source node should try to retransmit the message during a search multiple streams of data corresponding to the same message converges on intermediate nodes and the destination node at approximately the same time when two streams arrive at the same node two receivers present selection masks to the crossbar switch asking for the same set of transmitters it is the responsibility of the crossbar switch to arbitrate among its various inputs to guarantee that each transmitter is only connected to one output receivers which lose the arbitration are told that they are connected to no transmitters and consequently send back link close commands the routing mechanism searches the network using the pattern specified in the header no headers are invalid by changing the basic header pattern described earlier the number of paths searched can be increased or decreased as desired for example by using as many bytes as there are total moves to the destination plus one and setting only one bit in each header a single path can be specified in fig5 consider the header 500 for routing from 0 0 501 to 1 2 502 and its resulting search pattern the search pattern can be narrowed for messages which are being sent across many nodes by inserting extra zero bits in the middle of the columns of the header 600 an example of this is shown in fig6 notice that every line except the last must be non zero by including redundant movement positive and negative in the same dimension it is possible to expand the search pattern to include alternate.