To a router, a flow is a (1) of packets that share the same Characterstics, such as traveling the same (2) ,using the same (3) ,having the same kind of security, and so on. A router that supports the handling of flow labels has a (4) table. The table has an entry for each active flow label; each entry defines the (5) required by the corresponding flow label.

4（）

A．flow table

B．flow label

C．rout table

D．Tag table

屏蔽服具有（）作用、（）作用、（）作用。