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Putting in for a transfer

The move towards a packet based world continues. By Philip Ling.

Do you sometimes feel like you're on the edge? Motorola Computer Group (MCG) does. By that, it means it feels it can best serve the communications oem by concentrating on solutions for what is commonly called the edge of the network. Essentially, that means the kit that sits on the edge of the core and processes the data passing between it (the core) and the access points.

This isn't without its difficulties. Bandwidths within the core are up to 10Tbit/s, only falling to less than 100Gbit/s at the edge, which means anything sitting on the edge needs to provide the interface between multi terabit streams down to 10/100Mbit/s streams at the access layer. And, to make it really interesting, while the core is still predominantly circuit switched time division multiplexed (tdm) or packet switched asynchronous transfer mode (atm), access is more likely to be internet protocol (IP), which continues to move deeper within the network towards the core. This trend towards 'everything over IP' is the focus for MCG (which now includes what was Blue Wave Systems).

What do you do?
It is just over a year since MCG outlined its telecoms strategy, introducing its first packet transport architecture, and its intention to supply a complete IP portfolio for telecoms oems. At the same time, it explained its application focus, using the acronym WENT, meaning: wireless; enterprise; network; transmission. This was all underlined with a high availability software strategy based on Linux on the server, a third party rtos for transmission, and Windows at the enterprise level. Back then, high availability and open platforms were emerging as supported solutions from companies such as MCG for the oem, and things were looking bright. Talk of converging voice and data traffic over IP was rife, the only fuzzy area was how the industry would get from circuit switched to packet transport architectures. But MCG set itself the task of creating native (all IP) platforms with five 9s (99.999%) reliability, operating at wire speed (no latency).

The path is clear
At the time of the initial announcements, communications was still buoyant. While the market may have gone quiet, MCG believes it is still evolving towards the converged data fabric, which involves handling multiple protocols at once. Its solution revolves around a meshed backplane – MCG's approach to backplane interconnect - a protocol free topology which combines the existing PICMG standards into a single platform, and adheres to the Intelligent Platform Management Interface (IPMI) for system management. The most recently adopted of these standards is the PICMG 2.16, which overlays an embedded Ethernet switching fabric on a CPCI platform. MCG believes this is most useful in the control plane at the edge of the network, where applications are processing intensive. The weakness is that PICMG 2.16 only supports IP, while the core remains tdm or atm. This is where MCG sees its mesh fabric providing the necessary flexibility to cope with all protocols, creating a migration path towards IP packet based networks from legacy systems.

Multiple support
In view of this, in September last year, MCG introduced two architectures: the H.110 packet transport platform (HXP), which supports tdm and IP; and the multi service packet transport platform (MXP), based on CPCI. The MXI architecture supports a switched mesh fabric, switched Ethernet fabric and IPMI on the same backplane. IPMI has been adopted by PICMG for CPCI shelves or chassis as the PICMG 2.9 standard, while MCG is submitting its mesh architecture to PICMG for consideration as an open industry standard.

The mesh topology is described as a superset of star topologies. A star topology, just one of the many topologies around for wiring boards and systems, uses a point to point configuration where each device uses a dedicated link to send and receive data from a central resource. Because the star topology uses a central resource, redundancy is required to guarantee reliability.

With mesh, this is taken a step further. As a customer adds interconnects to eliminate 'dead branches' in a star network, a point is reached when all nodes have connections to all other nodes. At this point the hierarchy disappears, and each node can become an endpoint, a router, or both.

Opening the gate
An example of how MXP may be configured would be a media gateway. Media gateways are used to interface a higher bandwidth packet network to a number of lower bandwidth tdm interfaces. They may be used in 'soft switch' applications where packet switching replaces tdm based switching, or to bridge networks, like a wireless network to a tdm network.

Since the purchase of Blue Wave Systems, MCG now has a greater presence in Europe for one thing, but it also has all the digital signal processing the company had developed. Part of that has gone into developing 'off the shelf' media gateway solutions. DSP boards perform the necessary processing to deal with the tdm world. This includes echo cancellation, compression and packet conversion. For modem of fax support, dsps provide tone recognition and demodulation.

For voice over IP applications, the IP network can be used to carry the data traffic. With dsps capable of 2000 channels, media gateways having up to 32,000 channels are possible within the MXP platform.
Rob Shaddock, who was chief executive officer at Blue Wave and who is now the director of gateway and wireless applications within MCG, said: "We're still supplying boards, but now with the software to make them work and, ultimately, to create complete subsystems. It is 'almost' a gateway, but the customer will still need to create the applications."

Author
Graham Pitcher

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