The New Access and Switching Products by Cascade Communications

Written in 1996

by Frank Barbetta

The new access and switching products introduced last month by Cascade Communications (Westford, MA) and Ascend Communications (Alameda, CA) share several general characteristics: First, the target markets for both are carriers, Internet service providers (ISPs) and large enterprise networks; second, the new equipment comes with smaller footprints, more redundancy and greater distributed intelligence; third, both companies are intent on beating or displacing Cisco Systems (San Jose).

The new systems - access devices from Cascade and Ascend and an IP switch/router from Ascend use RISC-based architectures and other processors that are tightly packaged to reduce total size and production cost, and thus the price tag to the ultimate buyer. The vendors also claim that these new packages result in better reliability and price/performance for a variety of tasks - processing, system control, modem communications, switching, throughput and routing table-lookup.

Cascade's AX 800/AX 1600

On April 22, the same day Cisco announced its plans to buy StrataCom for about $4 billion, Cascade announced a smaller but, in its view, equally ambitious deal: It paid $145.3 million in stock for privately owned Arris Networks (also of Westford, MA). Arris, whose president and cofounder Wufu Chen is a former Cascade vice president, will provide its new parent with high-performance remote access technology for cartier networks - i.e., large, scalable capacities, redundant electronics, power supply backups and telco-favored rack sizes.

The new AX 800 and AX 1600 access switches are Cascade's first results from the Arris acquisition. Jim Dolce, Cascade's vice president for remote access marketing and also an Arris co-founder, commented that "Existing commercial-grade remote-access servers were designed for enterprise telecommuting applications and cannot scale to meet demand."

The AX switches integrate analog modem-based ports with primary rate ISDN and channelized T1 and T3. Over time, the systems will interwork with Cascade's network management systems (e.g., the SNMP-based CascadeView/UX Network Management Station), plus its other products for service-provider access and backbone switching (e.g., the BX9000 and CX500), which support V.35 frame relay, 10/100 Base-T Ethernet, HSSI, frame relay, ATM and channel speeds ranging from 64 kbps (DS0) through T3.

The model 1600 supports up to 672 integrated digital modems or up to 1,152 simultaneous ISDN connections, which translates into 2,016 modems or 3,456 ISDN connections per eight-foot rack. The model 800 supports up to 288 modems or 672 ISDN connections.

The base configuration for the eight-slot AX 800 costs $27,500 and, depending on which cards are added, the price can go as high as $200,000; similarly, the 16-slot AX 1600 starts at $32,500 and can run as high as $485,000. Dolce claims that the per-port cost for a model 1600 is "on the order of $750." Both models become commercially available in the fourth quarter.

The AX's architecture distributes processing power to each system module. The architecture has three main elements - adapter modules, server modules and a high-speed, midplane, 1-Gbps bus. The adapter modules provide the physical interface for connecting local and wide area networks and pass information to an attached server module, where forwarding operations are performed, including delivery to peer processors via the high-speed backplane.

The server modules run on a 130-MHz PowerPC 603 RISC device designed by IBM (Fishkill, NY) and Motorola (Phoenix). Dolce explained, "There is no central or master CPU resource involved in routing/switching decisions, which can limit performance as a system expands. Instead, as the number of modules increases, so does the aggregate system level forwarding performance. Also, if a single module fails, the system continues to operate; only calls connected to a failed module are impacted."

The 1-Gbps bus interface, which is distributed on all cards in the system, uses high-speed field-programmable gate array (FPGA) technology - traditionally a custom-function component part - and also distributes digital signal processing (DSP) technology for digital modems.

Ascend's Next MAX

Not to be outdone, Ascend recently unveiled another generation in its MAX series of WAN access products - "The Next Thing" or TNT. Cascade and Ascend are essentially pursuing the same markets with their new products, and although a lot of access products are becoming available these days, analysts indicate the most likely "carrier