Overview
This lecture covers the four layers of the TCP/IP stack, explains the concept of sockets, and clarifies the role of MAC addresses in computer networking.
The TCP/IP Protocol Stack
- TCP/IP is a suite of protocols including Transmission Control Protocol (TCP) and Internet Protocol (IP).
- It consists of four layers that manage all incoming and outgoing data across a network.
- Each data packet passes down and up through these layers during transmission.
- The stack enables any device running TCP/IP to communicate and transfer data over the internet.
The Four TCP/IP Layers
- Application Layer: Handles protocols related to specific software applications, like HTTP or FTP, and adds an application header to data.
- Transport Layer: Uses TCP to establish end-to-end connections, splits data into packets, numbers them, and assigns port numbers for correct reassembly.
- Network Layer (Internet Layer): Adds source and destination IP addresses to each packet; routers use this to direct packets.
- Link Layer (Physical Layer): Adds source and destination MAC addresses and manages the physical network connection.
Sockets and Ports
- A socket combines an IP address and a port number, uniquely identifying a connection and the application that should receive the packet.
- Ports determine which application on a device handles the incoming data.
MAC Addresses vs. IP Addresses
- IP addresses are logical, can change, and operate at the Network Layer (Layer 3).
- MAC addresses are physical, hard-coded to each network interface card, never change, and operate at the Link Layer (Layer 2).
- MAC addresses are 12-digit hexadecimal numbers unique to every network device.
Key Terms & Definitions
- TCP/IP — A suite of networking protocols for communication across networks.
- Application Layer — The top TCP/IP layer handling protocols for applications.
- Transport Layer — Manages data segmentation, connection, and port numbers via TCP.
- Network Layer — Assigns IP addresses and directs packets through routers.
- Link Layer — Manages physical connections and uses MAC addresses.
- Socket — Combination of IP address and port number for network communication.
- MAC Address — A unique, hardware-based identifier for network devices.
Action Items / Next Steps
- Review the individual functions of each TCP/IP layer.
- Understand the differences between MAC and IP addresses.
- Learn more about common application-layer protocols (e.g., HTTP, FTP).