connectin establishment, session & TCP

binarysoul

What is the difference between the session layer and the transport layer with respect to connection establishment? TCP uses 3-way handshake, while session also starts, maints and terminates connection, so what is the difference?

Maybe I just discovered a duplication of functions...

agustinchernitsky

Transport layer is about "virtual circuits" between clients and server. It "transports" the packets from one side to another (actually network layer does this, that is way the virtual stuff), doing transport control.

Session layer only makes sure that data from one session does not get mixed with another internally.

Imagine two FTP clients on the same computer downloading data. Both use Layer 4 to establish a TCP session and use the session layer so that each clients manages its own connection. If it wasn't for the session layer, how would the FTP client distinguish each connection? This is the idea...

binarysoul

thanks it's much clear now

truesdq

agustinchernitsky

what did Binarysoul ask you this like Question was in my mind for so long but still i am confused about this Question because as TCP at transport layer one of its responsibility is to create connection between source to destination and maintained till completed all segments and then terminated connection and TCP is also stateless PROTOCOL because it creates separate connection for separate users if any and process to process delivery...
if TCP does this all then why session layer also does create any session means make connection b/w source to destination ?
and one thing else i found on internet and session layer work with UDP that session layer makes connection for UDP and maintained till to complete all segments being sent then terminates connection...

Zartanasaurus

I think the confusion stems from the fact that you are talking about the OSI session layer and trying to apply it to TCP/IP which has no session layer. OSI session layer functionality is split between Transport and Application layer in TCP/IP.

truesdq

this n0t matter as you supposed actually i had mentioned what are definitions of session layer and transport layer (TCP)
as session layer = defines as establishes connection b/w source to destination ,,, maintained and on completion it terminates ...
as TCP At Transport layer = defines as it makes connection host to host and terminates when all segments are being sent
although TCP has many others function as well but those which session layer does ... so tcp does too
I need some1 who make it clear to me
i will appreciate your assistance...