By Rich Pellegrini, Product Marketing, NMS Communications
The Advanced Telecom Computing Architecture (AdvancedTCA or ATCA) was defined by the PCI Industrial Computers Manufacturing Group (PICMG) to address the need for commercial off-the-shelf (COTS) components capable of supporting highly available (five-nines) solutions. ATCA’s predecessor, CompactPCI, although an improvement over earlier standard hardware components, failed to meet the needs of system developers, primarily in the areas of bandwidth and availability. ATCA addresses these shortcomings and allows system developers to purchase COTS components that respond to carriers’ requirements for value-added services with a shorter time-to-market.
ATCA System Components and Form Factors
Some of the key features of ATCA include:
- Support for up to 16 slots, for high-density solutions
- Larger board size, providing more room for increased DSP and packet processing power
- Cooling for 200W per slot, allowing the use of state-of-the-art processors
- Hot-swappable chassis components, for reduced MTTR
- An Intelligent Platform Management Interface (IPMI) for monitoring the physical health of all components
- 48 Vdc power for continual operation
The foundation of the ATCA family of specifications is the PICMG® 3.0 base specification, which defines the base shelf board and chassis mechanicals, including power distribution, rear I/O, power dissipation, and data transport (for system management and switching fabric interconnect). Additional sub-specifications (3.x) specify the various data plane fabric options/technologies, including Gigibit Ethernet (3.1), Infiniband™ (3.2), StarFabric (3.3), PCI Express™ (3.4), Serial RapidIO® (3.5), and Packet Routing Switch (PRS) (3.6). The data plane (Fabric Switch Interface) on the backplane is wired in one of three redundant topologies—Dual Star, Dual-Dual Star, and Full Mesh. Refer to the NMS white paper, AdvancedTCA: Next-Generation Architecture for Communications Applications, for more details on ATCA.
Additional form factor: Advanced Mezzanine Cards (AMCs)
One of the design intents of ATCA was to offer high levels of modularity and configurability. ATCA achieves this with Advanced Mezzanine Cards (AMCs), mezzanine daughter boards that mount on standard ATCA boards, both processing boards and “dumb” carrier boards. Standard ATCA boards can be purpose-built (e.g., Ethernet switch or DSP) or general-purpose (e.g., single board computer (SBC) or dumb carrier), each of which can provide one to four AMC sites for providing processing, I/O, DSP, disk storage, memory, etc.
Just like the full-size ATCA boards, AMCs are hot swappable, allowing for removal and replacement in a live running system to maintain availability. They can also be used directly in MicroTCA chassis (see Figure 1).
Figure 1: AMCs in ATCA and µTCA chassis
MicroTCA (µTCA)
The MicroTCA chassis standard, now ratified, is a small chassis form factor which allows AMCs to be plugged directly into a chassis backplane without the need for a carrier board. The standard provides most of the features of a full-size ATCA chassis. MicroTCA supports hot-swap, IPMI management, and a switched backplane fabric (AMC.1 PCI Express/Advanced Switching, AMC.2 Gigabit Ethernet (not yet ratified), AMC.3 Storage Interfaces, AMC.4 Rapid I/O), meeting carrier-grade telecom equipment requirements.
Use of AMCs in MicroTCA chassis is lagging about one year behind ATCA for deployed chassis sales. The first MicroTCA-compliant chassis hit the market in early 2007 for evaluation, with initial deployment sales expected in early 2008.
The two primary components of a MicroTCA system are:
- Advanced Mezzanine Cards (AMC)
- MicroTCA carrier hub (MCH)
The AMCs provide processing, storage, memory, and system I/O. The MCH provides system management, including platform management via the IPMI interface, the switch fabric, and performs functions similar to a carrier board in ATCA systems. As many as two MCH cards and 12 AMCs can operate together as a subsystem. MicroTCA provides scalable bandwidth up to 40 Gbit/sec and supports star, dual-star, and full-mesh topologies and provides availability from three-nines to five-nines. MicroTCA shelf densities range from 4 to 48 on average, with the largest shelf offering room for 192 AMCs as a composition of MicroTCA subsystems.
Differences in the MicroTCA chassis versus that of a full size ATCA chassis are as follows:
- Minimal subset of IPMI commands
- +12 Vdc payload power and +3.3 Vdc Management Power to AdvancedMC Modules versus -48 Vdc (-48 Vdc is converted by the chassis)
Form Factors and Market Suitability
While ATCA and MicroTCA are similar in some ways, each is more suitable for particular markets. Full-sized ATCA boards and chassis are best suited for implementing communications equipment that resides in the core and edge of converged telecom networks (e.g., media gateways, Multimedia Resource Function Processors (MRFPs), and the Call Session Control Function (CSCF)), where carrier-grade features and five-nines availability are required.
MicroTCA targets the access part of the network which consists of telecom edge applications (e.g., WiMAX access points, VoIP access gateways, cellular base stations) and customer premise equipment (e.g., enterprise IP PBXs and IP gateways). MicroTCA is also applicable to the medical, digital imaging, industrial, and federal market segments, including defense and aerospace.
NMS and ATCA
NMS has a long history in the development of next-generation standards in industrial computing. NMS was one of the first companies to introduce CompactPCI-based (PICMG 2.x) products in 1998 and is now actively involved in ATCA efforts. We are a constant participant at ATCA interoperability events and other activities. Our ATCA media processing blade, the MG 7000A, offers many high availability features, such as hot swap support, dual PPC controllers, dual Ethernet switches, a craft port, status lights, and front I/O . This special-purpose media processing blade is targeted at the value-added services (VAS) market, where feature-rich multimedia processing is required—such as a media resource function (MRF) supporting a next-generation converged network application.
Main features of the MG 7000A include:
- Up to 480 “universal” ports, allowing one blade to support a variety of applications on either IP or TDM networks
- 16 trunks of rear I/O
- ATCA 3.1 Gigabit Ethernet switch fabric support
- Full support for IPMB chassis management bus
- Fully hot swappable
Figure 2 shows the major components of the MG 7000A.
Figure 2: MG 7000A
Developer Considerations
When developing highly available, carrier-grade, core application-based systems with the MG 7000A, the ATCA chassis must support the following switch fabric options:
- Fabric Option: PICMG 3.1 Gigabit Ethernet
- Fabric Topology: Dual Star, Dual-Dual Star, or Full Mesh as a Node board (and Dual Star as a Hub board)
A unique feature of the MG 7000A media processing blade is that it includes on-board Gigabit Ethernet base and fabric switches and can act as an ATCA hub board in chassis with up to 5 slots, providing a Dual Star switch fabric topology with 1+1 switch redundancy as shown in Figure 3. That is, for a 5-slot media processing chassis, only MG 7000As and an ATCA single board computer (SBC) are required to deploy an ATCA media processing system.
Figure 3: MG 7000A and 1+1 Redundancy
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Rich Pellegrini may be reached at +1 508 271 1293 or rich_pellegrini@nmss.com.