Chapter 3 - Protocols and Models

The process of reassembling individual message fragments into the original message at the receiving host.

Manages the rate of data transmission, determining how much information can be sent and at what speed.

Defines the maximum time a device waits for a response from the destination before assuming a failure.

Determines when a device can send a message, handling situations like multiple devices sending data simultaneously.

Occurs when multiple devices send data at the same time, corrupting the messages.

One-to-one communication, sending data from a single source to a single destination.

One-to-many communication, sending data from a single source to a select group of recipients.

One-to-all communication, sending data from a single source to every device on the network.

A reliable, connection-oriented protocol that ensures data is delivered in the correct order and acknowledges successful transmission.

A connectionless, unreliable protocol, where data is sent without guarantees of arrival or order. It's fast but less secure.

The older version of Internet Protocol, using 32-bit addresses, which are becoming scarce.

The newer version of Internet Protocol, using 128-bit addresses, providing a much larger address space.

A technique that translates private IP addresses to public ones, allowing devices on a private network to access the internet.

A protocol used to report errors in packet delivery, providing feedback to the source host.

A protocol that translates IP addresses to MAC addresses, helping devices find each other on the same network.

A networking standard that defines how devices connect and communicate on a local network.

The OSI model is a conceptual framework that describes the functions of a network system. It consists of 7 layers: 1) Physical, 2) Data Link, 3) Network, 4) Transport, 5) Session, 6) Presentation, 7) Application.

The Physical Layer is responsible for the physical transmission of data bits over the network media, such as cables or wireless signals. It deals with the electrical and mechanical aspects of network communication.

The Data Link Layer is in charge of error detection and correction, addressing data frames, and controlling access to the physical media. It ensures reliable data transmission between two directly connected devices.

The Network Layer is responsible for routing data packets across the network. It determines the best path for data to travel from source to destination.

The Transport Layer manages the end-to-end communication between applications. It ensures reliable data delivery, provides flow control and error checking, and handles segmentation and reassembly of messages.

The TCP/IP model is a simpler reference model than the OSI model, combining some of its layers. The TCP/IP model focuses on the practical implementation of networks, while the OSI model is more theoretical and conceptual.

Segmenting messages is breaking large data chunks into smaller units, increasing speed and efficiency. This allows multiple data streams to share the network without tying up a single connection.

Multiplexing is combining multiple data streams into a single stream for efficient transmission. It allows multiple users to share a single network connection.

The process of adding information to the data by a protocol at each layer of the network model, creating a layered structure.

The specific format a piece of data takes at each layer of the network model, containing information related to that protocol.

TCP, or Transmission Control Protocol, is responsible for sequencing the individual segments of a message, ensuring they are ordered correctly at the destination.

The process of adding information to data starts at the application layer and works down through the network model, with each layer wrapping the data with its own information.

The process of removing information added by each layer as data travels up the network model, returning it to its original form.

Data is encapsulated through 5 main layers: Data (Data Stream), Segment, Packet, Frame, and Bits (Bit Stream).

Only the segments that fail to reach the destination need to be retransmitted, not the entire data stream, leading to increased efficiency.

Sequencing involves numbering the segments of a message to ensure they can be reassembled in the correct order at the destination.

An IP address is a unique identifier assigned to a device on a network. It acts as a digital postal code, guiding data packets to the correct destination.

Every IP packet holds two addresses: the source, where the packet originated, and the destination, where it's supposed to go. These addresses determine the packet's journey across the network.

An IP address has two components: the network portion, which identifies the network the device belongs to, and the host portion, which identifies the specific device within that network.

A MAC (Media Access Control) address is a physical address embedded in a network interface card (NIC). It's used for communication within the same network, making sure data reaches the correct device.

Devices on the same network share the same network portion in their IP addresses, while having unique host portions.

When devices have different network portions in their IP addresses, they belong to different networks. Communicating between them requires routing via intermediary devices.

The Network Layer uses IP addresses to route data packets from source to destination. It determines the best path for the packet to travel across the network.

The Data Link Layer uses MAC addresses for local communication. It establishes connections and facilitates data transfer between devices on the same network.

The Data Link layer handles local network communication. It assigns unique MAC addresses to each device on a network, enabling them to communicate with each other. When data needs to be sent beyond the current network, the Data Link layer uses the default gateway's MAC address to forward the data to the next network hop.

A default gateway is a router interface IP address that acts as a bridge between a local network and external networks. Devices on the local network use the default gateway to access other networks. Without a default gateway, devices would be limited to only communicating within their own local network.

The Data Link layer uses MAC addresses for local communication. These addresses change with each network hop as the data packet travels through different network devices. This is because MAC addresses are specific to each network interface.

The IP address remains the same throughout the entire data transfer process. This is because it represents the global destination address and is independent of the specific network hops.

PC1 uses its MAC address to send the data to the default gateway's MAC address. The default gateway then uses its MAC address to forward the data to the next network hop. The IP address of the web server remains constant throughout the process.

Data Link layer uses MAC addresses for local communication, which are unique to each network interface and change with each hop. Network layer uses IP addresses for global addressing, which remain the same throughout the entire journey.

When PC1 sends data to a remote server, the router (default gateway) receives the data frame. The router examines the destination IP address and uses its routing table to determine the next hop for the data packet. The router then prepares a new data frame, including the appropriate MAC address for the next hop, and sends the data to the next network device.

MAC addressing allows devices on a local network to identify and communicate with each other. When data needs to be forwarded to another network, the router uses the MAC address of the next hop to ensure the data is delivered correctly.