January 21, 2002 Week 3: Day 1
Welcome to Lesson 3 - Networking Media
Tangible (cables) and Intangible (wireless) media are at the heart of networked communications because they supply the network's "glue" making it possible for data to enter and leave a computer at some point which allows networked communication to actually occur.
Network media is comparable to a highway system in that it allows for data (the payload) to be carried from point A to point B.
Tangible Media: Primary Cable Types: (Click here to see what they look like)
General Cable Characteristics
*Bandwidth rating - describes how many bits or bytes of information a cable can carry over a unit of time. It is typically measured in some number of bits per second (for example, megabits per second, or Mbps.)
*Maximum segment length - How far a cable segment can transport the data before the signal begins to weaken beyond the point where it can be read accurately.
*Maximum number of segments per internetwork - A network of networks is subject to a maximum number of interconnected segments, simply because of the latency (the amount of time a signal takes to travel from one end of the cable to another) when signals travel from one physical end of the network to another.
*Maximum number of devices per segment -
*Interference susceptibility - The degree to which a particular cable type is susceptible to other signals that may be present in the environment. Ex. EMI and RFI
*Connection Hardware - the connectors associated with a particular type of cable.
*Cable Grade - Coding specific requirements usually aimed at the combustibility and toxicity of the sheath material and insulation that cover most cables.
*Plenum Rating - Plenum is the space between the false ceiling and the true ceiling in most office buildings, and any cables used in this space must be plenum-rated with a material that allows them to be used in the plenum area or within walls without being run through conduit. Because of this, using plenum-rated cable usually makes installing network cabling significantly cheaper.
*Bend radius - Refers to how easily cabling can be damaged due to bending during installation.
*Material costs - The associated cost per unit length. A good way to compare cables of the same type to one another. The cost of the cable itself is usually less than half the total installation cost.
*Installation costs - The cost of labor and auxiliary equipment used in installing a network.
Click HERE for Mini-Lecture 2: Wireless Applications
Intangible Media: Wireless Networking
Although it may sound like it, wireless does not mean without cables of any kind. Wireless networks are most often combined with a normal wired network, creating a hybrid network.
Wireless networks are common in situations like warehouses where users need access to the network, but cannot use a cabled computer to verify stock; two buildings on opposite sides of a river where physical cable runs are impossible.
Types of Wireless Networks
*Wireless LANs - Wireless components act as part of an ordinary LAN usually to provide connectivity for roving users or to provide connectivity to an area that is physically not feasible to connect.
*Wireless Extended LANs - In an extended LAN, an organization might use wireless components to extend the span of the LAN beyond normal distance limitations of regular cable types.
*Mobile Computing - Individual users communicate using a wireless networking medium such as radio or cell telephone frequencies that allow mobility while remaining attached to a network.
Wireless networking is primed to boom - see what one staff writer thinks about the prospects for wireless networking.
Bandwidth is one of the more important characteristics to consider when choosing network media. As network communication becomes more complex, the speed of the network link becomes more important. Network services like real-time video converencing require high-speed data connections.
Baseband and Broadband Transmission
An understanding of these two transmission types supplies a basis for understanding the naming conventions used in Ethernet.
Baseband Transmission - This method uses a digital encoding and a fixed signal. The entire bandwidth of the cable is used to transmit a single data signal. Using baseband, only one computer can send data at a time.
Broadband Transmission - This method uses analog encoding. Because of this, when the cable has sufficient bandwidth, multiple transmissions can be sent at the same time. Cable television uses broadband transmission to send many channels down a single cable.
Historically, broadband systems provide greater bandwidth than baseband systems.
Erica and Chad...why don't you take a stab at this question!
You are developing a workgroup network for your design department. There are nine computers, which need to be connected, and one printer. All lie are situated in a rough circle around a central wiring closet on one floor of a building. There is no great need for speed and costs should be kept low. Discuss the advantages of using both Thinnet and UTP in this configuration.
Please place your answers on the Discussion board by Friday!
Summary
When you are designing a network or working with network media - wired or wireless - careful attention should be paid to user requirements, budget, distance, bandwidth, and environment. Choosing an appropriate technology depends on weighing all these factors, meeting immediate needs, and leaving room for growth and change.
Remember to keep up with your on-line lessons and quizzes!
mdm and drw