CH5: Network Layer Network Transmission 路由器要事先進行路由設定/持續與其他路由器交換學習，根據收到的封包查表轉送至nexthop(下一跳) 終端使用者不須擔心routing問題，對外路由委由路由器處理，僅須設定好default gateway將離開區域網路的封包往gateway介面送 原則上來回的路由要一致，滿足此條件時稱為Symmetric Rout
CH4e: Link Layer 補充資料 Virtual Local Area Network (VLAN) 實際上共用同一實體設施 Advantage of VLAN: Creating multiple logical LANs on physical device for saving time and cost 運用邏輯切割 Managing grouped hosts in
CH4: Data Link Layer Introduction Data-link layer of a broadcast link Data Link Control Sublayer + Media Access Control Sublayer Pass through Router MAC address change IP address do not change
CH3: Physical Layer Digital-to-Digital Conversion Non-return to Zero Level (NRZ-L) 1: negative voltage 0: positive voltage synchronization problem: transmitting a long sequence of 1s or 0s Non
CH2: Network Model Protocol Layering 定義通訊上的規則 A protocol defines the rules that both the sender and receiver and all intermediate devices need to follow to be able to comunicate effectively Same
CH1: Introduction Data Communication Exchange of data between two devices via some form of transmission medium Kinds of data communication Simplex(單工) Only one of the two stations on a link