Planning and Cabling Networks

Chapter 10

                       

                        In this chapter we will examine the distinct roles they play with the devices that they connect. You will identify the cables needed to make successful LAN and WAN connection and learn how use device management connections. The Ethernet interfaces that match the technology of the switches at the center of the LAN. It is important to note that routers offer many services and features to the LAN. Each LAN will have a router as its gateway connecting the LAN to other networks. Inside the LAN will be one or more hubs or switches to connect the end devices to the LAN. Routers have the ability to break up broadcast domains and collision domains. Routers are also used to interconnect networks that use different technologies. The router’s LAN interfaces allow routers to connect to the LAN media. Routers can be expensive based on interfaces and features needed. Additional modules, such as fiber-optics can increase the costs. The media used to connect to the router should be supported without needing to purchase additional modules. Work area has a minimum of two jacks that can be used to connect, we use patch cables to connect individuals devices to these wall jacks. Straight-through cable is the most common patch cable used in the work area. Telecommunication room, patch cords make connections between the patch panels, where the horizontal cables terminate, and the intermediary devices. Telecommunication room also contains the servers used by the network. Backbone cabling also interconnects multiple telecommunication rooms throughout the facility. Backbone cabling, also known as vertical cabling and Distribution cabling, also known as horizontal cabling. The MDIX cables swap the transmit pairs internally. This swapping allows the end devices to be connected to the hub or switch using a straight-through cable.  When connecting different types of devices use a straight-through cable. And when connecting the same type of device, use a crossover cable. A straight-through cable has connectors on each end that are terminated the same in accordance with either the T568A or T568B standards. Use straight-through cables for connecting; Switch to router, Computer to switch, Computer to hub. Use crossover cables for connecting; Switch to switch, Switch to hub, Hub to hub, Router to router, Computer to computer, Computer to router. There are types of devices that maintain the link between a sending and a receiving device, Data Communications Equipment (DCE) a device that supplies the clocking services to another device. Data Terminal Equipment (DTE) a device that receives clocking services from another device and adjusts accordingly. Each subnets, as  a physical network segment, requires a router interface as the gateway for the subnet. The number of subnets on one network is also calculated using the formula 2^n, where n is the number of bits “borrowed” from the given IP network address available to create subnets.

                       

Ethernet

Chapter 9

                        This chapter examines the characteristics and operation of the Ethernet as it has evolved from a shared media, contention-based data communications technology. This chapter will be able to describe the evolution of Ethernet, Explain the fields of the Ethernet frame, describe the physical and data link layer features of Ethernet, explain the address resolution protocol, Ethernet standards and implementation and IEEE standards. LAN is the original version of Ethernet.  The first Ethernet was published in 1980 by a consortium of Digital Equipment Corporation, Intel, and Xerox (DIX). The IEEE 802.2 standard describes the LLC sublayer functions and the 802.3 standard describes the MAC sublayer and the physical layer functions. The Logical Link Control (LLC) handles the communication between the upper layers and the networking software, and the lower layers. The LLC can be considered the driver software for the Network interface Card (NIC). NIC is a program that directly interacts with the hardware. The Ethernet MAC sublayer has two primary responsibilities which is Data Encapsulation, Media Access Control. In data encapsulation have three primary functions which is frame delimiting, addressing, and error detection. Data encapsulation provides for data link layer addressing. Media access controls the placement of frames on the media and the removal of frames from the media. Ethernet has evolved to meet the increased demand for high speed LANs. Ethernet specifies and implements encoding and decoding schemes that enable frame bits to be carried as signals across the media. The foundation for Ethernet technology was first established in 1970 with a program called Alohanet. Alohanet was a digital radio network designed to transmit information over a shared radio frequency between the Hawaiian Islands. Alohanet required all stations to follow a protocol in which an transmission required after a short period of waiting. The first versions of Ethernet used coaxial cable to connect computers in a bus topology. OSI data link layer physical addressing, implemented as an Ethernet MAC address, it is used to transport the frame across the local media. Ethernet LAN technology offers ethernet hubs to cater number of hosts connected to them on a LAN, but these two have different characteristics and features. Hubs and switches have the same function. Hub is an intermediary device where in multiple nodes can be connected to it in a shared media environment.

DATACOM

Physical Layer

Chapter 8

                                Chapter eight is all about the Physical Layer. The purpose of the physical layer is to create the electrical, optical, or microwave signal that represents the bits in each frame. The signals are sent on the media one at a time. The physical layer also retrieve the individuals signals from the media, it can restore to their bit representations and pass the bits of data link layer as complete frame. There are three basic forms of network media which is copper cable, fiber and wireless. Copper cable media is the signals are patterns of electrical pulse. Fiber is the signals are patterns of light. And for the wireless media, is the signals are patterns of radio transmission. The physical layer consists of hardware, developed by engineers in the form of electronic circuitry, media and connectors. It is appropriate that the standards governing this hardware are defined by the relevant electrical and communications engineering organizations. As we saw in a previous chapter, the services and protocols in the TCR/IP suite are defined by the Internet Engineering Task Force (IETF) in RFCs. Physical buyer technologies are defined by organizations such as: ISO, IEEE, ANSI, ITV, EIA/TIA, FCC, and Physical Layer Technologies and Hardware. There are three Fundamental functions of the physical Components Data encoding and signaling. Encoding is a method of converting a stream into code: Signaling method used into a compatible standard so that the receiver can detect the signals. Data transfer can be measured in three ways: Bandwidth, Throughput, Goodput. Band width is typically measured in kilobits per second or megabits per second. Throughput is the measure of the transfer of bits across the media over a given period of time. Good put is the measure of usable data transferred over a given period of time. The physical layer is concerned with network media and signaling. This layer produces the representation and groupings of bits as voltages, radio frequencies of light pulses. Unshielded twisted-pair (UTP) cabling is used in Ethernet LANs; consist of four pairs of color-coded wires that have been twisted together. The UTP cabling commonly found in workplaces, schools, and homes conforms to the standards established jointly by the Telecommunication Industry Association (TIA) and the Electronics Industries Alliance (EIA).