are: Wellfleet Communications, Inc., Beford, Massi.; Proteon Inc., Westboro, Mass.; and Cisco Systems, Menlo Park, Calif. The primary advantage of this scheme is that host software and user procedures remain unchanged.

* OSI over TCP/IP: Rather than functioning with both protocol stacks in their totality, this approach combines strenghts of both in ahybrid arrangement. Documented in ISO Development Environment RFC 1006 from SRI International, Menlo Park, Calif., the use of protocols such as Ftam and X.400 provide double benefits. One, it employs the greater functionality of OSI application protocols; and two, it allows continuous usage of TCP transport and related services that have already been tested in the operational network.

In the Infonetics TCP/IP study, which polled 150 organizations from government, education and the private sector, users said they were interested in all of the above options but the dual protocol stacks approach was most favored. This option lets users continue to use their traditional approach on existing applications while bringing new applications up on OSI. Anaylsts believe that initiating the process with dual protocol stacks might not be the ideal way to start, because of the additional resources and expense. Users may also be reluctant to switch while they can rely on the old method. Therefore, analysts suggest an evolutionary migration from separate networks to OSI over TCP/IP, followed by a complete conversion to OSI.