< All CompTIA Network+ Notes

Tobraham | CompTIA Network+ | Module 1.2 - Devices & Protocols in Relation to OSI Model

By: Tobraham | Related Course: CompTIA Network+ | Published: February 3, 2018 | Modified: February 3, 2018
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NotepadOSI Devices & Protocols (Pt. 1)

 * any hardware that does not have to deal with IP-based routing usually falls into Layer 2. Once you start handling IP addresses, you bump up into Layer 3.

Cables [L1] 

  • it’s a piece of equipment (physical device) used to connect devices, so falls under layer 1

NIC (Network Interface Card) [ L1]

  • physical device 

Bridge [L2] – data link device

  • provides point-to-point connectivity so it falls under Layer 2
  • wireless bridge, ethernet bridge

MAC (Media Access Control) [ L2]

  • physical address of the network interface card (NIC) on the machine

EUI-64 [L2]

  • IPv6 global unicast (a unique address for a single network interface across the world).
  • not a logical address a fixed global address
  • this is layer 2 bc it doesn’t require logical addressing

Frames [L2]

  • a layer 2 protocol delivery unit
  •  a segment of data with a begin / end

Switches [L2]

  • allow us to connect multiple devices on the same subnet
  • for connecting devices that don’t necessarily require an IP address.
  • map to MAC addresses

Hubs [L2]– like a dumb switch. Spits out incoming data to all devices connected to it. No mapping of MAC addresses or IPs means it is a Layer 2 device.

Router [L3] – aka ”Layer 3 Switch”

  • allow us to connect to multiple different networks
  • bc they deal with IP addresses, these are Layer 3

IP Address [L3]

  • not physical addresses – they are logical addresses. 
    • the IP is mapped to a specific MAC

Packets [L3]

  • similar to frames but are a layer 3 protocol delivery unit

Multi-layer switch [L2/3]acts as an intermediary between Layer 2 and layer 3.

  • can perform at either L2 or L3
  • can perform basic switching functions [L2] but if necessary can also perform routing functions [L3]

Encryption Devices [L6]

  • formats our data, encrypts/decrypts. Because of this, even tho this is a hardware device, it falls into Layer 6 – Presentation.



NotepadOSI Devices & Protocols (Pt. 2)

OSI Model Recap
PDNTSPA (Please do not throw sausage pizza away)

1. Physical – things you can touch/measure/see physically  that sends out an electrical signal, or wireless signals.

  • cables, NIC cards, bits, electrical impulses/signals, wireless radio frequencies

2. Data Link – things that provide point-to-point (P2P) connectivity. Does no routing. Frames are sent to bridges, switches, MAC address, IPv6 address – all direct points

3. Network – IP addressing and routing

  • routers, multi-layer switches, L3 switches

4. Transport – manages how data is pushed via TCP / UDP

5. Session – provides connection mgmt: Handshake to establish connections, maintaining connections, termination of sessions.

6. Presentation – formatting data for manipulation. Encrypting

7. Application – protocols that manage how apps send/receive data across a network, how it creates sessions and use resources

  • http, ftp, SFTP, POP3, SMTP








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