OSI layer related question

sixth_sense

hi,

I m new to cisco world . preparing for CCNA exam. I am going through Todd lammle's CCNA study guide. my question is on OSI reference model.

I come to know, that, the session layer is responsible for setting up, managing and tearing down sessions for end to end communication.

so, whats the difference between session layer and Transport layer's connection oriented communication approch?

Webmaster

One of the key differences is mentioned in the first sentence of my Network+ OSI model TechNotes:
"Establishes, maintains and terminates end-to-end connections (sessions) between two applications on two network nodes."

When a connection on the transport layer has been established between two network nodes (=roughly the NIC and the TCP/IP stack for example) an application can use a session layer protocol to establish a session between two applications running on the network nodes (ie. SQL session protocol between client software and a SQL server). This allows session protocols to operate on different kind of network/transport protocols (ie. the session protocol Netbios over IPX/SPX or Netbios over Netbeui).

I hope this helps,

Johan

sixth_sense

hi johan,

Thnx for quick reply. so, can i make a concept this way, like; when i start "putty- ssh with linux server" or "terminal server client - with a windows terminal server" , first the "Data link layer" eastablish a session and then for aplication lavel communication (in this example, putty/terminal client) eastiblish another session "session layer" for communication ... I m correct ??

I guess so, because i know that request initiating node start sending PDU from upper layers and receiving node receives them from physical layer all the way to applicatoin layer (or any upper layer).


Thanks ,

sixth_sense.