问题：

[单选] Which of the following is not a characteristic of fast switching？（）

A . Fast switching reducesa routers CPU utilization， compared to process switching
B . All packets of a flow， except for the first packet， use the information in the fast cache
C . It can be enabled with the interface command ip route-cache
D . Fast switching uses a fast cache maintained in a router’s control plane
E . The fast cache contains information about how traffic from different data flows should beforwarded
F . Even though the fast switching is enabled， the first packet of a flow is still process switched