OSI Model

 

OSI Protocols

The OSI Model provides a conceptual framework for communication between computers, but the model itself is not a method of communication. Actual communication is made possible by using communication protocols. Each layer on the OSI Model has some protocols associated with it. Some important protocols on each layer are as in below:

OSI Model

 

 

OSI Devices

Similar to protocols, each layer has associated equipment with it. For example, Hubs, Repeaters & Media Converters operate at Layer1, L2 Switches & Bridges generally operate on Layer2, Routers & Layer3 Switches operate on Layer3, Firewalls work on Application Layers and some on Transport Layer4 as well.

OSI Model

 

 

How to remember Layer Names

In addition to remembering the functions, features, basics, protocols and devices of each OSI layer, we also need to remember the names of the layers. We can simply memorize them but relevant phrases are easy to remember. We can remember them by memorising some interesting phrases as in below:

OSI Model

In these phrases, the first letter of each word is the same as the first letter of an OSI layer name as highlighted in YELLOW in above. So, it becomes very easy to remember these layer names & order.

 

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Written by 

Waqas Karim is a seasoned Network Expert … Geek. He is the founder of ATech. ATech was started for learning & sharing. Over time the platform has grown to include other resources which continue to attract fellow networkers. Today it sees upward trend of a hundred thousand visitors per month, scattered all over the globe. His specialty is networking, but his interest & expertise spans from traditional IT to Network Security including Programming, Virtualization, Service Provider & so on... no matter the badge on the box. He is CCIE Certified (CCIE#56732) in addition to below badges: Telecom Engineer (BE) + CCIE-RS (CCIE#56732) + Huawei Certified (HW#706632) + MBA Microsoft Certified MCITP, MCSE#109*26, CCNP-Sec, CCNP-SP, CCNA-DC, CompTIA Security+, Nokia NRS-I, JNCIA, ITIL Certified (ITIL#*6373), CEH (Certified Ethical Hacker).

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Isabelle.Lily@yahoo.com
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Isabelle.Lily@yahoo.com

How is the multi-tasking done in network equipment & on which layer to be precise?

Dylan
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Detailed explanation … like it!

Noahn
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How many type of port numbers are there on transport layer in total?

Adrian_allan@googlemail.com
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Adrian_allan@googlemail.com

What does Transport Layer do exactly?

Ava Ellan
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What is CRC? On which layer does CRC work?

Zoe.A
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So, the real model we use is TCP/IP model?

LilyHarper7798@ymail.com
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LilyHarper7798@ymail.com

What is the different b/w TCP & UPD header?

Sophie
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Really nice & concise post. Keep it up )):

Fabian
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Great graphics!!!

Luis Diego
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What are media layers or upper layers? Are these OSI layers or TCP/IP layer names?