TCP/IP Networking Fundamentals
for Sysadmins
Networking 101 Back to Basics
Aaron Staines
NETWORK/SYSTEM ENGINEER | CCISO
Module
Overview
What Is the OSI Model (Overview)
Physical Layer of OSI Model
Data Layer of OSI Model
Network Layer of OSI Model
Module
Overview
Transport Layer of OSI Model
Session Layer of OSI Model
Presentation Layer of OSI Model
Application Layer of OSI Model
OSI Model Overview
OSI Model Overview
Layer 7 Application
Layer 6 Presentation
Layer 5 Session
Layer 4 Transport
Layer 3 Network
Layer 2 Data
Layer 1 Physical
What Is the Physical Layer of the OSI Model
What Is the Physical Layer of the OSI Model
Physical Issues – Cables/Equipment
Electrical Current as Data
Old School Telegraph
Hub – Don’t Use
What Is the Physical Layer of the OSI Model
What Is the Data Layer of the OSI Model
What Is the Data Layer of the OSI Model
Switches Live Here Generally
Data - Frames
Uses MAC Addresses
MAC Table – Maps MAC to Port
What Is the Data Layer of the OSI Model
ARP – IP to MAC Address
What Is the Data Layer of the OSI Model
192.168.1.4
192.168.1.2
192.168.1.1
192.168.1.3
What Is the Network Layer of the OSI Model
What Is the Network Layer of the OSI Model
Equipment – Routers / Firewalls / Switches
Firewalls Can Operate in Layers 3 – 7
Layer 3 Switch – Limited Layer 3
Layer 3 Switch – Cost Savings
What Is the Network Layer of the OSI Model
Other Equipment Types Exist
IP Addressing Lives Here
Layer 3 Has Protocols
What Is the Transport Layer of the OSI Model
What Is the Transport Layer of the OSI Model
Responsible – Transportation / Ports
Reliable Transportation
2 Port Types – TCP / UDP
What Is the Session Layer of the OSI Model
What Is the Session Layer of the OSI Model
Old School Switchboard Operators
Establish The Session
Maintain The Session
Reconnect Session
What Is the Session Layer of the OSI Model
Terminate Session
Session Termination – Not Always By Choice
2 Year Old – Destroy Sessions
What Is the Presentation Layer of the OSI Model
What Is the Presentation Layer of the OSI Model
3 Critical Functions
1. Makes Code Useable for Application Layer
2. Compresses Data – Think Zipping a File
3. Encryption – Obfuscation of Data
What Is the Application Layer of the OSI Model
What Is the Application Layer of the OSI Model
Where Users See Issues
Start at Layer 1
Work through the Layers until Resolution
Module
Review
OSI Cake
Acronym –
All People Seem To Need Data Processing
Physical Layer – Current / Don’t Use Hubs
Data Layer – Switches / MAC Addresses
Module
Review
Network Layer – Routers / Firewalls / IP
Transport Layer – Virtual Train / Ports
Session Layer – Modern Day Switchboard
Presentation Layer – Usable Data / Encrypt
Application Layer – Users Notice Issues Here