Introduction
簡介
Imagine you are a network technician at a rapidly expanding technology startup. The company has recently faced significant network slowdowns during peak operational hours. After investigating, you discover that the older Ethernet cables in some office areas cannot support the increased traffic, leading to delays and dropped connections. Also, several remote workers report inconsistent connectivity, likely due to suboptimal wireless setups. Having knowledge of the TCP/IP Link layer, as well as the Ethernet and Wi-Fi protocols, will help you identify the causes of delays and dropouts on the network.
假設你是一家快速成長的科技新創公司的網路技術人員。該公司近來在尖峰營運時段面臨明顯的網路延遲問題。經調查後你發現，部分辦公區域內較舊的乙太網路纜線無法負荷增加的流量，導致延遲與連線中斷。此外，也有多位遠端工作人員回報連線不穩定，可能是無線網路設定不佳所致。具備 TCP/IP 鏈結層以及乙太網路與 Wi-Fi 通訊協定的知識，將有助於你找出網路延遲與斷線的原因。
You realize the following:
你發現以下情況：
- The startup's rapid growth needs a robust network infrastructure that can handle both current and future demands.這家新創公司的快速成長，需要能夠應付目前與未來需求的強健網路基礎架構。
- Different areas of your network might require varied types of physical connections, such as high-performance Ethernet solutions for workstations, reliable wireless setups for mobile devices, and fiber optics for the network backbone. This way, you can optimize network performance and ensure reliability.網路的不同區域可能需要不同類型的實體連線，例如工作站使用高效能乙太網路方案、行動裝置使用可靠的無線設定，以及骨幹網路使用光纖。如此便能最佳化網路效能並確保可靠性。
- Understanding the physical aspects of network communication is crucial, particularly the specifics such as cable types, connectors, and the unique demands of wireless communication.了解網路通訊的實體層面非常重要，特別是纜線類型、接頭，以及無線通訊的特殊需求等細節。
As shown in the figure, users are complaining about slow Wi-Fi and internet connections. This example highlights several issues, including the use of an outdated Wi-Fi standard, poor Wi-Fi signal, an old category Ethernet UTP cable, and a legacy serial connection between the router and the ISP.
如圖所示，使用者抱怨 Wi-Fi 與網際網路連線速度緩慢。此範例凸顯了數個問題，包括使用過時的 Wi-Fi 標準、Wi-Fi 訊號不佳、老舊類別的乙太網路 UTP 纜線，以及路由器與 ISP 之間使用的舊式序列連線。
 | How would you strategically upgrade and optimize your network infrastructure? 你會如何有策略地升級並最佳化你的網路基礎架構？ |
As a network technician, understanding the intricacies of the TCP/IP link layer and how different physical media impact connectivity will enable you to determine the appropriate media, protocols, and cable types needed to upgrade the network infrastructure to meet the demands of a modern network.
身為網路技術人員，了解 TCP/IP 鏈結層的細節，以及不同實體傳輸媒介如何影響連線品質，將能協助你判斷升級網路基礎架構以符合現代網路需求時，所需的合適傳輸媒介、通訊協定與纜線類型。
In this course, you will learn the following:
在本課程中，你將學習以下內容：
- Role of the TCP/IP Link LayerTCP/IP 鏈結層的角色
- Specifics of different cable types各種纜線類型的規格
- Using connectors and modules接頭與模組的使用
- Frame structures and their uses框架結構與其用途
- Types of LAN communicationsLAN 通訊的類型
- Function of MAC addressesMAC 位址的功能
