REAL LIFE example!! (TCP/IP and OSI layers) // FREE CCNA // EP 4

NetworkChuck Technology Careers Career & Money

About this video

Episode 4 of his free CCNA course (sponsored by Boson Software, per the intro) uses Cisco Packet Tracer in simulation mode to follow one real request: a user browsing to networkchuck.coffee to order coffee. Walking the packet down the OSI model — while noting real networks use TCP/IP and that session and presentation are usually folded into application — he covers Layer 7 HTTPS, then Layer 4 transport: TCP for reliable, retransmittable delivery versus faster, less reliable UDP, with destination port 443 for HTTPS (port 80 for HTTP). Adding the Layer 4 header to data is encapsulation, producing a segment; adding the Layer 3 header with source IP 10.1.1.3 and destination IP 23.227.38.65 produces a packet; adding the Layer 2 header and trailer with MAC addresses produces a frame sent over the physical layer. He shows each hop: the switch reads only Layers 1-2 and forwards by its MAC/CAM table, the router de-encapsulates to Layer 3, checks its routing table, then re-encapsulates with new source/destination MACs for the next hop, and the destination server de-encapsulates layer by layer back up to the application before replying the same way. The video closes with two exam-style questions worked by elimination, identifying application-layer functions and TCP as the protocol using a three-way handshake for connection-oriented reliable transfer.

Key takeaways

Encapsulation names change per layer: data plus a Layer 4 header is a segment, plus a Layer 3 header is a packet, plus a Layer 2 header/trailer is a frame
Layer 4 chooses the transport: TCP is reliable and connection-oriented; UDP is faster but does not guarantee delivery — HTTPS uses port 443, HTTP port 80
Switches forward using only Layer 2 MAC addresses and their CAM table; they cannot see IP addresses or upper layers inside a frame
Routers de-encapsulate to Layer 3, route by destination IP, then re-encapsulate with fresh Layer 2 MAC addresses for each new hop
The receiving host reverses the process, de-encapsulating up through transport to the application layer, and the reply repeats the full encapsulation journey

Episode details: published August 6, 2020 · 16:50 long. Summary written by Self Growth Videos from the episode itself. Business results and any income figures mentioned are NetworkChuck’s own claims, shared for education — they are not typical or guaranteed.

← Previous: what is TCP/IP and OSI? // FREE CCNA // EP 3 · Next: you need to learn AWS RIGHT NOW!! (Amazon Web Services) →

All NetworkChuck videos · NetworkChuck profile · NetworkChuck on YouTube