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Advanced Telecommunications Computing Architecture

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Advanced Telecommunications Computing Architecture[1] is the largest specification effort in the history of the PCI Industrial Computer Manufacturers Group (PICMG), with more than 100 companies participating. Known as AdvancedTCA™, the official specification designation is PICMG 3.x (see below). AdvancedTCA is targeted to requirements for the next generation of "carrier grade" communications equipment. This series of specifications incorporates the latest trends in high speed interconnect technologies, next generation processors, and improved Reliability, Availability and Serviceability (RAS).

Mechanical Specifications

12U 14 Slot AdvancedTCA® Shelf

An AdvancedTCA®[2] board is 280 mm deep and 322 mm high. The boards have a metal front panel and a metal cover on the bottom of the Printed circuit board to limit Electromagnetic interference and to limit the spread of fire. The locking injector/ejector handle actuates a microswitch to let the IPMC know that an operator wants to remove a board, or that the board has just been installed. AdvancedTCA® boards support the use of PMC or AMC expansion mezzanines.

The shelf supports RTMs (Rear Transition Modules). RTMs plug into the back of the shelf in slot locations that match the Front Boards. The RTM and the Front Board are interconnected through a Zone-3 connector. The Zone-3 connector is not defined by the AdvancedTCA® specification.

Each shelf slot is 30.48 mm wide. This allows for 14 boards in a 19" rack mountable system and 16 boards in an ETSI rack mountable system. A typical 14 slot system is 12 or 13 rack units high. The large AdvancedTCA® shelves are targeted to the Telecommunication market so the airflow goes in the front of the shelf, across the boards from bottom to top, and out the rear of the shelf. Smaller shelves that are used in Enterprise applications typically have horizontal air flow.

Backplane Architecture

The AdvancedTCA® backplane provides point-to-point connections between the boards and does not use a data bus. The backplane definition is divided into three sections; Zone-1, Zone-2, and Zone-3. The connectors in Zone-1 provide redundant -48VDC power and Shelf Management signals to the boards. The connectors in Zone-2 provide the connections to the Base Interface and Fabric Interface. All Fabric connections use point-to-point 100 Ω differential signals. Zone-2 is called "Fabric Agnostic" which means that any Fabric that can use 100 Ω differential signals can be used with an AdvancedTCA® backplane.

The connectors in Zone 3 are user defined and are usually used to connect a front board to a Rear Transition Module.

The AdvancedTCA® Fabric specification uses Logical Slots to describe the interconnections. The Fabric Switch Boards go in Logical Slots 1 & 2. The chassis manufacturer is free to decide the relationship between Logical and Physical Slots in a chassis. The chassis FRU data includes a table that describes the relationship between the Logical and Physical slots.

The Shelf Managers communicate with each board and FRU in the chassis with Intelligent Platform Management Interface protocols running on redundant I²C buses on the Zone-1 connectors.

The Base Interface is the primary Fabric on the Zone-2 connectors. It is wired as a Dual-Star with redundant fabric hub slots at the core. It is commonly used for out of band management, firmware uploading, OS boot, etc.

The Fabric Interface on the backplane supports many different Fabrics and can be wired as a Dual-Star, Dual-Dual-Star, Mesh, Replicated-Mesh or other architectures. This fabric is used to move data between the boards and the outside network.

The Synchronization Clock Interface routes MLVDS clock signals over multiple 130 Ω buses. The clocks are typically used to synchronize telecom interfaces.

Update Channel Interface is a set of 10 differential signal pairs that interconnect two slots. Which slots are interconnected depends on the particular backplane design. These are signals commonly used to interconnect two hub boards, or redundant processor boards.

Fabrics

The Base Interface can only be 10BASE-T, 100BASE-TX, or 1000BASE-T Ethernet. Since all boards and hubs are required to support one of these interfaces there is always a network connection to the boards.

The Fabric is commonly SerDes Gigabit Ethernet, but can also be Fibre Channel, XAUI 10-Gigabit Ethernet, InfiniBand, PCI Express, or Serial RapidIO. Any Fabric that can use the point-to-point 100 Ω differential signals can be used with an AdvancedTCA® backplane.

Shelf Management

AdvancedTCA® Shelf manager

The Shelf Manager monitors and controls the boards and Field Replaceable Units (FRU) in the shelf. If any sensor reports a problem the Shelf Manager can take action or report the problem to a System Manager. This action could be something simple like making the fans go faster, or more drastic such as powering off a board. Each board and Field Replaceable Unit contains inventory information (FRU Data) that can be retrieved by the Shelf Manager. The FRU data is used by the Shelf Manager to determine of there is enough power available for a board or FRU and if the Fabric ports that interconnect boards are compatible. The FRU data can also reveal the manufacturer, manufacturing date, model number, serial number, and asset tag.

The Shelf Manager and the Intelligent Platform Management Controller (IPMC) on the blade or FRU communicate with IPMI protocols over redundant I²C buses. The Shelf Manager communicates with outside entities with RMCP, HTTP, SNMP over an Ethernet network. Some Shelf Managers support the Hardware Platform Interface, a technical specification defined by the Service Availability Forum.

PICMG Specifications

  • 3.0 is the "base" or "core" specification. The AdvancedTCA definition alone defines a Fabric agnostic chassis backplane that can be used with any of the Fabrics defined in the following specifications:
  • 3.1 Ethernet (and Fibre Channel)
  • 3.2 InfiniBand
  • 3.3 StarFabric
  • 3.4 PCI Express (and PCI Express Advanced Switching)
  • 3.5 RapidIO
  • 3.6 PRS (Packet Routing Switch)

See also

References

  1. ^ PICMG. "Reference". PICMG® 3.0 Revision 2.0 AdvancedTCA® Base Specification. http://www.picmg.org
  2. ^ PICMG. "Reference". PICMG® 3.0 Revision 2.0 AdvancedTCA® Base Specification. http://www.picmg.org
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