Understanding the network environment requires some basic knowledge. This article creates the foundation to get you on the right track.
Steps
Step 1. Try to understand what a computer network is made of
It is a set of hardware devices connected to each other, physically or logically, to allow an exchange of information. The first networks were based on time-sharing, used mainframes and connected terminals. These environments have been implemented on the IBM Systems Network Architecture (SNA) and on the Digital network architecture.
Step 2. Learn about LAN networks
- Local Area Network (LAN) has evolved hand in hand with PCs. A LAN allows multiple users in a relatively small geographic area to exchange messages and files, as well as access shared resources such as file and printer servers.
- A Wide Area Network (WAN) interconnects LANs with geographically distributed users to create connectivity. Some of the technologies used for LAN connection include T1, T3, ATM, ISDN, ADSL, Frame Relay, radio links and others. New methods are being created every day to connect dispersed LANs.
- High-speed LANs and switched internetworks are becoming widely used, largely because they operate at very high speeds and support high-bandwidth applications, such as multimedia and video conferencing.
Step 3. Computer networks offer several advantages, such as connectivity and resource sharing
Connectivity allows users to communicate with each other more effectively. Sharing hardware and software resources allows better use of these resources, as in the case of a color printer.
Step 4. Consider the drawbacks
Just like any other tool, networks have their own drawbacks, such as virus attacks and spam, as well as the expense of hardware, software, and network management.
Step 5. Learn about the network models
- The OSI model. Network models help us understand the various functions of the components that provide the networking service. The Open System Interconnection (OSI) model is one of them. It describes how information moves from one computer software application to another over a network. The OSI reference model is a conceptual model consisting of seven layers, each of which specifies particular network functions.
- Level 7 - Application Level. The application layer is closest to the end user, which means that the OSI application layer and the user both interact directly with the application software. This layer interacts with software applications that implement a communication component. These programs fall within the scope of the OSI model. The functions at the application level generally include identifying the communicating partners, determining the availability of resources and synchronizing the communication. Examples of application layer implementations include Telnet, Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), NFS, and Simple Mail Transfer Protocol (SMTP).
- Level 6 - Presentation Level. The presentation layer provides a variety of conversion and encoding functions that are applied to the application layer data. These functions ensure that information transmitted by the application layer of one system can be read from the application layer of another. Some examples of presentation-level encoding and conversion schemes are common data representation formats, conversion between character representation formats, common data compression schemes, and common data encryption schemes, such as eXternal Data Representation (XDR), used by the Network File System (NFS).
- Level 5 - Session level. The session layer establishes, manages and terminates communication sessions, which consist of requests and responses for services that occur between applications located on different network devices. These requests and responses are coordinated by the protocols implemented at the session level. Examples of session-level protocols are NetBIOS, PPTP, RPC and SSH, etc.
- Level 4 - Transport Level. The transport layer accepts data from the session layer and segments it to transport it across the network. In general, the transport layer must ensure that the data is also delivered in the correct sequence. Flow control usually occurs at the transport level. Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) are well-known transport layer protocols.
- Layer 3 - Network Layer. The network layer defines the network address, which differs from the MAC address. Some network layer implementations, such as the Internet Protocol (IP), define network addresses so that the selection of the path can be systematically determined by comparing the source address of the network with the destination one and applying the subnet mask. Since this layer defines the logical network layout, the router can use this layer to determine how to forward packets. For this reason, much of the network design and configuration work happens at layer 3, the network layer. The Internet Protocol (IP) and related protocols such as ICMP, BGP, etc. they are commonly used as layer 3 protocols.
- Layer 2 - Data Link Layer. The data link layer provides reliable transit of data across a physical network link. Different data link layer specifications define different network and protocol characteristics, including physical addressing, network topology, error notification, frame sequence and flow control. Physical addressing (as opposed to network addressing) defines how devices are addressed at the data link level. Asynchronous Transfer Mode (ATM) and Point-to-Point Protocol (PPP) are typical examples of Layer 2 protocols.
- Level1 - Physical Level. The physical layer defines the electrical, mechanical, procedural and functional specifications for activating, maintaining and deactivating the physical link between communicating network systems. Its specifications define characteristics such as voltage levels, timing of voltage changes, physical data rates, maximum transmission distances, and physical connectors. The most well-known physical layer protocols include RS232, X.21, Firewire and SONET.
Step 6. Try to understand the characteristics of the OSI Layers
The seven layers of the OSI reference model can be divided into two categories: upper and lower layers.
- The upper layers of the OSI model address application problems and are generally only implemented in software. The highest level, that of application, is closer to the end user. Both users and processes at that level interact with software applications that contain a communication component. The term top level is sometimes used to refer to any level above another within the OSI model.
- The lower layers of the OSI model handle the problems of data transfer. The physical layer and the data link layer are implemented partly in hardware and partly in software. The lowest level, the physical one, is the closest to the physical network medium (the cabling network, for example) and is responsible for inputting information on the medium itself.
Step 7. Try to understand the interaction between the layers of the OSI model
A given layer of the OSI model generally communicates with three other OSI layers: the layer directly above it, the layer directly below it, and the layer at its height (peer layer) in other network computer systems. For example, the data link layer in system A communicates with the network layer in system A, the physical layer in system A, and the data link layer in system B.
Step 8. Try to understand OSI level services
One OSI layer communicates with another to use the services provided by the second layer. Services provided by adjacent layers help a given OSI layer communicate with its peers in other computer systems. Three basic elements are involved in tier services: the service user, the service provider, and the service access point (SAP). In this context, the service user is the OSI layer requesting services from another adjacent OSI. The service provider is the OSI layer that provides services to service users. OSI layers can provide services to multiple users. SAP is a conceptual place where one OSI layer can request the services of another OSI.
