OSI & TCP/IP

Troubleshooting Protocols- OSI / TCP/IP

Open System Internet Connection (OSI)

A conceptual framework used to understand and implement network communication protocols in seven layers.

TCP/IP

A standard model for intercommunication between devices, primarily used for troubleshooting purposes.

OSI Layers

A model consisting of seven layers, each with specific functions, represented by the mnemonic "Please Do Not Throw Sausage Pizza Away."

Physical Layer (Layer 1)

The layer that represents data as bits and includes hardware components like connectors and Network Interface Cards (NIC).

Data Link Layer (Layer 2)

Responsible for frame delivery between Ethernet devices in a Local Area Network (LAN) and includes MAC addressing.

MAC Address

A unique identifier assigned to a hardware device for physical addressing in a network.

Switch

A main device in a LAN that manages MAC addresses and facilitates communication between devices.

Network Layer (Layer 3)

Provides packet delivery between LANs in a Wide Area Network (WAN) and includes routers for inter-network communication.

Transport Layer (Layer 4)

Connects physical and logical layers, ensuring transparent transfer of segments between end users.

Transmission Control Protocol (TCP)

A connection-oriented protocol that delivers information between networks using a three-way handshake.

User Datagram Protocol (UDP)

A transport protocol that does not guarantee delivery of packets.

Session Layer (Layer 5)

Manages connections between clients and servers, including setting up, maintaining, and tearing down sessions.

Presentation Layer (Layer 6)

Responsible for data formatting, encryption, compression, and translation for end-user accessibility.

Application Layer (Layer 7)

Contains protocols and services that allow end users to operate and interact with applications.

Protocol Data Unit (PDU)

The format of data as it moves through the layers of the OSI model.

Copper Cables

Commonly used cables for data transmission, with variations like Cat5, Cat5e, and Cat6 for different performance levels.

Fiber Optic Cables

Cables made of glass fibers that transmit data using light pulses, allowing for faster and longer-distance communication.

Crosstalk

Interference that occurs when an electrical pulse on one wire is detected on another wire.

Hub

A physical layer device that connects multiple computers but does not manage data traffic.

Switch

A data link layer device that inspects and forwards data based on MAC addresses.

Router

A device that forwards data between independent networks and determines optimal paths for data transmission.

Internet Service Provider (ISP)

A company that provides access to the internet.

Border Gateway Protocol (BGP)

A protocol used by routers to share data and learn optimal paths for traffic forwarding.

Servers

Devices that provide data or services to clients.

Clients

Devices that request data or services from servers.

Bit

The smallest unit of data in computing, represented as a one or a zero.

Modulation

The process of varying voltage to transmit data across cables.

Simplex Communication

A one-way communication method where data is sent from one device to another without feedback.

Duplex Communication

A two-way communication method allowing simultaneous data exchange between devices.

Ethernet

A wired networking technology enabling communication over Local Area Networks (LAN) and Wide Area Networks (WAN).

Which device(s) are located in layer 2 of the OSI system?

Switch

Which device(s) are located in layer 3 of the OSI system

Router

Hub

A physical layer device that allows for connections from many computers at once

Node

A device on a network