Improving the Networking Infrastructure by focusing on the OSI network diagramIf you want to win the Indy 500, is important not only to have a high performance engine, but the proper tires, suspension, driver, a solid race track and a efficient pit crew. Analogous to this, in order for the computers to perform well, the computer, network wiring, switches, routing, network services, operating system, and system administration staff should all be working well.
The approach is to improve the services based on the network OSI reference model. This has been included below. The concept is to start from the bottom and solidify each layer so that the layer above it can have a reliable basis to be built upon. The TCP/IP stack is not going to be re-written, or hacked, but instead the elements that correspond to the layers are going to be analyzed and solidified. Most of the emphasis will be on TCP/IP based assumptions, however, consideration is taken for the heterogeneous environment.
OSI Reference Model.
The Open Systems Interconnect (OSI) Reference Model has seven
layers that each defines a function
performed when data is transferred between applications across
a network. These layers are usually
pictured as a stack of blocks, leading to the common term "protocol
stack."
| Application Layer | application programs that use the network |
| Presentation Layer | standardizes data presented to the applications |
| Session Layer | manages sessions between applications |
| Transport Layer | provides error detection and correction |
| Network Layer | manages network connections |
| Data Link Layer | provides data delivery across the physical connection |
| Physical Layer | defines the physical network media |
Each layer of the stack defines a function that may be performed by any number of protocols. Any given protocol may perform multiple functions. Each protocol communicates with a peer that is an equivalent implementation of the same protocol on a remote system. Each protocol layer is only concerned with communication to a peer at the other end of a link. For example, e-mail is an application level protocol that communicates with a peer e-mail application on a remote system. The e-mail application does not care whether or not the physical layer is a serial modem line or a twisted pair Ethernet connection.
Information is passed down through the layers until it is transmitted across the network, where it is passed back up the stack to the application at the remote end. Each layer relies on the other layers to perform their functions. The individual layers do not care how the other layers operate. They only need to know how to pass information up or down from one layer to another.
TCP/IP utilizes a more simplistic reference diagram. Some of the layers
of the OSI diagram can be combined to
provide the following reference model. Since the focus of the document
will be to improve the performance of hosts
utilizing TCP/IP, Figure 1.2 will represent the network being referenced.
| Application Layer | Consists of applications and processes that use the network. |
| Host-to-Host Transport Layer | Provides end-to-end data delivery services |
| Internet Layer | Defines the datagram and handles the routing of data |
| Network Access Layer | Consists of routines for accessing physical networks |