CompactPCI Serial Mesh Architecture

Ethernet has established itself as the interface for systems containing several computers. In CompactPCI Serial systems it is possible to use a system slot CPU as a peripheral board, which makes building modular systems very easy. All CPU boards intercommunicate via Ethernet. As these are point-to-point connections, no switch board is needed and no infrastructure or special configuration is needed either.

CompactPCI Serial supports copper-based Ethernet standards (10, 100, 1000, 1G, 10GBaseT). These standards offer important advantages compared to special Ethernet backplane standards:

• interoperability through auto negotiation even at different speeds
• support of standard Ethernet chips
• Ethernet controllers already partly included in the chipset
• extremely robust and fault tolerant
• no retroaction of the boards in case of a failure due to inductive or capacitive coupling
• easy extensibility with more than 9 slots even between module carriers
• standard Ethernet switches can be used optionally

One drawback is the higher number of lines - 4 line pairs per connection compared to 2 in the Ethernet backplane standard 1000BASE-BX. Only 1 Gb/s are supported by this standard though. As much as 8 line pairs are needed for 10GBASE-BX4 - autonegotiation poses problems. BaseT is the future technology here, as it is simpler.

Does this mean that each CompactPCI Serial board has to be equipped with 8 Ethernet channels? Not at all! Ethernet on the backplane is an option. Even with only one channel, communication with a second, identical board is possible. If there are two channels, a full mesh with 3 CPU boards is possible, with 3 channels 4 boards can be interconnected etc. The backplane wiring is chosen in such a way that the CPU boards are completely wired, even with fewer interfaces, if they are plugged directly next to each other.

CompactPCI Serial enables easy and cost-efficient multiprocessing based on Ethernet communication. Switch boards are not required in systems with up to 9 slots. Interoperability and future-safety are guaranteed by choosing the 100…10GBaseT standard.