确定目标地址的路由-CCNA中文版PPT下载

1.确定目标地址的路由 2.触发数据包激活DDR呼叫 3.查找拨号信息 4. 传输流量 5. 断开连接 一般的DDR操作 “Interesting” packet arrives Dial connection ISDN or Basic Service DCE * Layer 4 of 4: Purpose: This figure explains DDR operation. Emphasize: Layer 4 adds fourth and fifth lines. After a user-defined idle period, the call is disconnected. Point out that static routes are configured between the routers to avoid periodic transmissions over the WAN that would be caused by dynamic routing.