Lecture 1 ‐ Networking concepts and protocols - Dleifnesor/NET-215 GitHub Wiki
Types of Layered Models
Protocol model:
this model closely matches the structure of a particular protocol suite
For example the TCP/IP model
Reference model:
describes what has to be done at a particular layer, but not describe how it should be accomplished
Application Layer (Layer 7)
Network: The data that the computer is sending/receiving
“I would like to view the webpage www.google.com”
Letter: The body of the letter
“To whom it may concern, I commend your organization for the excellent service I received….”
Presentation Layer (Layer 6)
Network: Compression, encryption, other encoding
Letter: Is it in code, abbreviated (texting?)
Session Layer (Layer 5)
Network: Session set up and teardown
Letter: Tracking Number
Transport Layer (4)
Network: Port numbers tell receiver what application the data is for
Port 80 – HTTP web traffic
Port 25 – SMTP e-mail
Port 22 - SSH
Letter: Internal routing info on envelope
Suite 36
Dept. C9
Network Layer (3)
Network: IP addresses of sender and receiver
Letter: Street address and zip code of sender and receiver
Data Link Layer (2)
Network: Defines how the packets get onto the media
When is it safe to send – prevent collisions
Is the recipient ready to receive
Letter: How do you get it to the postal service?
Carrier pick up from your mailbox
Take it to Post Office
Drop it in mailbox
Physical Layer (1)
Network: Physically send the bits over media
Copper wires
Fiber optic
Radio waves
Letter: What service to use
USPS
UPS
FedEx