Introduction

• Protocol -> a defined set of standards that computers must follow in order to communicat properly.

• Computer Networking -> the name we've given to the full scope of how computers communicate each other.

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The TCP/IP Five-Layer Network Model

• Physical Layer -> Represents the physical devices that interconnects computers. (signals)

• Data link layer -> Responsible for defining a common way of interpreting these signals so network devices can communicate. (Ethernet)

• Network layer -> Allows different networks to communicate each other through devices known as routers.(IP)

• Transport layer -> Sorts out which client and server programs are supposed to get that data.(TCP, UDP)

• Application layer -> application specific (lots of protocols)

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The Basics of Networking Devices

Cables

Connect different devices to each other,
allowing data to be transmitted over them.

• copper -> uses electrical voltages

• fiber -> use pulses of light

• Crosstalk -> When an electrical pulse on one wire is accidentally deteced on another wire.

Hubs and Switches

used to connect computers on a single network, usually referred to as a LAN, or local area network.

• Hub -> A physical layer device that allows for connections from many computers at once. (physical layer device)

• Collision domain -> A network segment where only one device can communicate at a time.

• Switch -> switch can actually inspect the contents of the ethernet protocol data and only send that data to one adequate system. (data link layer device)

Routers

A device that knows how to forward data between independent networks. (network layer device).
A router can inspect IP data to determin where to send things.

• Border Gateway Protocol -> Routers share data with each other via this protocol. which lets them learn about the most optimal paths to forward traffic.

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The Physical Layer

transmits bits accross computer networks.

• Bit -> The smallest representation of data that a computer can understand; it's a one or zero.
• Modulation -> A way of varying the voltage of this charge moving across the cable.
• Duplex Communication -> The concept that information can flow in both directions across the cable.
• Simplex Communication -> This process unidirectional.

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Data Link Layer

• CSMA/CD -> Used to determine when the communications channels are clear, and when a device is free to transmit data.

• Ethernet -> The protocol most widely used to send data across individual links.

• MAC(Media Access Control) Address -> A globally unique indentifier attached to an individual network interface.

• Octet -> any number that can be represented by 8 bits.

• unicast -> A unicast transmission is always meant for just one receiving address.

• Data packet -> An all-encompassing term that represents any single set of binary data being sent across a network link.

• Ethernet frame -> A highly structured collection of information presented in a specific order.

• Payload -> Actual data being transported, which is everything that isn't a header.