An Output Header Ring (OHR) serves as the queue for packets to leave on some interface. Priority logic generally dictates different queues for different priorities. This suggests that outgoing fibers with an OHR for each priority. This fits with the idea of different interface numbers for the same fiber depending on priority. If the CPU is a scarce resource then it might be strategic to duplicate IHR as well but I do not pursue that now. The idea needs to be conformed with software selection of syndrome times. The high priority queue is normally empty since most of the time is spent transmitting low priority traffic. Having transmitted a batch of high priority packets, it seems urgent to transmit a syndrome lest the high priority packets wait for subsequent low priority packets before being processed downstream.
In this scheme output indexing is determined by the hardware and thus the hardware might have to write the OIL.
Just now I realized that the interface number is xored with the steering nibble to compute the outgoing interface number. When I send a needle thru the net to a web server expecting to fetch data at some priority that I choose, the steering information that arrives at the server must contain the priority information that I have chosen. Assuming that a given link (two fibers) divides the capacity into priorities the same way going both directions, then it would suffice to send the needle with the same priority routing as what I want for the returned data. This may not be a good idea. One problem is that congestion may be much different in the two directions.
Either an input header ring or a field in the input header indicating which priority the packet traversed the latest link is necessary.
Moving data thru a network with varying congestion is a complex problem to be solved, I suspect, only with diverse algorithms interacting to price and service signals. These algorithms are outside the scope of the current design but priority remains a tactic to sell unreserved capacity to low demand customers. Many of the algorithms I imagine lead to data arriving at the destination out of order. The current Internet has made this seem an easy property to tolerate.