Fiber delay lines (FDL) is another solution for contention resolution in OBS when bursts are delayed in core routers because of the lack of random access memory.
Another possible contention resolution strategy can be deflection routing, when the optical burst switching matrix is sent to the next output port of a predetermined core router.
But questions arise about the sequence of contention resolution strategies which must be applied for bursts of various priorities coming to core node.
THE MATHEMATICAL APPROACH FOR INVESTIGATION OF CONTENTION RESOLUTION STRATEGIES APPLYING IN CORE ROUTER
It is assumed that all strategies for burst contention resolution are implemented in the OBS core router.
Priority differentiation phase ends once a helper sends its busy tone, and the contention resolution phase immediately starts since next minislot.
1] gets the opportunity to enter the contention resolution phase to contend the cooperation right.
In order to avoid the possible collisions caused by their concurrent cooperative packet transmissions and guarantee the application of packet piggyback mechanism, the contention resolution phase (CRP) of the same priority helpers is employed in our protocol.
4 shows an example of the contention resolution phase, where k=3 and M=5.