CompactPCI® Serial Ethernet Mesh Architecture

Version 1

    Author: Manfred Schmitz, CTO MEN Mikro Elektronik


    With the parallel PCI bus disappearing, a standard PC is now based on a simple star topology. The CPU chipset at the system's center controls peripheral devices and components through point-to-point connections. This allows high data rates, while no device needs to concede bandwidth to another.


    This simple structure is completely adequate for a standard computer. However, star architecture has its limits for complex multicomputer systems that are interlinked via Ethernet. A full-mesh architecture is a better approach here. In a full mesh, one Ethernet interface of every board is connected to one Ethernet interface of another board. CompactPCI Serial supports up to 9 slots (standard backplane). This makes 8 Ethernet interfaces on every board necessary, so that every board can communicate independently with any other board.


    The above example shows how symmetrical multiprocessing can be implemented in a CompactPCI system. This way, you can also realize an architecture of intelligent subsystems. Not all interfaces are used to do this:


    You can also connect the mesh network in the shape of a ring. This allows you to create redundant structures in an elegant and inexpensive way, where the failure of one board does not cause the failure of the entire system:


    These are only some examples of architectures which can be realized using CompactPCI Serial. And all this can be done with standard backplanes and standard boards. All of the 4 boards shown in the above examples can be of the same type. Ethernet usage is determined by software.


    The physical interfaces for Ethernet in CompactPCI Serial CPCI-S.0 are based on the 10/100/1000/10GBase-T standards. This allows the use of "ordinary" Ethernet controllers on the boards. As you can normally do without electrical or optical isolation between the boards, capacitive coupling is possible, saving space and costs.


    The simple star architecture allows to solve complex tasks at a competitive price. For more demanding tasks, you can use mesh structures. In this manner, CompactPCI Serial can cover anything from low-cost to high-end applications.