Multiple vendor equipment interoperates cohesively

Jan. 1, 1996

Multiple vendor equipment interoperates cohesively

George kotelly

Based on testing conducted by a third party at Southwestern Bell`s TRI facilities in Austin, TX, Alcatel Network Systems claims that its synchronous optical network, or Sonet, multiplexers meet the open systems interconnection, or OSI, seven-layer protocol-stack standard over data communications channels, as recommended by the Sonet Interoperability Forum and Bell Communications Research.

Representing an important milestone in Sonet networking, the company declares that interoperability has been achieved between the Alcatel 1648 SM and the Fujitsu FLM-2400 OC-48, 2.5-gigabit-per-second transport systems in conjunction with test equipment from Ando Corp., Rockville, MD, and Ocat software from Bellcore in Morristown, NJ.

According to Joe Bass, Alcatel vice president and general manager of lightwave products, "I would not say that the Alcatel and Fujitsu OC-48 equipment could be connected so that [network providers] could operate them as if they came from the same company. However, [network providers] could embed the two different products in the same network and manage them from a common location. Moreover, workarounds would not be needed. In addition, there [would be no need] to figure out how to get Fujitsu data back into the Alcatel memory management system, for example. With the data communications channels connected, the network would automatically bring the data back to the other vendor`s product, and vice versa."

Sonet interoperability testing is important because telephone companies and network providers have insisted on not being locked into a single-source supplier. They have continuously demanded that they be able to buy the same type of network transmission equipment from more than one vendor, plug the equipment into their networks and have all the vendors` equipment interoperate without major problems.

Until 1995, getting system transmission equipment made by different vendors to interoperate cohesively had seriously blunted the widespread implementation of Sonet fiber-optic networks. But at last year`s National Fiber Optic Engineers Conference, Fujitsu Network Transmission Systems in Richardson, TX, combined resources with Ando Corp. and Bellcore to demonstrate the first public test of the OSI protocols on its FLM-150 add/drop multiplexers (see Lightwave, August 1995, page 1).

Sonet goal

Because of the latest round of Sonet interoperability testing, network providers are presented with a choice between Alcatel and Fujitsu Sonet transmission equipment, and by selecting equipment from these two vendors, they will probably be able to get full interoperability. The Sonet goal is the implementation of a ubiquitous and standard network, so providers and users could choose products like commodities and install them everywhere. That goal has not yet been realized.

A third party ran a private test program for the Alcatel interoperability tests. This is in contrast to the public Sonet test presentation jointly exhibited by Fujitsu, Ando and Bellcore. Not surprisingly, therefore, attempts to obtain comments on the Alcatel test results from Ando and Bellcore officials were unsuccessful, even though the two companies` test equipment and system software, respectively, played major roles in the interoperability testing.

Greg Wortman, director of marketing at Fujitsu, says, "Sonet interoperability is not a new topic. Every supplier has had to prove its interoperability with other vendors` equipment because that`s what the customers [the regional Bell operating companies] are requiring.

"The Sonet Interoperability Forum has had the testing procedures defined for some time. Fujitsu first showed interoperability with several other vendors` equipment in a demonstration sponsored by Bell Atlantic in the early 1990s [at the WAVE trade show]. Further, Fujitsu showed data communications channels` interoperability with Tellabs [equipment] at the 1992 Supercomm trade show. For a Sonet vendor to sell its equipment these days, it must prove the equipment`s interoperability."

In contrast to the use of only Fujitsu transmission equipment in the 1995 NFOEC test demonstration, Alcatel testing apparently proved that equipment made by at least two competitive companies can communicate across the data communications channel, which links network elements. Other tests allegedly substantiated the network management application standards specified by the Sonet Interoperability Forum and Bellcore. With these standards, different vendors can access their network elements by remote means.

According to Bass, Alcatel accepted the opportunity to participate in the Southwestern Bell interoperability testing program. Testing was done on a neutral site because neither Fujitsu nor Alcatel would willingly ship equipment to a competitor`s test site. As a member and supporter of Sonet Interoperability Forum activities, Southwestern Bell is continually performing interoperability testing.

Bass notes that "Alcatel did not fund the tests. Most likely, all seven [Bells] funded the testing under an outstanding contract for an interoperability test series. Alcatel supplied its hardware and software and an expert to answer questions. The testing program was not initiated by Alcatel."

Alcatel could have tested interoperability on its own, with a special test set, says Bass, but decided that a more-detailed and meaningful test demanded the addition of another vendor`s network element. At least two products with two different designs and from two vendors connected to a common standard were considered necessary to determine whether the OSI standards were sufficient in scope. "I believe that the same setup used at last year`s NFOEC show was also used by the Southwestern Bell facility. Fujitsu claimed OSI conformance because of that testing. Now, Alcatel makes the same claim," states Bass.

After the test results are analyzed--the test report was not available at press time--the test areas that need additional work will be addressed by the Forum. Now that the first obstacle--getting different vendors` equipment to recognize each other--has been hurdled, the industry can move forward with more-sophisticated interoperability tests.

Interoperability is also a major step in the direction of a midspan meet. Midspan meets using different vendors` equipment have been performed before, but the data communications channels were always turned off. Only traffic data and protection switching were passed between products. Because of the latest interoperability testing, network providers should be able to reach through one vendor`s product and manage the other vendor`s product with the OSI network managing all the network elements end-to-end. q

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