Intelligent Packet Discard Methods work on what premise?
A.
That the cells carry non-critical traffic
B.
That the VPI/VCI pair is low priority
C.
That the cells come from large packets, segmented
D.
That the TOS (type of service) field in the IP header prioritizes some cells
E.
None of the above
Explanation:
Frame discard techniques embody the concept that if the network element must discard cells, it is far more effective to do so at the frame level rather than at the cell level. An ATM network can detect frame boundaries by evaluating the cell header. Under severe congestion situations, when a cell is dropped, the switch can immediately drop all cells associated with that specific frame. To improve higher-layer protocol efficiency, the switch should drop all cells except the cell thatsignals the end of the frame. This way, the higher-layer protocol immediately detects a failure and requests retransmission upon receiving an incomplete protocol data unit (PDU), instead of the source ES having to wait for a higher-layer protocol timeout before retransmitting the PDU, or, even worse, the boundary of the next PDU not being correctly identified and the next PDU also being affected.