Modified deficit round robin supports which of these functionalities?
A.
Priority queue
B.
Weighted fair queues
C.
Round-robin service of output queues
D.
LLQ
Explanation:
Modified deficit round robin (MDRR)—MDRR, a traffic class prioritization mechanism used only on
GSR platforms, incorporates emission priority as a facet of quality of service. MDRR is similar in
function to WFQ on non-GSR platforms.
In MDRR, IP traffic is mapped to different classes of service queues. A group of queues is
assigned to each traffic destination. On the transmit side of the platform, a group of queues is
defined on a per-interface basis; on the receive side of the platform, a group of queues is defined
on a per-destination basis. IP packets are then mapped to these queues, based on their IP
precedence value.
These queues are serviced on a round-robin basis, except for a queue that has been defined to
run in either of two ways: a) strict priority mode, or b) alternate priority mode.
In strict priority mode, the high priority queue is serviced whenever it is not empty; this ensures the
lowest possible delay for high priority traffic. In this mode, however, the possibility exists that other
traffic might not be serviced for long periods of time if the high priority queue is consuming most of
the available bandwidth.
In alternate priority mode, the traffic queues are serviced in turn, alternating between the high
priority queue and the remaining queues.http://www.cisco.com/en/US/docs/ios/12_0st/12_0st10/feature/guide/10st_cos.pdf