Week 1 NET 330 01 - JadenGil/Jaden-Tech-Journal GitHub Wiki

Sending a letter vs. a packet

Letter:

  • The minimum things needed to send a letter is zip code and street address
  • Put the letter in an envelope with a stamp then take it to the post office or your mailbox with the red flag up
  • You should add a return address
  • After it's in the office the mail carrier comes and brings it to the local post office
  • The local post office would mainly care only about the ZIP code- the street address doesn't matter to them if it's going out of state
  • The first digit in a ZIP code is regional meaning the post office will (usually) only need the first number to get the letter where it needs to be
  • For the PO to determine where to send the letter next they use "routing lists"
  • It then ends up at the local post office of the recipient where they will then deliver it to the recipient using the street address

Network data:

  • To send an email you need the name of the person's email address and an '@' followed by the domain (email server) the person uses
  • The email server is translated into the IP address by the computer
  • Add "headers" to data (Encapsulate)
  • Prepend bits for recipient and sender IP address to data
  • Send packet to the network interface controller (Your router that has your default gateway is kinda like the mail carrier bringing your letter to a post office)
  • The email will consider the path that uses the least possible hops
  • The computer uses the IP address to get the email to the recipient using the network part of the IP address (194.168.1.72.- The first 3 sections are the network ID)
  • To know where to send the email next it uses a "routing table" of IP networks and it eventually ends up at the local router of the recipient
  • The router then switches and sends it to the recipient using the host part of the IP address (The 4th segment of the address) and the host part of the MAC address (this whole possess is called ARC)

OSI Model

It's the groundwork of the entire internet (Become very familiar with the OSI Model)

image

Layer 7 is the Application Layer:

The data that the computer is sending/receiving “I would like to view the webpage www.google.com”

Layer 6 is the Presentation Layer:

Compression, Encryption, other encoding

Layer 5 is the Session Layer:

Session setup and teardown

Layer 4 is the Transport Layer:

Port numbers that tell the receiver what app the data is for

  • Port 80 -- HTTP web traffic
  • Port 25 -- SMTP email
  • Port 22 -- SSH

Layer 3 is the Network Layer:

IP addresses of the sender and receiver

Layer 2 is the Datalink Layer:

Defines how the pkts get onto the media

  • Decides when it's safe to send -- prevents collisions
  • Also determines if the receiver is ready

Layer 1 is the Physical Layer:

Physically sends the bits over media (Copper wires, fiber optic, radio waves, etc)

Another graphic for the OSI layer:

image

Net Addressing

Net ID:

  • First part of IP Address

Host ID:

  • Second part of IP Address

MAC Address:

  • Unique to every network adapter