I mean by "reservation of channels" reservation of physical CAN bus and standards which provide it (definition of faults, transition to the reserve bus, etc.).
I haven't heard of CAN standard protocols with parallel connections. My guess is that you need to route frames to a working bus by hand.
There are faults detections and tolerance over CAN, but no way to automatically switch from an unworking bus to a working one. You can also send simultaneously a same CAN frame on different buses (using different transceiver of course).