Scale Ahead Of N et Traffic With ATM Edge Switches By Joel Conover It seems like the more bandwidth you have, the more you need. A switched network architecture once held the promise of adding years to the life of your network, but now bandwidth-hungry users are draining life from it. Obscene amounts of traffic have sprung from corporate intranet applications, while real-time applications, multicast video and workgroup collaboration applications are lurking right around the corner. Your once-robust backbone suddenly seems inadequate, and soon you're back to square one, looking for a better backbone solution. On e possible answer is ATM. It's scalable, fault-tolerant, provides quality of service and it promises integrated WAN support. Migrating ATM should be an easy transition, thanks to industry standards that guarantee interoperability. Plus, you can have all of this at an affordable price per megabit. To view the Report card. At Network Computing's University of Wisconsin lab in Madison, we asked vendors for ATM edge devices that provide redundant ATM connections, load-balancing, scalability and the capacity to support at least 48 10BASE-T or eight 100BASE-TX connections. High-end devices from Bay Networks, FORE Systems and 3Com Corp. met our specifications. We tested these products in both single-vendor and multivendor environments, and found that these devices have tremendous capacity to scale, but they are less than well-behaved in a multiv endor environment. Of the products we tested, 3Com's CELLplex 7000 HD was the easiest to use and the most expandable. Its throughput capacity was top-notch, and with its advanced features, such as Available Bit Rate (ABR) support and the capacity for up to 32 ATM ports, you can't go wrong with this switch. I n the proprietary arena, you will find enhanced features, such as automatic switch-to-switch configuration (called Enhanced IISP by 3Com) and redundant, although not load-sharing, LAN Emulation (LANE) services. What Happened to the Big Guns? For this review, we invited a slew of vendors, including Cisco Systems, Digital Equipment Corp., IBM Corp. and Xylan Corp., to send us devices. Cisco did not respond; Digital promised equipment, but was unable to come through in time for our review. IBM declined to participate, and Xylan said it would not be participating in competitive reviews for the next six months. 3Com Corp. CELLplex 7000 HD 3Com's CELLplex 7000 HD is a high-performance, six-slot midsize chassis switch decked out for ATM performance. At the heart of the device is 3Com's ZIPChip, a segmentation and reassembly (SAR) ASIC that takes each frame of traffic and converts it into ATM cells, which are then put onto the 7000 HD's generous 5-Gbps backplane. The top two modules of the switch are reserved for the primary and secondary redundant switching engines. In the remaining four slots, you can populate the switch with up to 32 ATM ports, 144 10BASE-T Ethernets, 64 100BASE-TX or FX Fast Ethernets, or any combinations of these. The list price for the highest-density Ethernet configuration is $576 per port; Fast Ethernet interfaces list for $1,675 per port. The CELLplex 7000 HD took top honors for its high degree of expandability and its advanced ATM features. It can be used as a central ATM switch or as an edge device. It uses Network-to-Network Interface (NNI) connections to connect multiple switches, eliminating the need to type in static routes for every ATM switch in the network. Thanks to its proprietary Enhanced Interim Interswitch Signalling Protocol (IISP), 3Com networks automatically configure for load-balanced operation with other 3Com switches. To download an Adobe Acrobat .pdf format version of the ATM Edge Switches Feature chart, click here.

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