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


image


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