How Data Travels
How information actually moves across the internet.
This is the "plumbing", needed to make everything work - don't skip it.
Physical Layer
Here, all we care about are bits and signals
What's Covered
Hardware and the magic that makes it work
basics
hardware
timing
physics
line coding
timing
cabling
modulation
+ much more
Data Link Layer
Here, we care about where data is going locally
What's Covered
Rules that keep nearby devices behaving nicely
MAC addresses
flow control
link management
framing
error detection
loop prevention
VLANs
block coding
+ much more
Network Layer
Here, we care about where data is going globally
What's Covered
How data finds its way in the big network world
encapsulation
routing
multicast
IPv4/IPv6
forwarding
error detection
resolution
fragmentation
+ much more
Transport Layer
Here, we care about how data is delivered
What's Covered
Ports, connections, and delivery choices
TCP/UDP
sliding window
segmentation
header structure
5-tuple
security issues
3-way handshake
congestion
+ much more
How Data Becomes Useful
How apps and services turn that data into things you can see and interact with.
While the first 4 layers are the "nuts and bolts" that keep the everything running smoothly (or keep it from falling apart), Layers 5 through 7 are more "abstract".
“If you want a weird analogy, layers 5–7 are a zoo exhibit, where you get to look at lions and how they behave.
Layers 1–4 teach you how to build your own lion. Not from scratch, but by breaking one into pieces somewhere else, labeling them, shipping them across the world, and putting it back together at the destination.
Session Layer
Here, we care about keeping devices talking
What's Covered
How we start, manage and end sessions
behavior
checkpointing
preservation
dialog control
resumption
session loss
synchronization
state
+ much more
Presentation Layer
Here, we care about how data is formatted
What's Covered
How data is shaped and kept secret
endianness
character sets
encryption
serialization
schema
hashes
encodings
compression
+ much more
Application Layer
Here, we care about the user
What's Covered
Things used to actually get things done
web protocols
authentication
remote access
messaging
authorization
real-time stuff
directories
identity
+ much more