A digital message router , comprising: a first message input configured to receive a first input message (XI); a second message input configured to receive a second input message (YI); a first message output ; a second message output ; characterized in that the digital message router further comprises a switch circuit coupled to the first and second message inputs and to the first and second message outputs; and a routing circuit coupled to the first and second message inputs and configured to cause the switch circuit to couple the first input message to the first message output in response to the first and second input messages being valid, to couple the second input message to the second message output in response to the second input message being valid, and to couple the first input message to the second message output only in response to the first input message being valid and the second input message being invalid; the first message output being configured to be coupled to a first message input of another router in a first unidirectional ring; the first message input being configured to be coupled to a first message output of another router in the first unidirectional ring; the second message output being configured to be coupled to a second message input of another router in a second unidirectional ring; and the second message input being configured to be coupled to a second message output of another router in the second unidirectional ring. a first message input configured to receive a first input message (XI); a second message input configured to receive a second input message (YI); a first message output ; a second message output ; characterized in that the digital message router further comprises a switch circuit coupled to the first and second message inputs and to the first and second message outputs; and a routing circuit coupled to the first and second message inputs and configured to cause the switch circuit to couple the first input message to the first message output in response to the first and second input messages being valid, to couple the second input message to the second message output in response to the second input message being valid, and to couple the first input message to the second message output only in response to the first input message being valid and the second input message being invalid; to couple the first input message to the first message output in response to the first and second input messages being valid, to couple the second input message to the second message output in response to the second input message being valid, and to couple the first input message to the second message output only in response to the first input message being valid and the second input message being invalid; the first message output being configured to be coupled to a first message input of another router in a first unidirectional ring; the first message input being configured to be coupled to a first message output of another router in the first unidirectional ring; the second message output being configured to be coupled to a second message input of another router in a second unidirectional ring; and the second message input being configured to be coupled to a second message output of another router in the second unidirectional ring. <EOS>