Network Topology

CSP uses a network oriented terminology similar to what is known from the Internet and the IP model. A CSP network can be configured for several different topologies.

  +-------+-------+-------+-------+       bus: I2C, CAN, KISS
  |       |       |       |       |
+---+   +---+   +---+   +---+   +---+
|OBC|   |COM|   |EPS|   |PL1|   |PL2|     Nodes 128/8 (Space segment)
+---+   +---+   +---+   +---+   +---+
          ^
          |  Radio                        bus: RF
          v                               Nodes 192/12
        +---+          +----+
        |TNC|----------| PC |             bus: KISS, CAN, ETH
        +---+          +----+             Nodes: 196/12 (Space segment)
                          |       
                          |               
                          |               bus: ZMQ
                  +-----------+           Nodes: 96/9 (Ground segment)
                  |           |
                +----+     +----+
                | PC |     | PC |
                +----+     +----+

CSP v2 subnet mask	4	5	6	7	8	9	10	11	12
Available addresses	1023	511	255	127	63	31	15	7	3

For CSP v2, addresses from 1 to 16383 are available, with subnet sizes typically varying from 2²=4 to 2⁶=64. Address 0 is always reserved for localhost. Each address space has its highest address defined as a broadcast address, making the number of available addresses one less than the subnet size. Each interface in a sub-system has an independent address belonging to the particular logical interface.

A network is configured using static routes for every module, initialised at boot-up of each sub-system. The routing is configured by defining whether each interface in a sub-system is a default interface to use when a receiver address is not covered by any interface. On top of that, static routes can be defined to cover complex network setups with multiple satellites, multiple subnets in a satellite and ground segments split into multiple subnets.

Each physical network (a CAN bus, RF link, etc.) will have an independent logical network related, unless two interfaces are used to create a redundant physical network in a satellite or spacelink. In this case, the two (or more) physical interfaces in the sub-systems shall be configured to have the same CSP address and related properties, by which the CSP router knows that packets for that particular logical CSP subnet shall be transmitted on both physical interfaces.