OSI
OSI
Uhh...I THINK it stands for "Open Systems Interconnect". I believe that this is a standard brought forth by ISO. It is most widely recognized as the OSI Reference Model. This model breaks all communications between applications on hosts across a network into 7 steps, namely (starting at the top) Application, Presentation, Session, Transport, Network, Data-Link (divided into LLC and MAC in Ethernet networks), and Physical. Following is a brief explanation of each layer:
Application: well, applications. This is the program that delivers information to the user.
Presentation: this layer deals with things like encryption and compression. Basically it deals with manipulation of data prior to presentation to the application or session layers.
Session: establishes connections between computers and manages things like logins.
Transport: layer 4 deals with flow control and guarantee of delivery (TCP and UDP live here)
Network: chooses the most effective data path for network traffic (IP lives here)
Data-link: Layer responsible for the manipulation of data prior to delivery of information to or from the physical layer. In Ethernet this is subdivided into Logical Link Control (this buffers and controls the flow of traffic to minimize over and underrun) and Media Access Control (or MAC, which gives each computer a physical address and decides who as access to the wire at any given point). This is where Ethernet, as a protocol, lives.
Physical: this is the copper or fiber or whatever that is used to transmit the binary data from host to host.
When information reaches the remote host, it must traverse all these layers in the reverse order stripping off the header information added by the layers on the source host until it reaches its final destination layer.
Because all network systems have to follow these rules of engagement, so to speak, this guarantees interoperability of gear provided by different vendors. And, no, I don't know the RFC for that one.Oh, and by the way, for anyone that is even remotely interested in learning networking, it is CRITICAL that you understand this reference model completely.
That close enough?
[AK]Zorro
Chief Operations Officer
AugustKnights.com WizOp
Damn good work.
A little known fact of trivia is the OSI model (just that, a model for understanding the communication process) was once an actual protocol. Still exists but rarely used. The trivial part is that the OSI protocol was to be the standard protocol for Internet communication before the advent of TCP/IP. However, due to reasons which I won't bother listing which made the OSI model inferior to TCP/IP, TCP/IP was adopted as the standard.
Since then, usage of OSI as a viable protocol have been nearly non-existant. I've never seen the OSI protocol in actual usage - I've just read it DOES still exist and used *places*, who knows where. ...it surely isn't used across the Internet.
Again, good answer...
Regards,
The Wraith
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