TCP vs OSI Model

[Hill_1]

dear all,
How do we know which protocol is implemented in the HP Unix Workstation?
I was told that TCP is the implementation model and OSI is only the conceptual model. Is it true?
Do you have any idea on other protocol suite?
Thanks in advanced.

[James R. Ferguson]

Hi:

The OSI model is an abstraction and a generalization. For a quick look at how the model relates to the TCP/IP protocol, see here:

http://online.milwaukee.tec.wi.us/cis-105/tcp-ip_osi_model%20.htm

http://www.kempthorne.com/douglas/douglas/osi.html

Regards!

...JRF...

[Sridhar Bhaskarla]

TCP/IP was designed before ISO/OSI model. Unix implements TCP/IP suite. Application Layer in TCP/IP does the job of Application,Presentation and Session layers of OSI. However, TCP/IP's transport layer doesn't need to guarantee reliable packet delivery as it has UDP also at this level. This is one major difference. Network layer (also called IP layer) takes care of packet routing. Device drivers etc., fall under the category of Link layer.

You can give a leisure reading on Douglus E Comer's "Internetworking with TCP/IP". There are 3 volumes and they certainly are worth reading.

There is one short but cute tutorial on TCP/IP. I am sure there are plenty of stuff on the internet too.

http://www.doc.ic.ac.uk/~ih/doc/pc_conn/tcpip/intro/intro0.html

-Sri

[ramesh_6]

Hi
OSI model was designed by the International Standards Organisation as a Reference guide for communication.OSI mdoel consists of seven layers; TCP/IP actually relates to these layers.

TCP/IP's Application Layer

TCP/IP's application layer integrates the functionality of OSI model's appliation,presentation and session layer

TCP/IP's Transport Layer

This layer does the fucntionality of OSI's transport layer. Transport Communication Protocol(TCP & UDP) fucntions in this layer.

TCP/IP's Internet Layer

This layer does the fucntionality of OSI's network layer. Here is where the network components like router works. They actually work on the basis of a logical address which is nothing but an ip address

TCP/IP's Network Interface Layer

This layer does the functionality of OSI's datalink layer. This layer is responsible for defining rules for sending and recieving data. This layer is further subdivided into MAC (Media Access Control) layer LLC (Logical Link Control) . MAC layer contains the hardware address of the network card.

TCP/Ip's hardware Layer

This layer does the functionality of OSI's physical layer. This layer refers to physical part of the network i.e cables, connectors, circuits etc.

To summarize

TCP OSI

Application layer --> Application Layer
Presentation Layer
Session Layer

Transport Layer --> Transport Layer

Internet Layer --> Network Layer

NetworkInetrface --> Data Link Layer

Hardware Layer --> Physical Layer