In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

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