< All CompTIA Network+ Notes

Tobraham | CompTIA Network+ | Module 1.1 - OSI and TCP/IP Models

By: Tobraham | Related Course: CompTIA Network+ | Published: February 2, 2018 | Modified: February 2, 2018
Join Cybrary

NotepadOSI - Application Layer (L7)

Application Layer – which application is necessary for the task at hand? Email? File transfer? Web page?

  • Telnet, FTP, http, DNS SMTP
  • enables apps to access the net
  • determines availability of resources by checking other layers 
  • sync communications


NotepadOSI - Network Layer (L3)

Network Layer – aka ”IP Layer” – functional means of transferring data thru one or more networks

  • Uses IP addresses (these are logical addresses, not hard coded like MAC)
  • Translate logic address into physical addresses
  • performs network routing
  • fragment (outbound)  and reassemble (inbound) packets
  • Routers and packets are Layer 3


NotepadOSI - Physical Layer (L1)

Physical Layer – cables and bits, electricity. The first point of your data in your network.  

  • pinouts
  • voltages
  • cables specs
  • NIC cards


NotepadOSI - Physical Layer (L2)

Data Link Layer 

  • packages the bits into frames
  • transfer of data from point to point (A to B)
  • MAC (Media Access Control) Address – unique to your specific hardware device
    • once a bit is sent to a MAC address, you are at L2
  • Hub – ’dumb’ packet forwarding. Not selective with its destination


NotepadOSI - Presentation Layer (L6)

Presentation Layer (L6)  – translates data into a form that app layer can understand

  • encryption / decryption
  • processing XML data
  •  EBCDIC from one PC to ASCII on another


NotepadOSI - Session Layer (L5)

Session Layer (Layer 5) – ”Traffic Control”

  • controls connections between computers
  • establishes. manages, and terminates connections
  • regulates when a computer can send and how much
  • performs handshakes and says good bye


NotepadOSI - Transport Layer (L4)

Transport Layer (L4) mgmt and control

  • manage and control the data packets
  • split communications into different packages (TCP / UDP)
    • TCP – ”Transmission Control Protocol”
      • receipt of delivery
      • allows resending of packets of they were bad
      • slower but far more accurate
    • UDP – ”User Datagram Protocol”
      • no confirmation of delivery
      • just allows for streaming with no verification
      • Skype, VOIP, streaming video
      • faster bandwidth bc no confirmation
      • dropped packets result in audio skips or fuzzy video


NotepadOSI: 7 Layer

OSI Model = Open Systems Interconnection
Means of discussing how networks work by breaking it into layers.

Layers
(Please Do Not Throw Sausage Pizza Away)
(People Don’t Need To See Paula Abdul)

  1. Physical – hardware – NIC, cables
  2. Data Link – MAC addresses, switch, frames
  3. Network – IP addresses, routers
  4. Transport – breaks up session into packets
  5. Session – management of sessions – who’s allowed to talk and when 
  6. Presentation – encrypt/decrypt, format/prepare data to be presented to us on screen
  7. Application – dictates what aspects are allowed to communicate


NotepadTCP / IP

TCP / IP – describes our networking model in a different series of layers like OSI, but the layers are slightly different

N.I.T.A. ”Never Ingest Toxic Apples
Network Interface – similar to L1 and L2 on OSI model
Internet Layer – L3
Transport Layer – L4
Application Layer – L5 – L7


< All CompTIA Network+ Notes
Join Cybrary

Our Revolution

We believe Cyber Security training should be free, for everyone, FOREVER. Everyone, everywhere, deserves the OPPORTUNITY to learn, begin and grow a career in this fascinating field. Therefore, Cybrary is a free community where people, companies and training come together to give everyone the ability to collaborate in an open source way that is revolutionizing the cyber security educational experience.

Support Cybrary

Donate Here to Get This Month's Donor Badge

 
Skip to toolbar

We recommend always using caution when following any link

Are you sure you want to continue?

Continue
Cancel