Hypathetical scenario: I have a trunk port on a router going to a switch with subinterface fastethernet 0/0.1 for data, and 0/0.2 for voice. I want to perform LLQ or prioritize voice traffic on the 0/0.2 subif. Even though both data and voice have their own logical interface and therefore a FIFO queue for each, they eventually have to compete for the same physical transmit queue. How do I prioritize voice. Cisco documentation states that because logical interfaces do not support CBWFQ/LLQ, a higherarchical policy map needs to be created with the child map doing the CBWFQ/LLQ and the parent map doing shaping to create backpressure as a mechanism for CBWFQ to be engaged. However the documentation that I have read states to place the higherarchical policy map on the subinterface itself. This only works if I am trying to prioritize different flows that exist on the same subif but not if I want to prioritize flows on one subif over flows on the other subif. Do I place the higherarchical map on the interface itself (fastethernet 0/0)? If so, what shaping rate should be used and is there any documentation to this exact scenario. Maybe another question should be is there even a need to do this given the speed of fastethernet?