Understanding how data moves across an internetwork is a very important component of being a network engineer.You need a comprehensive grasp of the technologies and the standards they support, and you also need to know how those technologies and standards relate to the actual network.The OSI system model bridges that gap for you. Knowing the details of the network as well as the way end-user applications interact with the network is a powerful troubleshooting tool. (more…)

Wireless technology, as a networking component, is guided by the same standards processes and organizations defined for all other networking components in the industry. Although working in the networking industry can be difficult at best, there are many components to a network that can either make or break the system. In order to help standardize and define the areas a manufacturer must build their equipment to service, the International Organization for Standardization (ISO) created the Open Systems Interconnection (OSI) reference model. This model is a seven-layer approach to data networking. Each layer encompasses a specific set of tasks or standards that must be met in order for the network to function.We’ll review each layer in greater detail because this is a very important concept to understand.A comprehensive understanding of the OSI system model is of paramount importance for the internetworking designer, installer, or supportteam. (more…)

In LANs, there are two predominant methods of controlling access to the physical medium: Carrier Sense Multiple Access with Collision Detection (CMSA/CD) and deterministic access. CSMA/CD is the access method for Ethernet. CSMA/CD is best described as the same set of rules you would follow in a meeting. In a meeting, everyone in the room has the right to speak, but everyone follows the generally accepted rule of “Only one person can talk at one time.” If you want to speak, you need to listen to see if anyone is else is speaking before you begin. If someone else is speaking, you must wait until they are finished before you can begin. If nobody is speaking, you can speak, but will continue to listen in case someone else decides to speak at the same time. If they do, both speakers must stop talking, wait a random amount of time, and start the process again. If a speaker fails to observe the protocol of only one speaker at a time, the meeting will quickly lose all effective communication. (Sounds too familiar, doesn’t it?) (more…)

Within the definition of a network, points or nodes are connected by communication paths.These paths may vary significantly depending on the paths implemented. We cover four primary topologies: bus, star, ring, and mesh. Each topology has strengths and weaknesses, as well as different associated costs. A good network design will take each topology into consideration to determine the best solution. (more…)

Before we delve into the topic of WLANs, we need to cover networking in general. A network is defined as a series of points or nodes interconnected by communication paths.The points or nodes may be devices dedicated to a single function, such as a PC dedicated to client applications, or a router dedicated to interconnecting networks.This chapter covers some fundamental theories, technologies, and applications for networks. LAN Technologies such as Ethernet, Fast Ethernet, Gigabit Ethernet,Token Ring, and Fiber Distributed Data Interface (FDDI) are prevalent in the networking industry today. (more…)

Wireless local area networks (WLANs) can be employed to provide network connectivity almost anywhere. Consider the cost savings from not having to run network cable to every possible location that could have a computer or network device connected to it. Consider the convenience of a wireless-enabled conference room. Imagine the increase in accuracy of a medical professional’s data entered directly into a tablet computer during his rounds through the WLAN instead of transcribed from a clipboard at a central workstation. Conference rooms, warehouses, indoor and outdoor public access areas, and hospitals are all suitable locations for WLANs. Unfettered access to the network, regardless of physical location, or traditional cable distance limitations is one of the primary drivers for WLANs. (more…)