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 -48 VDC 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 Zone-3 area can also hold a special backplane to interconnect boards with signals that are not defined in the AdvancedTCA specification.
The AdvancedTCA Fabric specification uses Logical Slots to describe the interconnections. The Fabric Switch Boards go in Logical Slots 1 and 2. The chassis manufacturer is free to decide the relationship between Logical and Physical Slots in a chassis. The chassis Field Replaceable Units (FRU) data includes an Address Table that describes the relationship between the Logical and Physical slots.
The Shelf Managers communicate with each board and FRU in the chassis with IPMI (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 and allocates 4 differential pairs per Base Channel. 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. It allocates 8 differential pairs per Fabric Channel and each Channel can be divided into four 2-pair Ports. The Fabric Interface is typically used to move data between the boards and the outside network.
The Synchronization Clock Interface routes MLVDS (Multipoint Low-voltage differential signaling) 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.
Read more about this topic: Advanced Telecommunications Computing Architecture
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