In Part One of this series we looked at some of the basic terminology used in the tech world. Going forward in the series we will take a deeper dive by focusing on a specific topic.

Since it seems to be common practice to prematurely blame the network for most issues and unexpected outages, I thought this would be a great place to start.

Yes, I must admit that I am a little biased because of my background as a network engineer.

OSI Model overview:

To quickly isolate and troubleshoot infrastructure issues a clear understanding of the OSI Model is not only needed but is imperative. There are many different mnemonic methods for memorizing the seven layers of the OSI model but I want to share the one I used (this one starts at layer one and works up to layer seven):

Please Do Not Throw Sausage Pizza Away!

Pretty simple right? We’ll break this thing down backwards, which is the approach you would use when troubleshooting with a user.

Layer 7 (Application) – interacting with the application and/or operating system this is where web browsing, file transfers, email takes place; i.e. HTTP, SMTP, FTP, etc.

Layer 6 (Presentation) – Responsible for converting the data at the application so the underlying layers can understand them; i.e. ASCII, GIF, JPEG, etc.

Layer 5 (Session) – This layer is responsible for maintaining communication with the end device; i.e. NETBIOS, Appletalk, PTPP, etc.

Layer 4 (Transport) – At this layer flow control and error checking are established; i.e., TCP and UDP.

Layer 3 (Network) – In this layer the protocols, routing and addressing are assigned to the data; i.e. internet protocol (IP), ICMP (ping), IPSEC, ARP, etc.

Layer 2 (Data Link) – A physical protocol is defined at this level; i.e. ethernet, ATM, PPP, MAC Address, etc.

Layer 1 (Physical) – Is the hardware level and defines the physical connections such as cabling and connections; i.e. CAT 5, fiber, RJ45, RJ11, etc.

In part three of this series we are going take a more in-depth look at layers 7-4 and then in part four we will complete our tour of the OSI model by finishing with layers 3-1.

Wes Johns
Sales Engineer


Recent Posts
Transforming Partnerships
Transforming Partnerships: Reflecting on a Productive First Half of 2024 with SolarWinds
Digital Transformation
Digital Transformation is Driving Observability Adoption... and it’s Delivering Success!
Great Place to Work
Celebrating Success Loop1 Sri Lanka Ranks Among the Top 10 IT/ITES Workplaces
blog featured image
'Tis the Season of the Freeze
blog image
L1M3 Explainer Part 7 – Data Analytics and Business Outcomes
blog image
L1M3 Explainer Part 6 – Automation and Integration
blog image
L1M3 Explainer Part 5 – Security and Compliance
blog image
L1M3 Explainer Part 4 – Observability Data and Metrics
Shopping Cart
Scroll to Top