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Chapter 4 Network Access Types of ConnectionsA physical connection can be a wired connection using a cable or a wireless connection using radio waves. Network Interface CardsNetwork Interface Cards (NICs) connect a device to the network. Ethernet NICs are used for a wired connection , whereas WLAN (Wireless Local Area Network) NICs are used for wireless. An end-user device may include one or both types of NICs. The Physical LayerThe process that data undergoes from a source node to a destination node is: The user data is segmented by the transport layer, placed into packets by the network layer, and further encapsulated into frames by the data link layer. The physical layer encodes the frames and creates the electrical, optical, or radio wave signals that represent the bits in each frame. These signals are then sent on the media, one at a time. The destination node physical layer retrieves these individual signals from the media, restores them to their bit representations, and passes the bits up to the data link layer as a complete frame .
Physical Layer MediaThere are three basic forms of network media. The physical layer produces the representation and groupings of bits for each type of media as: Copper cable: The signals are patterns of electrical pulses. Fiber-optic cable: The signals are patterns of light. Wireless: The signals are patterns of microwave transmissions.
Physical Layer StandardsFunctionsThe physical layer standards address three functional areas: Physical ComponentsThe physical components are the electronic hardware devices, media, and other connectors that transmit and carry the signals to represent the bits. Encoding Encoding or line encoding is a method of converting a stream of data bits into a predefined "code”.SignalingThe physical layer must generate the electrical, optical, or wireless signals that represent the "1" and "0" on the media. The method of representing the bits is called the signaling method.

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