OSI vs TCP/IP

[nightcat]

As part of my studies I have to go through OSI Reference Model. As far as I understand it's an alternative to TCP/IP. Although, some sites I looked at say that TCP/IP is a part of OSI. It got me confused.

To my best knowlege most of the networking is done using TCP/IP, at least I never met OSI before. Saying that my teacher keeps on pushing OSI to us and all the work given to us includes OSI but doesn't even mention TCP/IP. I personaly think he's in the wrong.

I wanted to know your oppinion on the subject and, if possible, some info?

Which one of these two are wider used?
Which one of them is the one you generaly use?

I'll be very grateful for all your replyes.

[SirDice]

OSI is a representation of what different parts/levels of a network stack do (or at least should do).

TCP/IP isn't part of OSI and OSI isn't part of TCP/IP. OSI is just a model.

You can also apply the OSI model to other networking protocols like IPX/SPX.
That's why your teacher is pushing the OSI model.

[cacosapo]

As SirDice explained, your teacher is the right way.
When the time comes, you will see that you cant match TCP/IP stack and OSI model perfectly. In fact OSI has one perfect match: IBM/SNA protocol.
But it is usefull to analyze diferent protocols and other stuff.
For example, you will face some firewalls that can act above network layer, such as at application layer. OSI model will help you to see the diference

[di0strb]

like SirDice said
OSI its just a model of a network stack
Thera are several diffrent models, OSI is the most popular.
TCP belongs to the transport layer!!
and IP to the network layer!!

google next time
ex http://www.webopedia.com/quick_ref/OSI_Layers.asp

[nightcat]

Originally posted here by SirDice
OSI is a representation of what different parts/levels of a network stack do (or at least should do).

TCP/IP isn't part of OSI and OSI isn't part of TCP/IP. OSI is just a model.

You can also apply the OSI model to other networking protocols like IPX/SPX.
That's why your teacher is pushing the OSI model.

I thought about it as well. But, one of our tasks was to compare TCP/IP with OSI. OSI has 7 layers and TCP/IP only 5. Another thing is that TCP/IP model was developed a bit earlier then OSI.They've also been developed in a different way.

These particular facts got me wondering in the first place.

I decided to ask here because I'm not sure about wether I should do what my teacher wants us to, or relly more on my own knowlege. If I go for the second, it'll mean that my teacher is going to loose his job.

And to my best knowlege IPX/SPX also uses 5 layers rather then 7.

[mickylittle2000]

SirDice is right... OSI is just a model... it provides a standard to built up a network architecture.

As u must be knowing it was devised by ISO, which is a multinatonal body dedicated to wrldwide agreement on international standards. The purpose of devising the OSI model was to open communication between diff. systems without requiring changes to the logic of underlying hardware and software...its just a model .. and it doesnt specify any protocols to be used at any underlying layer.. its generic.

TCP/IP is a set of rules which uses these layers... it was designed prior to OSI there fore doesnt have all the layers same as OSI (the application layer covers up for session, presentation and application layers of OSI).

the internet works on TCP/IP only... as its a connectionless datagram protocol and hence is the most widely used in a way...

remember OSI is a model to build a network while TCP/IP is a set of protocols which work at the various layers of the network...

i hope it gives u a certain idea of the stuff...

[nightcat]

Thanks everyone for your answers. I guess I'll have to study more then

[SirDice]

Definitely study the OSI model. But as you already found out there are very few protocols that apply 1 on 1 to the OSI model. If networkstacks were build exacly like the OSI model it should mean you can replace one part (network layer ie) from CompanyA and replace it with one from CompanyB without any problems. Unfortunately this is all academic

[nightcat]

Academics are generaly annoying busturds aren't they ?