Santa Clara, Calif. To help deliver reliable carrier-grade services into the digital home, PMC-Sierra has developed a pair of SoCs that are based on its family of VoIP-enabled multi-service processors (MSP).
The MSP7120 is a MIPS-powered SoC/firmware product designed to address the needs of next-generation ADSL2+, VDSL2, and FTTH residential gateways, and the MSP7130 is tailored for passive optical networks (PON) and VDSL.
The MSP7120 has an integrated ADSL/ADSL2/ADSL2+ modem that interfaces gluelessly to the company's PM4381 ADSL2+ Analog Front End device. The MSP7130 provides an Ethernet WAN interface for support of VDSL2, xPON or home router applications. Both devices have PCI, USB 2.0 host/client interface and a TDM interface for connection to external SLIC/SLAC devices.
The MSP7120 and MSP7130 make up what PMC-Sierra is calling the MSP7100 residential gateway platform, delivering advanced IP services, such as IPTV, VoIP and multimedia services into the digital home. The residential gateway is becoming the central control and distribution point for the home network.
“The telcos look at the home network as a medium over which they can create and deploy a wide array of services that extend beyond IPTV and looking how they can turn the home network into a robust service deployment medium,” said Hamish Dobson, manager, residential gateway product marketing for PMC-Sierra.
The residential gateway needs to perform a number of new functions, such as unifying the various home networking segments, including the wired, wireless and USB connections, and home area networking technologies into a single logical network. It is also intended to extend the carriers' QoS functions from their access network past the traditional demark point into the home network so that they can ensure service delivery to the end appliance such as an IP phone or set-top box. The residential gateway also plays a key role in authentication of services.
“What this means from a SoC standpoint that sits inside the residential gateway is significantly higher performance. The need to handle more packets per second because of the faster broadband pipes that are being used in high bandwidth services that are being deployed into the home. But also the need to support more much processing on every packet that comes into the gateway,” Dobson said.
Indeed, QoS demands a lot of processing power to perform classification, scheduling and queuing. PMC-Sierra's devices are designed to handle that horsepower. They deliver 180,000 packets-per-second IP forwarding performance to support high-bandwidth broadband access technologies, such as VDSL2 and fiber-to-the-home.
Hardware multi-threading technology is an efficient and cost-effective way to increase packet processing performance in residential gateway applications, according to Dobson. While hardware multi-threading is not a new technique, the MSP7120 and MSP7130 are the first MIPS-based devices to employ the technology, he said.
“It buys us 3X performance improvement with a very small incremental cost and a 30 percent increase in core sizethat is a very cost-effective way of increasing the packet processing performance,” he said. PMC-Sierra is basing those claims against a single-threaded processor of the same frequency.
The processor core that PMC-Sierra is introducing has three key differentiating features. The first is a dynamic multi-processing core. The single processor core can be separated into multiple virtual processors. And each of those can run a different piece of software or operating system. What that enables PMC-Sierra to do is split the critical functions of the gateway across multiple cores.
“That enables us to take the Linux OS, the control plane and management plane and run it on one environment and then take the performance sensitive part of the gateway, which is the data path and run in on another environment and separate it from the rest of the gateway functions,” he explained.
It's very valuable to split the data path off from all of the other things that happen on the gateway, so there isn't contention for processor resources. This is especially useful in a multi-service environment where there's a need to accept video packets, classify them and queue them and get them through the gateway as fast as possible to minimize packet jitter. It's also useful in situations when there's a high amount of processing horsepower present in a system to handle the incoming traffic, creating a need to prevent packets from dropping.
The second is a hardware multi-threading core, which allows multiple threads to be assigned to the virtual processor that's running the data path. “That's where the 300% performance improvement per megahertz comes from,” he said.
And finally, the virtual DSP voice engine. It is very common to implement VoIP terminal adapters in next-generation multi-service gateways. Traditionally, that's been handled by putting a separate DSP core on the SoC to ensure that the real-time voice processing has dedicated cycles assigned to it, which is important when maintaining VoIP quality.
Because of the hardware multi-threaded processor and the concept of being able to divide it into multiple virtual processors and guarantee cycles to each of these virtual processor cores, the MSP7120 and MSP7130 can do the same thing with VoIP by implementing a virtual DSP.
This provides designers with the benefit of having a separate DSP core without having to incur the cost of an extra core, the memory that it requires and the communications logic on its MSP7120 and MSP7130 SoCs, he said.
The devices will be priced less than $13 each in quantities of 250,000.
PMC-Sierra Inc., 1-408-239-8000, www.pmc-sierra.com