1.0 Compare and Contrast OSI and TCP/IP model

Alright! have you read the title? Im hoping that you won’t stop scrolling down because at the first place, a CCNA reviewee must be an I.T./ engineering guy who dealt already with this OSI and TCP/IP model and probably has learned  a lot to their professors. So what’s the purpose of this blog, aside because I wanted to learn more, one thing that I struggled to compare these models is to make it easy for me to explain it in job interviews. Job interviews also let me explain the different layers and thier functions.So what I did is the keyword technique:

Application–>services to application processes

In simple, it provides network services to application processes, so come to think of a network service, we use network to transfer file, FTP and HTTP are there. So that is just my way to explain application layer.

Presentation-encryption,translation and compression

From the word itself, the goal of this layer is to ensure that the data is PRESENTABLE or READABLE by the system

SESSION- establish, manage and terminates

How I explain Session layer is how I use my facebook log-in,scroll down then log out, as simple as that.

TRANSPORT- responsible for the delivery of a message from one process to another.


With this layer, it ensures the whole message in tact and in order, we will deal further to this layer on the next blog

NETWORK- best path determination


The network layer is the layer that chooses what is the best path should a packet goes.

DATA LINK  – error control and hardware accessing

The function of data link layer is to combine packets into bytes and bytes into frames. Each frame has a header and  a trailer. Only the Data link has the trailer, it contains FCS for ERROR control

DATA LINK is divided into two;

LLC-  Logical link control used for error detection and flow control

MAC- for hardware accessing


PHYSICAL–>  delivery of bits from one device to another

Always think of physical layer as the physical connection or the medium used for communication.

I’m so sorry for beating around the bush, so let’s get into the topic- the purpose comparison or the pro’s and con’s of the TCP/IP and OSI

PURPOSE:  standardization of the devices; OSI was created by ISO to standardize the devices. It means your Samsung headset will work with your lenovo laptop. OSI and TCP/IP were the competing models before up until TCP/IP has won against OSI because OSI development suffered because of slow formal standardization process.By the way, TCP/IP was created by the US Department of Defense and a lot of volunteers from different universities helped the development of TCP/IP


That’s the simplest and the most noticeable difference of the OSI and TCP/IP.

I have this mnemonics for the OSI model: PaDaPa Na Tinira Si Pamela Anderson 

that’s from layer 1 to 7 and for the TCP/IP is simply ATIN–> from application to network

So if we have to summarize the difference of OSI and TCP/IP, we just need to look on layer differences. The TCP/IP application layer covers the OSI application, presentation and session layer, obviously they almost do the same function. The transport layer is the same for both models but that the thing is TCP/IP covers two main protocols called UDP and TCP which will discussed on the next blog. The internet layer is the counterpart of OSI network layer and Network access layer is the counterpart of the OSI physical and data link layer. The TCP internet layer is governed by internet protocol that defines how a packet should go to its destination. Logically, OSI is just created as a reference model or guidance tool around which the network is built while TCP/IP is in a way of implementation of OSI model.


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