Transwitch Corporation Says…
TranSwitch VTXP-24 Device Targets Next Generation MSPPs and Packet ADMs
New device meets carriers need for triple play services while maximizing ROI of existing fiber and network infrastructure

TranSwitch Corporation has announced the VTXP-24, an integral component of the company's solution for next generation MSPPs (multi-service provisioning platforms), packet ADM (add/drop multiplexing) and SONET/SDH optical edge devices. The VTXP-24 provides the brick-and-mortar to support the TranSwitch Any Service, Any Port (ASAP) architecture along with the company's PHAST-48V and VTXP-48 family of products.

The TranSwitch ASAP architecture, with NPF-based APIs, supports full in-service, traffic-agnostic scalable data, and TDM switching and routing. As a result, the VTXP-24 enables a smooth, cost-effective transition to an IP-based network architecture allowing OEMs and carriers to reduce their costs by at least 60 percent when deploying next generation ADM, MSPPs and micro MSPPs.

"Network convergence requires TDM, PDH and Ethernet rapid service creation at the demarcation line," said Jag Bolaria, senior analyst, The Linley Group. "TranSwitch's VTXP-24 device enables OEMs to achieve a multi-service solution and to support the emergence of new data-based services."

"The VTXP-24 has been designed to optimize the total cost of system ownership in light of carrier requirements for triple and quadruple play. Its support for data, voice and video services maximizes the ROI of existing fiber and network infrastructure, and facilitates the migration to the IP network infrastructure," said Radu Iorgulescu, director of Product Management for TranSwitch.

The VTXP-24 complements TranSwitch's "switchless switching" architecture allowing the in-service addition of data-based and PDH-based services. It can be used on any SONET/SDH or packet ADM system that requires bandwidth efficiency with VC-12/VT1.5 granularity. It can interface directly to SONET/SDH rings and provide hardware-based protection. In addition, it can interface to a multitude of framers, or Ethernet and PDH mappers. The VTXP-24 also provides extensive performance monitoring, intermediate path monitoring, and reporting capabilities on all virtual tributaries and SPE signals.

Designed to be compatible with the Advanced Telecom Computing Architecture (ATCA), the VTXP-24 integrated high-speed SerDes allows it to interface to TranSwitch's VTXP-48 and PHAST-48V family of products. It achieves the seamlessly scalable virtual tributary processing and cross-connect solution required for next generation Access and Metro networks. The VTXP-24 meets Telcordia and ITU-T recommendations plus ETSI and ATIS standards for SONET/SDH equipment, as well as the Telcordia and ITU-T network protection recommendations.

analogZONE Says . . .

Leave it to Transwitch to do things differently. While most companies in the telecom chip space are content to crank out relatively straightforward mappers, framers, and other almost-generic functional blocks, the wizards at Shelton have frequently come up with their own idiosyncratic products that cross traditional boundaries by mixing and matching elements to address specific markets. Consider, for example, their VTXP-24 crossconnect device, which at first looks like a scaled-down version of their PHAST-48v and VTXP-48 distributed cross-connect devices. But a second take reveals that it is also a key element of a distributed architecture that aims to reduce the cost of TDM and multi-service switches.

The turgidly-worded press release above focuses more on buzzwords and the markets it targets than what the part actually does so I'll try to wade in and clarify things a bit. When you look at the block diagram below (Fig. 1a and 1b), keep in mind that this device's basic function is to use its VT switch to select an OC-12 worth of VT1.5/2 channels from an OC-48 connection and pack them into the OC-12 framer. It can also drop a pair of switched OC-12 streams from the same source into a pair of on-chip telecom bus interfaces.

If you're wondering where the VTXP-24's OC-48 feed comes from you're not alone. While not clearly stated on the block diagram, a closer examination of the connection diagram (Fig. 2) reveals that the VTXP-24's OC-48 network-side connection consists of 17, 3.1-Gbit/s Ser Des interfaces, each configured in Transwitch's proprietary TFI-5 format that allows them to connect with other Transwitch devices across backplanes and PCBs. It functions like a serial version of the Telecom Bus and allows it to pass both traffic and OA&M signaling between switch nodes. Each of the 17 links transmits the same content from its tributary feed, but delivers 17 different streams to the cross-connect. This many-to-one scheme allows the VTXP-24 to deliver VT1.5/VC12-sized slices of bandwidth from any of the ETFI-5 links to the framer or telecom bus.

Because of its multiple SerDes connections the switch can easily be used in unidirectional path switched ring (UPSR) applications for telco-grade protect schemes. Its automatic performance monitoring function reads alarms embedded in OA&M signals that are encoded into the ETFI link. It provides full-rate monitoring of all flows through the device for all ANSI/Telcordia/ITU functions like BER, trace ident, and error messages, and can use this information to perform automatic selection of the best signal path in protect switching systems. It also eliminates the need for centralized OAM&P functions found in most normal centralized switches.

Its distributed switching and OA&M capabilities allows the VTXP-24 to sit on a telecom bus and pull off the services and connections it needs without assistance from a central switch fabric. This means designers can implement very cost-effective "pay-as-you-grow" blade-based multi-service systems that deliver additional slices of bandwidth to a customer with simple upgrade cards instead of a costly switch fabric upgrade.

And if you're really going to run a heavy mix of TDM and IP, traffic across your system, you can use one of Transwitch's "Envoy" Ethernet switches to separate out packet traffic, and keep the TDM traffic on the distributed portion of the architecture. Besides enabling lower-cost mixed-mode TDM/IP equipment, this approach allows graceful transition from TDM to packet traffic by migrating on a per-slot basis.

Given the fact that you can link nearly any port to any other one on the device, there are a huge number of configurations and applications you can use it for. But Transwitch has focused on four areas where it thinks the VTXP-24 is best suited for:

• It can act as a tributary interface for distributed TDM switches which use the VTXP-24 to deliver tributary-sized feeds to either EoS or traditional TDM mappers
• It can be used as a bi-directional pointer processor/performance monitor in centralized TDM switches
• It makes a dandy switching element in a combined IP/TDM switch
• It can also be used as the central switching element in stackable "pizza box" ADMs which use the TFI-5 SerDes channels as uplink stacking interfaces

Transwitch gets big points for the versatility and good value they put into this little switch element. It should see some good design wins in value-conscious multi-service applications, especially in Asia. I'd argue that, since it requires every slot to see the entire system's bandwidth, this architecture might not scale well for very large enterprise and carrier-class systems, but it's certainly got more than enough capacity for many edge and access products.

I'll cautiously award the VTXP-24 a relatively low Vapor Index Rating, although a few recent design misfires in their VCAT EoS products might suggest a little bit of extra due diligence might be in order to make sure all the features work as advertised on early silicon.

The VTXP-24 is sampling with production in Q2 2006. Pricing will be approximately $150 in 10-k piece lots. TranSwitch will also provide an evaluation board with associated software.