Which two benefits are of applying WRED? (Choose two.)

A.
helps to avoid TCP synchronization

B.
allows a different drop profile to be manually enabled for each IP precedence or DSCP

C.
provides minimal bandwidth guarantees

D.
provides bounded low latency

Explanation:
WRED and distributed WRED (DWRED)—both of which are the Cisco implementations of
RED—combine the capabilities of the RED algorithm with the IP Precedence feature. Within the
section on WRED, the following related features are discussed:
–
Flow-based WRED. Flow-based WRED extends WRED to provide greater fairness to all flows on
an interface in regard to how packets are dropped.
–
DiffServ Compliant WRED-DiffServ Compliant WRED extends WRED to support Differentiated
Services (DiffServ) and Assured Forwarding (AF) Per Hop Behavior (PHB). This feature enables
customers to implement AF PHB by coloring packets according to differentiated services code
point (DSCP) values and then assigning preferential drop probabilities to those packets.
WRED avoids the globalization problems that occur when tail drop is used as the congestion

avoidance mechanism on the router. Global TCP synchronization occurs as waves of congestion
crest only to be followed by troughs during which the transmission link is not fully utilized. Global
synchronization of TCP hosts, for example, can occur because packets are dropped all at once.
Global synchronization manifests when multiple TCP hosts reduce their transmission rates in
response to packet dropping, then increase their transmission rates once again when the
congestion is reduced.