>To Chuck, I do not agree that the OSI model is "crap". Sometimes it can >add confusion, but for the most part it is fairly well defined. Also, no >one ever said TCP/IP follows the OSI model 100%. The concept of layering >is just very easy to see with the OSI model. TCP/IP generally has only >layers such as the application, network, transport, and physical. You >could throw in datalink in there I suppose. It certainly helps people >understand networks. Without the OSI model, it seems like a lot of random >musings. TCP/IP has a very clear transport and network and application >layer.
Then how is it that the TCP/IP suite was developed before the OSI reference model was finished, largely by people that, at the time, were very hostile to the OSI work and vice versa. I was there at the time, and remember European delegates to ISO making comments like "we will never use protocols developed by the bomb-crazed American military." > >Not sure if there was sarcasm or an attack on the "reputable source" that >"UDP is an application layer" part. I am going to assume so, because it's >spot as a transport is very clear. > >So, it is wrong for me to say that ftp clients and telnet clients use layer >7? (referencing user application vs service application)? Then where >would it go? No where? (hence why you say the OSI model is crap?) Client/server is again one of those concepts that sometimes needs to be used precisely. In protocol theory, a client initiates request and a server responds to them, as opposed to a peer-to-peer implementation in which either end can initiate requests. The term "client" has been overloaded to include user applications _from_ which requests initiate. In formal OSI terminology, any given layer (N) provides a service to an (N)-user entity above it. In the case of the application layer, the (N)-user, where N is equal to layer 7, is above the OSI stack. The point of interface between the application service user and the application service provider is the Application Service Access Point (although this evolved further around 1988). You mention a UNIX background. Isn't the definition of a daemon a process that has no tty-equivalents directly attached? The application layer is the daemon; the user application is the tty-equivalent. > >To Jose, I feel they do not work at the network layer, and work at the >application layer. If it uses protocols, (EIGRP and OSPF) it uses IP RAW >which means it skipped the transport component, ultimately I still feel it >is at the application layer. In my sophomore year of high school, I _felt_ that a girl named Gail _should_ have reciprocated my affections and lust. She didn't. Just because, Carroll, you feel something, doesn't make it right. Ignoring the TCP/IP work, ISO says you are wrong in its "OSI Routeing Framework" document, in which routing protocols for layer N are defined as layer management protocols for and of layer N. The transport they use is irrelevant, because their payloads affect layer N directly. > >Perhaps it is just my roots that routing daemons are still just daemons, >programs which run on a box. They dynamically insert information into a >routing table. Unix machines still do it, a Cisco router is just an >appliance version of a unix box with a routing daemon with multiple >interfaces. (without extraneous baggage of course) Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=29191&t=29139 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
