单选题The policy action of color is used for congestion control under which circumstance?（）A congestion in an upstream routerB congestion in a downstream routerC contention for queue space on an egress interfaceD contention for queue space on an ingress inte
题目
单选题
The policy action of color is used for congestion control under which circumstance?（）
A
congestion in an upstream router
B
congestion in a downstream router
C
contention for queue space on an egress interface
D
contention for queue space on an ingress interface