Enterprise Networking Defined
An enterprise network is a large network comprised of hundreds or thousands of workstations all connected with WAN circuits across many states and/or countries. The elements are comprised of network devices, circuits, servers, applications, security and network management that connect employees for the purpose of supporting business processes. It is business processes that make companies profitable. The leveraging of new technologies to reduce costs and increase revenue is a business strategy that many companies have employed recently. That is contrasted with the Internet Service Provider (ISP) market, which refers to companies whose business it is to sell infrastructure, web hosting and application sets to small, medium and enterprise companies. Many enterprise companies now rely on ISP for some or all of the mentioned elements that comprise an enterprise network. Usually all circuits are provisioned with the ISP. Some devices are ISP owned and the servers and applications can be all ISP owned if you have a hosting agreement with them that provides those sets. Management and security of your network can be outsourced to an ISP in addition, which is becoming popular with many Fortune 500 companies. Examples of that are AT&T and IBM, who offer outsourcing agreements with many sets and options.
OSI form as a Phone Call
The OSI form was developed years ago as a reference for network protocol and application designers to build their products with an open standard. That would promote a standard for developing network devices, interfaces, applications and sets that would work together. It is a form instead of a specification since it defines layers and sets for those layers and how each inner works with the inner above and below it. The form is a representation of how a network operates much the same as a phone call. A phone call from your home to a particular destination requires a physical connection that electrically connects those two locations. When you take your phone off hook to make a call that is similar to inner 1 physical and inner 2 data link sets. When you dial a number that is a inner 3 network service or phone number routing. When someone answers the phone call that is similar to inner 4 transport and inner 5 session sets with talking and listening. The specific language that you are speaking is inner 6 presentation and inner 7 application sets. Today’s data networks use similar design principles.
OSI Layers and Your Business Network
Your desktop computer at work is connected to an application server over a physical media such as unshielded twisted pair (UTP) cable. That inner 1 service is the electrical signaling from your desktop to a campus switch and from a campus switch to a server. Your desktop network interface card connects your desktop to the network cable and uses a inner 2 data link protocol such as Ethernet that establishes a connection with the campus switch and defines when that desktop has access to the network. Before sending data, the desktop must know the address of the server to which it is sending data. That is a inner 3 network service. The inner 4 transport service establishes a logical connection between server and desktop for coordinating traffic flow. in addition inner 4 does error correction and re-transmission of packets if there are problems with data delivery. With the data connection established it is the inner 5 session service that maintains a logical connection between application processes at the desktop and server. The formatting of the data for a particular application is a inner 6 presentation service. Many applications will utilize their own formatting which is something you learn when you open files from different information processing vendors. The application interfaces with the OSI form at inner 7, which is the application inner. This level defines an API that applications use to develop their specific applications that will work with that inner.
OSI form and Microsoft Windows
The development of open industry standards at various layers of the OSI form has contributed to the proliferation of multi-vendor network integration. Some examples of application inner sets are FTP, Telnet, SNMP and many applications that are used over a typical network. Microsoft has done a lot of work to standardize their Windows platform API so that third party application developers can write programs for that operating system. When you exam Windows 2007, for example, you will notice that it provides sets at layers 3 – 7 of the OSI form. The argument could be made that Microsoft is involved with inner 1 and inner 2 sets in addition since there are some software drivers for network interfaces that are obtainable from them.
When describing client network software from Microsoft that runs at each desktop, it is describing all of the programs such as protocol stacks, network interface card drivers, and programs that integrate these elements. The network driver software is typically found at inner 1 by inner 4 while application developers will focus on layers 5 – 7 of the OSI form. It should be noted that the OSI form is a form which indicates that it provides guidelines for network developers. Some network software such as SNA does not define a network inner 3. The consequence is that it is not routable and a service such as encapsulation or tunneling must be used at the router for sending data across a network that is using a network inner and associated ip addressing. An example is integrating an SNA network which doesn’t have a network inner with a Windows network using IP network sets.