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TranSwitch draws metro processing, switching plans

Posted: 24 Jul 2002 ?? ?Print Version ?Bookmark and Share

Keywords:TranSwitch? Onex Communications? switching? processor? Ethernet?

Expecting the continuation of today's circuit-switched infrastructure, TranSwitch Corp. has developed a consistent four-element road map that brings together Onex Communications Corp.'s Omni switching and processor architecture. The four parts of the metropolitan transport architecture?switching, TDM processing, Ethernet framing and packet processing?will be upgraded in the next year, though packet processing will take a back seat to support time-division multiplexing at multiple granularities.

To unify Omni with TranSwitch's Aspen processor architecture, TranSwitch has released a suite of software development tools that include full application programming interfaces, software simulator tools, and C compilers and debuggers. Some tools came in with TranSwitch's acquisition of Onex a year ago, but TranSwitch also has worked with Tensilica Inc. on an instruction-set simulator and with Wind River Systems Inc. to integrate the WinSim product from VxWorks.

Paul DeBeasi, vice president of marketing at TranSwitch, said the company's metro product line will follow a simple basic tenet: TDM services and circuit-switching will not disappear from the WAN any time soon, particularly with incumbent carriers running the local exchange. As a result, expanding TDM to include support of STS-1 channels, virtual circuits and virtual tributaries is more important than planning for a near-term all-packet metro ring.

"We are moving into Ethernet with the new EtherMap-3 and EtherMap-48 mapping devices," DeBeasi said. "But we see primary Ethernet transport in the metro, and technologies like resilient packet ring playing a more fringe role compared to TDM."

That may be playing to TranSwitch's traditional strengths in Sonet, asynchronous transfer mode and T1/T3 framing, but it is borne out in the incumbent carriers' announced plans to stick with Sonet for now.

Sampling schedule

This summer, TranSwitch is sampling the first two products originally developed at Onex: the TXC-Omni Switch Element and the TXC-Omni Transport Processor. The switching device often gets compared with the vast array of packet-switch fabrics on the market but DeBeasi said the devices offer native support for TDM and thus only compete with the likes of products from Zarlink Semiconductor and special crosspoint devices from Vitesse, AMCC or TriQuint.

The SE switch device also can handle native ATM or packet switching, managing all three types of traffic through an on-chip RISC processor. The 30-Gbit/second switch chip is configured in a Clos-style topology, though it can support Banyan, Benes and mesh fabrics as well. Each port on the nonblocking 12-by-12 switch supports 2.5-Gbit/s speeds. A TranSwitch design team already is at work on the SE II device to support 10-Gbit/s ports.

The TXC-Omni Transport Processor is in early prototype and will be fully sampling in the fourth quarter. TranSwitch is touting the device as "a full ADM [add-drop multiplexer] on a chip," capable of supporting four 155-Mbit or 622-Mbit links at once, mapping as many as 1,344 VT1.5 channels to the Sonet circuits.

The processor, also with its own on-board RISC executive, is meant as a follow-on to TranSwitch's Phast-3 and Phast-12 TDM processors. The TP can support both unidirectional path-switched rings and bidirectional line-switched rings.

Both the SE and TP devices integrate serializer/deserializer physical-layer devices on-chip, allowing the easy integration across a common backplane of SE on a switch card and TP on a line card.

Support suite

Because next-generation Sonet systems are distributed across a backplane, TranSwitch made sure to augment its software with APIs intended for distributed systems. A full suite of system diagnostic tools and software simulators are being released to early customers this summer. TranSwitch also is offering a full reference system with chassis, power supply, line card, switch card and support materials such as Gerber files and bill of materials.

By using the SE and TP devices with the Ethernet mapping chips, designers can develop dense port support for next-generation Sonet systems that support Ethernet traffic. TranSwitch also will upgrade its network processing family by next year. Current Aspen processors can support ATM traffic; the future service processor will add support for forwarding a mix of packet types.

Despite business conditions, TranSwitch is convinced that the resurgence of incumbent architectures, as well as the continued resilience of TDM, has played to the company's talents. TranSwitch's potential customers still look to internally developed ASICs as an alternative to standard processors, DeBeasi said, but the "not invented here" factor is not as strong in TDM as it is in router-centric packet forwarding.

"Let's face it, when large OEMs cut their overall employment base by 40 or 50 percent, it becomes difficult to justify an internal ASIC development team anymore," he said. "We think that one of the first places that will be recognized is in TDM designs."

? Loring Wirbel

EE Times

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