This is from Cisco Oct 2001 Packet.. http://www.cisco.com/warp/public/784/packet/oct01/p76-training.html
It must be out of date :-) -Anil ------------------------ 5. Session Layer The session layer provides services in the application to manage inter-host communication. Think of this function as the old-time telephone switchboard operator: first, watching for a light on the switchboard indicating a connection was needed, next connecting and monitoring the call, and then finally disconnecting it by pulling the plug. For example, Network File System (NFS) is like an extended feature Telnet program for UNIX that keeps a connection (session) alive and available until the terminate command is given. Other examples include Structured Query Language (SQL), Remote Procedure Call (RPC), and X-Windows. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Priscilla Oppenheimer Sent: Saturday, December 08, 2001 3:13 AM To: [EMAIL PROTECTED] Subject: RE: Does session layer protocol use IP address ? [7:28378] That's 40% right. SQL, NFS, and XWindows are application-layer protocols. RPC and NetBIOS are session-layer protocols. We often have discussions about which books are best. Todd Lammle books can teach you basic router configuration. They are often wrong where protocol behavior is concerned. A better reference for learning about OSI is the OSI paper by Howard Berkowitz at http://www.certificationzone.com. Priscilla At 11:32 PM 12/7/01, anil wrote: > >The session layer is an elusive beast that is not implemented much >Yes, I checked it out.. >Session layer protocols include: >SQL, NFS, RPC, NetBios, Xwindows are examples of session layer protocols. >Page 9 of CCNA 2nd Edition study guide Todd Lammle > >-Anil > > > > >-----Original Message----- >From: anil [mailto:[EMAIL PROTECTED]] >Sent: Friday, December 07, 2001 11:17 PM >To: Priscilla Oppenheimer; [EMAIL PROTECTED] >Subject: RE: Does session layer protocol use IP address ? [7:28378] > > > >The session layer is an elusive beast that is not implemented much >Wait a sec, I thought SQL, NFS and netbios were session layer protocols? >Someone please correct me. >-Anil > > >-----Original Message----- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of >Priscilla Oppenheimer >Sent: Friday, December 07, 2001 9:55 PM >To: [EMAIL PROTECTED] >Subject: Re: Does session layer protocol use IP address ? [7:28378] > > >At 02:59 AM 12/7/01, mlh wrote: > >Hi, there, > > > >I read Todd Lammle's CCNA2.0 study guide and found this sentence: "Remember > >that none of the upper > >layers know anything about networking or network addresses." I am wondering > >if the session layer doesn't > >use network address, how can it establish a dialogue with other session > >layer in other host? > >I would probably disagree with Todd's statement, although it's taken out of >context and you haven't given us enough information to say that the >statement is definitely "wrong." > >However, try to picture the numerous OSI pictures you have seen. Most of >them show horizontal lines between a layer on one host talking to the same >layer on another host. So the session layer talks to the session layer on >the other host. That's probably what Todd was getting at. > >However, the pictures also show vertical lines. A layer calls on a layer >below to provide services. Each layer offers services to layers above it. > >The session layer is an elusive beast that is not implemented much. But one >example might help. NetBIOS is a session layer. On a Windows client, when >you access a Server Message Block (SMB) server, NetBIOS has the job of >setting up a session with the server. Before it can do that, however, it >must find the address of the server. If it's a modern Windows network, then >SMB and NetBIOS are probably running above TCP/IP and UDP/IP. So NetBIOS >sends a DNS or WINS query to find the IP address of the named server. It >then sets up a NetBIOS session with the server. Actually, first, the client >sets up a TCP connection. TCP has port numbers. The client sends to the >well-known TCP port for NetBIOS session (139) and use an ephemeral port on >its side. These port numbers could be considered "addresses" at the >transport layer. > >Anyway, back to the question. The statement is at best over-simplified. I >recommend you get yourself a sniffer and watch what really happens between >layers. (Ethereal is free by the way.) > >Priscilla > > > > >Thank you for your time. > > > >mlh >________________________ > >Priscilla Oppenheimer >http://www.priscilla.com ________________________ Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=28543&t=28378 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
