多选题Which three pre-conditions must be met before an OSPF router can perform graceful restart？（）ARouter must be ABRBRouter must contain one sham link.CThe network topology must be stable.DRouter must be able to forward packets.ENeighbors must support grace
题目
多选题
Which three pre-conditions must be met before an OSPF router can perform graceful restart？（）
A
Router must be ABR
B
Router must contain one sham link.
C
The network topology must be stable.
D
Router must be able to forward packets.
E
Neighbors must support graceful restart.