Network Discovery

When probing for routing switches, early network discovery techniques typically relied on each routing switch’s configuration port to respond to identification requests to confirm the routing switch’s presence. A request packet was typically dispatched to the configuration port, and a response packet provided confirmation of existence. This same request/response approach was generally used for node identification as well. Dispatching one or more requests to an active link (which might be a node or another routing switch) could produce a response if a node was present and it understood the protocol. The new probing technique involves a shift away from the request/response model. Rather than dispatching a request to some possible physical-path-address on the network, and awaiting a response from a packet receiving/processing/replying entity, a single packet is addressed with a round-trip physical-path-address that will essentially “loop” through a possible routing switch and be returned to the originator with all path-addressing bytes removed along the way out and back. Perhaps the best way to visualize this technique is to think of the SpaceWire routing switch as a “roundabout” intersection with a vehicle (packet) both entering and exiting the roundabout at the same point.