The real status of ATM cards.
The review team chose the ZeitNet ZN 1221/1225 ATM PCI-bus adapter card and the ZeitNet 1211/1215 ATM S-bus adapter card as the best 155 Mb/s cards available, based on a scenario using the test configuration noted below. The review is a snapshot of the industry today. It does not address 51 Mb/s, 25 Mb/s or other slower speed cards.
This was not intended to be a test of throughput but of functionality. Testing criteria were based on performance, interoperability, ease of use and installation, documentation quality and technical support. Figure 1 is a summation of scores. Performance aspects included absence of hardware and software conflicts. Ease of use and installation aspects tested included knowledge of networking required, knowledge of ATM required, and speed of installation and configuration. We looked for clarity, completeness and ease of reading under documentation. The technical support issue tested was the ability to acquire knowledgeable, friendly assistance in a timely fashion. The rating scale is 1 to 5 with 1 the lowest rating and 5 the highest. A perfect score is 35.
We had two network configurations, S-bus and PCI-bus, for the test. For the PCI-bus adapter cards, we used a Compaq Deskpro 575 and a Compaq Deskpro 590 Pentium-based PCs. Both are outfitted with 16 MB of RAM and Microsoft Windows NT Workstation Version 3.51. For the S-bus adapter cards, we used three Sun Microsystems SparcStations configured with Sun O/S 4.1.3. The ATM switch was a Fore Systems Forerunner ASX-200BX running software Version 3.4.2. The switch was configured with one four-port module. We used 62.5/125 micron multimode fiber for our connection.
The two Compaq computers and two Sun workstations were attached to the switch at one time when the PCI-bus tests were run. Three Sun workstations and one Compaq were attached for the S-bus tests. Each computer was configured to be on separate LANs but in the same subnet. The virtual LAN we established was classic IP over ATM as opposed to LAN emulation. We used switched virtual circuits (SVC) as opposed to permanent virtual circuits to allow for full utilization of available bandwidth. To control the SVCs, we configured the Forerunner switch as the ARP Server. Our source for desktop TCP/IP was standard TCP/IP services bundled with NT Workstation and the Sun O/S.
The overall results show the adapters are solid as regards capability. All of the vendors were helpful in overcoming initial problems. The only area of concern for the industry is the clarity an flow of documentation for installation and configuration. This is the area that gave ZeitNet the edge.
The beginning of a new technology is not for the faint of heart. The best analogy is from the adventure game scenario of achieving the overall goal by having with you all the keys to unlock the secrets of the universe. In the process you have to find and capture all the keys. With ATM the potential for success is always in front of you, but you seem to be one step away from realizing the goal.
Since each of the adapters had minor installation or configuration errors that prevented the systems from responding as documented, we were glad we had included in the review an area of technical support. Without good tech support we could not have had even the success we did have.
The large number of card manufacturers is surprising. In setting up the test, we discovered that not all card manufacturers are yet capable of meeting everyone's needs. Some had only S-bus cards, or only EISA bus cards; some only had UTP cards, others only multimode fiber; and others had limited LAN emulation capability. Further, availability of lower speed cards is just coming on line. This is also true for multiple vendors in the lower speed switches.
In each case where a vendor was not able to meet the test environment, the vendor had the missing piece in design or test.
Figure 2 is an annotation of the main features of ATM that each adapter supports. The supported features were not used as a deciding factor in the review. The information is provided as an indication of the variability in features. The data in the figure came from the documentation available with the adapter.
[Figure 1-2 ILLUSTRATION OMITTED]
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|Title Annotation:||Hardware Review; Zeitnet Inc's ZeitNet ZN1221, ZN1225, ZN1211, and ZN1215 ATM adapters|
|Author:||Hibner, Dale; Groom, Frank; Early, Greg|
|Date:||Jan 1, 1996|
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