Priorities
Received Priority = Pr ? This token/frame’s priority
Received reservation = Rr ? Someone on the ring wants to transmit at Rr
To transmit a message of priority Pm, you should get a free token with Pr < Pm
If free but Pr>Pm and Rr<Pm, reserve token by setting Rr=Pm
If busy and Rr<Pm then reserve by setting Rr ? Pm
When you transmit, set Rr=0, and busy=1. After transmission, issue a new token with Pr=Max{Pr,Pm,Rr}, Rr=Max{Rr,Pm}