Preemption techniques for use in conjunction with an interface between a physical layer device and a link layer device are disclosed. Segments associated with or comprising packets, cells or other protocol data units (PDUs) are communicated between the physical layer device and the link layer device via an interface bus. At least first and second consecutive start indicators having respective first and second data segments associated therewith are received by one of the devices from the other, and the second data segment is permitted to preempt the first data segment without signaling an interface protocol violation, subject to subsequent confirmation that the preemption is appropriate. If a number of consecutive end indicators is subsequently received that balances the number of consecutive start indicators, the preemption is confirmed as appropriate, and otherwise an interface protocol violation is signaled.
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