QoS機制中的分類，采用ip數據包中的哪個字段？

four switches， which one will be root switch.（no pic）.

What field in IP packet is used for classification by QOS？

What is the next state of initial in spanning-tree protocol？

What is method list for configure aaa？

如何實現(xiàn)擁塞避免？

As a CCNA candidate,you must have a firm understanding of the IPv6 address structure.Refer to IPv6 address,could you tell me how many bits are included in each filed?（）

問一個怎么樣的屬性，能讓路由不通告給任何的peer？

what is the advantage of policing opposite to shaping？

SPT初始狀態(tài)之后的一個狀態(tài)是什么？